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NAVY DEPARTMENTBUREAU OF ORDNANCE

WASHINGTON 25, D. C .

ORDNANCE PAfIPIILET 1017 (SECOND REVISION)FUZES FOR ROCKETS AND PROJECTOR CHARGE

1. Ordnance Pamphlet 1017 (Second Revision) describes the Rocket andProjector Charge Fuzes (except VT fuzes) and contains the general data, de-scription, functioning, safety features, disposal and servicing, installation, andpacking and marking information on these fuzes.

2. It is important that a full and complete report of malfunctioning ordifficulties encountered with any fuze be made to the Chief of the Bureau. ofOrdnance, Navy Department, Washington 25, D. C .

The report should contain a detailed identification, particularly the mark and mod, lot number, andany other discernible markings appearing on the fuze . The report should alsocontain all information concerning conditions, history, and description of thetrouble.

3. Ordnance Pamphlet 1017 (First Revision) dated 13 June 1944 andNavOrd OIII A5-44 dated 24 March 1944, are hereby superseded and shouldbe destroyed.

4. It is not intended that this publication be carried in aircraft for usetherein.

5. This publication is CONFIDENTIAL and shall be safeguarded inaccordance with the provisions of F. S. Navy Regulations. It is forbiddento make extracts from or to copy this classified document without specificapproval of the Chief of Naval Operations or originator, as applicable, exceptas provided for in article 9-10 of the United States Navy Security Afanualfor Classified flatter .

tq. X1 . XAXA. G. NOBLERear Admiral,, U. S. NavyChief of the Bureau of Ordnance

XCX�V IDENTIAL

CONFIDENTIAL

CON

CONTENTS

Section B-Nose Fuze Mk 155Mod 0 . . . . . . . . . . .

52

Page

56

56

61

64

. 64

67

70

72

74

76

76

79

83

83

88Section A-Fuze M1: 134 Mod 0

(Ejector Delay) .

. .

. .

.

.

88

impter Page ChapterIntroduction . . . . . . . . . . . 1 7 Nose Fuzes for 7.2-Inch Anti-Su6-

1 Nose and Auxiliary Detonating marine Rockets and 7.2-Inch Pro-Fuzes for Spin Stabilized Rock- jector Charge Ammunition . . .ets . . . . . . . . . . . . . . 4 Section A--Nose Fuze Mh 156Section A-Fuze 1\Ik 30 Mods 3 Mod 0 . . . . . . . . . . .and 4 (Point Detonating) . . 4 Section B--Nose Fuze Mk 158

Section B-Fuze i\1k 100 Mod 2 Mod 0 . . . . . . . . . . .(Nose-SQ And Delay) . . . . 9

Section C-Fuze 'Mk 44 Mod 2(Auxiliary Detonating) . . . 13 8 Base Fuzes for Fin Stabilized Air-

Section D--Fuze i\-1k 52 Mod 2 craft Rockets . . . . . . . . .(Auxiliary Detonating) . . . 16 Section A-Base Fuze Mk 157

2 Base Fuzes for Spin Stabilized Rock- Mods 0, 1, and 2 . . . . . .ets . . . . . . . . . . . . . . 17 Section B--Base Fuze X1k 159Section A-Base Fuze illk 31 Mods 0 and 1 . . . . . . .Mod 0 . . . . . . . . . . . 17 Section C--Base Fuze 1\'11: 163

3 Nose Fuzes for 4.5-Inch Surface Fin Mods 0 and 1 . . . . . . .

Stabilized Rockets . . . . . . . 21 Section D---Base Fuze 164Mod 0 . . . . . . . . . . .

Section A-Nose Fuze 1\1k 137 Section E-Base Fuze 1\1k 165Mods 0, 1, and 2 . . . . . . 21 Mod 0 . . . . . . . . . . .

Section B-Nose Fuze Mk 145Mods 0 and 1 . . . . . . . 25

Section C-Nose Fuze 1\1k 154 9 Deceleration Discriminating BaseMods 0, 2, and 3 . . . . . . 27 Fuzes for Fin Stabilized Rockets .

4 Nose Fuze for 7.2-Inch Chemical Section A-Base Fuze lIk 162Rocket . . . . . . . . . . . . 31 Mod 0 . . . . . . . . . . .Section A--Nose Fuze '_Wk 147 Section B---Base Fuze 111k 166Mods 0 and 1 31 Mod 0 . . . . . . . . . . .

5 Nose Fuzes for 7.2-Inch DemolitionRockets . . . . . . . .. . . . 36

10 Base Fuze for the 7.2-Inch Demoli-Section A-Nose Fuze Mk 152 . 36tion Rocket . . . . . . . . . .Section B--Nose Fuze Mk 141

Mod 0 . . . . . . . . . . . 39 Section A-Base Fuze Ml: 161

6 Nose Fuzes for Fin Stabilized Air- Mod 0 . . . . . . . . . . .craft Rockets . . . . . . . . . 45Section A--Nose Fuze '\1l-: 149 11 Miscellaneous . . . . . . . . . .

1\1od o . . . . . . . . . . . 45

IV

ILLUSTRATIONS

CON

Figure Page Figure Page1 Fuze Mk 30 Mod 3 (Point Detonating), 15 Nose Fuze 111 154 Mod 3, External

External View, Actual Size (approx- View, Full Size (approximately)imately) . . 5 except for Burster Tube Length . 28

2 Fuze Mk 30 llod 4 (Point Detonating), 16 Nose Fuze Mk 154 Mod 3, Cross Sec-External View, Actual Size (approx- tion View, Unarmed Position . 29imately) . . 5 17 Nose Fuze .\-Ik 154 1Tod 3, Cross Sec-

3 Fuze Mk 30 Mod 3 (Point Detonating), tion View, Armed Position 30Cross Section View, Unarmed Posi- 18 Nose Fuze Mk 147 Mod 1, Externaltion . . . . 6 View with Guard Removed, Full

4 Fuze Mk 301Tod 3 (Point Detonating), Size (approximately) except forPartial Cross Section View, Armed Burster Tube Length . . . . . 31Position . . 7 19 Nose Fuze Mk 147 Mod 1, Cross Sec-

5 Fuze 111: 100 1lod 2 (Nose-SQ and tion View, Armed and UnarmedDelay), External View, Full Size Position . . . . . . . . . . . . 32(approximately) . 10 20 Noze Fuze Mk 152, Cross Section View,

6 Fuze Alk 100 1Tod 2 (Nose-SCE and Armed Position . . . . . . . . . 37Delay), Sectional View, Armed and 21 Nose Fuze Mk 141, External View . 40Unarmed Position . 11 22 Nose Fuze 151. 141 Mod 0, Cross Sec-

7 Fuze Mk 44 or Fuze lfk 52 (Auxiliary tion View, Unarmed Position . 42Detonating), External View, Full 23 Nose Fuze Mk 141 plod 0, Cross Sec-Size (approximately) . 13 tion View, Armed Position . 43

8 Fuze Mk 44 Mod 0 (Auxiliary Deto- 24 Nose Fuze Mk 149, External View,nating), Cross Section View, Armed Full Size (approximately) . 46and Unarmed Position . 14 25 Nose Fuze 14'lk 149 1Tod 0 Showing the

9 Fuze Mk 44 Mod 2 (Auxiliary Deto- Clamp Pin, Clamp Bushing, Chimp,nating), Partial Cross Section View, Gasket, Safety Wire, and ProtectiveArmed Position . 15 Cap Removed . . . . . . . . . . 47

10 Base Fuze till. 31 lTod 0, External 26 Nose Fuze Mk 149 Mod 0, Cross Sec-

View, Full Size (approximately) . . 17 tion View, Unarmed Position . 4S

11 Base Fuze Mk 31 Mod 0, Cross Section27 Nose Fuze Mk 149 plod 0, Cross Sec-

View, Assembled and Firing Posi-tion View, Armed Position . 49

tion . . . . 1828 Nose Fuze DTk 155, External View,

Full Size (approximately) except for12 Nose Fuze. lIk 137 1Tod 2, Cross Sec- Burster Tube Length . . . . . . 53

tion View, Armed and Unarmed 29 Nose Fuze Mk 155 \Tod 0, Cross Sec-Position . . 22 tion View, Unarmed Position . 54

13 Nose Fuze Mk 145, External View, 30 Nose Fuze Mk 155 1Tod 0, Cross Sec-Full Size (approximately) 25 tion View, Armed Position . 55

14 Nose Fuze lTk 145 'Mod 1, Cross Sec- 31 Nose Fuze lik 156 and 111: 158, Ex-tion View, Armed and Unarmed ternal View, Full Size (approximate-Position . . 26 ly) . . . . 57

CONFLDXN.TV,1. , ILLUSTRATIONS

v

Figure Page Figure age32 Nose Fuze *,%Ih 1'56 Mod 0 or _Mk 158

Mod 0, Cross Section View, Un-armed Position 58

41

42

Base Fuze \Ik 164 'Mod 0, ExternalView, Full Size (approximately) .

Base Fuze Mk 165 Mod 0, Partial73

33 Nose Fuze l1k 156 Mod 0 or Mk 158 Cross Section View, Unarmed Posi-Mod 0, Cross Section View, Armed tion . . . . 74Position . . 62 43 Base Fuze \1k 165 'Mod 0, External

34 Base Fuze '-\Ik 157 'Mod 2, External View, Full Size (approximately) . 75View, Full Size (approximately) . 65 44 Base Fuze 1Ik 162 Mod 0, External

35 Base Fuze 'Mk 159 Mod 1, External View, Full Size (approximately) . 77View, Full Size (approximately) . 68 45 Base Fuze Mk 166 Mod 0, External

36 Base Fuze JIk 159 Mod 0, Cross Sec- View, Full Size (approximately) . 80tion View, Armed and Unarmed 46 Base Fuze \[l. 166 Mod 0, Cross Sec-Position . . 69 tion View Showing Unarmed Posi-

37 Base Fuze 1Ik 159 'Mod 1, Unarmed tion, Position of Parts after Creep,Position Showing Gas Cliecking . 70 Position of Parts after Rapid De-

38 Base Fuze 1Ik 163, External View, celeration and Firing . 81Full Size (approximately) . 71 47 Base Fuze 'Mk 161, Cross Section

39 Base Fuze \Ik 163 'Mod 1, Partial View, Unarmed Position . 84Cross Section View Showing the. 48 Base Fuze Mk 161, Cross SectionOperation of the Setback Block View, Armed Position 85when Rocket Accelerating . 71 49 Fuze ,\ .Ik 134 'Mod 0 (Ejector Delay),

40 Base Fuze lIk 163 'Mod 1, Partial External Vie«- 88Cross Section View, Armed Posi- 50 Fuze Mk 134 'Mod 0 (Ejector Delay),tion . . . . 72 Cross Section View. 89

CONHD"6,\L

PurposeThe purpose of this Ordnance publication is to

acquaint personnel with the rocket and projectorclinrge fuzes now in use and those rocket fuzeswhich maynot have been produced for the purposeof issue but which may be released for productionshould circumstances warrant.

Content of PublicationIllustrations are included for each type of fuze.

In general, the explanatory matter is arranged tocover General Data, Description, Functioning,Safety- Features, Disposal and Servicing, Installa-tion in Rocket, and Packing and Marking for eachfuze described . In addition the. introduction listsand briefly describes the various forces whichdetermine - rocket fuze design, explosive compo-nents utilized, safety features and methods oftest . Radio proximity fuzes are not included inthis pamphlet but are described in OP 1470 andOP 1450 .

Classes of Fuzes Used in RocketsThere are three general classes of fuzes used in

rockets which are as follows :Nose FuzesBase FuzesAuxiliary Detonating Fuzes

Types of Rocket FuzesRocket fuzes may be classified according to the

type of rocket in which they are employed :1 . Fuzes for fin-stabilized (non-rotating) rock-

ets which include; both nose and base fuzes . Thisincludes rockets launched from aircraft and thoselaunched from ground or shipboard .

2 . Fuzes for spin-stabilized (rotating rockets)which may be either nose or base and also includethe auxiliary detonating fuzes when nose fuzesare employed .

3 . Fuzes for anti-submarine rockets or pro-jector charges which generally depend on passagethrough water to complete arming .

COiaf" DENTI L

INTRODUCTION

Forces Used in Arming Rocket FuzesThe forces which are utilized in rocket fuzes

depend upon the characteristics of the rocket forwhich the fuze is designed . The principal forcesused in arming gun ammunition fuzes are thosedue to setback in the bore of the gun, and cerntrif-ugal force due to spin . The principal forceutilized in bomb fuzes is that exerted by the windstream as the bomb falls tlurough the, air. Theseforces are also present in rockets but in differentdegrees and the design of rocket fuzes is controlledto a great extent by what forces are available thatcan be utilized .

1 . Acceleration (setback) .

Long burning timesand low accelerations, as compared to gunammunition, are characteristic of rockets .

Accel-oration attained is greatly dependent upon theinitial temperature. of the propellant, of the rocketmotor and is quite low for lower temperatures .Because of this condition, fuzes actuated by set-back forces must be designed to operate at theminimum acceleration . Setback is often. utilizedto delay the arming of rocket fuzes. Small set-back forces are made effective where applicableby making the parts operated by setback relativelymassive and springs relatively weal. as comparedto gun. ammunition fuzes.

.

2. Wind forces .

The force exerted by thewind stream past the rocket in flight is utilized toarm many rocket nose fuzes for fin-stabilizedrockets.

3 . Gas pressure of burning propellant .

Duringthe burning of the rocket motor propellant, pres-sure of the resulting gases is exerted on tlne base oftho rocket head and base fuze, if present. Thispressure is fairly constant during burning and isin the magnitude of several hundred pounds .Because the pressure lasts for a considerable time,its entrance into the fuze can be controlled andutilized_ to start as well as delay the arming of thefuze .

OP 1017 (2ND REV.) FUZES

4., Centrifugal force.

This force is available inspin-stabilized rockets, due to the rotation of therocket and attains its maximum at the end of burning after the rocket is launched . The spin is ofthe same order as that of projectiles, and has per-mitted the adoption of some gun ammUI itionfuzes for rockets where forces other than centrifugalforces are not required to arm the fuze .

5 . Creep (deceleration) . This is a continuousinertia force caused by drag which tends to moveinternal fuze parts toward the nose of the round .In some cases these forces are controlled in rocketfuzes by anti-creep springs to prevent fuzeinitiation until the fuze strikes a target withsufficient impact to overcome the springs .

6. Friction . Frictional forces due to setbackand creep are not high in rockets. However, theymust be considered iii their effect on moving parts.Friction clue to centrifugal force may be quitehigh in rockets.Explosives Used in Fuzes

The explosive materials used in rocket fuzes arethe same as those used in bomb and projectilefuzes and are subject to the same requirementsand composed of the same materials.The explosive train in a rocket fuze usually

consists of the following components :1 . The primer, ,N-hich is initiated mechanically

by the firing pin. There are two types used,namely, the stab type, and the percussion type .The stab type is initiated by penetration of asharp-pointed fining pin through the metal cascfinto the primer mixture and the percussion typeis initiated by crushing the primer mixture, be-tween an anvil and the indentation of the primercup caused by a round-pointed firing pin . Stabtype primers are in general used when instanta-neous fuze action and increased sensitivity aredesired and the percussion type when the fuzecontains a delay eloment. Primer mixtures areintended to produce flame and hot gases andparticles as a result of mechanical disturbance,and are generally composed of an initiating sub-stance (lead azide or mercury fulminate), anoxidizing agent (potassium chlorate) and a reduc-ible substance (antimony sulfide) and may alsocontain a friction-creating material (fine carbo-rundum crystals) . Lead azide primer mixture isusually used for stab-type primers because of its

2

Safety Features

slower rate of decomposition .

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,eprimer mixture is often used in percussion primersfor fuzes because of its greater sensitivity.

2 . The delay element, a compressed pellet ofblack powder which is ignited by the primer . Thedelay time obtained with a given primer is variedby adjusting the composition of the black po,vder,the pellet pressure, and the thickness of the wallthat must be burned through.

3. The detonator, which is initiated by theprimer or delay element. It is composed of apure initiating explosive, usually lead azide, followed by a small amount of tetryl . The. abovematerials may be sealed iu small containers sepa-rately or they m.ay be sealed together in onecontainer .

4. The lead-out and lead-in, which are smallpellets of tetryl used to reinforce the small detOna-tion of the detonator, and to transmit it to thebooster. A lead-out is not necessarily used ; ifused, it usually moves witli the detonator duringanning .

5. The booster, a comparatively large tetrylpellet, loaded in a container as a part of the fuze,which is initiated by the lead-in and in turninitiates the main high explosive filler of the head,either directly or through an auxiliary booster ofgranulated TNT.

The safety requirements for rocket fuzes are iiigeneral similar to those for gun anununition andbomb fuzes. The fuze must contain adequatesafety features to prevent detonation from anycause during normal transportation, handling,assembly, loading, and launching of the rocket .Design requirements stipulate that the fuze bedetonator safe, that is, the explosive chain must beinterrupted, so that if the detonator is prematurelyinitiated while the fuze is in the unarmed condition,the booster of the fuze and hence the explosivefiller of the head will not be detonated. This isaccomplished by interrupting the explosive trainbetween the detonator and booster. The armingprocess in a fuze consists essentially in. the alirv-ment of these components . Ordina-ily it is en-deavored to have at least two-indepciident safetyfeatures to prevent functioning before and duringthe initial stages of flight .

CONFIDENTIAL

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CONFIDENTIAL

Test of Safety FeaturesReference to the applicable specification for each

fuze will be required to ascertain the specific testsrequired for production lots of fuzes .The first three tests listed below are tests which

are considered to be more severe than conditionsencountered during normal shipment andhandling .After the tests the fuzes are disassembled andexamined for evidence of functioning of explosivecomponents, and any dangerous condition arisingfrom derangement of parts or missing parts .

1 . A drop test, requiring that fuzes assembledin inert loaded heads be dropped (usually 40 feet)on nose, side, and base onto armor plate .

2 . A jolt test, requiring that fuzes be mountedin a fixture in a standardized test machine andsubjected to 1,750 drops in each of various positions from a height of 4 inches onto a leather-covered anvil .

3 . A jumble test, requiring that fuzes be placedin a closed rectangular box mounted in a machinewhich revolves the box around one of its longdiagonals at 30 rpm for 3,600 revolutions .

4 . A vibration test (si nulation), requiring thatfuzes be subjected to a simple harmonic vibratorymotion parallel and perpendicular to the fuze axiswhen packed in the shipping containers as well aswhen assembled in a rocket head or suitable testfixture. The duration of test covers a period of24 hours at frequencies ranging from 700 to 3000cycles per minute and amplitudes varying from0.030 to 0 .009 inch . The purpose of the test is todetermine whether or not the fuze is capable ofwithstanding transportation vibration withoutdamage .

5 . Various other tests may be specified at themanufacturing or loading plant to check armingspin, arming pressure, etc.

INTRODUCTION

Functioning TestsPerforrnanee tests are usually conducted on fuzes

when assembled in loaded rounds to determine theoverall functioning of the fuze . These tests pre-sent an opportunity to determine if the fuze func-tions as designed, and that it has been assembledand loaded in the proper manner . It also permitsa check on quality which may reveal any designand manufacturing weaknesses . The details ofacceptance tests of each fuze are stated in theindividual fuze descriptions .

Special NotesInstallation and removal of rocket Fuzes .

In anyoperation involving fuzing, unfuzing, assembly, dis-assembly, cleaning, painting, etc., of all types ofmunitions, the work shall be accomplished in themost suitable location, taking into account saferemoval from other explosives and possible dam-age to vital installation, and shall involve expos-ing the smallest number of rounds practicable.Only those persons actually essential for the workshall be in the vicinity .

The ideal situation wouldbe that where work wouldbe performed on only oneround at a time, in alocation on deck, ITlnote fromall magazines, from ready stowage, from othersupplies of ammunition or explosives, and fromvital installations .

Use of lubricants and preservatives . No lubri-cants or preservatives of any kind shall be used oilany fuzes unless so indicated.

Reports of malfunctionings .

Fuze malfunctions orany difficulties encountered with fuzes should bereported to the Bureau of Ordnance .

The reportshould contain all pertinent information concern-ing the fuze such as mark and mod number, lotnumber, manufacturer, date of production, etc.,together with the details and description of theconditions .

4

The fuzes described in this group are as follows:Section A-Fuze ilk 30 Mods 3 and 4 (Point

Detonating)Section B-Fuze Mk 100 '-\Iod 2 (Nose--SQand Delay)

Section C-Fuze Mk 44 Jlod 2 (AuxiliaryDetonating)

Section D--Fuze Mk 52 Mod 2 (AuxiliaryDetonating)

Chapter 1

NOSE AND AUXILIARY DETONATING FUZESFOR SPIN STABILIZED ROCKETS

Section A-Fuze Mk 30 Mods 3 and 4

1 . General DataUsed in :5.0-inch Rocket Read Mk: 10 (High Capacity)5.0-inch Rocket Head tilk 12 (High Capacity)5.0-inch Rocket Head '-\Ik 13 (High Capacity)

Overall dimensions and weight of fuze :Length---------- 4.57 inches .Diameter (rnaxi-mum)--------- 2.30 inches .

Body threads---- 1 .70 inches-14 NS--1 RII.weight--------- 1 .40 lbs . approx .

Applicable specification : OS 3303General arrangement drawing :422326 (Mod 3)562339 (llod 4)

Sketch list of drawings & specs :1091'13 (1lod 3)165551 (,\Iod 4)

Explosive components :A sensitive stab type Detonator ?\Ik 25 (lead

azide priming mixture and lead azide)located in the head of the fuze .

A Relay Detonator '\lk 29 (lead azide) lo-cated in a bakelite detonator holder in thebody- of the fuze .

2 . Description

The fuzes described in sections A, B, C, and D,of this chapter, require only spin to arm andare either outright adoptions of gun ammuni-tion fuzes or modifications of gun ammunitionfuzes to function in rockets . Fuze Mk 30 Mod 3may be used in gun ammunition as well as rockets.Fuzes '.\, lh 30 i\Iod 4, '-\Ik 100 llod 2, N-Ik 44 Mod2, and ilk 52 Mod 2 are authorized for use inrockets only .

(Point Detonating) (Centrifugal Arming)

General . Fuze Nlk 30 was originally developedfor use as a projectile nose fuze ; however, FuzehTk 30 Mod 3 or 1\Iod 4 has been adopted for usewith the spin-stabilized rocket . Fuze Mk 30 isa centrifugal arining, impact firing, nose fuze andis completely armed when the rotational velocityof the rocket reaches the range of 1500 to 2000rpm . The fuze is designed to fire superquick onimpact with suitable targets. Fuzes ilk 30Mods 3 and 4 differ from Fuzes Mk 30 Nods 0,1, and 2 (obsolete) by the addition of a safetydisc, between the exhaust end of the flash tubeand the relay detonator to prevent occasionalinitiation of the relay detonator by the flash fromaccidental firing of the nose detonator when thefuze is unarmed.

Fuzes ilk 30 plods 0, 1, 2, and3 have a plastic ogive whereas Fuze Nlk 30 Mod 4has a drawn steel ogive . Fuze Alk 30 is alwaysused in conjunction with an auxiliary detonatingfuze to assure the complete initiation of the mainexplosive charge of the rocket head and to provideadditional safety .

, ,

CONFIDENTIAL

CONFIDENTIAL

Figure 1--Fuze Mk 30 Mod 3 (Point Detonating),External View, Actual Size (approximately).

Use. Fuze Ml: 30 Mods 3 or 4 is used in the5.0-inch High Capacity Spin Stabilized SurfaceRockets (Complete Rounds) Ml: 10 AIod 0,Mk 13 Mod 0, and Mk 16 Mod 0 (see OP 1415) .The above rockets are used for bombardmentpurposes .

Functioning mechanism. The fuze consists offour basic units, namely : (1) Body assembly, (2)Plastic or steel ogive, (3) Flash tube, and (4)Head assembly .The body, located at the base end of the fuze,

is threaded to engage the fuze adapter of the rockethead and houses the centrifugally actuated in-terrupter assembly, the safety disc, the relaydetonator, the. detonator holder, and the bottomclosing screw assembly .,

1 11

^,

CONFIDENTIAL

SPIN STABILIZED ROCKET FUZES

Figure 2-Fuze Mk 30 Mod 4 (Point Detonating),External View, Actual Size (approximately) .

The interrupter assembly consists of a solid .cylindrical metal interrupter, a cylindrical settingsleeve with an eccentric bored interrupter guidewell, and an interrupter spring bearing againstthe spring cup and the bottom of the interrupterguide well . The assembly is held in position witha tension spring and setting sleeve retainer .The interrupter bears against the spring cup

and extends slightly into the guide well of thesetting sleeve . In the OFF-OFF position theinterrupter rests against a narrow shoulder formedby a, shallow counterbore in the guide well and islocked in place, blocking the flash channel. Whenthe setting sleeve is rotated through 90 degreesto the OAT-SQ position, the interrupter is coali-ally aligned with the guide well and. is free to move

5


DETONATOR RETAININGSCREW

SETTING SLEEVERETAINER

Figure 3-Fuze Mk 30 Mod 3 (Point Detonating), Cross Section View, Unarmed Position,

out of the flash channel against the spring and intothe guide well when centrifugal force acts uponthe interrupter .The flash tube, threaded at each end, serves a

double purpose in transmitting the flash from theinitiating detonator to the relay detonator and inproviding a, means of assembling and securuig thebody, ogive, and head. One end of the flash tubeis screwed into the body until seated, the ogive isthen slipped over the body, and the head issere-wed down on the forwarc1 end of the flash tube

b

UNARMED POSITION

DETONATOR CUSHION

OGIVE

until the head bears against the loci. washer on theplastic or steel ogive.The head houses a thin metal closing disc, a

firing pin, a light metal firing pin support, and astab type detonator with its retaining sere«- .The stab type detonator is fired when sufficientforce applied at the nose of .the fuze deforms theclosing disc and drives the pointed firing pin backto collapse. the firing piii support and to penetratethe primer mixture.

RELAY DETONATORASSEMBLY

BOTTOM CLOSINGSCREW ASSEMBLY

CONFIDENTIALa

RELAY DETONATORASSEMBLY

Figure 4-Fuze Mk 30 Mod 3 (Point Detonating),Partial Cross Section View, Armed Position .

3. Functioning

ARMED POSITION

Arming . Prior to firing, the setting sleeve isrotated to the ON-SQ position . When therocket is fired and it reaches a rotational velocitywithin the range of 1500 to 2000 rpm, whichrepresents approximately 15 to 25 feet of travel inthe rounds in which it is used, the interruptermoves out against the interrupter spring andclears the flash channel thus arming the fuze .

Table 1


The rotational velocity or spin rate remainsufficiently high to maintain the armed conditionuntil after impact .

Firing . Firing is initiated by impact with a.nymaterial offering sufficient resistance such as wood,metal, ground, or water . Under the force ofimpact the closing disc is deformed and thepointed firing pin is driven back to collapse thefiring pin support and to penetrate the primermixture, thus initiating the stab type detonator.The flash from the stab type detonator passesthrough the flash tube and initiates the relaydetonator which fortifies the action required toinitiate the auxiliary detonating fuze detonator,which in turn initiates the auxiliary detonatingfuze lead-ins, booster charge, and finally the mainexplosive charge of the rocket head .

Acceptance test data . Sample fuzes chosen atrandom from each production lot are subjected toroutine safety tests and ballistic tests when firedin gun ammunition in accordance with table 1 .

