Law and Disorder: Rearming the M72 LAW

8/12/2019 Law and Disorder: Rearming the M72 LAW

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A PALADIN PR SS BOOISBN 087364 764 5

Fred rown

Rearming the66mmLightAnti TankeaponSBN 0-87364-764-5

9J780873 647649


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LAW amiDisorderRearming the 66mm Light Anti Tank Wenponby Fred BrownCopyright 0 1994 by Fred BrownISBN 0-87364-764-5Printed in the United Slates of AmericaPublished by Paladin Press, a division ofPaladin Enterprises, Inc., P.O. Box 1307,Boulder, Colorado 80306, USA .(303) 443 -7250Direct inquiries and/or order s to the above address.All rights reserved . Except for use in a review, noportion of this book may be reproduced in aoy formwithout the express written permission of the publisher.Neither the author nor the publisher assumesaoy responsibility for the use or misuse ofinformation contained in this book.

INTRODUCTION: 1

PART ONE: verview 3P RT TWO: Using the LAW 9

PART THREE Rearming the LAW 23APPENDIX: Warhead 47

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0 your arsenal of homemade weapons isalmost complete. You've got handguns, rifles,machine guns, and grenade launchers; CNgas, CS gas, and Mace; mantraps and boobytraps. You ve maybe even knocked up a fewmissiles. But what about the LAW No, not the guys who

chased you last Saturday night, I m talking about theLight Anti-tank Weapon, M72, 66mm type .The LAW is available in inert, fired, or deactivated

form on the surplus/collector/und erground market and

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is su rpris in gly eas y t o rear m . This little man ua ldescribes how to do just that , showing in illustrated,step-by-step form how to disassemble, rebuild, andrearm the weapon's internal firing components and construct a suitable projectile.In the United States, surp lus LAWs are li kely to befound wi th the designations M72AI, M72A2, M72A3,and Practice Launcher M190. In Europe th e same systemis li k ely to be found with a designat ion su ch as RK66mm HEAT LIA2Bl or LNCHR RKT 66mm HEATLI A3B .Be warned . This m anual is for n orm ation purposesonly You shou ld never me ss wi th propellan ts, projectiles, rocket launchers, igniters, explosives , raw fish , 0poisonous toadstools withou t first checking with Momand Dad that it is safe. Always wear gloves, goggles, safety boots, a hard ha t, cl ean socks, and a tic . This ensuresthat if you do blow yourself up you wi ll be smartlydressed for the funeral.When dealing with improvised exploding things lETs),it pays to check periodically for missing body parts, e.g., afinger . These bits are often the first to disappear when anexperiment goes wrong. Coun t and m ak e a note of thenumber offingers you have now, for future reference.

riginally developed in the mid--l960s forthe U.S. Ar my, the M72 66mm LAW isa veteran of many conflicts . Although itis n ow obsolete or obsolescent in itsoriginal form by virtue of the improvem ents i n tank armor, an enhanced v ersi on theM72E4(S(6 series, manufactured by the Tall ey DefenseSystems(Raufoss consortium) is still in pr oduction at

the time of this writing. The M72E4 has an armor-penetration capability of 355 millimeters . In the U.S. Army

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TAWCP FZ

RSI I1t

RS;SL TB, ,BFIGURE1: Crosssection of the M7 66mm LAW system

IT Inner tubeOT Outer tubeRSH Rear sight housingS Rear sight(temperature compensating)TB Trigger bar

SL Safety lever

FS Front sightTS Transportation safety pinsRE Rear end-capCB Close-down buttonPB Primer block housingSF Spring-loaded fins(folded forward)

FB

FIGURE2: Exterior of the 66mm LAW rocketWH Warhead section (black with RL Round lock (transit safety)caliber and model designatio n, RM Rocket motor housingammunition lot number, andtype o warhead inyellow lettering)NC NosecapCL Closure

6 H u

(anodized aluminum)FB Fuze and booster section(anodized aluminum)FS Fins (6, spring-loaded)