For every twentieth lot eight ground impactsare substituted for the water impacts, and firedin 6"/47 DP projectiles . If these are not avail-able, 5"/54 or 4"/50 IIC projectiles are used.Angles of fall and striking velocities should dupli-cate short and long range bombardment by thesame type of gun in service . In every twentiethlot ;s incli mild steel is substituted for the woodtarget .No prematures are allowable . Two duds out

of.all fuzes fired from each lot are allowed, and inaddition to the two duds not more than one failureto give instantaneous action is allowed . Instan-taneous action is defined as the destruction of thewood or steel target by blast and fragments of theprojectile acting on the side towards the gun, or

*Any caliber normally assembled with Fuze T4k 30 is used .

5"/54 caliber and 6"/47 dual purpose is to be usedwhenever practicable .

Gun elevation inust exceed eight degrees, and at least two fuzes from each lot are fired at proof(generally 15 percent greater than service pressure) or near proof, preferable in a 3"/50 caliber gun.

CONFIDENTIAL' . 7

Caliber Rounds Velocity Nlaterial Obliquity Range

3"/50_______________________ 2 2700f/s____________ 1" wood----------- 0 400'3"150_______________________ 2 1400f/s____________ 1" wood___________ 0 400'4"/50_______________________ 2 2900f1s------------ 1" wood___________ 0 400'4"/50_______________________ 2 1400f1s ___________ 1" wood___________ 0 400'3"/50 to 6"/47 DP*__________ 8 Service_____________ water impact------- -------------- Various

4. Safety FeaturesDetonator safety .

The stab type detonator as-sembly is always in line ; therefore sufficientimpact on the nose of the fuze will cause crushingof the firing pin support and permit the firingpin to penetrate the pricier mixture . In theevent the stab type detonator does fire (shouldthe fuze be subjected to impact durirng roughhandling), the interrupter twill block the passageof the. flash to the relay detonator .

1=3otvever, toincrease the safety in the event that some flashgets around the interrupter, a thin aluminumsafety disc (0 .010 inch thick) blocks this flash.from initiating the relay detonator . Complete.arming can only be accomplished after a sustainedcentrifugal force of the magnitude attained inflight when the setting sleeve is set on the ON-SQ position . Under such conditions, the inter-rupter moves out of the flash channel, and thesafety disc does not appreciably impede thefunctioning of the detonating train .

Additional safety of the round is brought aboutby the use of an Auxiliary Detonating Fuze whichhas both lead-in and detonator out of line andrequires a rotational velocity greater than theminimum arming spin of the nose fuze to becomefully armed .

During shipping and stowage .

Fuze samples fromproduction lots are subjected to rough handlingtests which are considered to be more severethan conditions encountered in normal stowageand shipping . Failure of the samples to passthe tests is cause for rejection of the lot.Should the stab type detonator function while

the fuze is in the unarmed condition, the lockedinterrupter and safety disc prevent initiationof the balance of the explosive train .

8


in case of water or ground impacts the apparentburst of the projectile on contact with the groundor water without intermediate ricoclict .

Ballistic tests should be frequently conductedin guns in the last third of their normal life .

Sensitivity limits .

The fuze will detonate on ;zinch wood, or water, or ground impacts at non-ricochet angles . In the case of ground impacts,functioning is reliable at angles of fall of eightdegrees or greater ; for water impacts, functioningis reliable in rockets at angles of fall of twelvedegrees or greater.

6. Installation Instructions

5. Disposal and Servicing (Ma hTeAah6k)

X X` ..General. In the event that an unfired fuze is

darna.ged because of rough handling, an examin-ation of the condition of the closing disc in thehead assembly will determine the method ofdisposal of the fuze . If upon examination it isfound that the closing disc has been deformed orbroken, there is the possibility that either thestab type detonator has been fired and has renderedthe fuze inactive or that the detonator has merelybeen pierced and has not been fired .

In either casethe fuzed rocket l.cad, or the rocket fuze if not as-sembled into a rocket head should be disposed ofby gently lowering into deep water or by ExplosiveOrdnance Disposal Personnel in accordance withexisting instructions . If upon examination, it isfound that the closing disc has not been damagedand the setting sleeve is set to the OFF-OFFposition, the fuze may be considered afe tohazidle, or if the closing disc is not damaged inany manner and the setting sleeve has been set toON-SQ position, the fuze may be rendered safefor handling by rotating the setting sleeve tothe OFF---OFF position .

Disassembly. Disassembly of this fuze is notpermitted except at authorized activities whendirected by the Bureau of Ordnance .

1 . Remove the nose shipping plug from therocket head . Inspect the threads and the inte-rior of the rocket head nose fuze cavity . Clean ifnecessary . Be certain that the auxiliary deto-nating fuze is present in the rocket head .

2. Remove Fuze i\Ik 30 Nods 3 or 4 from thecontainer and examine it for damage and setting.3. Install the fuze into the rocket head and be

certain that it seats properly .4. The fuze is shipped with. the setting sleeve

set to OFF--OFF position . Before firing, set thesetting sleeve to ON-SQ position by inserting ascrewdriver or similar tool into the slot orn thesetting sleeve and turning it so that the slot alignswith . the ON-SQ lettering on the ogive .Removal from round.

The fuze may be removedfrom the rocket head with the proper fuze wrench .and returned to the shipping container. Theclosed shipping container can should in turn besea-led with adhesive tape along the broken sur-

±XNFIt}XXJTIAL

CONFIDENTIAL

face .

Before Xeinoval of the fuze from the round,the setting sleeve shall be returned to the OFF-OFF position . The shipping plug with gasketmust be replaced into the rocket head after thefuze is removed .7 . Packing and Marking

Packing .

Fuze A,1k 30 D1ods 3 or 4 is issued inan individual hermetically scaled metal can.Twenty-four individual cans are packed in a woodbox 25% inches by 16;2 inches by 6;12 inches whichrepresents a total of 1 .5 cu . ft . and a total weightof 65 pounds .

1 . General Data

Section B-Fuze Mk 100 Mod 2 (NOSE-SQ AND DELAY)(Centrifugal Arming, Point Detonating)

Used in : 5.0-inch Rocket Head A-Ih 7 (GeneralPurpose) .

Overall dimensions and weight of Fuze :Length- ------------ 4.15 inchesDiameter (maximum)- 2.955 inchesBody threads-------- 1 .700 inches--14 NS--1Weight-------------- 1 .60 1bs. approx .

Applicable specification : (To be prepared)General arrangement drawing : 562303Sketch list of drawings & specs : 165472Explosive components:A sensitive stab type Detonator %lk 25 (lead

azide priming mixture and lead azide)located in the head of the fuze .

Two Relay Detonators Nlk 49 Nlod 0 (leadazide)

Primer Nlk 104Black powder delay pellet

2. DescriptionGeneral . Rocket Fuze N1k 100 Mod 2 is a

centrifugal arming, impact firing, nose fuze similarin action to the Fuze Mk 30 but with an extendedrange of useful applications . This fuze warsdeveloped by combining the Navy Point Detonat-ing Projectile Fuze Nlk 29 and the. Army ArtilleryFuze N14SA2 . (The Fuze Nil: 29 and the Fuze %1k30 are identical except for contour and length offlash tube .)

The addition of the plunger assemblyof the Army Fuze N14SA2, containing a delay

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Marking . The lettering OFF-OFF and ON-SQ is stamped on the ogive . These markings are-it right angles to each other and are spaced aroundthe hole for the setting screw with the fuze noseend up . ON-SQ is positioned vertically andOFF-OFF horizontally.

The fuze is marked or stamped with the lettersPDF, the mark, mod, and lot number, the manu-facturer's initials or symbol, the initials or symbolof the loading facility, the month and year of theloading, the anchor stamp, and the inspector'sinitials .

element, to the Fuze \1k 29 gives Fuze i\1k 100two fundamental diferpnces over Fuze Alk 30 ; onebeing the choice of either instantaneous or delayaction, and the other being the added reliabilityinherent in the fact that the plunger assembly isindependent in action and is always active regard-less of whether instantaneous or delay action isselected . In the event of failure upon impact ofthe instantaneous feature, when set for instautan-eous action, the plunger assembly will functionnormally and follow with a delayed detonation .

Fuze Mk 100 arms when the rotational velocityof the round reaches the range of 1,500 to 2,000rpm and will fire upon impact with any materialoffering sufficient resistance such as wood, plate,ground, or water targets.

Fuze Nlk 100 'Mod 2 is always used iii conjunc-tion with Auxiliary Detonating Fuze NIk 441\'Iod 2.Use. Fuze Nlk 100 is used in the 5.0 inch

General Purpose Spin Stabilized Surface Rocket(Complete Round) Mk 7 Mod 2 . (See OP 1415.)This rocket may be used effectively againstparked aircraft, vehicles, personnel, small build-ings, light fortifications, shipping, etc . Since theround has limited penetration characteristics, theeffectiveness is dependent on the type of action(instantaneous or delay) selected as «yell as thenature of the target .

Functioning mechanism. Fuze Nlk 100 Mod 2 isbasically identical with Fuze \11: 30 llod 3 or Mod4 with three exceptions, namely, the. addition ofthe plunger assembly, length of flash tube and a

9


change in size and shape of the ogive .

When thesetting sleeve is set to SQ-SQ (superquick), thefiring action of the Fuze N-Ik 100 is identical withthat of the Fuze; N11c 30 ; however, when the settingsleeve is set to DELAY-DELAY, the flashchannel is blocked (as in Fuze DII: 30 whet. thesetting sleeve is set to OFF-OFF), and theplunger assembly independently initiates theauxiliary detonating fuze. after a delay of 0.025seconds.

The manual setting of the setting sleeveon the Fuze lt-lk 100 is identical Nvitb the FuzeMk 30 . However, the SQ-SQ position on theFuze Mk 100 corresponds to the ON--SQ on theFuze Mk 30 and the DELAY-DELAY positioncorresponds to the Fuze N-Ik 30 OFF--OFF posi-tion . The plunger assembly arming ineclianisrnis completely independent of the setting sleeveposition and to arm requires only the centrifugalforce developed by the rotation of the round.The plunger assembly is located in a well at

the base end of the fuze body and is secured Nviththe bottom closing screw assembly . The plungerassembly consists of a plunger housing, a plungerbody assembly, a plunger support, and a plungerrestraining spring .

The plunger, housing, a lightmetal cup, serves as a housing for the componentsas well as a base for the delay firing pin. Theforward end or bottom of the cup has a centralflash hole, three internal punched centering tabsto serve as guides for the plunger support, and anoft-center mounted fixed firing pin extending intothe cup .

The forward end of the plunger supportrests between the three centering tabs . Theplunger restraining spring fits over the plungersupport and bears against the flange at the for-ward end of the plunger support. The plungerbody assembly, containing the arming and explo-sive elements (including the delay element),mounts over the plunger support and bears againstthe rear end of the plunger restraining spring .

Analigning pin extending from the side of the plungerrides in a small elongated guide hole in the plungercap and serves to align the plunger with the fixedfiring pin as well as to allow the plunger assemblyto float against the plunger restraining spring .The plunger body assembly consists of a cylindri-cal brass body with a central flash hole, a. threadedwell to accommodate the delay detonator assein-bly, a milled slot extending into the flash hole toaccommodate the centrifugal pin lock, two din-

1 0

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Figure 5-Fuze Mk 100 Mod 2 (Nose-SO and Delay),External View, Full Size (approximately) .

metrically opposite spring loaded centrifugalplunger pins and a secondary relay detonator atthe rear end of the flash hole . The delay deto-nator assembly -which consists of the delay primer,the black powder delay pellet, and the primaryrelay detonator is secured in. the detonator wellby a threaded retaining bushing. A diagonalflash channel connects the primaryrelay deto-nator in the rear end of the plunger assembly .The secondary relay detonator is in line with thestab type detonator in the nose of the fuze . Thetwo centrifugal pins extend partially into thecentral flash. channel of the plunger assembly andserve to prevent the plunger from moving forwardon the plunger support.3. FunctioningArming . When the rotational velocity of the

round reaches the range of 14QQ-?Qt?0 Lpin, whi+.;1?

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CONFIDENTIAL


DETONATORCUSHION

--X._ f®XX11XL:iX,W\\

LOCK WASHER

DETONATORRETAINING SCREW

SETTING SLEEVERETAINER

CENTRIFUGALPLUNGER PIN LOCK

UNARMED POSITION

Figure 6-Fuze Mk 100 Mod 2 (Nose-SO and Delay), Sectional View, Armed and Unarmed Position .

CONFIDENTIAL793360-45--3

ARMED POSITION

PLUNGER SUPPORT

PLUNGER RESTRAINING SPRING

CENTRIFUGAL PLUNGER PINS

BODY

WASHER

RELAY DETONATOR ASSEMBLY

CLOSING DISC

OGIVE

INTERRUPTER SPRING

INTERRUPTER

DELAY FIRING PIN

LOCK CHECK WASHER

PRIMER

BAFFLE

DELAY PLUNGER


represents approximately 6 feet of travel of theround, sufficient centrifugal force is developed tomove the pins out, against their springs and unlockthe plunger body . The centrifugal plunger pinlock rotates out and locks the centrifugal plungerpins in the outward position . The plunger re-straining (anti-creep) spring prevents the plungerbody from moving forward when the fuze isacted upon by deceleration such as air resistanceor very light impacts. Upon sufficiently highimpact the inertia of the plunger body overcomesthe plunger restraining spring which allows thepercussion primer to be indented and initiated bythe round-pointed firing pin.

Firing .

Instantaneous or superquick firing uponimpact is identical with that of Fuze Mk 30 .

Theplunger assembly also functions upon impact ;however, the flash from the stab type detonatorreaches the secondary relay detonator and initiatesthe round (via the auxiliary detonating fuze)before the delay assembly can complete its func-tion . Delay initiation is accomplished by block-ing off the action of the stab type detonator iiithe nose of the fuze with the interrupter and thusallowing the plunger assembly to complete itsnormal delay firing cycle.Acceptance test data .

The acceptance data forthe superquick action of the Fuze Mk 100 i1Tod 2is the same as for Fuze Mk 30 .

The Fuze RTic 100Mod 2 is a modification of the previous mods toimprove performance of the delay action . As ofthe date of the publication sufficient data had notbeen accumulated to relate the acceptance dataand sensitivity of the fuze when set for delayaction .4 . Safety Features

Detonator safety.

The stab type detonator inthe head assembly is always in line, therefore,sufficient impact on the nose of the fuze willcause crusblng of the firing pin support andpermit the fining pin to pierce the stab typedetonator.

However, the fuze must be subjectedto rotation in the range of 1500 to 2000 rpm inorder to open the detonation train . A'ben thesetting sleeve is set to SQ--SQ, the interruptercan only move out of the flash channel when sulli-cient centrifugal force is developed by the round'srotation . Wien the setting sleeve is set to theDELAY-DELAY position, the. interrupter isblocked from moving out of the flash channel ;

12

however, for the delay assembly to function, thefuze must undergo sufficient rotation to enablethe centrifugal plunger pins to move out and tofree the plunger body from its locked position .Additional safety of the round is brought aboutby the use of the Fuze iflk 44 11-1od 2 (AuxiliaryDetonating) which has both lead-in and detonatorout-of-line and requires a rotational velocity of3000 to 4500 rpm to become fully armed .

During shipping and stowage.

Theinterrupter inthe fuze is set on the DELAY-DELAY positionduring shipping and stowage. The centrifugalplunger pins also prevent the plunger body of theplunger assembly from moving forward . Therelay detonators are insensitive to shocks encountered inhandling .

Fuze Mk 100 Mod 2 maybe considered safe during normal shipping, stow-age, and handling .5. Disposal and Servicing (Maintenance)General.

(See Disposal and Servicing-Generalfor Fuze Mk 30 for instructions pertaining to theobservation of the closing disc on the fuze whichare applicable for Fuze XIlc 100 ,\To(I 2 .)

If it isfound that the closing disc has not been damagedand the setting sleeve is set to the DELAY-DELAY position, the fuze may be considered sitfuto handle, or if the closing disc is not damaged inany manner and the setting has been set to SQ-SQ position, the fuze may be rendered safe forhandling by rotating the setting sleeve to theDELAY--DELAY position .Fuze Mk 100 Mod 2 is unsafe to handle after

the round has been launched since the delayassembly, when once armed, remains locked in thoarmed position . Dud rounds should be treatedwith extreme caution and should be disposed ofby gently lowering base first into deep water, orby Explosive Ordnance Disposal Personnel inaccordance with existing instructions .

Disassembly.

No disassembly of this fuze is per-mitted except at authorized activities when di-rected by the Bureau of Ordnance .6. Installation Instructions

1 . Remove the nose shipping plug from therocket, head . Inspect the interior of the rockethead nose cavity and check the threads . Cleanif necessary . Be certain that the auxiliary deto-nating fuze is present in the rocket head.

2 . Remove Fuze NTk 100 \,1od 2 from the con-tainer and inspect it for damage and. settkic

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3. Screw the fuze into the rocket head and becertain that it seats properly .4. When packed for shipment the. fuze is set

DELAY--DELAY. The setting sleeve may beturned to the instantaneous position by insertinga screw driver or similar tool into the slot on thesetting sleeve and turning it so that the slot alignswith the lettering SQ-SQ on the ogive.Removal from round .

The fuze may be removedfrom the rocket head with the proper fuze wrench.and returned to the shipping container. Theclosed shipping container can should in turn be.sealed with adhesive tape along the broken surface .

Before removal of the fuze, turn the settingsleeve to the DELAY-DELAY position .

Whenthe fuze is removed from the rocket head, theshipping plug and gasket must be replaced intothe rocket head .

Section C-Fuze Mk 44 Mod 2 (Auxiliary Detonating) (Centrifugal Arming)

1 . General DataUsed in :

5.0-inch Rocket Head Mk 10 and Mk 12(High Capacity)

5.0-inch Rocket Head Mk 7 (GeneralPurpose)

Overall dimensions and weight of fuze :Length ---------------- 1 .821 inchesMaximum diameter- - - - 1 .5610 inchesBody threads---------- 1 .5610 inches-

20 NS-2LHWeight--------------- 0 .50 lb . approx .

Applicable specification : OS 2985General arrangement drawing : 440406Sketch list of drawings & specs : 165193Explosive components:

Flash type Detonator Mk 37 (lead azideand tetryl)

Lower rotor lead-in charge (tetryl)Booster lead-in charge (tetryl)Booster charge (tetryl) approximately 25grams

2. DescriptionGeneral . Fuze Mk 44 Mod 2 (Auxiliary Det-

onating) is identical with Fuze Mk 44 Mod 1

except for a modified cover disc and the inclusion

CONFIDENTIAL.


7. Packing and MarkingPacking . Fuze 11k 100 Mod 2 will be shipped

packed in individual hermetically sealed cans .Twenty-four individual cans are packed in a woodbox 2532 inches by 16;2 inches by 612 inches whichrepresents a total of 1 .5 cu . ft . and a total weightof 72 pounds .

Marking. The words SQ-SQ and DELAY-DELAY are stamped on the plastic ogive . Thesemarkings are at right angles to each other and arcplaced around the hole for the setting screw withthe nose end up. SQ-SQ is positioned verticallyand DELAY-DELAY horizontally . The fuze,is marked or stamped with the letters NF, themark, mod, and lot number, the manufacturer'sinitials or symbol, the initials or symbol of theloading facility, the month and year of loading,the anchor stamp, and the inspector's initials .

Figure 7-Fuze Mk 44 or Fuze Mk 52 (AuxiliaryDetonating), External View, Full Size (approxi-mately) .

of a moistureproofing sealing cover .

Fuze l1k 44Mod 2 version of this fuze was designed for usein rocket ammunition .

It is essentially a boosterwhich houses two off-center rotors (upper andlower) carrying a detonator and a. lead-in respec-tively which are locked out-of-line (unarmedposition) by spring-held detests . Below therotors are a fixed lead-in and. a tetry boostercharge .

1 3


1 4

COVER .

DETONATOR

t--- ROTORASSEMBLY

SECTION B-B

Fuze Mk 44 X-Iod 2 is always used in conjunc-tion with a nose fuze to provide additional safetyand to assure detonation of the main high explosivecharge in the head of the rocket . It providesadditional safety because it embodies independentsafety features, arms independently of the nosefuze, and requires a greater spin to arm than isrequired for the nose fuze with which it is used .The detonation train of the Fuze Mk 44 Mod 2(after being aligned through sufficient centrifugalforce) is fired by the detonator in the nose fuze .Fuze Mk 44 :1lod 2 is assembled in, the rocket

head at the rocket loading activity .

BOOSTER SPACING DISCS

SECTION C-C

DETENTPIVOT PIN

LOWER ROTOR

UPPER ROTOR

Figure 8-fuze Mk 44 Mod 0 (Auxiliary Detonating), Cross Section

ROTOR SHAFTS -T

,-LOWER ROTOR

UNARMED VIEW

SECTION D-D

CONFIDENTIAL

View, Armed and Unarmed Position.

Use. Fuze Mk 44 Mod 2 is used in the 5 .0-inch High Capacity Spin Stabilized SurfaceRockets (Complete Rounds) Mk 7 Mod 2, Mk 10

,Tod 0, and Mk 13 Mod 0 (see OP 1415) .There were a number of rocket heads loaded

during World War II. with the Fuze AIk 44 AIod 0or Mod 1 . Subsequent loadings will utilize theFuze 2NIk 44 Mod 2 because of the more reliableperformance of the Fuze .1\-1k 44 Alod 2 design .

Functioning mechanism.

Fuze Mk 44 Mod 2 con-sists of a. threaded body which holds the rotorhousing assembly, the booster lead-in and the-,booster magazine . It is closed at the forward

BOOSTERPELLETS

DETENTPIVOTPIN

RIGHTHANDSPRING

CONFIDENTIAL .

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'CONFIDENTIAL

Figure 9-fuze Mk 44 Mod 2 (Auxiliary Detonating),Partial Cross Section View, Armed Position .

end by a cover disc, which has a hole in thecenter aligned with the central flash channel ofthe nose fuze, and an 0.002-inch thick coppersealing cover crimped in place . Near the baseend of the body there is a partition between therotor housing assembly and the booster magazine .The partition has a hole in its center which receivesthe booster lead-in. The threaded booster rnaga-zinc containing the booster charge pellet isassembled to the body and the tetryl pellet isseparated from the partition by a light paperbooster separating disc (washer) .The rotor housing assembly consists of a die

cast block with accommodation for an upper anda lower rotor, two upper and two lower torquespring loaded detents, and two rotor shafts .Both rotors are modified semi-cylindrical blocksrotating about the rotor shafts in the eccentricwells located on diagonally opposite sides of therotor housing. Each rotor is weighted oil. oneside and has a flat section cut out to engage astop located in the well so that the rotation of therotors will be restricted to align the detonator,located in the upper rotor, with the lead-in chargelocated in the lower rotor. Two detents engagetwo slots in each rotor to lock it in the unarmedposition with the explosive elements out of line .The rotors in the unarmed position act as inter-rupters in blocking the central flash channel .

3. FunctioningArming . Fuze '.\11c 44 arms in two stages .

When the rotational velocity of the round reachesthe range. of 3000 to 4500 rpm, the detents aremoved outward against the springs by centrifugal


force and the rotors are unlocked . The rotorsthen rotate under centrifugal force until theymeet the rotor stops . At this point the fuze isfully armed with the upper rotor detonator andthe lower rotor lead-in aligned with the flashchannel and the booster lead-in.

Firing . The detonator and/or relay detonatorof the main fuze initiates theupper rotor detonatorwhich in turn initiates the lead-in in the lowerrotor, the booster lead-in, and the booster charge .Firing is practically instantaneous.Acceptance test data .

Sample fuzes from everyproduction lot are tested., assembled in standardservice loaded projectiles with ignition fuzes orpoint detonating fuzes capable of firing the auxil-iary detonating fuze and of such known per-formance that failure of the projectile to burstmay be considered a failure of the auxiliarydetonating fuze being tested . For acceptancetests all auxiliary detonating fuzes will be locatedon the axis of rotation of the projectile and mustfunction as high-order detonations when initiated .Two rounds are fired at near proof pressure .

Atleast 90% performance is required .At the discretion of the Bureau of Ordnance,

ten fuzes from any lot are assembled, by means ofa proper adapter, 3s-ineli off the axis of rotationof the projectile and tested as before, two roundsbeing fired at near proof pressure . At least 80%performance is required . Failure of this testis sufficient cause for consideration by the Bureauof Ordnance of the acceptability of other lots onwhich the off-center test was not required . Inthe event of any lot failing an off-center or anon-center test, twenty additional fuzes from thatlot are fired in the same manner and acceptancebased on the same percentages as before, for allthirty, i. e., 90% for the on-center and 80% forthe off-center tests.


Fuze N1k 44 Mod 2 is det-onator safe . The two detents locking eachrotor in the unarmed position are displaceddiametrically so that they both tend to move outonly under centrifugal force developed by therotation of the round. Any force other thancentrifugal force, which might unlock one set ofdetents would tend to hold the opposite set ofdetents securely in the locked position .

1 5

v y


Durin-g shipping and stowage .

Samples of fuzesfrom each production lot are subjected to roughhandling tests which are considered to be moresevere than conditions encountered in normalstowage and shipping .

Failure of the samples topass the tests is cause for rejection of the lot.

5 . Disposal and Servicing (Maintenance)General . Any dud round containing a Fuze

Mk 44 (which has previously attained the pre-requisite arming spin in flight) may be consideredto be fully armed since the rotors do not return tothe unarmed position once they have moved intothe armed position . This fuze is in itself notconsidered to be a sensitive dud since it doesnot incorporate a sensitive primer mix or firingpin. However, the rocket nose fuze may be ex-tremely sensitive which might render the roundextremely- dangerous. A dud round should bedisposed of by gently lowering the round, base


5.0-inch Rocket Head Mk 1.3 (HighCapacity)

Applicable speciFication: OS 2985 (where perti-nent)

General arrangement drawing : 563653Sketch list of drawings & specs: 165988

2. DescriptionGeneral. Fuze Mk 52 Mod 2 (Auxiliary Det-

onating) is identical with Fuze Mk 44 Mod 2

1 6

Section D-Fuze Mk 52 Mod 2 (Auxiliary Detonating) (Centrifugal Arming)

Overall dimensions and weight of Fuze :Length ------------------- 1 .£21 inchesMaximum diameter--------- 1 .5610 inchesBody threads-- - _

-- _ - _ _ --

1.5610 inches--20NS-2LH

'Weight ------------------ 0 .50

lb .

ap-prox .

Explosive components :Flash type Detonator '_%1k 37 (lead azide &

tetryl)Lower rotor lead-in (tetryl)Booster lead-in (tetryl.)Booster charge , (tetryl) approximately 25grams

4 . Safety FeaturesSame as Fuze Mk 44 Mod 2 .

5. Disposal and Servicing (Maintenance)Same as Fuze 111k 44 Mod 2 .

6. Installation InstructionsSame methods as Fuze Mk 44 Mod 2.

7. Packing and MarkingSame as Fuze Mk 44 Mod 2 .

tr Xf R

CONFIDENTIAL

first, into deep water or by Explosive Ordnance -Disposal Personnel in accordance with existinginstructions .

Disassembly. No disassembly of this fuze ispermitted except by authorized activities whendirected bv the Bureau of Ordnance .

6. Installation InstructionsRocket beads utilizing the Fuze Mk 30 and Fuze

Mk 100 are shipped with the Auxiliary DetonatingFuze installed in the rocket head .

7. Packing and MarkingPacking.

The fuze is shipped assembled in theround .

Marking.

Thefuze is marked with the abbrevi-ated words Aux. Dot. Fuze, the marl:, mod, andlot number, the manufacturer's initials or symbol,the initials or symbol of the loading facility, themonth arid year of loading, the anchor stamp, andthe inspector's initials .

(Auxiliary Detonating) with the one exceptionthat the detent springs in Fuze Mk 52 are weakerto allow the fuze to arm at. a lower rotational veloc-ity. Fuze Mk 52 arms at a . rotational velocitywithin the range of 1600 to 1900 rpm which repre-sents approximately 30 feet of travel in the roundin which it is used .Use.

Fuze Mk 52 Mod 2 is used in the 5 .0-inchHigh Capacity Spin Stabilized Surface Rocket(Complete Round) XIk 16 Mod 0 (See OP 1415) .


(Same as Fuze :\1k 44Mod 2)

3. FunctioningSame as Fuze ilk 44 Mod 2 except that the

rotational velocity is 1600 to 1900 rpm .

CONFIDENTIAL.

d0WIDENTIAL


5.0-inch Rocket Head Mk 8 (Common)Overall dimensions and weight of fuze :

Length------------------- 4.67 inchesMaximum diamete-------- 1 .8 inchesBody threads------------------ 1 .5

inches12 NF-3 LR

Weight------------------ 1 .60lb .approx.Applicable specification: OS 3429General arrangement drawing: 423486Sketch list of drawings & specs: 109344Explosive components :DETONATOR PLUNGPrt-Sensitive Primer NTk

102 (fulminate of mercury priming mix-ture) ; Secondary Primer lZk 101 (fulminateof mercury priming mixture) ; DetonatorMk 33 (lead azide) ; detonator plungerload (tetryl) ; plunger lead-outs (tetryl) .

Fuzr BODY-Booster lead-ins (tetryl) ;boosters (tetryl) .

Approximately 3.2 grams.

2 . DescriptionGeneral. Fuze '.N-Ik 31 Mod 0 was originally

developed for use as a 4"f50 caliber projectile basefuze ; however, it has been adopted for use in the.spin-stabilized rocket . Fuze Mk 31 Mod 0 is acentrifugal arming, impact firing, base fuze whicharms completely when the rotational velocity ofthe rocket reaches the range of 3000-4500 rpmwhich represents approximately 30 feet of travelof the rocket . The fuze will fire reliably uponimpact with suitable targets.

Use.

Fuze Mk 31 Mod 0 is used in the 5 .0-inchCommon Spin Stabilized Surface Rocket (Com-plete Round) Mk 24 Mod 0. (See OP 1415) .The round is utilized for bombardment purposesand has a maximum range of approximately10,000 yards.

CONFIDENTIAL

Chapter 2

BASE FUZES FOR SPIN STABILIZED ROCKETS

Section A-Base Fuze Mk 31 Mod 0 (Centrifugal Arming, Impact Firing)

Figure 10--Base Fuze Mk 31 Mod 0, External View,Full Size (approximately) .

17

OP 1017 ( 2ND REV.) FUZES

SENSITIVE FIRING PINDETENT SPRING

18

FIRING PINDETENT

COVER PLUGSENSITIVEFIRING PINDETENT

ANTI-CREEPSPRING OUTER

CUP

ASSEMBLED POSITION

FIRING POSITION

Figure 11-Base Fuze Mk 31 Mod 0, Cross Section View, Assembled and Firing Position .

Functioning mechanism .

The. external parts of

the fuze consist of a. fuze body, booster cover, nose

cap, and a plunger retaining plug . The steel

fuze body is machined to accommodate the auxili-

ary plunger assembly, the detonator plungerassembly, the two detonator plunger detents, the

anti-creep spring assembly, and the entire explo-sive train from the sensitive primer to and includ

ing the two side-wall boosters .

T17e aft end of the.

fuze body is provided with external threads toallow installation of the fuze into tdic rocket headand internal threads to engage the steel plungerretaining plug . The retaining plug integral withthe fuze flange is finally secured to the fuze bodyand held in place by two locking pins peened inposition .

tit the forward end of the body, extermrlthreads and a wide shoulder provide for installa-tion of the nose cap which also retains the light,metal external booster coyer.

CONFIDENTIAL

CONFIDENTIAL

The auxiliary plunger, a cylindrical brass inertiablock (with a small well at the forward end con-taining a. desiccant mixture), floats on four rowsof ball bearings in the auxiliary plunger cavity ofthe fuze body. The base of the auxiliary plungerbears against the plunger retaining plug while theforward end bears against the detonator plunger.The detonator plunger houses the sensitive primer,the secondary firing pin, the secondary primer,the spacer, the detonator, the detonator plungercharge, and the booster lead-outs .

A shoulder atthe after part of the detonator plunger bearsagainst the two spring loaded detonator plungerdetents. The forward end of the detonatorplunger is guided by the anti-creep spring assem-bly and bears against the firing pin detents in thenose cap.

Two aligning pins extend from the wallof the detonator plunger and ride in slots in thefuze body .The aluminum alloy nose cap houses the sensi-

tive primer firing pin, the spring loaded firing pindetents, and the two firing pin locking pins . Thefiring pin floats against the two firing pin detentsand is positioned in its well by the two lockingpins . Two diametrically opposed holes, exter-nally sealed with cover plugs, placed at 90 ° to andslightly aft, of the firing pin detents are for thepurpose of locking the detonator plunger in placewhen firing occurs upon impact .

A lock screw orpin is installed in the wall of the nose cap to secureits assembly to the fuze body. The anti-creepspring assembly consists of a light metal tubularinner cup which is lipped at its base to provide afooting for the anti-creep spring, the outer cupwhich serves as a guide, and the anti-creep springwhich bears against the inner cup lip at the aft, endand against the outer cup at the fore end. Theinner cup is assembled to the detonator plungerat the forward end and is held in position by thesensitive primer holder .The two boosters and two booster lead-ins are

located diametrically opposite in the sidewalls ofthe fuze body .3. FunctioningArming . Fuze. Nlk 31 arms when the rocket

reaches a. rotational velocity within the range of3000 to 4500 rpin which represents a distance oftravel of appro.:urnately 30 feet . At this pointunder centrifugal force the firing pin detents andthe detonator plunger detents move out against

CONFIDENTIAL

SPIN STABILIZED ROCKET BASE FUZES

their respective load springs and allow both thedetonator plunger and the auxiliary plunger on itsball bearings to float against the anti-creepspring .

Firing . Upon impact and retardation of therocket head, the inertia of the auxiliary plungerand the detonator plunger forces them forward tocompress the anti-creep spring and impinge thesensitive primer against the sensitive printer firingpin to pierce and fire the sensitive primer . At thispoint the detonator plunger is forward and thebooster lead-outs in the detonator plunger arealigned with the booster lead-ins in the fuze body.As the sensitive primer fires, the expanding gaspassing through small ports in the primer and fir-ing pin container creates an internal pressurewhich bulges the wall of the inner anti-creepspring cup at the points adjacent to the two lock-ing holes in the nose cap. The bulging of tlicinner anti-creep spring cup locks the detonatorplunger in the forward position and assures complete alignment of the explosive train.

Theshearwire securing the plunger or secondary firing pinis sheared under the gas pressure and the plungeror secondary firing pin is forced into the secondaryprimer .

The functioning of the secondary primerfires the detonator which fires the detonatorplunger load and the two booster lead-outs, thetwo booster lead-ins, and the two boosters whichinitiate the main explosive charge in the rockethead . The fuze fires with a slight inherent me-chanical delay peculiar to all inertia plunger typebase fuzes (0 .003 seconds approximately) .

Acceptance test data .

Random

sample

live-loaded fuzes from each lot are assembled in 4"150caliber HC projectiles arid fired in accordancewith the ballistic acceptance tests iii Table 2.

Table 2

Rounds

Velocity I Obliquity `

Plate

2______2200f/s__I

45°

3/8" m. s.2------

____1000 f/s_ _1

0° 13'S" m . s.1 (from 1st and each 1 2200

Water impact at non5th lot thereafter)

ricochet anglesi

Detonation of tested samples must take placeat not more than four feet behind the plate whenthe projectile is fired at 2200 f/s velocity and notmore than two feet at 1000 f1s velocity . For theplate iznpa.ct test, an overall performance of 75%

1 9

CAP 1017 (2ND REV.) FUZES

high-order functioning is required for acceptanceof each lot. Forthe water impact test, satisfactoryperformance, when combined with the plate impact test, shall be 80% high-order functioning .

Apremature functioning of any fuze shall causerejection of the lot.

Sensitivity limits . Fuze 11k 31 1-1od 0 willfunction reliably upon impact with targetsoffering sufficient resistance such as ground, plate,or wood and upon impact with water at angles offall of 5° or greater. Tests in rockets have indi-cated that the fuze will function on S5% of hitson ;8-inch mild steel plates at angles of obliquityup to 55 ° wheir fired in the 5.0-inch Rocket HeadXIk S. On special. treatment steel of thickness ofone inch or greater, rocket head breakup, generallyoccurs .


Fuze -NIlc 31 Nlod 0 is detonatorsafe .

Thedetonator lead-outs and the boosterlead-ins are. not aligned until the detonatorplunger moves forward upon impact after thedetonator plunger detents have moved out undercentrifugal force.


Fuze samples fromproduction lots are subjected to rough handlingtests which are considered to be more severe thanconditions encountered in normal stowage andshipping . Failure to pass these tests shall because for rejection of the lot .

20

5. Disposal and Servicing (Maintenance)General .

Fuze 1VIk 31 Mod 0 is unsafe to handleafter the round has been launched . Any dudaround utilizing this fuze should be disposed of bygently lowering it, base down, into deep water orby Explosive Ordnance Disposal Personnel inaccordance with existing instructions .

Noattempt should be made to remove the fuze fromthe round .

Disassembly. Disassembly of this fuze or theremoval of the fuze from the rocket head is notpermitted except at authorized activities whendirected by the Bureau of Ordnance .

6. Installation InstructionsThe rocket head loading activity installs the

Fuze AIlc 31 Mod 0 in the rocket head and assem-bles the gas check gaskets. Before aascmblinXXthe rocket ]lead to the rocket motor, be certainthat the fuze is present, gas checked, and properly

installed into the rocket head .

7. Packing and MarkingPacking .

Fuze Nfh 31 is shipped assembled intothe rocket head .Marking. The fuze is marked at the base end

of the plunger retaining plug. with the mark, mod,and lot. number, the manufacturer's initials orsymbol, the initials or symbol of the loadingfacility, the month and year of loading, the in-spector's symbol, and the anchor stamp .

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CONFIDENTIAL

NOSE FUZES FOR 4.5-INCH SURFACE FIN STABILIZED ROCKETS

The fuzes described in this group are as follows :

1 . General DataUsed in : 4 .5-inch Rocket Head Mk 3 (High

Capacity)Overall dimensions and weight of fuze:

Length-------------- 2 .9 inchesDiameter (maximum)- 2.7 inchesBody threads --------- 1 .50 inches-12 NF-2

RHWeight-_ _ _--------- 0.9 11). approx .

Applicable specification : OS 2864General arrangement drawing :

344523 (Mods 0 R, 1)437988 (i1-1od 2)

Sketch list of drawings & specs :102930 (Mods 0 &; 1)109467 (Xfod 2)

Explosive components:Detonator Mk 23 (azide primer mixture with

lead azide and tetryl) housed in the slaitter .Booster lead-in (tetryl) housed in the lead-in

disc.Booster charge (9 grams tetryl) housed in the

booster magazine .

2. DescriptionGeneral . Fuze Mk 137 i\led 0, or Mod 1. or

Mod 2, is a setback and air arming, impact firing,rocket nose fuze . The fuze was designed primarilyfor use in rounds to be launched from small craftin beach barrage actions ; however, its use has beenextended to many other tactical applications .

CONFIDENTIAL

Chapter 3

Section A-Nose Fuze Mk 137 Mods 0, 1, and 2Section B-Nose Fuze Mk 145 plods 0 and 1Section C-Nose Fuze Mk 154 Vlods 0, 2, and 3

Section A-Nose Fuze Mk 137 Mods 0, 1, and 2 (Setback and Air Arming, Impact Firing)

Fuze Mk 137 arms during flight and fires instan-taneously upon impact with suitable targets.Fuze Mk 137 Mod 0 has a propeller with eightvanes. Fuze RIk 137 Mod 1 has a propeller withten vanes and internal changes. Fuze Mk 137Mod 2 has the modifications of Fuze Ml: 137Mod 1 plus a rivet head stop on the propeller hubin place of an embossed stop .

Use.

Fuze Ml: 137 Mod 0, or Mod 1 or

fod 2,is used in the 4 .5-inch High Capacity Fin Stabil-ized Surface Rocket (Complete Round) Mk 1Mod 0.

(See OP 1415).

The round is utilized forbarrage purposes .


Fuze Mk 137 consistsof a brass fuze body which provides housing forthe threaded firing pin, the setback block withpropeller locking pin, the setback spring, thefiring pin guide, the spacer sleeve, the shutterwith the detonator and locking detent, the lead-indisc with lead-in charge, and the booster magazinewith booster charge . The multivane propellerand its hub are mounted externally at the forwardend of the threaded firing pin .The forward section of the fuze body is tapered

slightly towards a flat nose surface . At the baseof the taper a narrow ledge serves as a mountingsupport for the propeller guard and as a shoulderfor the external installation threads.

A deep borewith counterbore provides the internal housing forthe fuze elements . The thin nose wall is drilled

21


SET-BACK

/-PROPELLER

SAFETY LOCKING WIREBLOCK

SHUTTERSPRING

MAGAZINE

ARMED POSITION

UNARMED POSITION

STOP

GUARD

v-PROPELLER LOCKING PIN

SCREW

GASKET

SLEEVE

DETENT SPRING

SHUTTER DETENT

DETONATOR ASSEMBLY

LEAD-IN CUP

AUXILIARY BOOSTERWRAPPER

AUXILIARY BOOSTER PELLET

DETONATOR --,

rSHUTTER

SHUTTER

DETENTDETENT

LOCKING HOLE

PIN SPRING-/ PIN

SECTION Z-7

SECTION X-X

Figure 12-Nose Fuze Mk 137 Mod 2, Cross Section View, Armed and Unarmed Position .

22

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CONFIDENTIAL

and threaded at the center to receive the firingpin and a second hole is drilled off center to ac-commodate the propeller locking pin . The coun-terbore at the base of the fuze is threaded toengage the booster magazine.The firing pin is secured to the propeller as-

sembly by means of a cotter pin passing throughthe firing pin shaft and the propeller hub . Belowthis hub there is a threaded surface on the firingpin which engages the threads in the nose of thebody, and beyond the threads a machined shoulderprevents the complete retraction of the firing pinduring air arming . The shoulder tapers downtoward the base of the firing pin forming a conicalsurface .

An elongated portion of the same diam-eter as the base of the conical surface extendsapproximately %-inch and then tapers to a point .The setback block, a steel inertia collar with anintegral propeller locking pin, floats around thefiring pin on the setback spring and bears againstthe nose wall . The propeller locking pin whichlocks the propeller assembly extends from the sur-face of the setback block through the guide holein the nose wall to engage a rivet or embossedstop in the arming vane bub .

The setback springat its forward end bears against the setback.block and at its base against the firing pin guide.The firing pin guide, a flat steel disc with thecenter portion raised to align the setback springand drilled to accept the pointed shaft of thefiring pin, bears against the shoulder provided bythe fuze body cavity .

The bottom surface of thefiring pin guide provides the base for the shutterhinge pin and shutter stop pin . The modifiedsemi-circular shutter houses the detonator androtates about the shutter hinge pin under the,force of a torque spring . A small. spring-loadeddecent in the shutter engages a small well in thefiring pin guide after arming . A split ring typespacer called a sleeve, bears against the fining pinguide and positions the lead-in disc with itscharge.

The booster magazine and charge is in-stalled into the base of the fuze body and bearsagainst the lead-in disc separated by a thin paperbooster disc . A removable safety locking wirewhich clips over the propeller guard passes throughaligned holes in the fuze body and engages a slotin the setback block to lock the setback block andpropeller locking pin in the forward position .

CONFIDENTIAL

4.5" SURFACE FIN STABILIZED ROCKET FUZES

3. FunctioningArming . The safety locking wire is withdrawn

prior to the firing of the round . When the rocketis fired, setback force, due to acceleration, forcesthe setback. block rearward and compresses thesetback spring . This movement withdraws thepropeller locking pin from engagement with thepropeller hub .

The air stream, acting on the pro-peller, causes it to rotate and thereby unscrew thefiring pin forward in the fuze body.

The setbackforce acts on the setback block during the burningof the rocket propellant then the setback springreturns the block to its original forward position .However, the firing pin has in the meantime un-screwed froin the fuze body sufficiently to preventre-engagement of the propeller locking pin withthe -propeller hub .

Rotation of the propeller continues to unscrewthe firing pin until the unthreaded section isreached and the shoulder of the stop on the firingpin contacts the top of the fuze body. Before thefiruig pin is unscrewed, it holds the detonatorshutter to one side so that the detonator is out ofalignment with the firing pin and booster lead-in .When the firing pin is unscrewed sufficiently, theshutter is released under influence of the torquespring and the shutter is pivoted until it contactsa stop pin in the firing pin guide .

At this instantthe shutter decent engages the well in the firing pinguide to lock: the shutter in aligned position .

Thedetonator is now aligned with the firing pin and thebooster lead-in, and the fuze is completely armed .The arming distance of Fuze Mk 137 is approxi-mately 125 feet .

Firing .

On impact, the firing pin is forced backto shear the light screw threads in the nose wall ofthe fuze body and to pierce and fire the detonatorwhich in turn fires the lead-in charge and thebooster charge .Acceptance test data .

Completely

live-loadedrandom sample fuzes from each lot shall be in-stalled in suitable live-loaded rockets and therockets fired for high order functioning on groundor water impact.

All rockets shall be fired froma launcher which is set at an angle of elevation ofapproximately 45 degrees . Acceptance is basedon a cumulative test plan designed to accept (95%of the time) lots in which 95% of the fuzes func-tion satisfactorily : lots poorer than 95% will besubject to rejection with lots 82% effective being

2 3


rejected 900/0 of the time .

Based on wartime pro-duction acceptance records, Fuze Mk 137 gavebetter than 97% performance.


Fuze NIk 137 will function in-

stantaneously superduick upon impact with water,

plate, or ground targets at angles of fall of 15degrees or greater.


This fuze is detonator safe .

In the unarmed position, the detonator is held out

of alignment with the explosive train.

Should thedetonator function prematurely while the fuze isunarmed, the force of the detonator action will

be dissipated forward through a hole in the fir-

ing pin guide and away from the remaining ex-

plosive components .

The fuze is not armed until

the setback force withdraws the propeller locking

pin and the propeller rotates and withdraws thefiring pin to a point where the detonator shutteris released .


Sample fuzes from

each production lot are subjected to rough han-

dling tests which are considered to be more severe

than conditions encountered in normal stowage

and shipping .

Failure to pass these tests is causefor rejection of the lot.

Fuze 1\1k 137 is provided with a safety lockingwire which passes through holes in the fuze bodyto lock the setback block in the forward position

so that the propeller locking pin engages the pro-

peller hub . The locking wire also engages the

propeller to prevent it from rotating . The pro-

peller guard gives protection. to the propeller dur-ing normal handling .

5. Disposal and Servicing (Maintenance)General . If the fuze becomes accidentally

armed, whether assembled into the rocket or not,no attempt should be made to unarm it . If thefuze is armed, turning the propeller counter-clockwise will cause the firing pin to pierce the

detonator and initiate the booster and main charge .

The fuze shall be considered armed if the pro-

peller is out of engagement with the propellerlocking pin so that the propeller is free to rotate .Armed fuzes must NOT be installed in rounds for

any purpose.

To dispose of a, h ze or fuzed round,

the fuze propeller should first be carefully tapedand the fuze or fuzed round, as the. case may be,disposed of by gently lowering it, ba:;e down, into

deep water or by Explosive Ordnance Disposal

24


g1491? 1514TIAL

Personnel in accordance with existing instructions.Disassembly. Disassembly of this fuze is not

permitted except at authorized activities whendirected by the Bureau of Ordnance .

Examine each fuze before installation in therocket to check if the propeller has been unscrewedso that the forward tips of the propeller bladesextend out beyond the plane of the rim of thepropeller guard. If the fuze is found in this con-dition, it should be considered armed ; the propellershould be taped so that it cannot be moved ; andthe fuze should be disposed of by methods de-scribed underparagraph 5, Disposal and Servicing .

After each fuze has been examined as above,and the propeller has been found to be below therite of the propeller guard, remove the safety lock-ing wire and try to turn the vane in a clockwisedirection (when the. fuze is viewed from tho nose)to see if the vane is locked by the vane looking pill .Do not turn the vane more than one-half a turn . Ifthe propeller can be turned, consider the fuzearmed and dispose of it .

If the propeller cannotbe turned in the clockwise direction, try to t,in-uit in the opposite direction .

If the propeller can-not be turned, replace the safety locking wire, andthe fuze is safe for use. If the propeller can beturned counterclockwise, turn it one-half a. turnand see that the propeller locking pin snaps intothe nearest hole in the propeller hub. Then re-place the safety locking wire, and the fuze is safefor use or stowage.NOTE: The sealed metal containers iii. which

these fuzes are shipped should not be opened forthe sole purpose of checking the fuzes. Rather,the checking should be clone at the time the sealedcans are opened preparatory to installing the fuzein the rocket body .

After the above examination, proceed as follows :1 . Remove the shipping plug, shipping plat=

gasket, and paper tube from the rocket body .

Inspect the liner and clean if necessary.

Be certainthat the auxiliary booster is present in the fuzeseat liner.

2 . Examine the fuze for datauage . If defec-tive, (but not armed) repacl, seal contaiater withtape, and return to an ammunition depot.

3 . With the fuze gasket in place, screw thefuze securely into the nose of tlac racket wit)lhe ,proper fuze spanner wrench .

-

CONFIDENTIAL

CONFIDENTIAL

4. 11s the rocket is placed in the launcher, re-move the safety locking wire .

5 . If, for any reason, it becomes necessary toremove the rocket from the, launcher, the safetylocking wire should immediately be replaced, andthe fuze may then be removed from the rocket .

7. Packing and MarkingPacking .

Each fuze is packed in a hermeticallysealed can; 48 cans are contained in a wood box

1 . General Data

Section B-Nose Fuze Mk 145 Mods 0 and 1 (Setback and Air Arming, Impact Firing)

Used in : 4.5-inch Rocket Head Mk 3 (1-1ighCapacity)

Overall dimensions and weight of fuze :

Length-------------------- 3 .0 inchesDiameter (maximum.)____-- 2 .7 inchesBody threads------------- 1 .500 inches---

12 NF-2ti'Peight ------------------ 0.9 11) . approx .

Applicable specification: (to be prepared)

CONFIDENTIAL


23',4 inches by 15 inches by 8's inches which repre-sents a total of 1 .7 cu. ft . The «eight of thefuzes and packing is approximately 72 pounds .

Marking. The fuze is marked or stamped toshow the letters NF, the mark, mod, and lotnumber, the manufacturer's initials or symbol, thedate of manufacture, the initials or symbol of theloading facility, the month and year of loading,the anchor stamp, and the inspector's initials .

General arrangement drawings:344601 (Mod 0)422548 (Mod 1)

Sketch list of drawings & specs:102957 (Mod 0)109583 (NIod 1)

Explosive components :Delay assembly consisting of a Detonator i\1k

31 and a Primer Mk 106. Delay is 0.02second .

Booster lead-iij housed in the magazine .Booster charge (approximately 11 .5 grams of

tetryl) housed in the magazine .

Figure 13-Nose Fuze Mk 145, External View, Full Size (approximately) .

25


DELAY

DETONATORASSEMBLY

26

ARMED POSITION

2 . DescriptionGeneral .

Nose Fuzes Mk 145 Mods 0 and 1 arerocket fuzes designed principally for rocketslaunched from. small craft to provide a beachbarrage prior to lancling operations . The fuzesare air arming and impact firing and are similarto the Alk 137, but incorporate a, 0.02 seconddelay in the detonator assembly .

Use.

Fuze '\Ik 145 is used in the 4.5-inch IIig-hCapacity Fin Stabilized Surface Rocket (CompleteRound) 11-Ikl 1-lod 0 (see OP 1415 .)

This fuze isused when a delay detonation on impact is desired.

SECTION Y-Y

SECTION X-X

Figure 14-Nose fuze Mlc 145 Mod 1, Cross Section View, Armed and Unarmed Position .

GUARD

SET-BACKBLOCK

SHUTTER DETENT

SET- BACK SPRING

GASKET

FIRING PIN GUIDE

DETENT SPRING

LEAD-IN CHARGE

BOOSTER PELLET

SHUTTER DETENTa DETENT SPRING

i

XII1011lIlNfN

XT

G.

UNARMED POSITION

MAGAZINE

CLOSINGDISC

Functioning mechanism. The functioning n1eclh-anism of Fuze 1\'Ik 145 is similar to the mechanismof Fuze )vIk 137. The differences incorporated inthe mechanism of Fuze A'Ik 145 are :

1 . The arming shaft which mounts the pro-peller is attached to the firing pin by means of alocking pin.

The purpose of the - locking pin(which may be sheared upon impact) is to preventthe firing pin from being forced too cleeply into theshutter thus disrupting the delay element onheavy impact .

l

ePROPELLER LOCKING PIN

SAFETY LOCKING

WIRE

RING PIN

-SHUTTER

SLEEVE

BODY

MAGAZINE

CONFIDENTIAL

CONFIDENTIAL

2. The fuze cotitaius a delay element whichis initiated by a firing pin -witli a rounded point .

3. The magazine is designed to receive thebooster lead-in which eliminates a separate lead-iiidisc .

Differences in mods .

The Fuze Mk 145 Mod 0is similar to the Fuze AIk 137 A1od 1 but has a0 .02 second delay. The Fuze All. 145 Alod 1 issimilar to Fuze Allc 137 Mod 2 with a 0.02 seconddelay.

3 . FunctioningArming . Arining of Fuze '.\-11: 145 is identical

with Fuze A-Ik 137 .

4.5'SURFACE FIN STABILIZED ROCKET FUZES

Firing . Similar to firing of Fuze All. 137, butfuze functions with a 0.02 second delay aftermpact.

4 . Safety FeaturesSee Fuze Mk 137.

5 . Disposal and Servicing (Maintenance)See Fuze -'\-lk 137.

6. Installation InstructionsSee Fuze Mk 137 .

7 . Packing and MarkingSee Fuze All: 137 .

Section C-Nose Fuze Mk 154 Mods 0, 2, and 3 (Setback and Air Arming,

1 . General DataUsed in : 4.5-inch Rocket Heads Aik 7 and Ml.

10 (Smoke)Overall dimensions and weight of fuze :

Length------------------- 16 .25 inchesDiameter (maximum)------ 2 .7 inchesBody threads --------------

1.5

inches----l2 NF-2

«'eight ------------------ 1 .401bs .approx .

Applicable specification : OS 3577General arrangement drawings :

423844 (ATod 0)423847 (Mod 2)423848 (Mod 3)

Sketch list of drawings & specs :109411 (Mod 0)165110 ('Mod 2)165074 (A1od 3)

Explosive components :Detonator \Ik 23 housed in shutter.Booster lead-in housed in lead-iii disc .Burster charge (apimoximately 65 grains of

tetryl)

2. DescriptionGeneral. Nose Fuze Mk 154 Alod 0, 'Mod 2,

or A-Iod 3, is identical with Fuze ATk 137 excepta tetryl filled burster tube replaces the booster.

The mods of the fuze differ as follows :1 . Fuze Ahk 154 Mod 0 consists of a, Fuze Mk

137 Mod 1 with a 14 .06-inch long tetryl filledburster tube (0 .630-inch din.meter) which is rigidlyattached to the fuze body .