LAW AND SOR R_

FIGURE 3: Crosssection of 66mm LAW rocketPB Primer block FZF5 Spring-loaded fin TBFT Flashtube WBIG Igniter LWFL Fin lugs CCSP Stud plate HEPGCT Propellant grainsClosure threads NCTA

FuzeTetryl boosterWarhead bodyLead wire (running from TA to FZ)Copper coneHigh explosiveNose capTerminal assemby ( LUCKY )

th e boos ter charge of tctr yl and , vi a th is, t h e ma inshaped charge. The copper cone is converted in to a highly pene trating jet of plasma. Th e difference between theM72Al and M72A2 is simply the improved armor penetration of the latter.

T SIGHTSThe rear sight of M72A l an d lat er- seri es sy s tem sincorporates a spring-loa ded aperture plate t hat compensates automatically for temperature variat ions. A rubbercover is fixed to th e top of the sight. The front sight con

sis ts of a central, ver t ical range li ne indicating rangesfrom 50 t o 350 meters in 25 meter increments. Rangeestimation is faci li tated by two diverging stadia li nes,which will bracket a 6-meter (20-foatJ-long target at thatrange. The range-fin ding system assumes tha t the targetis twice as long as it is h igh . Provision for aim -off (lead)on a moving target takes the form of crosses , w hich are

OVERVIEW . ....... ... ...... ... . .. ................ ......... ......... ....... .. .. .. 7


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visib le on the extreme left and right of the sight plate .These give the correct lead for a directly crossing targettraveling at 24 kilometers per hour [km/h], or 15 mph.

THE TRAINING LAUNCHERIn troduced for the purposes of rea listic in stru ct ion,the training launcher consists of a normal M 72A1 tubecontai n ing a telescoping M190 subcal iber launcher

assem bly an d the M73 35mm su bcali ber rocket. Thesubcaliber insert is reusable. Sighting and firing proce-dures are the same as for the tactical weapon .The M73 35mm rocket consists of a de tonating war-head, rocket motor, motor closure, and igniter assembly.The warhead is made of ri gid p lastic a nd containsapproximately 1.5 grams of M Ocomposition mixtur e.The front part of the motor closure contains a base deto-nat ing fuze an d an M26 stab primer. When the rocketstrikes a target an inert ia-driven firing pin st rikes theprimer, thereby sett ing offth e head cha rge. Although pri-m ari ly a s potting ch arge produ cing noise, a fl ash , andsmoke th is will penet ra te approximately3 m illimetersof steel plate or 20 mi llimeters of soft wood .Th e rocket motor casing itself is metal an d containsth ree tub u lar grains of M7 propellant. Stabili zation inflight is provided by six molded plastic fins.

Th e foll owing section is a r eprint of th e U.S. ArmyLAW user manu al. It contains full details of how to arm,aim, and fire the system, as well as the actions that shouldbe tak en in the event of a m isfi re . T his in for mationapplies to tubes of American and European m anufacture.

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l 1 ~ ; ~ ~ J i ~ ~ 1 1 l l l l j l i ~ I [ ~ l l ~ l lA RIEfDESCRIPTIONWEAPON DATA

Tactica.l PracllcoM72A l M72A2 . M72A3 Launche r M190,,/R ackel M73

Wo ight S.l Lb . s.r-ue, S.Lb .Coto; Identificat ionLaunch. rFiring In,truc. ion lab el Backg roundWh i,. Prin,lno

BackgroundWh it. Printi ng BackgroundWh ito Printin gModol. 14tNo , DoteMfg 14bo l W/ Y. owPrin ting

W/ YoUowPrinting 0 0 WI YollowPrintingWa rhoad M72 (Hoot) M72Al (Hcal) Sporting eha rgoCampl. to L..n9th(Clo.od) Nominal(Opon) Naminol

24.7-ln.34 .7 ln.

24.7-ln.34.7 1 . 25.3- ln.35 .4- 1 .

iam et e r 4 .9- n. 4.9-ln. 4.9.ln.

M 72A2 OPM 12A3

WE PON

EXTHIDEO (READY FOR USE)

NOTE EXTERN AL V IEW OF TACT ICA L AN D PRACTICE WEAPON ARE IDENT ICAL

L W AND SOR R USING TH L W. . . . . . . . . . . . . . . & 10

EXTERNAL VIEW AS ISSUE (NOT EX TENDED)

L B ELSND

ONRIGHTSIDE

LABEL FORPRACTICE ITEM

U 5 ARMYUI,JOIP. .. Ito,or~ 1 \ W G t D U 10 .. 1Usrc lQ lUIP. - 40 r. . Ita ,


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--

THIS PAGEINTINTIOHALLYLfI'T ' LA NK

ollowing applies to tactical weapononly.SERVICE UPONRECEIPT OF M TERIEL

CH PTEROPER TION

O KEEP MARKING NOSE END"OF BOX FACI NG LEASTHAZARDOUS AREA

A STA NO TO SIDE V Of NOSE l !No-MA RKING. o REACH OVERU TO P OF BOXA ND UNFASTENWIRE HOOPS

llllllllllllllllll tl \llllll lll iiillll ,,!!:!NO T US E SHARP 1 1 11 ~ I I!

1I I [IiIll!i

A PUll FLAPW AT NOSE ENDOF BARRIER BAGAND OPEN T O EXPOSECONTAINER END

{ PULL PREPARED TEARSTRIPS OFF COI'lTAINEREND AND REMOVE COVER

OREMOVE, Cl;SHIONINGAND WEAPON

..

FOLLOWING PPLIES TO T CTICAL ND PR CTICE WE PONS ~ E CH WE PON SYSTEM FORc";;,t - CRACKED TUBE FRAYED SLING DENTED PARTS LOOSE OR BENT REAR HOOKMISSING PARTS LOOSE OR DAMAGED SAFETY MECHANISMSLOOSE PARTS BLURRED OR INCORRECT NOMENCLATURE

TRIGGER SAFETY HANDLE MUSTBE IN SAFE POSITION

W RNING00 NOT EXTEND LAUNCHER UNTIL READY FOR USE.

LAW AND D ISORDER THELAW.. . . . . . . _ u - _ _ - 12 13


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FUR TACTICAL WEAPDNS ONLY

IF TIME PERMITS I /CHECK IGNIT ER FOR DAMAGE(BROKEN, CRACKED OR SPLIT) I(SEE INSTRUCTIONS FORRElvIOVING CARRYING SLING) I\IF SO D M GED \\TAPE OAMAGD IGNITERS TO \PREVENT LOSS OF IGNITIONMAiER :AL REPLACE SLING ASSEMS LY .CLOSe REAR COVER AND REPLACEPULL PIN.

...-/

\t

C RRYINGPOSITION

TO CARRYSL:NG OVER S ~ O U L O E R

WARNINGDO NOT CARR":' WAPC1'l IN EX :'E:NCEDFOS;110N.

. ,

L W AND DISORDER14

B CK BL ST D NGER ZONES

-TARGET1. SGck

DANGeR IN THIS AREA FROM BlJ'ST.2. ody x t , . . a re cleo t o f KEAT AND PROJECTED MA TE RII\ LS.ZON E "A "

I 40 METERS

cr'"w::E

m ~ ; : : : B ; t H ; WARNINGUNLESS blaot GreG is d oo r afp. n o ne l a nd o st ru tions.

Rockot exha ust e nd. ZONE 8 IN fH IS AREA FROMPROJECTED MA TERIALS

= '' : ~ FORFIR NGr". .y _ . . . . . ./ ';" _ .- All weaponsO Th o Following Steps ArePorform ed At Th . Firing Point .o REMOVE PULL PIN

USING THE LAW


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I I. . . c I~', ~ l f A ~ o 'HOO LAUNCHER \I .