CONFIDENTIAL793260-18--5

Impact Firing)

2 . Fuze 'Mk 154 i\'Tod 1-Never assigned .3 . Fuze AIk 154 Clod 2 consists of a Fuze AIk

137 \Iod 2 with a. 14.06-inch tetryl filled burstertube Nvlnclr is rigidly attached to the fuze body .

4. Fuze 111: 154 ATod 3 consists of a Fuze Mk137 A1od 2 with a 14 .06-uich tetryl filled burstertube . Its attachment to the fuze body is suchthat a certain degree of flexibility is obtained .This is accomplished by a steel retaining collarbrazed to the upper end of the burster tube . Arubber gasket is inserted between the burstertube collar and the adapter. Between the wallof the burster tube and the inside wall of the adap-ter a clearance of approximately 0.03 inches exists .Thus flexibility aids in the assembly of the longfuze into. the rocket head burster well when theburster tube is not. perfectly concentric with thefuze body threads.

Use.

Nose Fuzes AIk 154'Mods 0, 2, and 3 areused in the 4 .5-inch Smoke Fin Stabilized SurfaceRockets (Com.plete Rounds) TVIk 4 Mod 0, Alod 1,and ATod 2 (see OP 1415) .

Those fuzes are de-signed to detonate a tetryl filled burster tube anddistribute the smoke filler of the rocket head onimpact with the surface of the ground or water.


(See Fuze A1k 137)

3 . FunctioningArming .

(Same as Fuze Nlk 137)Firing .

(Sa:Tne as Fuze AIk 137)Acceptance test data . Completely live loaded

fuzes are. selected front each production lot andare installed in 4.5-inch "FS" loaded rocket headsassembled with 2 .25-inch Rocket 'Motors ATk 9

27


4. Safety FeaturesSame as Fuze 1%X1k 137.

28

and fired ,it 45 degrees quadrant angle .

Half ofthe fuzed rounds are fired for growid impact andthe other half for water impact . ti 90% highorder fimctioning is considered satisfactory .

Anypremature shall be cause for rejection of the lot.

Figure 15-Nose Fuze Mk 154 Mod 3, External View, Full Size (approximately)except for Burster Tube Length .

C`OKFIDEW IIAX

5 . Disposal and Servicing (Maintenance)Same as Fuze 'T%'Ik 137.

6. Installation InstructionsNo auxiliary booster is present or required in

srnol:e filled rocket heads receiving the Fuze Mk154. All other installation instructions ns relatedfor Fuze illk 1 :37 are applicable for Fuze Mk 154.

CONFIDENTIAL

CONFIDENTIAL

COTTER PIN

PROPELLER

GUARD

PROPELLER LOCKING PIN

SCREW

FIRING PIN GUIDE

GASKET

BODY

SHUTTER SPRING

SLEEVE

SHUTTER

SHUTTER DETENTLOCKING HOLE

Figure 16-Nose Fuze Mk 154 Mod 3, Cross Section View, Unarmed Position .

7 . Packing and MarkingPacking.

Fuzes are individually- packed in her-metically sealed cans . Twenty'-four fuzes arepaclXed in a box 23.3 inches by 15 inebes by 19 .2inches which represents a total of 3.9 cu . ft . and atotal weight of S3 pounds .

CONFIDENTIAL


SET-BACK BLOCK

SET-BACK SPRING

FIRING PIN

STOP PIN

RETAINING COLLAR

WASHER

ADAPTER

SPANNER HOLES

BOOSTER DISC

BURSTER TUBECHARGE (TETRYL)

BURSTER TUBEUNARMED ASSEMBLYPOSITION

Marking. The fuze is marked or stamped toshow the letters NF, the mark, xnod, and lotmimber, the manufneturer's initials or symbol, thedate of maimfacture, the initials or symbol of theloading facility, the month and year of loadirng, theanchor stamp, and the inspector's initials .

29


PROPELLER

GUARD

PROPELLER LOCKING PIN

SHUTTER


SET-BACK SPRING

FIRING PIN

FIRING PIN GUIDE

DETONATOR ASSEMBLY

SHUTTER SPRING

SLEEVE

BODY

RETAINING COLLAR

LEAD-INSHUTTER HINGE PIN

SPANNERSHUTTER SPRING -

X

\

HOLES

"b14IDENTI'AL

ARMED POSITIONSEGT ION Z-Z

Figure 17-Nose Fuze Mk 154 Mod 3, Cross Section View, Armed Position .

BURSTER TUBECHARGE (TETRYL)

BURSTER TUBEASSEMBLY

3 0

CONFIDENTIAL

CONFIDENTIAL

NOSE FUZE FOR 7.2-INCH CHEMICAL ROCKET

.1 (Setback and Air Arming, Impact Firing)Section A-Nose Fuze Mk 147 Nods 0 and

1 . General DataUsed in : 7 .2-inch Rocket Head Ml: 7 (Chemical

or Smoke)Overall dimensions and weight of fuze :Len th____-____-_--___ ___ 16 .1 inches

(Mod 0)16 .2 inches(Mod 1)

Diameter (maximum)______ 1 .750 inchesBody threads -------------- 1 .500 inches-

12 i\ F-2Weight------------------ 1 .3011bs.approx .

Applicable specification : OS 3579General arrangement drawing :

394940 "Mod 0)42384 (lIod 1)

Sketch list of drawings & specs :109548 ('Mod 0)109372 (\Iod 1)

Explosive components :A sensitive stab type cornpotuid detoliatorM1: 23 plod 0 (lead azide primer mixture,lead azide, and tetryl)

Burster lead-in charge (tetryl)Burster charge (tetryl 65 grains approxi-mately)

2 . DescriptionGeneral . Fuze 1Ik 147 Mod 0 or Mod 1 is a

nose fuze designed for 7.2-inch chemical rockets .The fuze is setback and air-arming, impact firing .It functions instantaneously upon impact with asuitable target .Fuze '-\Ilc 147 '-Mod 0 is fitted with a Fixed cylin-

drical guard which protects the propeller fromdamage. The propeller vanes ar-e bent to au angleof 70°. Fuze lllc 147 Mod 1 has a detachableshipping cap which protects the propeller fromdamage duriin,, - shipping and the fuze from «weather .Since the air stream is more effective on tlXc, FuzeMk 147 Mod 1, the vanes are bent to an angle of78 ° to keep the arming distance the same as forthe Fuze 1(0=17 Mod 0.

The shipping cap on theFuze 11k 147 -Mod 1 is removed as the rocket isloaded on the launcher .CONFIDENTIAL

Chapter 4

(Oti'ER)V! I P.E.

GE SN1D IC UGlF IVX [7- D .

Figure 18-Nose Fuze Mk 147 Mod 1, External Viewwith Guard Removed, Full Size (approximately)except for Burster Tube length .

31


COTTER PIN

PROPELLER

HUB' PROPELLER LOCKING PIN

FIRING PIN GUARD

SETBACKBLOCK

SET-BACKSPRING GASKET

FIRING PINGUIDE

SLEEVE SHUTTERSHUTTER DETENT

SPRINGLEAD IN

DETENT SPRING

DISC

DETONATOR BOOSTERASSEMBLY DISC

LEAD-IN

ARMED

UNARMEDPOSITION

POSITION

SHUTTERSPRING

DETONATOR

SHUTTERDETENT

SHUTTER

STOP PIN

BURSTER TUBEASSEMBLY

SECTION B-B

Figure 19-Nose Fuze Mk 147 Mod 1, Cross Section View, Armed and Unarmed Position,

CONFIDENTIAL

32

CONFIDENTIAL

CONFIDENTIAL

Fuze .

Fuze'Ik 147'-Iod 0 or Mk 147 'Mod 1 isused in the 7 .?-inch Rocket Ilead'Ik 7 when as-sembled with the 3 .25-inch Rocket 'Motor Mk 5.The complete round is fin stabilized and surfacelaunched for use in dispersing, chemical or smokeagents . It has a maximum range of approxi-mately 3,400 yards.


Fuze 171: 147 consists ofa brass fuze body which provides housing for thethreaded firing pin, the setback collar witli pro-peller locking pin, the setback spring, the firingpin guide, the spacing sleeve, the shutter with thedetonator and locking detent, the lead-in disc withlead-in charge, and the burster adapter with external burster tube and charge .

The propeller andits hub are mounted externally at the forward endof the threaded firing pin and are secured in po-sition g,3- means of a cotter pin .The forward section of the fuze body is tapered

slightly towards a, nose surface . Below the taperedsection the body diameter increases to serve as amounting support for the vane guard in Fuze 'Mk147 'Mod 0 and as a shoulder for the externalinstallation threads . A deep bore with counter-bore provides the internal housing for the fuzeelements . The thin nose wall is drilled andthreaded at the center with light shear threads,and a second hole is drilled off center to accom-modate the propeller locking pin . The counter-bore at the base of the fuze is threaded to engagethe burster adapter .The propeller assembly consisting of the propel-

ler and hub is secured to the firing pin . Belowthe hub the firing pin is threaded for a shortdistance and these threads engage the threadedhole in the nose of the fuze body. A shoulder onthe firing pin below the threads tapers rearwardto form a conical surface which is followed by anelongated section tapered at its end to a sharppoint . The shoulder prevents the retraction ofthe firing pin beyond the threads during armingand the conical surface acts as a stop to controlthe depth of penetration of the firing pin on im-pact . The. setback block, a steel inertia blockwith an integral propeller locking pin, floatsaround the firing pin on the setback spring andbears against the nose wall .

The propeller lockingpin extends from the forward surface of the setbackblock through the guide hole in the nose wall toengage a rivet or embossed stop in the propeller

CONFIDENTIAL

7.2" CHEMICAL ROCKET NOSE FUZES

hub which locks the propeller assembly .

The set-back spring at its forward end bears against thesetback collar and at its base against the firingpin guide . The firing pin guide, a flat steel discwith the center portion raised to align the setbackspring and drilled to accept the pointed shaft ofthe firing pin bears against the shoulder providedby the counterbore . The firing pin guide has ahole drilled in its base which receives the shutterhinge pin . The modified semi-circular shutterhouses the detonator and pivots by means of theshutter hinge pin under the force of a torquespring after the firing pin has been retracted . Asmall spring loaded detent ixi the shutter engagesa small well in the firing pin guide after arming .A ring type sleeve bears against the firing pinguide and positions the lead-in disc with its charge.The burster tube and burster adapter are installedinto the base of the fuze body and bear againstthe lead-in disc separated by the thin paper booscordisc . With Fuze 'Ik 147 Mod 0 a removablesafety locking wire clips over the propeller guardand passes through aligned holes in the fuze bodyand also engages a slot in the setback: block toloci: the setback block and propeller locking pinin forward position . With Fuze '.Wk 147 Mod Ithe propeller guard is replaced by a removablecap type guard, and the safety locking wire passesthrough aligned holes in the fuze body and setbackblock in the same manner as indicated above .


After the rocket has been loaded intothe launcher, the shipping cap (iii Fuze IN& 147Mod 1 only) and safety wire are removed . Whenthe rocket is fired, the setback: force, due to theacceleration of the round acting on the setbackblock, forces the block back, compressing thesetback spring . This movement withdraws thepropeller locking pin from engagement withthe hub . The air stream acting on the propellerassembly causes it to rotate and unscrew thefiring pin from the fuze body.

The setback forceacts on the setback block only during burning ofthe rocket motor, after which the setback: springreturns tho block to its original forward position .However, the firing pin has meanwhile unscrewedfrom the fuze body sufficiently to prevent re-enga,geinent of the propeller locking pin with thepropeller . The propeller is so adjusted thatunder the least favorable conditions (short burning

33


distance at maximum service temperature) thefiring pin assembly inal:cs the required twocomplete turns during acceleration of the rocketto advance the firing pin sufficiently to preventre-engagement of the propeller locking pill withthe stops on the hub before the end of burning ofthe roclXet.

Rotation of the propeller continues to unscrewthe firing pin, until an unthreaded section isreached and a shoulder on the pill comes ill)against the top of the fuze body, after which thefiring pill assembly rotates freely . Before thefiring pin is unscrewed it holds the detonatorshutter to one side, so that the detonator is outof alignment with the firing pin and boosterlead-in. When the firing piia unscrews, theshutter is released, and the shutter spring rotatesthe shutter against a stop pin. A shutter detentengages a hole in the firing pin guide and locksthe shutter in position . The detonator is nowaligned with the firing pin and the booster lead-ill,and the fuze is fully arined .

The arming distance for Fuze \Il: 147 used inthe 7.2-inch chemical warfare rocket is about 200feet .

Firing .

On impact, the fining pin is forced backto shear the liglit screw threads in the nose wallof the fuze body and to pierce and fire the detona-tor which in turn fires the lead-in charge and theburster charge .

Acceptance test data . Sample fuzes chosen atrandom from each production lot are subjectedto routine ballistic test when fired in rocket ammu-nition in accordance with the following procedure :Completely loaded fuzes from each lot shall beinstalled in "FS" smoke loaded 7 .2-inch RocketHeads Mk 7 with live loaded motors and fired forfunctioning. Half of the rockets shall be fired forwater impact and the other half for ground impact .All fuzes shall be fired at an angle of elevation ofapproxiinatcly 45 degrees. Ninety percent highorder functioning shall be considered acceptable .Any preinatures shall be cause for rejection of thelot.


This fuze will fire reliably onwater and ground impact, except at small anglesof impact .

The niirii3nuin angle of impact on softground for consistent firing is 1 .5 degrees.

34

c4AtIii E,NT IAt


Fuze _Mk

147 is detonatorsafe .

In the unarmed position the detonator is out.of alignment Nvith the explosive train.

Should tile,detonator function prematurely, the force of thedetonator will be dissipated forward through ahole in the firing pin guide and away from the ex-plosive components . When the fuze is installedin arocket head, it is locked in the unarmed positionby the propeller locking pin.

Thefuze is not a-rineduntil the setback force withdraws the propellerlocking pin, and the propeller rotates arid unscrewsthe firing pin to a point where the detonatorshutter is released .


Sample fuzes fromproduction are subjected to rough handling testswhich are considered to be more severe tlian con-ditions encountered in normal stowage and shipping .

Failure to pass the tests is cause for rejec-tion of the lot. Additional safety is providedduring shipping, stowage, and until the rocket isloaded into the launcher, by use of n safety wire.The safety wire passing through the fuze bodylocks the setback block in forward position so thatthe propeller locking pin engages and locks thehub. The guard or cap protects the propellerfrom damage duringnorrnal coil ditlolls encounteredin stowage and handling .

5. Disposal and Servicing (Maintenance)General. If the fuze is accidentally arined,

whether assembled in the rocket head or not, noattempt should be made to unarm it . The fuzeshall be considered armed if the propeller is out ofengagement with the propeller locking pin so thatthe propeller is free to rotate . If the fuze isarmed, turning the awning vane counterclockwiseas viewed from the nose will cause the firing pinto pierce the detonator and initiate the burster.Replacing the safety wire will not render an armed orpartially armed fuze safe .

Tho safety wire merelylocks the setback block and propeller locking pin,arld if the latter does not engage the propeller, thesafety wire serves rag purpose . Armed fuzesmust not be fired from rocket launchers. If thefuze in an assembled round is armed accidentally,the propeller should be carefully- taped to preventfurther rotation, and the fuze then carefullyremoved from the rocket taking care not to droptiler round or the fuze on its nose or in, any waystrike the fuze . Dud rounds should be treated

CONFIDENTIAL

CONFIDENTIAL

with extreme caution . If the propeller is bent ordriven flush with the nose of the fuze body, thefuze is in a fired condition . In such a condition,the firing pin or propeller should not be disturbed,as the firing pin may be imbedded in the detonatorand any movement may create sufficient frictionto initiate the sensitive detonator . The fuze orfuzed round should be disposed of by gently lower-ing into deep water or by Explosive OrdnanceDisposal Personnel in accordance with existinginstructions .

Disassembly . Disassembly of this fuze is notpermitted except at authorized activities whendirected by the Bureau of Ordnance .

6. Installation Instructions1 . Remove the dummy nose plug from the

rocket, head and inspect the liner and clean ifnecessary .

2 . Remove the fuze from the container andexamine to see that- the gasket is present and thefuze is not damaged. If defective, repack, seal,and return to an ammunition depot .

3 . Screw the fuze with gasket securely into thenose of the rocket head, using the proper fuzespanner wrench .

4 . After placing the rounds on the launcher,remove the guard (applicable for Fuze '-%Ik 147

CONFIUEgTiAL

7.2" CHEMICAL ROCKET NOSE FUZES

Mod 1) and the safety wire . In some launchersthis is not possible . For these the safety wireand shipping guard should be removed immediatelybefore loading the round. Do not discard thesafety -wires until the rounds rare fired.Removal from round .

Should it become neces-sarv to remove the rocket from the launcher, thesafety -wire and shipping guard should, if possible,be replaced first .

The fuze may then be removedfrom the rocket head with proper fuze spannerwrench and returned to its shipping container.The. closed shipping can should be scaled withadhesive tape along the broken surface. Theshipping plug must be replaced in the rocket headafter the fuze is removed .

7. Packing and MarkingPacking . Fuzes are individually packed into

hermetical1v scaled cans . 'Twenty-four fuzes arepacked into a box 23 .3 inches by 15 .0 inches by18 .1 inches which represents a, total of 3 .6 cubicfeet and a total weight of 89 pounds .Marking .

The fuze is marked or stamped withthe letters \F, the mark, the mod, and the lotnumber, the manufacturer's initials or symbol, theinitials or symbol of the loading facility, themonth and year of loading, the anchor stamp, andthe inspector's initials .

35

NOSE FUZES FOR 7.2-INCH DEMOLITION ROCKETS

The fuzes described in this group are as follows :

1 . General Data

Used in : 7 .2-inch Rocket Head '-\1k

5

(HighCapacity)


Length ------------------.-

5 .5 inches

36

. Section A-Nose Fuze'Ml< 152 (Air Arming, Impact Firing)

Diameter (maximum)___-_ _ 4.75 inchesBody threads------------- 1 .75 inches---

14 NS-3Weight------------------- 4 .1Olbs . approx .

Applicable specification: OS 2374 (where per-tinent)

Outline drawing: 423659Explosive components :

A sensitive stab type compound DetonatorMk 21 (pom-porn mixture and mercuryfulminate)

Auxiliary booster lead-in (tetryl) 0.11 gramsBooster separator lead-in (tetryl) 0.20 grainsBooster (tetryl) 25.5 grams

2. DescriptionGeneral .

Fuze Ml: 152 is identical with BombFuze AN-Mk 219 except that it has been partiallyarmed fifty turns of the arming vanes and a metalband (fork) is inserted between the vane carrierand the fuze body to take up the space left bythe prearming process .

In addition, the pitch ofthe vanes has been increased to 40 degrees iil con-trast to the pitch of the vanes on the AN-Xfk 219of 18 degrees. The fuze is air arming, and itsfunctioning is instantaneous on impact .

Chapter 5

Section .-1--Nose Fuze Mk 152Section B-Nose Fuze Mk 141 Mod 0

4CQNFhCi,ENTIAL

Use.

Fuze '.Mk 152 is used in the 7 .2-inch HigliCapacity Fin Stabilized Surface Rockets (Com-plete Rounds) Mk 1 Mod 0 and Mod 1 (see OP1415) .

The, complete round i8 used for demolitionpurposes in the destruction of beach obstacles .

Functioning mechanism . The vane carrier is un-locked from the striker flange by withdrawal ofthe arming tivire . The vane carrier then rotatesby action of the airstream on tlic vane driving thereduction gearing.

The reduction gearing reducesthe motion so that 23 turns of the vane carrier arenecessary to produce one revolution of the shaft.The gearing is so arranged that the lower gearcarrier engages the slot of the inner sleeve .

Theupper gear, therefore, takes up the rotation andadvances the central shaft oil its threads untilstopped by the shoulder on the shaft screw . Atabout this instant the lug on the lower gear carrieris disengaged from the slot in the sleeve, allowingthe lower gear and carrier to rotate.

As the rota-tion of the shaft and upper gear is stopped, themotion is transferred to the lower gear and carrierwhich rotate approximately 345 degrees therebybringing into alignment the firing pin extension,firing pin, and detonator with the booster lead .As this rotation is completed, a locking detentengages the lower gear carrier to maintain properalignment of the explosive train.


The Fuze \1k 152 arms in two stages .During the first stage, the upper gear is free torotate and the lower gear, being attached to the

CONFIDENTIAL

CONFIDENTIAL

COVER

SPACER WASHER

LOWER GEAR

LOWER GEAR CARRIER

hammer carrier which in turn is locked by the in-ner sleeve, is held stationary . During the secondstage, the hammer carrier has risen to clear theinner sleeve and the lower gear is free to rotatewhile the upper gear is held stationary as it isattached to the arming shaft which was threadedup until it locked against the shaft extCI)Si0T1 nut .

CONFIDENTIAL .

ARMED POSITION

7.2" DEMOLITION ROCKET NOSE FUZES

Figure 20-Nose fuze Mk 152, Cross Section View, Armed Position .

First stage.

As the rocket is launched, the arm-ing wire is withdrawn and the vanes are free torotate . Through the system of reduction gears,the upper gear rotates to thread the arming shaftup until the head of the screw on the shaft locksagainst the shaft extension nut.

A collar on theshaft lifts the hammer carrier and the entire arm-

37


ing assembly .

Simultaneously with the locking ofthe arming shaft and the upper gear, the hammercarrier clears the inner shaft to free the lower gear .

Second stage .

The lower gear and hamnnercarrier are rotated in a counterclockwise direction .

The aligning lug on the hammer carrier en-gages the firing pin carrier, lining up the firing pillextension with the firing pin . Further rotationcauses the firing pin carrier to engage the det-onator carrier, lining the firing pin up with thedetonator. The hammer carrier, firing pin car-rier, and detonator carrier continue to rotate untilthe lip on the detonator carrier engages the innersleeve .

Simultaneously, the spring-loaded detentin the striker straps into a recess in the harrnrnercarrier, thus locking the firing train componentsin an armed position .

Since the upper and lowergears are both locked, the two copper pins securingthe lower gear to the hammer carrier are shearedand the vanes rotate freely .

(If the air speed isless than 300 mph, the air pressure will not, besufficient to shear the pins and the vanes willmerely cease rotating.)

The fuze is armed afterapproximately 100 revolutions of the arming vane .

Firing . After the above actions the fuze isfully armed. On impact, the entire upper as-sembly of the fuzc, is forced inward . The shearwire in the arming shaft is cut as the upperpart of the shaft telescopes into the lower partand the shear wire through the firing pin is cutas the firing pin extension forces the firing pininto the detonator. The detonator sets ofd' theauxiliary booster lead-in, booster lead-in, booster,and main charge successively .Acceptance test data . Since Fuze Nlk 152 is

a conversion of loaded Bomb Fuzes A1-1Ik 219,acceptance tests were previously accomplishedon the fuze as all A\7-NIk 219. Acceptancetests in rockets were not accomplished .

Sensitivity . Fuze NIk 152, after arming, willdetonate the rocket head instantaneously onimpact with water or denser medium.


Fuze

Nlk

1.52

Clod

0

isdetonator safe . The detonator is out of align-ment with the booster lead-in, the firing pin isout of alignment with the, detonator and thefiring pin extension is not aligned with the firingpin. .

If the dctonzitor should function prematurely

38

the gases would expand to the space above andwould be dissipated away from the explosivecomponents .


A safety pin locksthe vane and prevents rotation . Fuzes N11;152 NIod 0 are packed and the shipping containersmarked in such a manner to provide that thefuzes rest on their booster end . This is done tokeep the weight of the body of the fuze off thefiring pin shear pin, which condition exists if thefuze is resting on its nose in the partially pre-armed condition.

5. Disposal and Servicing (Maintenance)General . Fuze Mk 152 Mod 0 is completely

armed when the striker flange has moved awayfrom the edge of the outer sleeve a distance of%R inches and the lower gear and carrier rotatedabout 345 degrees. If the striker flange hasmoved away froin the outer sleeve more th ;m iiainches, the fuze should be regarded as armed.If it has not moved more than iic inches, the fuzemay be considered as partially armed. If thefuze is accidentally armed, whether assembledin the rocket head or not, no attempt should bemade to unarm it except by Explosive OrdnanceDisposal Personnel. In the event Explosive Ord-nance Disposal Personnel are not available thearmed fuze (or rocket head containing till armedor part,ialty arnned fuze) should be disposed of bylowering gently into deep water, base downward .

Disassembly . Disassembly of this fuze is notpermitted except at authorized activities whendirected by the Bureau of Orchnance.

6. Installation Instructions1 . Remove the dummy nose plug from the

rocket head nose adapter and inspect the liner andthreads and clean, if necessary. The cavity lineris to contain one Auxiliary Booster 1-11. 2, one Aux-iliary Booster '_\Tlc 3, and a cardboard spacer ap-proximately ?." inch thick placed below the auxiliaryboosters .

Tests have indicated that a high orderdetonation can still be expected if an additionalcardboard spacer is used in place of the AuxiliaryBooster Mk 2 ; however, use of the booster ispreferred.

2 . Remove the fuze from the cont,airner andexamine to see that the fuze is not damaged. Ifdefective, repack, seal, and return to an ammuni-tion, depot .

,CONFIOENTIAL

CONFIDENTIAL

CONFIDENTIAL

3. Screw t.be fuze securely into the nose of therocket head, using a spanner wrench to tighten.4. After the round is placed on the launcher,

remove the safety band .5. Check the arming pin to ascertain that it

passes through the striker flange and the vanecarrier, and that it is secured by a Falinestocl: clipresting snugly against the vane carrier.6. Attach the ring of the awning ,)In (which

extends toward the base of the fuze) to the armingwire .Removal from round.

The fuze may be removedfrom the rocket head in the following manner:

1. Detach the arming wire from the ring onthe arming pin.

2. Replace the safety band.3. Remove the round from the launcher and

remove the fuze with the proper spanner wrench .

1 . General DataUsed in : 7.2-inch Rocket Head Mk 5 (High

Capacity)Overall dimensions and weight of fuze :

Length ------------------- 7 .6 nichesDiameter (inaximuin) .----- 3 .00inches(Pro

peller)Body threads------------- 2.000 inches-

12 NS---2Weight------ _ ----------- 2.7 lbs. approx .

Applicable specification : OS 3605General arrangement drawing : 440263Sketch list of drawings & specs: 165109Explosive components :A sensitive stab type compound detonator

1\Ik 23 Nlod 0 (lead azide primer mixture,lead azide and tetryl)

Booster lead-in charge (tetryl)Booster charge (tetryl 54 grams, gpproxi-

mately)2. Description

General.

Fuze Xlk 141 Mod 0 was developedby a modification of the Bonib Fuze AN-M11OA1as a replacement for Fuze Nll. 152 .

The fuze iswater discrinunating and so designed that it will

CONFIDENTIAL


4 . Place the fuze in its shipping can and sealthe can with adhesive tape along the brokensurface .

5. Reassemble the dummy nose plug into therocket head.7. Packing and Marking

Packing . Each fuze is hermetically scaled in ametal can . Six cans are packed in a metal pack-ing box, and four packing boxes are placed in ashipping box 25 .8 inches by 17 .6 inches by 15.1inches which represents a total of 4 .0 cubic feetand a total weight of 177 pounds .

The shippingcases containing Fuze Mk 152 are marked "ForUse In 7 .2-Inch Rockets Only" .

Marking.

Since the Fuzes Mk 152 in stock ti"ereprepared by modifying loaded Bomb Fuzes AN-Mk 219, all markings indicating Fuze Mk 219have been defaced and the lettering N . F. X-Ik 152lifts been substituted.