SLIGHTLY AWAY 'FROM BODY ~ KEEPLAUNCHERON TARGET

I ] I I ~ l l ~ ~ @ I I ~ ~ I I ~ ~ ~ U UNCHER OPEN FAIL CLOSE AN D SET SYSTEM ASIDEFOR DISPOSAL 8Y AUTHO RIZI D

PERSONNEL(SEE SECTION X FOR

i i l i \ r ~ ~ r l i l l i I i ~ [ I

y \ 1 SNA? \\ ....

W ~ I1) EXTEND OUT WITH RIGHT HAND

EXTENDING THE WEAPON TOO SLOWLY CANWARNING RESULT IN FAILURE TO COCK THE WEAPON.

{) GRASP REAR SIGHTJ O V E R HOLD FIRMLY

__ BE SURE LAUNCHER SNAPSC \ ~ O C K ~ S f T l

.....

KEEP ON TARGET

RING POSITIONS c-

/

TR T_ ~

PLACE FINGERTI PS ONo TRIGGER SPRING BOOT ASFAR BACK AS POSSIBLE

oPLACE SIGHT ATEASY READINGDISTANCE

RE DY

TARGETDR MOVINGT HEAD-ON

- :>J00 . O N$ 0/ STATIlO O TARG- A T 2.:. & .l asMETERS )' 0IM / j ~ __ .f,':' ...1\ M,\ RKERLEAD MARKER

(TARGET MOVING ]:\ I ' O?:ISMPHI =t '0\ +., \ 1 1 ':1 \ r::;\ I ' .. \ lOO 1-,,0 IFRON T

RUBBER S' GHT

IUSING RAHGE MARKI R FORSIOl virw RAN Gl lSTIMATIO Nnr===T '0T 100 ..

151~ ' . \L .- SIGHT I , \ :Q?:.. \ T , 'L..! ,.BOOT --SI ~ ~ I ~ ,.- 1I .j. I

USIN G RANGI MARKI R FORHEAD . ON IlANGl ESTI MATIO NSIGHT S ARE COATEDTO AID IN NIGHT FIRING(EXCEPT M72A3)

., 11 \ '-'_I - I J>oON TARGET(MOVING)

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e WAIT 1 SECONDS

BEFORE RECOCKINGIf time i not available loy we pon dow n pointinga t torget - ab a ndon .

KEEP ONT RGET&.lIl PA RTIA LLY CLOSE LAUNCHERI. A PPROX I M ATE LY 4 INCHES)

eSHARPLY SNAPLAU NCHER OP ENIN TO LOCKED POS ITION "I I

o PLACE LAUNCHER BACK ON SHO ULDERe AIM

DEPU SS TRIGGERIF AHAS MISFIRED

NOT FIRE,SAFElY HA NDLE

POSITION

NOTIFYPERSONNE!.. FOR

CARHULLY LAY WEA PONTARGH AN D EVACUATE - ,

BOOr FIRMLY TO RECOC KED WEAPON WH I CHSTILL DOESPUSH TR IGGERTO "SA FE"

AND W AIT1 SECONDS

THENON GROUND FACAR EA

AUTHORI ZED DISPOSALDISPOSAL OF W EAPON

IT RG T )CA REFULLY REMOVEWEAPO N FROM SHOULD

o RET URN SAFETY TO SAF 7


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DIS SS BLYdisassembly and reconstruction proce-

dures outlined here are to be performedwith the LAW tube in the closed statewi t h the safety catch on "safe." Checkthat your LAW is empty A good rule ofthumb here is that i you can see through the tube it isindeed, empty. This assumes ho wever, that you haveremoved the end caps.

Undo the two screws [ ] visible at the rear of the tube

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asshown in Figure4. This will all owthe primer housingblockcoverBC) tobeliftedoff.f the housingissecuredwith r ivets rather than screws, grind or cu t theri vetheads awayand drift out the remaining pins . Obtain selftappingscrewsofasuitable length anddiameterforsubsequent replacement ofthe housing. Better still, usewing nu t- typefasteners ,as th is-mak esforvery rapidrepea tedrearming.