Section B-Nose Fuze Mk 141 Mod 0 (Air Arming, Impact Firing)

not fire on impact with water but will be actuatedby impact with the earth or soft sand, providedthe water travel before impact is not more thantwenty feet . Fuze action is instantaneous . Arm-ing is accomplished sclely by air travel .Use.

Fuze Mlc 141 is used in the 7.2-inch HighCapacity Fin Stabilized Surface Rocket Mk 1 Mod1 " (See OP 1415) .

The complete round is em-ployed primarily for the destruction of underwaterbeach obstacles .


The fuze is essentiallycontained in three main assemblies : the bodywhich houses the arming, mechanism, the adaptermagazine in which the detonator shutter and lead-in disc are housed, and the magazine to which isassembled a threaded adapter for securing thefuze to the rocket head .

These three assembliesare threaded in order that they may be assembledtogether .A propeller is secured to the awning hub which

protrudes through the forward end of the fuzebody . To the after end of the arming hub astationary gear is fixed, so called because it doesnot move fore or aft. Threaded inside the arminghub is the arming sleeve to lyliich the movablegear is fixed .

The firing pin and firing wheel are

3 9


40

Ii ROUND ISIiU- D

REPL YAFErY WIRE

.X_

EI

I

Rl:MC:'-VII' GAWING WIRE

Figure 21-Nose Fuze Mk 141, External View .

DO NOT,, REMOVE

UNTIL ARMING WIRE

.HAS BEEN ATTACHED

; NFIDEN71AL

CIVER

OVER

CONFIDENTIAL

CONFIDENTIAL

secured to the arinina'seeve by a copper shear wireand the firing pin extends through the firing pinguide into the detonator shutter cavity . Both thestationary gear and movable gear mesh with a,pinion which rotates on a pin filed to the body.Extending rearward and secured to the firing

pin guide are two projecting pins called a shutterhinge pin and a shutter stop pin . Under influenceof a shutter spring the shutter, containing thedetonator, is pivoted on the shutter hinge pin intothe armed position and is stopped by the shutterstop pin after the firing pin is retracted . Thelead-in-disc assemblywhich is below the shutteris held in place by tlie inaaazine and a shoulderin the magazine adapter .

Attached to the body is in arming wire guide .Until such time as the fuze is used a safety wire,passed through a hole in the propeller and throughthis guide, prevents the propeller from turning .On the launcher an arming wire is used in place ofthe safety Wire .

3 . FunctioningArming . Arming is accomplished in two steps .

First, the arming wire is withdrawn as the rocketleaves the launcher, and, in the .second step, airtravel rotates the propeller to retract the firingpin permitting the alignment of the detonatorwith the firing pin and booster lead-in .The propeller, nut, outer ball race, arming hub,

and stationary gear rotate as a unit, but cannotmove forward or aft because of the collar on thearming hub . The movable and stationary gearsmesh with the pinion gear, and, since the movablegear has one more tooth than the stationary gear(33 teeth for the stationary gear and 34 teeth forthe movable gear), for each rotation .of the pro-peller, the movable gear lags one tooth thusscrewing the arming sleeve into the arining hub .As the arming sleeve moves forward, it moves thefiring wheel forward and withdraws the firing pinfrom the shutter cavity . When the firing pin iswithdrawn from the shutter cavity, the shutter isreleased, and the shutter spring rotates the shutterinto position against a stop pin .

A shutter detentthen engages a hole in the firing pin guide thuslocking the shutter in this position . The det-onator is now aligned With the firing pin andbooster lead-in, and the fuze is fully armed .The arming distance of Fuze MI.: 141 as used

in the 7 .2-inch Rocket Head Mk 5 is over 300 feet .

CONFIDENTIAL


Firing . Upon the force of impact the firingwheel is driven rearward which shears the coppershear wire and drives the firing pin rearward topierce and fire the detonator .


Completely live loadedfuzes chosen at random from each production lotare installed in live-loaded 7.2-inch demolitionrockets and the rockets fired into shallow water orshore. The angle of elevation of the rocketlauncher should be approximately 25 degrees .Acceptance is based on a cumulative test plandesigned to accept (95 070 of the time) lots in which9470 of the fuzes function satisfactorily . Lotspoorer than 94070 will be subject to rejection withlots 60 0]0 effective being rejected 90070 of the time.


The fuze is water discriuninat-i11.g and so designed that it will not fire on impactwith water, but will be fired by impact with earthor soft sand, provided the water travel before im-pact is not more than twenty feet .

`


Fuze Mk 141 is detonatorsafe . In the unarmed position, the detonator isout of alignment with the explosive train . Thedetonator is vented through a hole in the fifiDO' Pillguide, thus should the detonator function prema-turely, the force of the detonator will be dissipatedaway from the explosive components .

The firingtrain cannot be aligned until the safety wire orarming wire, as the case may be, has been with-drawn and the propeller rotated 90 to 130revolutions .


Sample fuzes fromproduction are subjected to rough handling testswhich are considered to be more severe than con-ditions encountered in normal stowage and shipping .

Failure to pass these tests shall be cause forrejection of the lot . The propeller is kept fromrotating by a safety wire which is replaced by thearming wire in preparation for firing .

5 . Disposal and Servicing (Maintenance)

.General . If the fuze is accidentally . armed,

whether assembled in the rocket head or not, noattempt should be made to unarm it .

If a gap of?;-inch or more exists between the striker and thearming hub, the fuze should be considered armed .If the fuze is armed, turning the propeller counter-clockwise as viewed from the forward end willcause the firing pin to pierce the detonator and

41


SHUTTER-n

SHUTTER DETENT

42

PINION

STATIONARY GEAR

SHEAR WIRE

MOVABLE GEAR

MAGAZINE ADAPTER

DETONATOR


SHUTTERSPRING

STOP PIN

SHUTTERHINGE PIN

UNARMED POSITION

eXXNIXJXXXXXAt40

FIRE WHEEL

ARMING SLEEVE

ARMING WIREGUIDE

LOCKING PIN

BODY

11 IN,

-FIRING PIN GUIDE

FIRING PIN

Figure 22-Nose Fuze Mk 141 Mod 0, Cross Section Yiew, Unarmed Position .

LOCKING PIN

SHUTTER

LEAD-IN CUP

LEAD-IN CHARGE

RETAINING PIN

MAGAZINE

TETRYL BOOSTERPELLETS

BOOSTER SEALING CUP

--FELT DISC

CONFIDENTIAL

L CONF'16ENTIAL

EL

VE

RE

IE

IN

)Y

)E

,IN

IN

=R

)P

iE

IN

IE

:R

P

P

C

FIRING WHEEL

ARMING HUB

PROPELLER

TETRYLBOOSTERPELLETS

CONFIDENTIAL


SHUTTER SPRING

DETONATOR

STOP PIN

FIRING PIN 1N ARMINGSLEEVE SUB-ASSEMBLY

OUTER BALL RACE

OUTER BALL CAGE

ARMING WIRE GUIDE

STATIONARY GEAR

MOVABLE GEAR

SHEAR WIRE

-FIRING PIN GUIDE

DETENT SPRING

SHUTTER DETENT

SECTION Z-Z

Figure 23-Nose fuze Mk 141 Mod 0, Cross Section View, Armed Position .

SHUTTERDETENT

SHUTTER

43


explode the booster . Armed fuzes must not befired from rocket launchers . If the fuze in anassembled round is armed accidentally, the firingwheel must be positively prevented from movingrearward, during handling by means of placing a.spacer between the firing wheel and arming hub,such as to assure the preservation of the gap.Then carefully unscrew the fuze from the rockettaking care not to drop the round or the fuze onits nose or strike the fuze in any way.Dud rounds should be treated with extreme

caution . If the firing wheel is flush with thearming hub, the fuze is in a fired condition . Insuch a condition, the firing wheel should not bedisturbed as the firing pin may be imbedded in thedetonator and any movement might create sufficient friction to initiate the detonator .

The fuzeor round should be disposed of by gently loweringbase or tail down into deep water or by ExplosiveOrdnance Disposal Personnel in accordance withexistinn instructions .

Disassembly. Disassembly- of this fuze is notpermitted except at authorized activities whendirected by the Bureau of Ordnance .

6. Installation Instructions1 . Remove the dummy nose plug and spacer

from the rocket head and inspect the liner to seethat the two auxiliary boosters, or the one boosterwith cardboard spacer, (the spacer being placed sothat the auxiliary booster is against the fuze) arein place.2. Remove the fuze from the container and

examine to see that the fuze is not damaged. Ifdefective, repack, seal, and return to an ammuni-tion depot.

3 . Screw the fuze securely into the nose of therocket head, using a spanner wrench to fit theholes i . the adapter .4 . After placing the round on the launcher, in-

sert the arming wine (which has been secured tothe launcher) in the hole provided nest to thesafety wire .

Remove the safety wire .5. Place the Falhnestock clip on the arming wire

and adjust the Fahnestock clip so the arming wireis slack and not just tight.

6 . Cut off excess arming -wire leaving two orthree inches projecting out in front of the fuze.Remove any burrs on the end of the arming wire .

Removal from round.

The fuze may be removedfrom the rocket head with the proper fuze -wrenchand returned to the shipping can.

The closed ship-ping can should in turn be sealed with adhesivetape along the broken surface .

Before removal ofthe fuze fl -0111 the round the safety -wire should bereplaced . The dummy nose plug must be re-placed in the rocket head after the fuze is removed .

7. Packing and Marking

CONNIDbriAL

Packing .

Fuzes are individually packed in her-metically sealed calls. Twenty-four fuzes arepacked into a box 25.5 inches by 16 .5 inches by9 .7 inches which represents a total of 2.4 cubicfeet and a total weight of approximately 107pounds .

Marking.

The fuze is marked or stamped, withthe letters NF, the mark, mod, and lot number,the manufacturer's initials or symbol, the initialsor symbol of the loading facility, the month andyear of loading, the anchor stamp, and the inspec-tor's initials .

CONFIDENTIAL

The fuzes described in this group are as follows:

Section A-Nose Fuze Mk 149 Mod 0 (Setback and Air Arming, Impact Firing)


NOSE FUZES FOR FIN STABILIZED AIRCRAFT ROCKETS

3 .5-inch RocketPurpose)

3 .5-inch RocketPurpose)

5.0-inch RocketPurpose)





Overall dimensions and weight of

Length-------------------- 4 .22 inchesDiameter (maximum)------ 2 .99 inchesBody threads------------- 1 .700

inches14 NS-1

Weight------------------ 2 .6 lbs. approx .Applicable specification : OS 338SGeneral arrangement drawing : 393783Sketch list of drawings & specs: 109204Explosive components:A sensitive stab type compound DetonatorMk 23 (lead azide primer mixture., lead

CONFIDENTIAL

Chapter 6

Section A-Nose Fuze Mk 149 Mod 0Section B-Nose Fuze 1\M 155 Mod 0

Head Mk 3 Mod 0 (General

Head Mk 5 'Mod 0 (General


Head 1\41: 5 Mod 0 (General



Head 1\11. 6 Mod 1 (General

fuze :

azide and tetryl) located in the shutter be-tween the firing pin guide and the lead-indisc .

A lead-in assembly charge (tetryl) located inthe lead-in disc between the shutter andmagazine .

A booster charge (approximately 9 grams oftetryl) located in the magazine at the baseof the fuze .

2. DescriptionGeneral. Fuze Mk 149 Mod 0 was developed

to replace the now obsolete Fuze 1\11. 148. Aero-dynamically the external shape of the fuze isgenerally adaptable to the ogiva.l configurations ofthe higher velocity rockets . The Fuze Ml.: 149Mod 0 is used singly and in combination with theBase Fuzes Mk 157 Mod 0, Mk 159 Mod 0, Mk159 Mod 1, Mk 164 Mod 0, and lIk 165 Mod 0.A cap, which fits over the propeller on the nose ofthe fuze, makes the interior of the fuze waterproofand allows the fuze to be carried on the exteriorof aircraft without the propeller assembly becom-ing badly iced . The fuze will fire superquickupon impact with suitable targets. Because ofits basically rugged construction, it may be firedin the unarmed condition, when used in combina-tion with base fuzes, and penetrate moderatelythick steel plate and reinforced concrete withoutbreaking up the fuze or head in a manner thatwould impair the effectiveness of the round.

45


45

Figure 24-Nose Fuze Mk 149, External View, Full Size (approximately) .

Use . The fuze is used in the 3 .5-inch GeneralPurpose Fin Stabilized Aircraft Rocket (CompleteRound) 3-11 8 Mod 0 and in the 5.0-inch GeneralPurpose Fin Stabilized Aircraft Rockets (CompleteRounds) 1\1k 1 Mod 0 ; Mk 1 'Xlod 2, and the,Mk 4 Mod 0 (See OP 1415) . Fuze -'\Ik 149 -Mod 0is 'effective against shipping, vehicles, personnel,moderately heavy and light plate, fortifications,parked aircraft, buildings, and beach obstacles .


The internal mechanismof the fuze is housed in a rugged conical steel body .The body cavity is closed at the base by themagazine containing the tetryl booster, and theforward end by the nose plate. The firing pin isthreaded into the nose plate from the body cavity

CONFIDEN-,IAL

and extends forward out of the plate.

A propellerhub is riveted to the forward end of the firing pinand a propeller is riveted to the hub. The firingpinextends rearward, inside the fuze body, throughthe propeller locking pellet, shutter locking pellet,firing pin guide and into the shutter cavity whereit holds a spring actuated shuttor in in unarmedposition . This shutter, hinged on a pin pressedinto the firing pin guide, is located between theguide and the lead-in disc which holds the boosterlead-in assembly . The shutter contains a springloaded detent which locks the shutter to the firingpin guide when the shutter is in an armed position .A propeller locking Pill, pressed into the propellerlocking pellet, passes through a hole in the noseplate into a bole in the propeller hub and prevents

CONFIDENTIAL

CONFIDENTIAL AIRCRAFT ROCKET NOSE FUZES

the hub and propeller from turning until a set-back force acting on the propeller locking pelletmoves it rearward, against the force of a setbackspring, and discnga;es the propeller locking pinfrom the hub. This setback spring holds theshutter loehlrlg pellet and propeller locking pelletagainst the nose plate until the round is launched .A shutter locking pin, pressed into the after endof the shutter locking pellet, extends into thefiring pin guide at a position «-licre it will loci:the shutter in an unarmed position as the setbackspring is compressed . The fuze is waterproofedat the forward end of the body by a cap assembly .The open end of the cap is pressed against a fibergasket, called the outer gasket and held in thisposition by a clamp. The cap assembly consistsof a cap, a cap spring, and cap rivet . Tlie cahprotects the propeller from damage during han-dling, the cap spring pushes the cap assembly andclamp away from the propeller during arming,and the cap rivet holds the spring in place and

CONFIDENTIAL

Figure 25-Nose Fuze Mk 149 Mod 0 Showing the Clamp Pin, Clamp Bushing,Clamp, Gasket, SafetyWire, and Protective Cap.

prevents the firing pin from turning to an armedposition while the cap is clamped to the body .The clamp is made up of two half circular steelstrips, hinged together . Each edge of each stripis formed to a channel shape that will pull thebody and cap together as the clamp is closed andtightened. Each clamp arm, 180 ° away from theclamp hinge, is flanged away from the center ofits half circle . These flanges are drilled and heldtogether by a clamp pin, a bushing and a safetywire . The clamp pin is shaped somewhat like aflat head rivet, the head being too large to gothroua;h the drilled holes of the clamp flange . Itsshank has two holes drilled to match two holes inthe bushing. After the clamp pin is placed in theclainp flange holes, the bushing- is placed over theshank of the pin and a, safety wire inserted in theouter hole of the bushm0- and pin. After loadingthe complete round onto the plane, the arming wireon the plane is placed in the innermost hole of thebushing and then the safety «"ire is reinoved .

47


' CONFIDENTIAL-

PROPELLER -PROPELLER LOCKING PIN

CLAMP PIN

SHUTTER LOCKINGPELLET

FIRING PIN

SHUTTER

LEAD-IN (TETRYL)

BOOSTER (TETRYL)

SHUTTER(UNARMED POSITION)

FIRING PIN

DETENT

UNARMED P®SITI®fl

CAP

DETONATOR

Figure 26-Nose FuzevMk 149 Mod 0, Cross Section View, Unarmed Position .

CAP SPRING

PROPELLER HUB RIVET

GASKET

CLAMP

PIVOT PIN

PROPELLER LOCKINGPELLET

BODY

SET-BACK SPRING

SHUTTER SPRING

FIRING PIN GUIDE

SHUTTER SPRING

4 8

CONFIDENTIAL

SHUTTER LOCKING PELLET

FIRING PIN

DETENT

DETONATOR-

I_,

CONFIC:5r.

X

CONFIDENTIAL

AIRCRAFT ROCKET NOSE FUZES

ARMED POSITION

SECTION X-X

Figure 27-Nose fuze Mk 149 Mod 0, Cross Section View, Armed Position .

- PROPELLER LOCKING PELLET

SHUTTER (ARMED POSITION)

PIVOT PIN

SHUTTER SPRING

49


3. Functioning

50

Arming . NNrhen the rocket is fired, the armingwire is pulled from the clamp pin and bushing,allowing the clamp to open . The compressed capspring then throws the cap and clamp away fromthe fuze . Inertia forces, incurred by acceleration,cause the two locking pellets to move rearward,thereby, unlocking the propeller hub and inter-posing a shutter lock by means of the shutterlocking pin .

The firing pin is withdrawn from theshutter after eight revolutions which are acconn-plished in a short distance, however, the shutterlocking pill continues to hold the shutter in anunarmed position until the end of burning . Atthe end of burning, the setback spring forces thepellet forward, withdrawing tireslmttvr lockingpin from the shutter cavity, thus permitting theshutter spring to pivot the shutter against theshutter stop pin where it is secured in tlIC firingposition by the shutter detent . The firing pill,detonator, and booster lead-in are now in align-ment and the fuze is fully armed . Beclruse theshutter is locked in a safe 1>ositiolr c1urirrg accelera-tion, arming NN - i11 not occur until after acceleration .Observations indicate an awning delay of about0.1 second after acceleration has ended. I'lrere-fore, the arming distance in the 3.5-inch Aft' willvary front about 425 feet to 900 feet, in 5 .0-inchAft2 from 275 feet to 600 feet, and in the 5 .0-inchHVAK3 from 650 feet to 1100 feet, dependingupon the temperature at Which tile rounds arefired .

Tests to deternnirnn the partial awning dis-tance, that is, the distance at which the firing pinhas advanced completely, for rounds fired fromaircraft, indicated that this distance is variable,ranging from about 5 feet to 65 feet .

Firing .

Upon impact, with a target offering suffi-cient resistance, tire firing pin is driven rearwardinto the detonator after shearing the nose platethreads . The detonator initiates, conse"crrtively,the booster lead-in and the booster . ti1rlreu theFuze Mk 149 is used in combination with basefuzes, it is often launched "safe" . In this case

1 3.5-inch rocket head a scinbled with a 3.25-inch rocketmotor.

a 5.0-inch rocket head assembled -,vith a 3.25-inch rocketmotor.

3 5.0-inch rocket head assembled with a 5.0-inch rocketmotor.


4. Safety Features

GONFID,X OI

the nose cap remains in place and prevents thefuze from arming after the rocket is launched.

1 . FIRED Fitom LAND L:lu`cHERS . Coln-pletely loaded fuzes from each lot are installed inlive loaded 3.5-inch or 5 .0-inch aircraft rocketswith an arming wire and Falinestock clip attachedand fired from a land launcher as follows :

a . Half of the fuzes are fired for waterimpact, The rockets are fired at an angle ofelevation of approximately 15 degrees . The temperature of tile rocket motor at the time of firingis at least 60 degrees Fahrenheit . Only the 5 .0-inch motor may be used with the 5 .0-inch headfor this test .

b . The remaining fuzes are fired in tilesame manner except the angle of elevation is ap-proximately 45 degrees . Any ambient temperature at tile time of firing is satisfactory .

Eitherthe 3.25-inch or 5.0-inch motor may be used withthe 5 .0-inch head for this test .

Ninety peITcrrt pcrformrurcc of all testsaunples in this group is satisfactory . Any prema-ture. cause rejection of the lot .

2 . Finn:) FROM PL_NNES . Completely loadedfuzes from every tenth lot are fired from aircraftfor Avater or ground impact .

The angle of fall istit least 15 degrees . Half of the fuzes are as-sembled in 3.5-inch live loaded aircraft rocketsand the balance are assembled in. 5.0-inch liveloaded aircraft rockets for this test . The pre-scribed service arming wire arrangement is used .Half of the samples of each caliber are fired forground impact . A minimum of 87?z pereentperformance of all test samples is consideredsatisfactory . Any premature is cause for rejec-tion of tile lot .


Sensitivity data is not com-plete for this fuze, however, it will probably fireconsistently oil three-sixteenths inch mild steelplate at 0° obliquity, and when aircraft larlrrchcd,will also fire on ground or water impact when theangle of fail is 15 degrees or greater .

Detonator safety .

This fuze is detonator safe .When the fuze is unarmed, the detonator is heldpositively out of line with the booster lead-in bythe firing pin which protrudes into tile shuttercavity and holds the shutter inn an unarnnecl

CONFIDENTIAL.

CONFIDENTIAL

position ..1. 1

Tile firing pin

cannot

be withdrawnfrom the shutter cavity until the protective: cap isremoved, and cannot be rotated out of the shuttercavity until setback takes place. The shuttercannot move the detonator ill line with the lead-in until the propeller has turned the firing pin outeight revolutions and, finally until setback hasceased and the setback spring has moved theshutter locking pin out of the shutter cavity . ,


Sample fuzes fromproduction lots are subjected to rough handling-tests which are considered to be more severe thanconditions encountered during normal shippingand stowage.

Failure to pass these tests shall because for rejection of the lot .

The propeller can-not turn the firing pin out of the shutter cavity aslong as the nose cap is in place.

If the nose capshould become accidentally removed from thefuze, it would be necessary- for a prolonged set-back to take place at the swine time that a turning-force was applied to the propeller in order to armthe fuze .

5 . Disposal and Servicing (Maintenance)General . If the fuze is accidently armed,

whether assembled in the rocket head or not noattempt should be made to unarm it .

If the fuzeis armed, turning the propeller counterclockwiseas viewed from the nose will cause the firing pinto pierce the detonator and explode the booster .The fuze, is safe as long as the cap assembly isheld in place by the safetywire, or by the armingwire .

If the cap assembly conies off by accident,the fuze is still safe as long as the propeller isengaged by the propeller locking pin . This canbe determined by visual inspection. The fuzeshall be considered armed if the propeller is,out of engagement with the propeller lockingpin so that the propeller is free to rotate .Armed fuzes must not be fired from rocket launchers.If the fuze in an assembled round is armed inad-vertently, the propeller should be carefully- taped.to prevent further rotation and the fuze thencarefully unscrewed from the rocket, taking carenot to drop the round or the fuze on its nose orstrike the fuze. in any way. This work shouldbe done by Explosive Ordnance Disposirl Person-nel if avaihnble . The armed fuze should be dis-posed of by gently- lowering into deep water or bythe most feasible means, as determined by thecireunnstances .

If for any reason the cap has been

CONFIDENTIAL


removed from the fuze, but visual observation re-veals the fuze to be intact and the propeller posi-tively locked by the propeller locking pin, then thepropeller nnay be. securely taped, and the fuze re-turned to storage. Careful handling will be neces-sary, however, to avoid propeller dtnnnage andfuture usage will be limited to ground or shipboardlaunching- .

Disassembly . Disassembly- of this fuze is notpermitted except by authorized activities whendirected by the Bureau of Ordnance .

6. Installation Instructions1 . After the motor has been assembled to the

head, remove the nose plug from the rocket headand inspect the fuze seat liner. Clean if necessary.Make sure that the auxiliarybooster is present inthe bottom of the liner.

2 . Remove the fuze from the container and in-spect for damage . Check the cap and clamp as-sembly for corrosion. If slight corrosion exists,grasp clamp and rotate it around body so that itslides freely on body and cap. If the cap andclamp are badly corroded, it is best not to use thefuze.

If considered necessary a light coat of vase-line may be applied to the clamp assembly to aidin the prevention of corrosion and icing . If thefuze is defective, repack, and return it to an am-munition depot .

3. Install the fuze into the rocket head using theproper fuze -wrench. Be sure that both the fuzeand fuze adapter are seated properly .

4. After the assembled round is loaded on thelauncher, turn the clamp so that the clamp pin andbushing are on the same side of fuze as the armingwire .

Insert the. arming wire in the hole providednext to the safety wire .

Remove the safety wire .DO NOT REVERSE THIS ORDER. Save thesafety wire for reinsertion if the round is not fired.

5.safety

one Fahnestock clip on the free end ofthe arming wire and slip it ;against. the clamp bushing.

Adjust so that there is just enough slack 'inthe armingwire, between the arming wire releaselatch (on the aircraft) and fuze, to insure that thearming wire retaining plate does not get pulled outof the catch in the arming wire release .

Leave nomore slack than necessary.

6 . Clip the arming wire off about two or threeinches beyond the Falnnestock clip and dress thewire for burr removal .

5 1


Removal from round.

1 . Before removing the round from the launcher,insert the safety wire in its hole in the clampbushing. It may be necessary to squeeze thebushing and pin assembly longitudinally withpliers to line up the holes. After the safety wireis in place, remove the. arming wire . DO NOTREVERSE THIS ORDER .

2 . Remove the round from the launcher and un-screw the fuze . Examine the cap and clampassdmbly for damage or moisture .

Wipe off the

Section B-Nose Fuze Mk 155 Mod

1 . General DataUsed in : 3 .5-inch Rocket Head Mk 6 Mod 0

(Smoke)Overall dimensions and weight of fuze :

Length------------- 17 .44 inchesDiameter (maxi-mum) ------------ 2 .99 inches

Body threads------- 1 .700 inches---14 NS-1Weight------------ 3 .21bs. approx .

.Applicable specification : OS 3578General arrangement drawings : 423845Sketch list of drawings & specs : 109406Explosive components :A sensitive stab type compound DetonatorMk 23 (lead azide primer mixture, leadazide and tetryl) located in the shutterbetween the firing pin guide and lead-in disc .'

A lead-in assembly charge (tetryl) located inthe lead-in disc between the shutter andburster tube .

A burster tube charge (approximately 65grains tetryl) located in the burster tube .

2. DescriptionGeneral . The Fuze 111k 155 differs from the

Fuze Mk 149 only in that it is provided with aburster tube assembly instead of amagazine . Theburster tube has a 0.630-inch diameter and is14 .06 inches long .

Use . The fuze is used in the 3 .5-inch FinStabilized Aircraft Smoke Rockets (CompleteRounds) Mk 3 Mod 0 and Mod 1 (See OP 1415) .


The Fuze 'Mk 155 isexactly the same as the Fuze Mk 149 except atetryl filled burster replaces the tetryl filled boosterat the base end.

52

clamp if moist or corroded .

Replace the shippingplug in the head .7. Packing and Marking

Packing . 'Fuzes Ml. 149 are packed in indivi-dual, sealed, metal containers . Twenty-four fuzesare packed in a wood box 26 inches by 1632 inchesby 6% inches which represents 1 .6 cu . ft . and atotal weight of 96 pounds .Marking .

The fuze is marked to show the lettersNF, the marl:, mod, lot number, manufacturer'sinitials, date of loading, symbol of loading plant,and the anchor stamp.

0 (Setback and Air Arming, Impact Firing)


Same as Fuze Mk 149 Mod 0 .Firing .

Same as Fuze Mk 149 Mod 0 .Acceptance test data.

Completely loaded fuzesfrom each lot are installed in "FS" Smoke loaded3 .5-inch Rocket Heads Mk 6 Mod 0, using a3 .25-inch Rocket Motor NIlc 7, an arming wire andFahnestock clip, and fired from a land launcher at15 degree quadrant angle for water impact .

Thetemperature of the rocket propellant must be atleast 60 degrees Fahrenheit .

Acceptance is basedon a cumulative test plan designed to accept (95 0/0of the tithe) lots in which 98% of the fuzes functionsatisfactorily . Lots poorer than 98% will besubject to rejection with lots 91% effective beingrejected 90% of the time .

Any premature causesrejection of the lot. Eight completely loadedfuzes selected from the combined samples of fiveproduction lots are assembled in smoke loadedheads and fired from aircraft for water or groundimpact . The prescribed service arming wirearrangement is used . Half the samples are firedfor ground impact . Satisfactory performance isconsidered to be the high order functioning of atleast seven of the eight fuzes. Any prematurecauses rejection .

4. Safety FeaturesSame as Fuze Mk 149 Mod 0 .

5 . Disposal and Servicing (Maintenance)Same as Fuze i\7k 149 Mod 0.

6. Installation InstructionsThe assembly of the Fuze 7.\11,- 155,into the head

differs from the assembly of`the Fuze 114k 149 into

... CONFX&PNTVAl. . .

CONFIDENTIAL17-

the head only in that the burster tube of the FuzeMk 155 fits into a burster well and no auxiliarybooster is used .

7. Packing and MarkingPacking. Fuzes '-%Ik 155 are packed in indi-

vidual, sealed, metal containers . Twelve fuzes

CONFIDENTIAL


SAFETY PIN MUST NOT BE" REtXIOVED UNTIL ARMING WIREHAS SEEN INSERTED (USE: ONECLIP), AND ROCKET HASUEEN PLACED IIIN' LAUNCHERIF ROCKET I S NOT FIREDSAFETY PIN MUST RE REPLACEDBEFORE REf*91ING AR"JIN; DIRE

Figure 28-Nose Fuze Mk 155, External View, Full Size (approximately) except for Burster Tube Length .

are packed in a wood box 18 inches by 12 .8 inchesby 23 inches which represents 3.1 cu. ft . and atotal weight of 77 pounds .Marking. The fuze is marked to show the

letters NF, the mark, mod, lot number, manu-facturer's initials, date of loading, symbol ofloading plant, and the anchor stainp .

53


LEAD-IN (TETRYL)

BOOSTER (TETRYL)

54

UNARMEDPOSITION

SHUTTER STOP PIN

FIRING PIN

NOSE PLATE

PROPELLER LOCKING PELLET

SET-BACK SPRING

BODY

FIRING PIN GUIDE

SHUTTER SPRING

Figure 29-Nose Fuze Mk 155 Mod 0, Cross Section View, Unarmed Position .

SECTION X-X

BURSTER TUBE ADAPTER

£. F

CONFI0 ENTIAL.

CAP

CAP SPRING

PROPELLER HUB RIVET

GASKET

CLAMP

WASHER

CQNF.A DENT I-AL

L

CONFIDENTIAL


P

T

T

'P

E

CG

fG

.R

R

;R

R

R

PROPELLERLOCKINGPELLET

SHUTTER STOP PIN

SHUTTER

SHUTTER HINGE PIN

;;cal l _,,--SHUTTER SPRING

SECTION Z-Z

ARMED POSITION

Figure 30-Nose Fuze Mk 155 Mod 0, Cross Section View, Armed Position .

CONFIDENTIAL

55

56


7 .2-inch Rocket Head 1\11: 5 (High Capacity)7 .2-inch Projector Charge Head lfk 4 (High

Capacity)Overall dimensions and weight of fuze :

Lengtll-------------------- 7 .385 inchesDiameter (maximum)-__ _ -- _ 3 .125 inchesBody threads -------------- 2.00

inches-12 NS-2

Weight ------------------- 2 .81bs.approx.'Applicable specification : OS 3418General arrangement drawing : 438552Sketch list of drawings & specs : 109482Explosive components :

Detonator i\-1k 23 *Mod 0 (lead azide primingmixture and lead azide) contained inshutter assembly .

Booster lead-in charge (tetryl) contained inlead-in disc .

Booster charge (approximately- 9 grams tetryl)contained in magazine .


The Rocket Nose Fuze Mk 156 Mod 0is very similiar to its predecessor, Fuze Mk 131,except that it incorporates numerous changesfound desirable after extensive tests .

It is a verysensitive contact fuze which depends on setbackin air and passage through water to arm. After

Chapter 7

The fuzes described in this group are as follows :Section A-Nose Fuze Mk 156 Mod 0Section B-Nose Fuze bfk 158 i\fod 0

CCJNFIDENRAL

NOSE FUZES FOR 7.2-INCH ANTI-SUBMARINE ROCKETS AND 7.2-INCHPROJECTOR CHARGE AMMUNITION

Section A-Nose Fuze Mk 156 Mod 0 (Water Travel Arming, Impact Firing)

arming the fuze functions instantaneously uponimpact with any underwater obstruction and themechanism is so constructed that either normal oroblique impact will cause functioning. Arming isaccomplished by four to eight vane revolutionswhich occur within 15 to 25 feet of water travel .

Use . Fuze Mk 156 11-1od 0 is used in 7.2-incbHigh Capacity Surface Fin Stabilized Rockets(Complete Rounds) 1\1k 1 Mod 0 and 1\fk 1 Xfod 1(see OP 1415) . The fuze is used exclusivelyagainst submarines and its aerodynamic charac-teristics limit its use to low velocity rounds .

Functioning mechanism . The fuze housing con-sists of the fuze body, plug, and magazine . Thesteel fuze body is machined to accommodate thelead-in disc, shutter assembly, and firing assein-bly. The forward end of the body is providedwith external threads to engage the rocket head.when the fuze is installed and internal threads toengage the plug .The steel plug is machined out and provided

with internal threads to accommodate the am ingscrew. The aft end has external threads to en-gage the fuze body.The arming vane and arming vane hub are

secured to the arming screw by a set screw. Asetback collar is fitted over the plug neck andthe a.rining vane hub which provides a means oflocking the arming vane until the rocket is fired.

CONFIDENTIAL_

L

CONFIDENTIAL

7.2" A/S ROCKET AND PRO. CHARGE FUZES

>nieDr

isns;l .;hts.1ly,c-

n-hehen-edadto

edT1S

91-

.reAadof

,0 .

SAFE.TY PI<+s

2F-10 4`11, i

XL CONFIDENTIAL

Figure 31-Nose Fuze Mk 156 and Mk 155, External View, Full Size (approximately) .

57


ARMING VANE (4 BLADES)

SET SCREW

Z

SECTION X-X

Figure 32-Nose Fuze

SAFETY PIN MUST8E IN POSITIONDURING TRANSITAND STORAGE

010

X !dim X apor

PARTSECTION Z-Z

SHUTTER

DETONATOR

SHUTTERDETENT

UNARIVED POSITION

PbotXrXafALa

ARMING VANEHUB

SET-BACK COLLAR

PLUG

SAFETY PIN

ARMING SCREW

COLLAR SHEAR WIRE(Used on Nose FuzeMk 158 Mod.O. Notused on Mk 156

Mod . 0)

FIRING PIN SPRING

SLEEVE SPRING

STOP

SHUTTER

LEAD- I N DISC

LEAD-IN

BOOSTER

Mk 156 Mod 0 or Mk 158 Mod 0, Cross Section View,' Unarmed Position .

BODY

WEIGHT

58

.- .. . CONFIDENTIAL

GASKET

SEALING WASHER

SEALING COLLAR

BALLS (3)

FIRING PIN SLEEVE

FIRING PIN

SHUTTER HINGE PIN

SHUTTER DETENTSPRING LOCKING

HOLE

CONFIDENTIAL

Locking pins in the arming vane hub and theplug, respectively, fit into a slot in the setbackcollar, positively locking the arming vane untilthe setback force causes the setback collar tomove backward on the plug. The setback collaris maintained in the forward position by thetension of the flat spring plate on the lockingpins .An internal radial shear wire (inserted into

matching holes in the arming screw and plug)prevents the air stream from turning the armingvane and arming the fuze during air travel .The firing assembly located in the body cavity,

consists of the firing pin, the firing pin spring,the firing pin sleeve, the sleeve spring, the firingpin head, the weight, the retaining ring, andthree balls . When the fuze is unarmed, thefiring assembly is held in place by the armingscrew and the firing pin rests in a well in the shutterretaining it in the unarmed. position . With thefiring assembly in the unarmed position, thefiring pin is held in the cocked position, with thefiring pin spring compressed, by three steel ballswhich are wedged between the. firing pin headand the angular lip on the weight . The forceof the firing pin spring under compression keepsthe wedging action constant until the armingscrew is withdrawn and impact forces the weightforward.The shutter is located immediately below that

portion of the body tyhich forms the firing pinguide . The shutter contains a spring loadeddetent which locks it in the armed position . Atorsion spring rotates the shutter into the armedposition as soon as the firing pin is withdrawnfrom the shutter cavity .A lead-in disc containing a tetryl lead-in is

inserted immediately below the shutter and thebooster magazine containing a tetryl charge isscrewed into the base of the fuze body .

3. FunctioningArming . When the rocket with the fuze in-

stalled is fired from a launcher, setback forces atthe instant of firing cause the setback collar tomove backward and unlock the arming vane .The setback collar is prevented from moving for-ward again by the flat spring plate dropping downbehind the locking pin in the plug . The internalradial shear wire between the vane hub and theplug preveiitt the air stream froin turning the

CONFIDENTIAL

7.2" A/S ROCKET AND PROJ. CHARGE FUZES

arming vane and awning the fuze during airtravel . Upon impact with the surface of thewater, the impact force causes the arming vaneto rotate and shear the radial shear wire . Con-tinuing rotation of the arming vane withdrawsthe arming screw and arms the fuze . The firingassembly moves with the arming screw underforce of the sleeve spring until the firing pinsleeve meets the retaining ring . At the end oftravel of the arming screw, the rubber sealingwasher is jammed between the plug and thesealing collar, which is fastened to the armingscrew by a cotter pin, thereby sealing the fuze .As the firing assembly moves forward, the firing

pin is withdrawn from the shutter cavity, releasingthe shutter . The shutter spring rotates theshutter against the stop pin thus aligning thedetonator in the shutter nvith the booster lead-inand with the firing pill . Two pairs of sleeve stopsare pushed inward by the stop springs, one pairjust before the firing pin releases the shutter, andthe other pair just after the release .

Firing . Firing is initiated (after the fuze hasarined) by impact with any underwater obstruc-tion offering sufficient resistance . Inertia causesthe weight to move forward on normal impact orlaterally on oblique impact, thereby allowing thethree balls to move out and release the springdriven firing pin . The firing pin pierces and ini-tiates the detonator which in turn initiates thelead-in and magazine charge and in turn the mainexplosive charge in the rocket head .Acceptance test data .

Sample fuzes selected atrandom from each production lot are subjected toroutine safety tests and ballistic tests when fired inrocket ammunition in accordance with the follow-ing procedure :

1 . PREMATURE AND BLADE TEST--Fuzes fromeach lot, completely loaded except for inertboosters, shall be assembled in 7.2-inch rockets .Half the rounds shall be launched at a strikingvelocity of 170 feet per second, and the balance'at190 feet per second, into 25 feet of water with theround attached to a line and spring arrangement .All the rounds shall be recovered by suitable betsbefore striking the bottom, and the fuzes shall befully armed but not fired . Failure of any fuze; topass this test shall cause rejection of the lot .All of the fuzes used in this test shall be saved forthe "Functioning Test" described in the nestparagraph .

59

60


2 . FUNCTIONIXG TEST-The fuzes used forthe Premature and Blade Test shall be reused inthis test .

The fuzes shall be assembled in 7 .2-inchrockets (inert loaded to a Aveight of 65 pounds) .The rockets shall be fitted Avith a retarding discsuitable to limit the underwater terminal velocityto 22 or 23 feet per second . The fuzes shall beprearmed by the Premature and Blade Test anddropped in water so that the terminal velocity isreached, and the nose of the fuze strikes No. 1grade fir battens 1 ;4-inch x 3-inch laid flat Aviths4-inch spaces between them on supports two feetapart . The slats shall be firmly fastened to sup-ports which have a solid foundation . Ninetypercent high order functioning shall be consideredsatisfactory .

Sensitivity limits . Fuze Mk 156 Mod 0 is equip-ped with a spring driven firing pin and will fireafter arming upon impact with any underwater ob-struction which creates sufficient deceleration tomove the «--eight either forward on a normal im-pact or laterally on an oblique impact . Obstruc-tions such as the steel surface or the wooden deckgratings of a submarine will consistently functionthe fuze .


The fuze is detonator safeThe firing pin, protruding into the shutter cavitywhen the fuze is unarmed, holds the detonatorout of alignment with the tetryl lead-in and boostercharge .

Premature functioning of the detonatorwhile the fuze is unarmed will not detonate the.booster lead-in and booster .


Sample fuzes fromproduction lots are subjected to rough handlingtests Nvbich are considered to be more severe thanconditions encountered in normal stowage andbandling . Failure to pass the tests is cause forrejection of the lot . The setback collar preventsrotation of the water arming vane until the set-back forces, acting on the. collar at the instant offiring, cause it to move backward on the plug,thereby freeing the arming vane (except for theradial shear wire) .

A safety pin, NA-Inch is insertedthrough the setback collar, a plug, and an armingscrew, prevent movement of the setback collarduring transportation and stoNvage . The radialshear «wire, in addition to its primary function ofpreventing the vane from turning during the airtravel after being fired, also provides a, safety

feature . The arming vatic. Avill not be rotated,even if the setback collar has moved back on theplug, unless considerable force is applied to thevane.

5 . Disposal and Servicing (Maintenance)

General .

This fuze is very dangerous to handlewhen armed, therefore, disposal and handlingunder such circumstances is considered mosthazardous . Accordingly, the precautions beloware to be rigidly followed :

1 . The safety pin must be in place through thesetback collar at all times and not removed until justprior to the firing of the round .

In case the salvo isnot fired immediately after removal of the safetypin, the safety pin must: be reinserted .

2 . The setback collar of this fuze must not bemanually retracted under any operating conditions .

Disassembly .

Disassembly of this fuze` is notpermitted except at authorized activities whendirected by the Bureau of Ordnance .


To install the fuze in the rocket :1 : Remove the steel fuze cap and the shipping

plug from the nose of the charge .2 . Remove the cardboard shipping spacer

from the fuze seat liner .3 : Flake sure that the auxiliary booster

shipped with the charge is properly located .4 . Remove the fuze from its scaled container

and make sure that the safety pin is securely inplace .

5 . Screw the fuze into the nose of the rockethead, making sure that the gasket between thefuze and the fuze seat liner is in place . Tighten.with a spanner wrench so that the joint is water-tight . (NOTE : The pins of the spanner wrenchused (BuOrd Sk 119362) shall be fitted into theholes in the fuze body and not into the holes in theplug ; that is, they shall be fitted into the outerpair of holes .) Do not grasp the fuze by the armingvane or use a pipe wrench or any other tool on theplug, setback collar, or arming vane when installingthe fuze in a rocket. If this precaution is not fol-lowed, the plug may be unscreNved and/or thearming vane turned, thereby arming the fuze .There. is on record a serious accident caused bythe use of improper tools .

,CQNF1DENTIAL

CONFIDENTIAL_

" 6.- fteplr'ce the ftzzdXap over the fuze, forprotection against the weather and safety in han-dling. This coinpletes the installation for readyammunition .

7. After the, rockets are placed on thelauncher, and just prior to firing, remove thefuze cap and the safety pin through the setbackcollar .

Save the safety pins, so that they can bereinserted into the setback collars in case the salvois not fired . Daily inspections should be madeof all fuzed rounds to make sure that the fuze isin a safe condition and that the safety pin ispresent.

It is important that the following points bechecked:

1 . That the correct fuze is installed in theproper rocket and used with the proper launcher .

2 . That the fuze cap and safety pin are re-moved just prior to firing of the round .

3 . That the setback collar is in the forwardposition, with the spring plate over the vane lock-ing pins after installation .

4 . Daily inspections should be made of anyfuzed rounds which arc; on the launcher rails tosee that the safety pins are correctly installed andthe fuzes have not been partially or fully armedby some accidental means.Removal from round.

Should it become necessary,the fuze may be removed from the rocket headand returned to its container .

However, first besure that the safety pin through the setback collaris in place.

The fuze should be removed from the

CONFIDENTIAL_

Section B-Nose Fuze MI; 15£3 Mod 0

1 . General DataUsed in : 7 .2-inch projector charge Head 11Ik 4

(High Capacity) with Projector Charge TailMk 6.

Overall dimensions and weight of fuze :Length -------------------- 7 .385 inchesDiameter (maximum)---_ --- 3 .125 inchesBody threads-------------- 2 .00

inches-12 NS-2

Weight------------------- 2 .8 poundsApplicable specification: OS 3418General arrangement drawing: 438552Sketch list of drawings & specs: 109483Explosive components: Identical with Fuze NIlc

156 Mod 0.

7.2" A/S ROCKET AND PROD. CHARGE FUZES

round if for any reason the round is to be takenbelow decks . Use a spanner wrench (BuOrd Sk119862) to remove the fuze . (NOTE : The spannerwrench should fit the holes in the fuze body andnot the holes in the plug ; that is, it should fit theouter pair of holes.)

Do not grasp the fuze by thearming vane or use a pipe wrench or-any other tool onthe plug, setback collar, or arming vane when removingthe fuze from the rocket .

If this precaution is notfollowed, the plug may be unscrewed and/or thearming vane turned, thereby arming the fuze .

7. Packing and Marking

Packing . One fuze is packed in a sealed cylin-drical metal container 33i6 inches nominal diameter,and 8 .0 inches nominal length . The weight of thefuze and container is 3.36 pounds . A scoredmetal tear strip facilitates opening of the container.

The container is stamped with the markand mod of the fuze .Twenty-four fuzes, packed in the fuze con-

tainers, are packed in a wooden slipping box 25.5inches by 16 .5 inches by 9 .7 inches representing2 .3 cu . ft . The weight of the box and fuzes isapproximately 108 pounds .Marking.

The fuze body is marked or stampedwith the mark, mod, and lot numbers, the manu-facturer's initials or symbol, the initials or symbolof the loading facility, the month and year ofloading, the anchor stamp, and the inspector'sinitials .

(Water Travel Arming, Impact Firing)

2 . DescriptionGeneral .

Fuze Mk 158 Mod 0 is identical withFuze Mk 156 Mod 0 in all respects except thatFuze Mk 158 Mod 0 has a setback collar shearwire through the setback collar and the plug as anadded safety feature.

Fuze AR 158 Mod 0 is usedonly in the 7.2-inch Head \Ik 4 when assembledwith the Projector Cliarge Tail Mk 6. The pro-jector charge round («-hick is not a rocket) asfired from a Projector 11-lk 10 or 111. 11 is subjectedto considerable setback 'which permits the use ofa setback collar shear wire .

The propellant in the7.2-inch rocket, incorporating a Fuze Ml. 156,does not impart sufficient setback to sever a collarshear wire .

6 1

ARMING VANE (4 BLADES)


"CONS,IMXTIAL

SHUTTER

SHUTTER) Z-1 LDETONATORSECTION X-X

ARMED POSITION

Figure 33-Nose Fuze Mk 156 Mod 0 or Mk 158 Mod 0, Cross Section View, Armed Position .

62

CONFIDENTIAL

CONFIDENTIAL

The description and all instructions outlinedfor Fuze __Wk 156 Mod 0 apply to Fuze Mk 158Mod 0 . The addition of the setback collar shearwire does not change the functioning of the fuzein any way except that it requires a greater initialsetback force to initiate. arining.

Use.

Fuze itIk 15S Mod 0 is used in the 7.2-inch High Capacity Projector Charge Head lIlc 4assembled with the 2 .25-inch Projector ChargeTail Mk 6.

3. Functioning

Firing .

Instantaneous or superquick firing uponimpact is identical with Fuze 1-I1. 156 Mod 0.


The acceptance data forFuze Mk 15S Mod 0 are the same as for Fuze Ilk156 \Tod 0 except that in the Premature andBlade Test half of the fuzed rounds are launchedat 130 feet per second and the balance are launchedat 150 feet per second instead of at 170 feet and190feet per second .

In addition a collar shear wiretest is required on the Fuze Mk 158 llod 0.

Thisrequires that inert fuzes from every tenth lot be

CONFIDENTIAL

7.2" A/S ROCKET AND PROD. CHARGE FUZES

assembled in 7.2-inch Heads -'\,Ik 4, inert loaded,«-ith loaded Projector Charge Tails JTlc 6 and firedat a propellant temperature of approximately 0°I+' .for ground impact from a Projector Mk 10. Thefuzes are suitably protected by a reinforced capto prevent mutilation of the fuze and inspectionis made. to ascertain that the collar shear wire hasbeen sheared.

Failure shall cause rejection of thelot.4 . Safety Features

See Fuze Mk 156 Mod 0 and substitute Pro-jector Charge for Rocket .5 . Disposal and Servicing (Maintenance)

See Fuze 'NIk 156 1Tod 0 and substitute Pro-jector Charge for Rocket.6. Installation Instructions

See Fuze -'\Ik 156 Mod 0 and substitute Pro-jector Charge for Rocket .7. Packing and MarkingSee Fuze -'\Ik 156 Mod 0 and substitute Pro-

jector Charge for Rocket .

63

64

The fuzes described

*Base Fuzes

'

Chapter 8

BASE FUZES FOR FIN STABILIZED AIRCRAFT ROCKETS

in this group are as follows :

1 . General DataUsejl in :

1\Ik 157 '-\Iod 0 in 5 .0-inch Rocket Heads i1Tk 1and Alk 1 Mod 1 (General Purpose)

Mk 157 X-Iod 1 in. 11 .75-inch Rocket HeadIN1k 1 (Common)

1Mk 157 Mod 2 in 11 .75-inch Rocket Heads

XIls 1 \Tod 1 and Z-Ih 2 (Common)Overall dimensions and weight of fuze :Length

6.170 inches (Mod 0 & 1)6.196 inches (Mod 2)

Diameter (maximum) :2 .933 inches (i\.Iod 0 & 1)3 .200 inches (1Iod 2)

Body threads------- 2 .750 inches-14 NS-2Weight

3.40 lbs. approx . (Mod 0 & 1)3.50 lbs. approx . (\Iod 2)

Applicable specification : OS 3535General arrangement drawings :

438015 ('-\Iod 0)439629 (Mod 1)439630 (1lod 2)

Sketch list of drawings & specs :109475 (Mod 0)165111 (_NIod 1)165123 (J1od 2)

Section A--Base Fuzes '_\1k 157 '_Wods 0 *, 1 *,and 2Section B-Base Fuzes AIk 159 Mods 0* and 1Section C--Base Fuzes '-\ik 163 Mods 0 and 1Section D-Base Fuze -',\Ik 164 'Mod 0Section E-Base Fuze Mk 165 'Mod 0

11k 157 Hods 0 and 1 and AIk 159 lfod 0 have been withdrawn from service and issue .

Section A-Base Fuze Ml< 157 Mods 0, 1, and 2 (Pressure

Explosive components :

CONFIDENTIAL

Arming, Impact Firing)

Delay detonator assembly (adapted froin thedelay detonator assembly of Fuze Mk145 .) The assembly consists of a mercuryfulminate Percussion Primer Mk 106, anexpansion space, the 0.020 second blackpowder delay element and tl)e lead azideRelay Detonator Mk 31 Mod 0 all in a.single case closed by a crimp and located inthe shutter.

Booster lead-in charge (tetryl) located inlead-in disc .

Booster chharge (approximately 12 gramstetryl) located in magazine .


Fuze Ml. 146, which is now obsolete,was originally developed for use in the 5 .0-inchAircraft Rocket'.

Service use of the 5 .0-inch. Air-craft Rocket soon indicated that a longer delaythan that inherent in Fuze '-\lh 146 was necessarvin order to obtain the desired penetration of tar-gets before detonation .

For this reason Fuze Xllc146 was modified to incorporate a 0.020 second

115.0-inch rocket head assembled with a 3.25-inchrocket motor.

'CONFIDENTIAL

CONFIDENTIAL

delay detonator and designated Fuze '-\Ilc 157Mod 0 . Since the delay detonator has a per-cussion primor, the stab type firing pin of FuzeMk. 146 is replaced by a firing pin with a roundedpoint.

Fuze XIk 157 Mod 1 differs from Fuze Mk 157Mod 0 in that the head andbody are manufacturedfrom pearlitic manganese steel for additionalstrength, also the 2 .75-inch diameter threads onthe fuze head extend the full length of the bead .Fuze Mk 157 Mod 2 is identical with the FuzeMk 157 Mod 1 except that it provides for externalgas checking by means of the copper and leadgaskets .

Use .

Fuze A-lk 157 D-Iod o is used in the 5 .0-inchGeneral Purpose Fin Stabilized Aircraft Rockets(Complete Rounds) AIk 1 Mod 2, Ml. 1 Mod 4,Mk 1 Mod 5, and Mk 4 Mod 0 (see OP 1415) .Rockets employing these fuzes are used againstshipping, light fortifications, such as pill boxes, andpersonnel .

Fuzes Mk 157 Mod 1 and 'Mod 2 areused in the 11 .75-inch Common Fin StabilizedAircraft Rockets (Complete Rounds) NIk 3 \Iod 0and Mk 3 Mod 1 (sec OP 1415).

The 11 .75-inchAircraft Rockets utilizing Fuzes Mk 157 Mod 1and Mod 2 are used against shipping and heavyfortifications . Fuze Mk 157 and Nods will firewith a 0.020 second delay upon impact withsuitable targets.


Two parts called thehead and bodv house the fuze mechanism .

Thehead containsVa gas chamber formed by the plugand the diaphragm .

Gases from the rocket motorare permitted to flow slowly into the gas chamberthrough an orifice in the inlet screw, after firstbeing filtered by the inlet screen . Immediatelybeneath the diaphragm and in the body, an alumi-num arming plunger is held in position by a shearwire .

In the unarmed position. the awning plungerholds a locking hall in such a position as to lochthe firing pin body and firing pin in the forwardposition, compressing the firing pin spring . Whilein the forward. position, the firing pin extendsthrough the firing pin guide and into a cavity inthe shutter. This cavity in the shutter is sopositioned that when envagcd by the firing pin thedelay detonator assembly is out of alignment withthe tetryl booster lead-in and the firing pin .Rotation of the shutter to bring the explosive

CONFIDENTIAL

AIRCRAFT ROCKET BASE FUZES

Figure 34-Base Fuze Mk 157 Mod 2, External ViewFull Size (approximately).

elements in line, when released by withdrawal ofthe firing pin, is accomplished by means of theshutter spring . Since the firing pin must notpuncture the cover of the percussion primer, thefiring pin is made so as to shoulder against theface of the detonator case so that the point willindent the proper distance into the primer . Toavoid crushing of the detonator case by the weightof both the, firing pin and firing pin body on heavyimpacts, the firing pin is secured in the firingpin body by means of a shear wire . On heavyimpacts the inertia of the firing pin body shears

65


the wire holding the firing pin, and the two partstelescope .A lead-in disc containing a tetryl lead-in charge

is inserted in the fuze body between the shutterand the tetryl magazine clia.rge .3. FunctioningArming .

The fuze head screws into an adapterfixed in the base of the rocket head . The gasketand the luting on the threads of Fuze Mk 157Mods 0 and 1 or the projectile type gas theca.used with Fuze Mk 157 Mod 2, are provided tomake a gas tight seal in the adapter between- therocket motor and the interior of the rocket head .The rear end of the fuze (the exterior surface ofthe plug) is exposed to the. front end of the rocketmotor.

The fuze arms in two stages :1 . Gases from the rocket motor, at pressures

ranging front 300 to 1600 psi for the 3 .25-InchMotor Ml: 7 and 800 to 2350 psi for the 1.1 .75-inchMotors Mk 1, enter the pressure chamber in thehead of the fuze through a small orifice in theinlet screw. Debris from the rocket motor isfiltered out by the inlet screen . When pressurein the chamber lras reached a value of 275 to 325psi, which is delayed by the small orifice untilapproximately half the propelbint burning time isconsumed, the diaphragm collapses . forcing thearming plunger clown and shearing the shear wirewhich holds the arming plunger in place. Jlove-ment of the awning plunger releases the lockingball, which, in the unarmed condition, locks thefiring pin body- in place, and allows the latter tomove toward the rear under the force of the firingpin spring and the inertia of the firing pin bodydue to acceleration . The firing pin, attached tothe firing pin body, is thus witlrdrmvn from thedetonator shutter, which it normally locks in thesafe position .

2. When the rocket accelerates, the inertia ofthe sbutter forces it back against the firing pinguide, coinpressing the shutter spring and engaging the shutter locking pin in a hole in thefiring pin guide. About midway during accelera-tion, the firing pin is withdrawn from the shutter ;but the shutter, held by the shutter locking pin,remains locked in the safe position .

Wlren acceleration is over, the shutter springforces the shutter forward against the lead-in discdisengaging the shutter locking pin from the bolen the firing pin guide. The shutter spring then

- 66

CONFlPENTIAL..rr . r, a

swings the shutter into the armed positiontonator assembly in line with firing pin and lead-in) where it is locked by the deterit. (See para-graph 4 for arming distance of Fuze _Mk 157 andNods.)

Firing . The fuze fires upon impact with anymaterial offering sufficient resistance . Under theforce of impact the inertia of the, firing pin bodydrives the firing pin forward, striking and initiatingthe percussion primer in the detonator assembly .'1'he percussion primer initiates the explosive trainin the detonator assembly (i . e., black powderdelay and relay detonator) . The detonatorassembly in turn initiates the tetryl lead-in andtetrvl booster, which detonates the main explosivecharge of the rocket head, either directly or throughthe auxiliary booster .


Sample fuzes selected atrandom from each production lot are subjected toroutine safety tests and ballistic tests when firedin rocket ammunition in accordance with thefollowing procedures :

1 . Completely live-loaded fuzes from eachlot shall be assembled in explosive loaded 5.0-inchRocket Heads Ml: 1 fitted with fiat nose shippllrnplugs and 3 .25-inch Rocket Motors 'Mk. 7 andshall be fired at angles of elevation from 8 to 11degrees for noticeable delayed action high orderfunctioning after water impact . Satisfactory per-formance for this test shall be considered 90%delayed action high order functioning .

2. Completely live-loaded fuzes from each ofthe first twenty lots and from the 25th, 30th,35th, etc., lots thereafter shall be assembled inexplosive loaded 5 .0-inch Rocket Heads Nllc 1fitted with pointed steel nose plugs and 3 .25-inchRocket Motors NII.: 7 and fired for impact againstX-inch, 31-inch, 1?-inch, "-inch, and 1-inch STSplates at the discretion of the Naval ProvingGround for the purpose of adding to the presentknowledge of the plate performance of this fuze .Performance of the fuzes in this test shall bereported but shall not be an essential criterion indetermining the acceptance of the lot.

Sensitivity limits.

Because the percussion primeris less sensitive than the stab type sensitiveprimer, Fuze 'Mk 157 is less sensitive than FuzeNlk 146. Tests of Fuze Mk 157 against plateindicated that functioning on mild steel platetargets less than ;/ inch in thickness is unreliable .

CONFIDENTIAL

C6NFI NTIAL


Fuze 11k 157 i\-1ods 0, 1, or 2is detonator safe . In the unarmed position, thedetonator assembly is out of alignment with theexplosive train . Should the detonator assemblyfunction prematurely, the force of the detonationwill be dissipated upward tbrouglr a bole in thefiring pin guide and away from the balance of theexplosive train. Because of the delay in ad-mission of gas from the rocket motor to thepressure chamber, the first stage in arming doesnot occur until approximately one-quarter to one-half of the rocket propellant burning time iscompleted . Because of this delay, if the rocketmotor blows up before it leaves the launcher, thefuze should not arm. Awning is not completeduntil after acceleration has dropped to a valuecorresponding to nine g. The burning distance,and therefore the arming distance, will vary withthe temperature . On the average, arming iscompleted about 0 .1 second after the end ofburning.

Approximate arming distances for FuzeMk 157 and Mods in the 5.0-inch and the 11 .75-inch aircraft rockets are :


Sample fuzes fromeach production lot are subjected to roughhandling tests which are considered more severethan conditions encountered during normal ship-ment and stowage. Failure to pass these testsshall be cause for rejection of the lot.5. Disposal and Servicing (Maintenance)

General . From an examination of the exteriorof the fuze, it is impossible to tell whether ornot the fuze is armed. If, for any reason, it is


Section B-Base Fuze Mk 159 Mods 0 and 1 (Pressure Arming, Impact Firing)

_\lk 159 Mod 0 in 5 .0-inch Rocket Head M1. 6Mod 0 (General Purpose)

l\Ik 159 'Mod 1 in 5.0-inch Rocket Head 1Ik6 Mod 1 (Generrd Purpose)

CONFIDEIVIAL


thought that the fuze may be armed, it should betreated as an armed and sensitive fuze . Noattempt should be made to remove the fuze fromthe rocket body. The complete fuzed roundshould be disposed of by gently lowering it, tailfirst, into deep water, or by Explosive OrdnanceDisposal Personnel in accordance with existinginstructions .

Disassembly . Disassembly is not permitted ex-cept at authorized activities when directed bythe Bureau of Ordnance .6. Installation InstructionsThe fuze is shipped installed in the base of the

rocket head . A safety wire is not necessary andno preparations are required to ready the fuzefor use .

A shipping plug or shipping cap protectsthe exposed end of the fuze and the outside threadsof the head . The shipping plug or the shippingcap should be kept in place until the round isassembled and should be promptly replaced if theround is disassembled . Before assembling therocket head to the rocket motor be certain thatthe fuze is in place in the base adapter, and that thegas cheek gaskets are properly installed whererequired .

7. Packing and MarkingPacking . Fuzes will be shipped assembled in

the rocket heads and protected by a shipping plugwhich screws into the base adapter or by a ship-ping cap which screws over the outside threadsof the head.Marking .

The fuze is marked or stamped withthe mark, mod, and lot number ; the date of load-ing; the manufacturer's initial or symbol ; and theinitials or symbol of the loading facility ; themonth and,year of loading ; the anchor stamp ; andthe inspector's initials .

Overall dimensions and weight of fuze :Length :

5 .812 inches (Mod 0)5 .813 inches (Mod 1)

Diameter (maximum) :2 .965 inches (Nlod 0)3 .200 inches (Mod 1)

67

a o a

Temperature------------------ 0 F. 70 F. 135 F.5.0-in . AR (3 .25-in . Ml. 7 Motor)- 575 ft . 350 ft . 250 ft.11 .75-in . AR (11 .75-in . Mk 1

Motor) --------------------- 670 ft . 450 ft . 350 ft .

6 8


Body threads------- 2.750 inches-14 NS-2Weight :

3 .4 lbs. approx . (Mod 0)3.5 lbs. approx . (l Tod 1)

Applicable specification: OS 3585General arrangement drawings :

422550 (Mod 0)439631 (Mod 1)

Sketch list of drawings & specs:109605 (-Iod 0)165124 (-NIod 1)

Explosive components:Delay detonator assembly (adapted from the

delay detonator assembly of Fuze _\Ik 157.The assembly consists of a mercury ful-minate Percussion Primer lIk 106, an ex-pansion space, the 0 .015 second blackpowder delay element and the Relay Det-onator Mk 31 \rod 0 (lead azide) assem-bled in a single case closed by a crimp con-tained in shutter.

Booster lead-in charge (tetryl) contained inthe lead-in disc .

Booster charge (approximately 12 gramstetryl) contained in magazine .

2. DescriptionGeneral . Fuze Mk 159 is a modification of

Fuze Xlk 157 to satisfy the fuze requirements fora higher velocity fin-stabilized rocket employinga 5 .0-inch rocket motor and a 5.0-inch rocket head.Accordingly the arming constants were adjustedto the burning characteristics of the 5 .0-inchRocket Motor Nfk 1 and 2 . The major cba.ngesincorporated in Fuze ilk 159 are as follows :

1 . Diameter of inlet orifice-0.0145 inches .2. Diameter of shear wire-0.064 inches .3. Groovedinlet-washer used instead of screen .4. Fuze must arm betvv-een 325 and 375 psi.5. Delay of 0 .015 second .

Fuze Ilk 159 !\Iod 0 is sealed in the rocket headby a. copper gasket under the fuze head flange .Fuze Mk 159 XIod 1 has the flange head diameterincreased to 3 .2 inches and a projectile type gascheck is used .

Use . Fuze Mk 159 -\Tod 0 is used in the 5.0-inch General Purpose Fin Stabilized AircraftRocket (Complete Round) '-\Ik 4 '-\Iod 0 (see OP1415). Fuze Mk 159 Mod 1 is used in the 5 .0-

Figure 35-Base Fuze Mk 159 Mod 1, External View,Full Size (approximately).

inch General Purpose Fin Stabilized AircraftRockets (Complete Rounds) Mk 4 Jlod 0 and Mk26 Mod 0 (see OP 1415) . Just prior to assemblyof the round on aircraft, a Nose Fuze \lk 149 isusually installed in the bead .

The latter fuze, canbe fired instanteous or safe, depending upon thetarget . This permits the use of a, round withselective fuze action (instantaneous or 0.015second delay) at the tune of firing . The aboverockets are used against light fortifications, tanks,locomotives, and similar targets.

CONFIDENTIAL-

CONFIDENTIAL

SHEAR WIRE

HEAD LOCKING SCREW

LOCKING BALL

BALL RETAINING PLUG

ARMING PLUNGER

FIRING PIN BODY

FIRING PIN SPRING

FIRING PIN

FIRING PIN GUIDE

DETENT SPRING

DELAY DETONATORASSEMBY

X-DETONATOR

LEAD-IN

LEAD-IN DISC ASSEMBLY

SHUTTER SAFETY PIN

BODY

MAGAZINE

BOOSTER PELLETS

ARMED POSITION


Same as Fuze Mk 157-except as previously noted above.3 . FunctioningArming .

Arming is identical with Fuze X-Ik 157.Firing . Firing upon impact is identical with

Fuze AIk 157 .

CONFIDENTIAL


UNARMED POSITION

Figure 36-Base Fuze Mk 159 Mod 0, Cross Section View, Armed and Unarmed Position .


Those fuzes selected forfunctional test are assembled in the proper rockethead fitted with a flat nose shipping plug and a5.0-inch Rocket 'Motor Mk 2 and fired from asurface launcher at 15 degrees elevation for waterimpact . Acceptance is based on a cumulative

69


7 0

UNARMEDPOSITION

Figure 37-Base fuze Mk 159 Mod 1, UnarmedPosition Showing Gus Checking .

1 . General Data

Section C-Base Fuze Mk 163 Mods 0 and 1 (Pressure Arming, Impact Firing)

Used in : 11 .75-inch Rocket Head \1k 1 _1od 1and Mk 2 Mod 0 (Common)

Overall dimensions and weight of fuze :Length-------------------- 6.49 inchesDiameter (maximum)--_ _ --- 3 .2 inchesBody threads-------------- 2 .75 inches-

14 NS-2Weight -------------------- 3.41bs .approx.

Applicable specification : OS 3699General arrangement drawing : 561459Sketch list of drawings a: specs:

165238 (Mod 0)165442 (Mod 1)

Explosive components:Delay detonator assembly (adapted from the

delay detonator assembly of Fuze NIk 157.The assembly consists of a mercury fulmi-nate Percussion Primer N1k 106, an expan-sion space, the 0.020 second black powderdelay element, and the Relay Detonator

COPPER GAS CHECK GASKET test plan designed to accept (95% of the time) lotsin which 95% of the fuzes function satisfactorilylots poorer than 95% will be subject to rejectionwith lots 80% effective being rejected 90% of thetime .

Sensitivity limits . The sensitivity of Fuze Mk159 is the same as for the Fuze loll: 157.

4. Safety FeaturesSame as Fuze Mk 157 .

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5. Disposal and Servicing (Maintenance)Same as Fuze Ml. 157 .

6. Installation InstructionsSame as Fuze Mk 157 .

7. Packing and MarkingSame as Fuze N11: 157.

Mk 42 Mod 0 (lead a,zide) assembled in asingle case closed by a crimp and containedin shutter .

Booster lead-in charge (tetryl) .Booster charge (approximately 12 grams

tetryl) contained in magazine .2 . Description

General.

TheBase Fuze Mk 163 Hods 0 and 1was developed by modifying Fuze Alk 157 Alod 2.It has essentially the same functioning mechanismwith the following modifications included to im-prove the performance on heavy oblique impacts :

1 . A setback block and setback spring is in-cluded in the lead-in and shutter lock assemblywhich takes the place of the lead-in disc in FuzeMk 157.

The setback block with the shutter lockpin attached provides a more positive setbackoperated, arming delay. During acceleration ofthe rocket, the setback spring is compressed bythe inertia of the setback block, and the shutter-lock pin engages the detent hole in the shutter.When acceleration is over, the shutter-lock pin,. is .

CONFIDENTIAL

CONFIDENTIAL

CONFIDENTIAL

Figure 38-Base Fuze Mk 163, External View,Full Size (approximately) .

withdrawn, releasing the shutter, which in turnis then rotated into the armed position by theshutter spring.

2 . The possible gap of 0 .05S inches betweenthe detonator and lead-in is reduced to 0.025inches, for more positive assurance of high orderfunctioning.

3 . The shutter is hinged at both ends of thehinge-pin, and another detent is added. The useof two detents reduces the probability of the


SHUTTERHINGEPIN

SAFETYDETENT--_MFX I WW,X'SHUTTER

SPRINGLEAD- IN

SHUTTERLOCK PI

SET-BACKBLOCK

SPRING XX\\, ,

, t --

N

(Positionwhen rocket

SPACER-/

occeleroting)

SECTION Y - YUNARMED POSITION

DELAYDETONATORASSEMBLY

Figure 39-Base Fuze Mk 163 Mod 1, Partial CrossSection View Showing the Operation of the SetbackBlock when Rocket Accelerating.

shutter being knocked out of position by an ob-lique impact . The shutter spring functions onlyas a torsion spring and. not as a compression andtorsion spring as in Fuze X-lk 157 .The overall length of Fuze NTk 163 is approxi-

mately 0 .33 inches greater than that of Fuze Ml.157 'lod 2. The additional length requires adeeper fuze cavity in tl)e head filler .

Fuze '-\fk 163 Nlod 0 has arming constant thesame as the -fk 157 b'Iod 2. When the inletscreen was replaced by 4 filter formed by compress-ing Inconel wire mesh and the inlet orifice andshear wire were replaced by those from the FuzeMk 159'XTod 1, the fuze was designated the -\Tk163 Alod 1 . 'These changes increased the armingpressure (310 to 375 psi) and partial arming delay .

7 1


LEAD-IN

\

I \\`\

MEWASHERANDSHUTTERLOCK

/X\ S /.V

\1 1.11"/11 ' 11/1,

1

BOOSTERASSEMBLY '

CHARGE

72

ARMED POSITION

DELAYDETONATOR

w v

- SHUTTERASSEMBLY-

SPRING

SECTION Z-Z

Figure X30-Base Fuze Mk 163 Mod 1, Partial CroslSection View, Armed Position .

Use.

Fuze 1Xlk 163 NIods 0 and 1 is used in. the.11 .75-inch Common Fin Stabilized Aircraft Rock-ets (Complete Rounds) Mks 3 _\-7od 0 and NIk 3Mod 1 (see OP 1.415) . The 11 .75-inch Rocket

1 . General DataUsed in : 5.0-inch Rocket Head Mk 6 '-,\Iod 1

(General Purpose)

Overall dimensions and weight of Fuze :Length -------------------- 6.18 inchesDiameter (maximum)------- 3.2 inches

DELAYDETONATORASSEMBLY

SHUTTERHINGEPIN

Head Mk 2 Mod 0 contains three Mk 163'Ftizcs,,The complete round is used against shipping andheavy fortifications . Fuze '-\Ik 163 will fire with0 .020 second delay upon impact with a suitabletarget .

Functioning mechanism. The functioning mech-anism in Fuze 2\Tk 163 is the same as in Fuze 1VIk157 except as noted in paragraph 1, General .3. FunctioningArming . Arming of Fuze Mk 163 is identical

with Fuze _lk 157 except that the shutter is keptfrom rotating into the armed position by theshutter locking assembly until acceleration hasceased .

Firing . Firing upon impact is essentially thesame as with Fuze -\Ik 157 .Acceptance test data .

Those fuzes selected forfunctional tests are assembled in explosive loaded5.0-inch Rocket Heads 11k 6 11Iod 1 fitted with aflat nose shipping plug and 5.0-inch Rocket MotorsMM 2 .

The rounds are fired from a ground launch-er at an angle of elevation of approximately 15degrees for water impact .

Acceptance is based ona curnuhitive test plan designed to accept (95% ofthe time) lots in which 92% of the fuzes functionsatisfactorily ; lots poorer than 92°/o will be subjectto rejection with lots 78% effective being rejected90% of the time .

4. Safety FeaturesSame as Fuze kIk 157.

5 . Disposal and Servicing (Maintenance)Same as Fuze Mk 157.

6. Installation InstructionsSame as Fuze Mk 157.

7. Packing and MarkingSame as Fuze Mil: 157 .

Section D-Base Fuze Mk 164 Mod 0 (Pressure Arming, Impact Firing)

Body threads --------------- 2 .75

inches-14 NS-2

Weight------------------- 3 .40

lbs.

ap-prox .

Applicable specification : OS 3675General arrangement drawing : 561460Sketch list of drawings & specs: 165239

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Figure 41-Base Fuze Mk 164 Mod 0, External View,Full Size (approximately) .

Explosive components:

Delay detonator assembly (adapted from thedelay detonator assembly of Fuze ilk 157.The assembly consists of a mercury fulmi-nate Percussion Primer lIk 106- an expan-sion space, the 0 .015 second black powderdelay element and the Relay Detonator2\1k 42 llod 0 (lead azide) assembled in asingle case closed by a crimp and containedin shutter.

Booster lead-in charge contained in the lead-in and shutter lock assembly (0 .243 gramstetryl).

Booster charge (approximately 12 grantstetryl) contained in inagazino .

CONFIDENTIAL

2. Description


General . The Fuze 111c 164 Jlod 0 is essen-tially the same as Fuze D'Ik 159 'Mod 1 with thefollowing exceptions :

1 . The lead-in and shutter lock assembly ofFuze -'\Ik 163 replaces the lead-in disc of FuzeMk 159.

2. The shutter is hinged at both ends of thehinge-pin and two detsnts are used as in FuzeA'ik 163.

3. The possible gap of 0.058 inches betweenthe detonator and the lead-in is reduced to 0 .025inches for more positive assurance of high orderfunctioning .

4 . The Fuze Nlk 164 uses an Inconel meshfilter covered by a plain flat washer .

Use. Fuze

164 is used in the 5 .0-inchGeneral Purpose Fin Stabilized Aircraft Rockets(Complete Rounds) 'Mk 4Mod 0 and Nlk 26 Mod 0(see OP 1415) .

A -Nose Fuze IVIk 149 which canbe fired instantaneous or safe is usually assembledin the nose of the rocket head to provide pre-selective fuze action of either instantaneous or0.015 second delay . The complete round is usedagainst tanks, locomotives, gun emplacements, andsimilar targets.


The functioning mecha-nism of Fuze 1Ik 164 is the same as Fuze 'A1k 163 .

3 . FunctioningArming . Arming of Fuze 111. 164 is identical

with Fuze N1k 163 .Firing . Firing upon impact is identical with

Fuze NIk 163.Acceptance test data .

Same as Fuze '-\-Ik 163 .

4 . Safety FeaturesSame as Fuzc ilk 157.

5 . Disposal and Servicing (Maintenance)Same as Fuze X1k 157.

6. Installation InstructionsSame as Fuze *_%, 1k 157.

7. Packing and MarkingSame as Fuze 1\1k 157.

73

2* Description

3 . Functioning

74


1 . General DataUsed in : 5.0-inch Rocket Head Mk 1 and Mk 1Mod 1 (General Purpose)

Overall dimensions and weight of fuze .Length ------------------- 6 .97 inchesDiameter (maximum)------ 3 .885 inchesBody threads------------- 3 .625 inches-

12 NS-2Weight------------------- 5.31bs . approx .

Applicable specification : OS 3817General arrangement drawing: 561458Sketch list of drawings & specs : 165240Explosive components:Delay detonator assembly (Same as Fuze 1`7k

163 Mod 0 and 1)Booster lead-in charge contained in the lead-

in and shutter lock assembly .Booster charge (approximately 12 grams

tetryl) contained in magazine .

General.

Fuze Mk 165 Mod 0 is a. modificationof Fuze Ml. 157 Mod 0. The functioning mechan-ism is essentially the same except that it containsthe improved shutter and lead-in and shutter lockassembly from Fuze Mk 163 .

The fuze head andfuze-to-motor adapter are made in one piece toimprove the seal between the rocket motor andthe interior of the rocket head .

Use. Fuze Ml. 165 Mod 0 is used in the 5.0-inch General Purpose Fin Stabilized AircraftRockets (Complete Rounds) Mk 1 Mod 2, Mlc 1Mod 4, and Mk 1 Mod 5 (see OP 1415) . Therocket is normally fired with a Nose Fuze Mk 149assembled in theV rocket head to permit pre-selec-tive fuze action of instantaneous or 0_Q2"econddelay. The round is used against personnel andlight targets.

Arming . The awning of Fuze 12k 165 is iden-tical with Fuze Mk 164.

Firing . Firing upon impact is identical . withFuze Mk 164.

4. Safety Features

Section E-Base Fuze Mk 165 Mod 0 (Pressure Arming, Impact Firing)

CONFIDENTIAL

Figure 42-Base Fuze Mk 165 Mod 0, Partial CrossSection View, Unarmed Position .

Same as Fuze Mk 157.


Fuzes selected for func-tional test are assembled with explosive loaded5.0-inch Rocket Heads Mk 1 fitted with flat noseshipping plugs and 3.25-inch Rocket Motors Mk7 and fired from a surface launcher at approxi-mately 15 degrees elevation for water impact .Acceptance is based on a cumulative. test plnn toaccept (95% of the time) lots in which 920/0 ofthe fuzes function satisfactorily ; lots poorer"than92% will be subject to rejection -,with lots 780effective being rejected 90% of the time .

5. Disposal and Servicing (Maintenance)-Same as Fuze Mk 157 .

6. Installation InstructionsSame as Fuze Mk 157.

7. Packing and MarkingSame as Fuze Mk 157.

CONFIDENTIAL.

's

e

0ifny0

CONFIDENTIAL


Figure 43-Base Fuze Mk 165 Mod 0, External View, Full Size (approximately).

.L CONFIDENTIAL

75

76

Fuzes Mk 162 and Mk 166 constitute the fuzesin the groupknown as Deceleration DiscriminatingRocket Fuzes . These fuzes in their cycle offunctioning depend on pressure awning fromrocket motor gases, deceleration in air (creep), anddeceleration after impact . The latter permitsdiscrimination of targets until the decelerationreaches a certain amount in accordance with thefuze design .The -complex nature of the fuze requires that a

considerable variety of tests be made to establishthe complete details of performance. Most ofthese tests were performed . However, rocket fuzedesign and development for the Bureau of Ord-

Section A-Base Fuze Mk 162 Mod

1 . General DataUsed in : 11 .75-inch Rocket Head A-Ik 2 Mod 1

(Common)Overall dimensions and weight of fuze :

Length------------------ 6 .795 inchesDiameter (maximum)--_-- 3 .200 inchesBody threads------------ 2 .75 inches-

14 NS--2AV, eight----------------- 4.90 lbs .

approx .Applicable specification : OS ;3856General arrangement drawing : 561465Sketch list of drawings & specs : 16,5244Explosive components :

A Percussion Primer Mk 101 (mercuryfulminate primer mixture) located inthe primer holder at the aft end of thedetonator case .

A 0.010 second black powder delay ele-ment, located in the delay pellet containerin the detonator case .

Chapter 4

DECELERATION DISCRiMINATINC BASE FUZES FOR FINSTABILIZED ROCKETS

0 (Pressure Arming, Deceleration Firing)

CONFIDENTIAL

nance was accomplished almost entirely by theCalifornia Institute of Technology . Inasmuch asthese fuzes were amongst the latest fuzes designedby that activity, the end of the war and consequenttermination of fuze activities prevented the com-pletion of some additional tests that appeareddesirable . For these reasons and because of fuzesafety problems that were encountered in thedesign by Bureau production contractors, theFuzes *-11k 162 Mod 0 and tiIlc 166 Mod 0 are notconsidered fully developed as of the. date of thispublication. Bureau projects, now under way,have been instituted to develop a more reliablefuze under all conditions of use and testing.

A Detonator Mk 33 Mod 1 (lead azide) lo-cated in the detonator case .

Two detonator case lead-outs (tetryl) locatedin the detonator case .

Twobody lead-ins (tetryl) located in the body .Two body lead-outs (tetryl) located in theforward end of the body .

A booster (approximately 28 grams tetryl)located in the magazine at the forwardend of the body .

2 . DescriptionGeneral. Fuze Mk 162 is designed to detonate

the round as it nears the end of its stable under-ground or underwater trajectory, or at any pointwithin this trajectory after an impact, or afterpassing through a. target backed by air. Thefuze fires after the deceleration of the round hasdropped below about 45 g. This corresponds to adistance of approximately 200 feet of unobstructedunderwater travel when the striking velocity ofthe round is 1300 feet per second .

. CONFIDENTIAL

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Figure 44--Base fuze Mk 162 Mod 0, External.

View, Full Size (approximately) .

Use. The fuze is used in the 11 .75-inch Com-mon Fin stabilized Aircraft Rocket (CompleteRound) -Nile 3 -Mod 2 (see OP 1415) .

The round is

CONFIDENTIAL

DECELERATION DISCRIMINATING BASE FUZES

particularly effective against shipping, earthcovered pill boxes or bunkers, light and heavyfortifications, and very heavy vehicles and stune-tures.


The fuze housing con-sists of a. steel body, the forward end of which isclosed by a booster magazine and the after endof which is closed by a gas chamber plug .The mechanism is contained in the fuze body,

the after end of which contains a double chamberformed by the plug, the baffle cup, and the dia-phragm . Gas from the rocket motor, utilized inarining the fuze, enters these chambers throughthe inlet valve . The diaphragm seals off theremainder of the fuze body cavity . Immediatelybeneath the diaphragm an aluminum armingsleeve is held in position by a shear wire . A pinthrough the arming sleeve engages the rotor, whichis spring loaded by a torsion spring . The axialslots inside the rotor, which engage the armingsleeve pin, also engage the detonator plunger pinof the detonator plunger, and two pins pressedinto the trigger block engage the rotor.

A springloaded firing pin is contained in the detonatorplunger, to which is attached the detonator casecontaining the Primer Xlk 101, the 0 .010 seconddelay, Detonator N1k 33 Mod 1, and the detonatorcase lead-outs .

1n the unarmed position the detonator caselead-outs are so oriented that the detonatorplunger assembly must be rotated 90 ° and alsomoved forward to line up the lead-outs with thebody lead-ins . In the unarmed position thedetonator plunger assembly is constrained frommoving forward by the stop pins in the side of thefuze body . The locating pin in the fuze bodyserves to orient the detonator plunger assemblyand rotor cap assembly with respect to the fuzebody. The spring loaded firing pin is held cockedby four lock balls, which are held in place by thetrigger block. The trigger spring is compressedbetween the trigger latch and a shoulder on thetrigger block. The trigger latch balls, bearingagainst the detonator plunger and a groove in thetrigger latch, lock the trigger latch with respectto the trigger block. The closing plug serves toobturate and close the end of the fuze body cavity,and the magazine containing a tetryl boosterpellet covers the eiid of the fuze body .

77

3. Functioning


Arming . The arming schedule utilizes thefollowing forces : 1 . Forces due to motor gaspressure, 2. Spring force, 3 . Creep force, 4. Im-pact forces . The four principal steps of armingoccur in the following manner :

1 . Fuze arming is initiated by gas from therocket motor, which enters the fuze through theinlet valve. Residue associated with burning ofthe propellant is filtered out by the inlet valvefilter, which is made of Inconel wire mesh. Gasentering through the inlet orifice impinges on theinlet valve ball, forcing it forward off its seatto compress the inlet valve spring, and permitthe gas to enter the first pressure chamber slowly.The gas is then allowed to flow more slowly intothe second pressure chamber through a smallerorifice drilled in the baffle cup . When thepressure in the second chamber reaches a value ofapproximately 525 psi, the diaphragm collapses,forcing the arming sleeve forward and shearingthe shear wire .

The time at which the gas pres-sure in the second pressure chamber reaches thearming pressure value of 525 psi is dependentupon the pressure of the propellant gases in therocket motor, which in turn depends upon initialpropellant temperature.

2. When the shear wire has been sheared, thearming sleeve and rotor are free so that the torsionspring can turn the rotor.

The rotor, which alsoengages the detonator plunger pin and the triggerblock (by means of the trigger block locating pins),rotates the detonator plunger trigger block assem-bly 90° until the rotor is stopped by the rotor-stoppin. The lead-outs in the detonator case are thenlined up along the axis of the fuze with the lead-insin the fuze body, but are still off-set with respectto them along the fuze axis .

3. Slots in the end of the detonator plungerand stop pins in the body are also aligned by therotation so that the detonator plunger triggerblock assembly is free to move forward under theaction of creep force until the trigger block restsagainst the shoulder in the fuze body .

4. Friction of the firing-pin lock balls onthe trigger block prevents the detonator plungerfrom moving farther forward until impact .

Uponimpact the detonator plunger moves forwarduntil it is stopped by the shoulder in the fuze

78

CONFIDENTIAL

body. At this point the slots of the plungerengage the stop pins, the detonator case lead-outis aligned with the body lead-ins, and the plungeris locked by the detents. At the same time thetrigger-latch lock balls fall in behind the shoulderon the detonator plunger, releasing the triggerlatch, which was formerly locked with respectto the trigger block, which renders the triggerspring active . The trigger spring is then effect-ively compressed between the shoulder on thetrigger block and the shoulder in the fuze bodycavity and tends to force the trigger.block towardthe rear .

Firing . As long as deceleration of the round ishigh, the inertia of the trigger block keeps thetrigger spring compressed ; but as soon as thedeceleration is reduced below approximately 45 g,the spring overcomes friction forces and theinertia of the trigger block forces the trigger blockto the rear off the firing-pin loci: balls . Theballs thus released move outward and releasethe spring-loaded firing pin. The firing pininitiates the primer, which initiates the blackpowder delay pellet (0.010 seconds) which inturn initiates the detonator and thus causesdetonation of the explosive train of the fuze andthe explosive filler in the head .


Loaded fuzes from each lotare assembled in explosive loaded 5.0-inch sphereogive rocket heads fitted with 5 .0-inch RocketMotors it-1k 1 or 1"1k 2 . The rockets are firedfrom a. ground launcher into smooth water so thatthe angle of impact with the water is approxi-mately 5 °. Impact with the water is at a dis-tance from the launcher that is greater than themaxiinum burning distance of the rocket motor.The water into which the rocket is fired is atleast 30 feet deep at the point of impact . Theround shall detonate high order after more than50 feet of underwater travel as measured alongthe surface.

Acceptance is based on a cumulativetest plan designed to accept (95% of the time)lots in which 95% of the fuzes function satisfac-torily ; lots poorer than 95% will be subject torejection with lots 82% effective being rejected90% of the time .


Very little information on the-plate sensitivity of the Fuze Mk 162 has beenobtained .

CONFIDENTIAL .


Fuze Allc 162 is detonatorsafe . The detonator lead-outs and the boosterlead-ins are out of alignment until after ariningand impact .

The lead-outs and lead-ins are bothlongitudinally and angularly out of alignment untilafter the first two arming steps have taken place .A large longitudinal displacement remains untilafter creep action is completed and lesser displace-ment exists until after impact forces becomeeffective .


Sample fuzes fromeach production lot are subjected to rough han-dling tests which tire considered to be more severethan conditions encountered in normal stowageand shipping . Failure of the fuzes to pass thetests shall be cause for rejection of the lot .

5 . Disposal and Servicing (Maintenance)General . This fuze becomes quite sensitive

after arming is completed and can be detonatedrather easily . If an extremely light impact hasresulted after gas pressure force, spring force andcreep force have taken place, the fuze may be firedby an additional slight jar .

A fuze which. remainsunfired after heavy impact is also very sensitive,inasmuch as it may be expected that the firing pinhas struck the detonator, and that subsequentfriction between the firing pin and detonator, as

1 . General DataUsed in : 5.0-inch Rocket Head illk 2 plod 2(Common) I

Overall dimensions and weight of fuze :Length --------------- 6.492 inchesDiameter (maximum)- 2.475 inchesBody threads --------- 2.125 inches-12 NS-2Weight ------------- 3.901bs . approx.

Applicable specification : OS 3906General arrangement drawing : 56201.1

Stability of the rocket is ab=olutely essential to theperformance of the Fuze 'lk 166. Since the above headis very likely unstable underwater, new head designs withspecial contours are being developed for use against under-water targets.

CONFIDENTIAL


incurred by rough handling, may fire the fuze .In any event, it is recommended that the fuze orfuzed round be disposed of by Explosive OrdnanceDisposal Personnel in accordance with existinginstructions .

Disassembly. Disassembly of this fuze is notpermitted except at authorized activities whendirected by the Bureau of Ordnance .6. Installation Instructions

General . The fuze is shipped installed in therocket head . No safety wire is provided, andno preparations are required to ready the fuze foruse .

The shipping cap, protecting the rocket headbase, protects the fuze also .

This cap should re-main in place until assembly of the round beginsand should be replaced on disassembly .

Beforeassembling the rocket head to the rocket motor becertain that tl)e fuze is present and properly in-stalled, and that the assembly is properly gaschecked .7 . Packing and MarkingPacking . The fuze is shipped assembled into

the base of the rocket head .Marking .

The fuze is marked or stamped withthe mark, mod, and lot number, the manufacturer'sinitials or symbol, the initials or symbol of theloading facility, the month and year of loading,the anchor stamp, and the inspector's initials .

Section B-Base Fuze Mk 166 Mod 0 (Pressure Arming, Deceleration Firing)

Sketch list of drawings & specs: 165443Explosive components:A sensitive Primer Mk 102 (mercury ful-minate primer mixture) located in the sensi-tive primer holder at the, aft, end of thedetonator case .

A Detonator NI1: 33 lled 1 (lead azide) lo-cated in the detonator case .

Two detonator case lead-outs (tetryl) locatedin the detonator case .

Two body lead-ins (tetryl) located in thebody.

Two body lead-outs (tetryl) located in theforward end of the body .

A booster (approximately 28 grams tetryl)located in the magazine at the forward endof the body .

79

2. Description

80


General . Fuze Mk 166 is identical with FuzeMk 162 except as noted under Functioning Mech-anism. Fuze '.\Ik 166 Mod 0 fires after the de-celeration of the round has dropped to about 75 g.This corresponds to a distance of approximately180 feet of unobstructed underwater travel whenthe striking velocity of the round is 1700 feetper second .

Use. Fuze Mk 166 is used in the 5.0-inchCommon Fin Stablized Aircraft Rockets (CompleteRounds) l\-Zk 23 Mod 0 and lllc 231\Zod 1 (see OP1415) . The 5.0-inch Rocket Head Nll: 2 is notconsidered to maintain the required stability afterwater or ground impact to assure reliable fuzeaction, therefore, new head desila-ns tire underdevelownent.


Fuze llk 166 has thesame functioning mechanism as Fuze 111: 162except :

1. The external configuration of the bodydiffers in that the maximum diameter of Fuze J-Ik166 is less than that of Fuze Mk 162, and the external body thread diameter is correspondinglyreduced .

2 . Fuze 1-Ik 166 utilizes a washer and an In-conel wire inesh combination as a gas chamberinlet filter whereas Fuze Mk 162 utilizes an inletshield and wire mesh combination as the filter .

3. The baffle cup inlet orifice to the secondstage of the pressure chamber is larger for FuzeMk 166 . The larger orifice promotes a reducedarming time which is in keeping with the highervelocity characteristics of the 5.0-inch roundversus the 11 .75-inch round.

4 . The creep force or air-drag force on the11 .75-inch Aircraft Rocket is much less than forthe 5.0-inch High Velocity Aircraft Rocket .

Thesensitivity of Fuze D7"k 166must be reduced to com-pensate for this . The sensitivity is reduced bythe addition of a slight shoulder on the forwardinner diameter of the trigger block which increasesthe force necessary to pull the trigger block off thefiring pin lock balls .

5 . The 5.0-inch High Velocity Aircraft Rocketexperiences a larger deceleration underwater thandoes the 11 .75-inch Aircraft Rocket .

The triggerspring of Fuze Mk 166 is therefore stronger thanthe trigger spring of Fuze Mk 162.

. CONFIDENTIAL

Figure 45-Base Fuze Mk 166 Mod 0, External View,Full Size (approximately) .

6. The detonator case explosive trains of thefuzes differ in that in Fuze ilk 166 the Primer Mk102 replaces the Primer Xlh 101 of Fuze Mk 162,and that no delay element is used in Fuze iG-lk 166 .

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CONFIDENTIAL

CONFIDENTIAL

COPPER GAS CHECK GASKET

LEAD GAS CHECK GASKETBODY

PLUG

INLET VALVE BALL

INLET WASHER

INLET VALVE

HALF CUP

ARMING SLEEVE

VIEW SHOWINGFINIAL POSITION

OF PARTS AFTER

CREEP FORCE

VIEW SHOWING POSITION

OF PARTS ON IMPACT AND

DURING RAPID DECELERATION

FIRING VIEW


LOCATING PINCLOSING RING

TORQUE SPRING

TRIGGER SPRINGFIRING PIN SPRING

FIRING PINDETONATOR PLUNGER DETENT

LEAD-IN

DETONATORSTOP PINPRIMER MAGAZINEDETONATOR PLUNGER

DETENT SPRINGBOOSTER PELLET -

STAKING PINFIRING PIN LOCK BALLTRIGGER BLOCK

Figure 46-Base Fuze Mk 166 Mod 0, Cross Section View Showing Unarmed Position, Position of Parts after

Creep, Position of Parts after Rapid Deceleration and Firing.

8 1


7. The firing pin of Fuze --\-Ilc 166 is a pointedstab type firing pin suitable for use -,vith PrimerMk 102 rather than the round pointed firing pinused to initiate Primer :.Ik 101 in Fuze \11. 162 .

3. FunctioningArming .

The arming of Fuze Mk 166 is identi-cal with Fuze Mk 162 . The fuze will arm atfrom 450 to 5S0 feet from the launcher .

Firing . As long as deceleration of the round ishigh, the inertia of the trigger block. keeps thetrigger spring compressed, but as soon as thedeceleration is reduced below approximately 75 g,the spring overcomes friction forces and the in-ertia of the trigger block forces the trigger blockto the rear off the firing pin loci: balls . The ballsthus released move outward and release the. spring-loaded firing pin. The firing pin initiates the

82

primer which in turn initiates the detonator andthus causes detonation of the explosive train ofthe fuze and the explosive filler of the head .Acceptance test data .

The acceptance plan andmethod of test are the same as for Fuze Mk 162.


Fuze 1\1k 166 should fire re-liably on plate as light as %-inch mild steel atobliquities ranging from 0° to about 60 °.4. Safety FeaturesSame as Fuze X1k 162 .

6. Installation InstructionsSaine as Fuze Mk 162 .

7. Packing and MarkingSame as Fuze Mk 162.

CONFIDENTIAL

5. Disposal and Servicing (Maintenance)Same as Fuze Mk 162 .

CONFIDENTIA L

BASE FUZE FOR THE 7.2-INCH DEMOLITION ROCKET

Section A-Base Fuze Mk 161 Mod 0 (Pressure Arming, Impact Firing)

1 . General DataUsed in . 7 .2-inch Rocket Head _NIk 10 Mod 1

(High Capacity)Overall dimensions and weight of Fuze :

Length------------------ 6.661 inchesDiameter (maximum)-__- 3 .885 inchesBody threads----------- 3.625 inches--

12 NS-2Weight---------------- 5.2 lbs . approx .

Applicable specification: (To be prepared)General arrangement drawing : 440295Sketch list of drawings & specs: 165126Explosive components:

A senstitive primer and detonator assemblyconsisting of the Priiner Mark 102 (mer-cury fulminate) and the Detonator ill:23 Mod 0 (lead azide primer mixture,lead azide, and tetryl) assembled into asingle case closed by a crimp. The as-sembly is contained in the shutter be-tween the firing pin guide and the lead-indisc .

A lead-in charge (tetryl) contained in thelead-in disc between the shutter and. themagazine .

A booster charge (approximately 12 gramstetryl) contained in the magazine at theaft end of the fuze .

2. DescriptionGeneral.

Fuze NIk 161 Mod 0 is a. base detonat-ing fuze which is armed by the pressure of thegases from the rocket motor. The design wasadopted from the obsolete Fuze Mk 146 Mod 1except that the fuze head and base fuze-to-inotoradapter are made; iii one piece .

CONFIDENT!

Chapter 10

Use. Fuze Mk 161 Mod 0 was designed to re-place the Fuze 11lk 146 for use in the 7.2-inch HighCapacity Fin Stabilized Surface Rocket (CompleteRound) Mk 1 Mod 2 . The complete round iscalled a 7 .2-inch demolition rocket which is usedfor short range, land firing from launchers installedon tank turrets. Firing action is instantaneousupon impact with suitable targets.


Two pieces, called thehead and body, house the fuze mechanism.

Thehead is machined out in two bores and each step issupplied with internal threads.

The first bore orlargest inside diameter takes the place of the motoradapter and the second bore accommodates thediaphragm and plug . The insertion of the dia-phragm and plug into the head forms a gaschamber into which the gases from the rocketmotor flow . The gases flow through the inletscrew after first being filtered by the inlet screen .The outside diameter of the head is supplied withexternal threads to engage the mating threads inthe rocket head. The forward end of the fuzehead contains internal threads to accommodatethe fuze body .The body consists of a thick walled steel tube

with an external threaded section which engagesthe internal threads in the forward end. of the fuzehead . The forward end of the body has internalthreads into which the magazine is screwed .Within the body is contained the firing meclian-

isin which consists of an aluminum armingplunger located immediately below the diaphragm.The plunger is held in place by a shear wire in-serted througli it and extending into two dia-metrically opposite recesses in the body .

83

OP 1017 ( 2ND REV.) FUZES

SHUTTER

SENSITIVE PRIMERLOCKING

AND DETONATORPIN -,

ASSEMBLY

SHUTTERSHUTTER-J __

HINGE PIN

84

SECTION X-X

UNARMED POSITION

DETENTSPRING

Figure 47-Base Fuze Mlc 161, Cross Section View, Unarmed Position.

In the unarmed position the arming plunger

holds a locking ball in such a position as to loch the

firing pin body and the firing pin in the forward

position, compressing the firing pin spring. Wbilc

in the forward position, the firing pin extends

HEAD LOCKINGSCREW

LOCKING BALL

BALL RETAININGPLUG

LEAD-IN DISCASSEMBLY

through the firing pin guide and into a cavity in

the shutter. This cavity in the shutter is so

positioned that when engaged by the firing pin the

detonator assembly is out of alignment with the

tetrvl booster lead-in and the firing pin .

Rotation

CONFI.D NTIAL

HEAD-

INLET SHIELD

INLET SCREW

INLET SCREEN

PLUG

DIAPHRAGM

SECTION Y-YARMED POSITION

CONFIDENfAL

ARMING PLUNGER

FIRING PIN BODY--

BODY-

FIRING PIN SPRING

DETENT SPRING

SHUTTER DETENT

SENSITIVE PRIMERAND DETONATOR

ASSEMBLY

Figure 48-Base Fuze Mk 161, Cross Section View, Armed Position .

of the shutter to bring the. explosive elements intoline when released by the firing pin is accomplishedby torsional force of the shutter siring.A lead-in disc containing a tetryl lead-in charge

7.2" DEMOLITION ROCKET BASE FUZES

to transmit the explosive force from the detonatorassembly to the magazine charge, is contained inthe fuze body between the shutter and the tetrylmagazine charge .

ARMED POSITION

MAGAZINE

85


86

3. FunctioningArming . The fuze screws into the base of the

rocket head . Inasmuch as the fuze head andbase fuze-to-motor adapter are manufactured inone piece, it is not necessary to use any sealbetween the fuze and the rocket head . The ex-terior surface of the plug is exposed to the forwardend of the rocket motor. The fuze arias in twostages :

1 . Gases from the rocket motor at pressuresranging from 900 to 2200 psi enter the pressurechamber in the head of the fuze through a smallorifice in the inlet screw.

Debris from the rocketmotor is filtered out by the inlet screen . Thesmall orifice, for the. entrance of gas delays thebuild-up of the pressure until approximately halfthe burning time has passed . Then, when thepressure in the chamber reaches a: value of 275 to325 psi the diapbragin collapses, severing the shearwire, and forcing the awning plunger down .Movement of the plunger releases the locking ball,which, in the unarmed condition, locks the firingpin body in place ; this allows the firing pin bodyto move toward the rear under its o-,wn inertiaforce, due to acceleration, and the force of thefiring pin spring .

The firing pin, which is attachedto the firing pin body, is thus withdrawn from thedetonator shutter, which it normally locks in thesafe position .

2 . When the rocket accelerates, the inertia ofthe shutter forces it back against the firing pillguide, compressing the shutter spring and engagingthe shutter locking pin in a hole in the firing pinguide. About midway during acceleration, thefiring pin is withdrawn from the shutter ; but theshutter, held by the shutter locking pill, remainslocked in the safe posit-ion.When the acceleration is over, the shutter spring

forces the shutter forward against the lead-in-disc,disengaging the shutter locking pin from the holein the firing pill guide. The shutter spring thenswings the shutter into the armed position (det-onator assembly- in line with firing pin and lead-in) where it is locked by the decent .

Firing .

The fuze fires on impact with any material offering sufficient resistance .

Under the forceof impact the inertia of the firing pin body drivesthe pointed firing pin forward piercing andinitiating the sensitive primer in the detonatorassembly . The detonator assembly initiates thetetryl lead-in and the tetryl booster.

The fuze functions with a slight" inl er en iXdflit yg,:aXequivalent to the time required for the firing pinbody and firing pill to move forward to strike theprimer .


Acceptance

tests

havenot yet been established due to the fact that thefuze was not produced for service issue.


Firing tests with the Fuze __\Ik146, which has the same functioning mechanismas the Fuze _\1k 161, in the 7 .2-inch demolitionrocket, indicated that the fuze functions on bothground and `eater impacts, but does not functionconsistently at very low angles of impact .

4. Safety Features

CONFIDENTIAL

Detonator safety .

Fuze Nfk 161 Nfod 0 is de-tonator safe . In the unarmed position the de-tonator assembly is out of alignment with theother increments of the explosive train. Shouldthe detonator assembly function prematurely, theforce of the detonation will be dissipated upwardthrough a hole in the firing pin guide and awayfrom the balance of the explosive train.

Because of the delay in admission of gas fromthe rocket motor to the pressure chamber, thefirst stage in arming does not occur until approxi-mately one-half the burning is over . Because ofthis delay, if the rocket motor blows up before itleaves the launcher, the fuze should not arm.Arming is not completed until after accelerationhas dropped to a value corresponding to 9 g.The burning distance, and therefore the armingdistance, will vary Nvith the temperature.

Oil theaverage, arming is completed within 0.1 secondafter the end of burning. Approximate calcu-lated arming distances for the 7.2-inch demolitionrocket are :

Temperature ('F.) --------------

0

70

1357.2-inch Demolition Rocket (2 .25-

inch 'Motor i\fk 3) (ft.) --------

65

50

35During shipping and stowage .

The light weightaluminum arming plunger and the 0.057-incltphosphor-bronze shear wire make the fuze safefrom arming by accidental dropping in a fullweight projectile from heights up to at least 40feet .

5. Disposal and Servicing (Maintenance)General . From an examination of the exterior

of the fuze, it is impossible to tell whether or notthe fuze is armed.

If, for any reason, it is thought .

CONFIDENTIAL

that the fuze may be armed, it should be treatedas an armed and very sensitive fuze . (No attemptshould be made to remove the fuze from the rocketbody.) The complete fuzed round should be dis-posed of by gently lowering it, tail first, into deepwater, or by Explosive Ordnance Disposal Per-sonnel in accordance with existing instructions .

Disassembly . Disassembly is not permittecl ex-cept at authorized activities when directed by theBureau of Ordnance .

6. Installation InstructionsThe fuze is shipped installed in the base of the

rocket head . A safety wire is not necessary andno preparations are required to ready the fuze for

7.2" DEMOLITION ROCKET BASE FUZES

use . A shipping plug protects the exposed end ofthe fuze and the threads of the fuze-to-ihotoradapter . The shipping plug should be kept inplace until the round is assembled and should bepromptly replaced if the round is disassembled .

7 . Packing and Marking

Packing, Fuzes will be shipped assembled inthe rocket heads and protected by a shipping plugwhich screws into the fuze-to-motor adapter .Marking . The fuze is stamped with the mark,

mod, lot number, date of loading, the manufac-turer's initial or symbol, and the initials or symbolof the loading facility .

1 . General Data

88

Used in :3 .5-inch Rocket Head Mk 10 (Window)3.5-inch Rocket Head Mli 14 (Window)3.5-inch Rocket Head Mk 15 (Window)3.5-inch Rocket Head Ml: 15 (Flare)


Length-------------------

1.28 inchesDiameter (maximum)-__--- 2.97 inchesWeight------------------ 0.201b. approx .

Applicable specification : OS 3541General arrangement drawing : 447337Sketch list of drawings & specs : 165013

Explosive components :

20 grams of black powderEnsign Bickford Fuse with quickmatch

2. DescriptionGeneral . Fuze Mk 134 Mod 0 consists of a

closed plastic case containing 20 grams of blackpowder and a length of Ensign Bickford Fusehaving one end exposed . The Ensign BickfordFuse is sheathed in Irvolite tubing ; one sheathedend is inserted in the base of the plastic containerso it projects approximately his' of an inch, and theother end is surrounded by the black powder inthe case . The exposed end of the tubin(r iscemented in place to the plastic case, and theprojecting fuse is slit and receives a length ofquickmatch . The fuse and quickmatch. areclamped together with a fuse clamp .

Use . Fuze Mk 134 plod 0 is used in the 3 .5-inch Window Fin Stabilized SurfaceRockets (Com-

Chapter 11

MISCELLANEOUS

Section A-Fuze Mk 134 Mod 0 (Ejector Delay)

3 . Functioning

figure 49-Fuze Mk 134 Mod 0 (Ejector Delay),External View.

plete Rounds) hlk 4 Mod 1, Mk 4 Mod 2, ZIk 4Mod 3, Mk 4 Mod 4, Mk 4 Mod 5, and Mk 4 Mod8 (see 01' 1415) .

Firing . The 3.5-inch Rocket Heads NIk 10,Mk 14, or 11k 15 have at their base a closure-adapter which receives the 3.25-inch rocket motor.This closure-adapter also serves to carry the igni-tion system which ignites the Fuze X1k 134 Mod 0.

CONFIDEt4TIAL

SPACER------' /

CONTAINER8 FUZE SUBASSEMBLY

Figure 50-Fuze Mk 134 Mod 0 (Ejector Delay),Cross Section View.

Theignition system consists of a copper diaphrngm,to the center of which is fixed a small firing pin.Pressure from the burning of the rocket motorpropellant, upon ignition, forces the diaphragmforward and the firing pin strikes the primer ofa modified .32 caliber blank cartridge . The flashfrom the .32 caliber cartridge ignites the exposedend of the Ensign Bickford Fuse .

After this fuse

FUZE MARK 134 MOD O (EJECTOR DELAY)

burns for appoximately 15 seconds, it ignites theblack powder and ejects the rocket head load .4. Safety Features

General. The collapse of the diaphragm isnecessary to initiate the fuze . Fuze Mk 134141od 0is considered safe during normal handling andstowage .5. Disposal and Servicing (Maintenance)

General. Since the Fuze Mk 134 Mod 0 isassembled within the rocket head there is no wayof determining its condition by external observa-tion .

Damaged rocket heads containing Fuze Mk134 shall be disposed of by lowering into deepwater or by Explosive Ordnance Disposal Person-nel in accordance with existing instructions .

Disassembly. Disassembly of this fuze is notpermitted except at authorized activities whendirected by the Bureau of Ordnance.6. Installation InstructionsThe Fuze Mk 134 Mod 0 is installed in the

rocket head by the loading activity .7. Packing and Marking

Packing. The fuze is shipped assembled in therocket head .

Marking. Each Fuze Mk 134 Mod 0 is markedor stamped with the mark, mod, lot number, thedate of loading, and the symbol of the loadingactivity .

*Applicable Addressees14 June 48/10M/1

DISTRIBUTION

Requests for additional copies of OP 1017 (Second Revision) should be sub-initted on NavEtos 158, Stock Fornis and Publications Requisition, throughthe District Publications and Printing Office by which addressee is serviced .Standard Navy Distribution List No . 51 (Part 1) and Edition No. 9 (Part 2)

to Catalog of Activities of the Navy.2 copies unless otherwise noted.1 . (1 copy), A, C, E, G, H, I, K, L (2) . (4), M, N ; 2. A (1-18, 22-24, 26-28,37, 38), B (1-4, 11, 12), C, F, G, Il, I, Ii, L. N, S ; 3. (5 copies), B, C, D ; 3 . E,F, H, X, Y, MM, PP, QQ, NVNtiIV, YYY, CCCC ; 6 . A, B ; 7 . A, B, C, J, Ii,L, l-I, N, P, Q, R, S, V, Y, Z (2), PP (2), (3), XX, EEE, FFF, HIIH2, GGG;7 . (5 copies), E, G, H, I, 1\y ; 8 . 1I, T23, T42, T60, U1, Vl-7, 9, tillT, NN ;10 . E; 11 . (CNO, BuAer, BuShips, BuOrd*) ; 12 . BuOrd Special List 12 . A, DE (a), (b), (c) ; 13 . A, C, D, F, G, 11, 1, N, T.

N:X6CK FV . 5 . GOVERNL!CNT PRIHJENG 6FFICE P9¢p?y X.̀

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