BCFIGURE4:Prime r blockhousingcover 5 Screws BC Blockcover

FIGURE5: andflashtubePrimer blockstub

Scrape and pull away any silicone waterproofingmaterial that ispresent. Youshould now belooking atthe primer blockassembly FBI and [ifyou re lucky)thestublike remainsof theplasticflashtubeIFTS) .

Pry out th eprimerlo k with aleveringaction usingthelongeroftheLAW'ssafety-pinpair, the pointedbitofaSwissArmy penknifebot tle-openerblade,oranyotherexped ient too lthat canbe inserted beneath the lashtu bestub.Donot damagethestubunnecessarily.

Now removeth eexi sting[used]primer. Usually,th eLAWfiringpinwill haveseriouslypiercedthe faceofth eprimer.Thisbeingthe casesimplyenlarget heholecarefullywi thakn ifeblade until am edium-sizedPhi ll ipsscrewdrivercanbeinserted .(Thecrossheadbit catchesthe damaged brass bet terthan a fla thead does. )Twistth escrewdrivertoloosenth eprimer in its pocket,thenleveror pull outtheprimer withapair ofpliers.

Check no wtha t thevent hole a t t he bottom of the

FT

PBipp

FIGURE6: primer block (stubattached)removed from housingPBH Primerblock housing FTS FlashlubestubPP Primer pocket FTC FlashtubechannelPB Primer block

LAWAND DISORDER REARMING THELAW .... .......... ......... .. ..... .24 25


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I I11

I ICROSS SECTIONMMH

pp I 2MMPPJ I ,oMMFTS

VIEW FROM ABOVEHpp

FIGURE 7: Schematic diagram of primer blockPPJ Primer pocket insert FTS Flash tube stubPP Primer pocket H Hole

primer pocket is not blocked and that the small stub offlash tube remaining on the primer block is clear also.Trim the edges of the stub so that there are no split orflared ends. i the stub section is too short or even missing (hav ing been burnt away during the original firing),then clean up the area around the hole left in the blockand attach a replacement stub made from hard plastic ormetal piping.Drill out the hole in the block slightly if required

to fac il itate accurate fitting of the replacemen tSecure wi th epoxy adhesive applied to th e o uter rit he st ub and immediate block area only. D on't geinside the tube.

If the primer block is missing from your LAW a repm ent can be m ade using t h e above specifications.ny lon dowel or even a cut-down, fired, 7.62-millim Boxer pr ime red rifle case. In the case of the latteopen end of the case can be sealed with a fri ction-fit disk soldered in place for security. Use aluminum soas this joins brass more easily than s tandard electricader, although a higher bi t temperature is requi red. Remthe primer before commencing any modifications.A fl ash channel in se rt [fo r us e with t h e cu t -dcase) can be made from stiff plastic tube of approximly 2- to 2.5-millimeter internal diameter and 4-millter extern al diameter. This worked well in tes ts. Mpiping coul d be employed just as easily. Th e insert ias sh own in Figure 8 an d installed and secured initwith a sm all am oun t of adhesive at each end. Whenhas dried, the rem ainder of th e space inside the casebe filled wi th epoxy prior to sealing th e end.

CUT H R FCFe

CUT HERE . - - - - IFIGURE 8: 7.62mm casing primer block

FC Flash channel insert FTS Flash tube stubCC Cut down case I lnsertS Solder

LAW AND iSOR ER REARMING THE LAW r _ _ _ '26 2

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The hole for the flash tube stub should be drilled to adiameter that allows the tube to be inserted a li ttle waysinto the body of th e block . It can be secured wi th epoxyadhesive (assuming a nylon block and pl astic tube) orwith solder (if using a metal block and m etal tube). Ifusing epoxy, thread a pipe cleaner (via the primer pockethole) through the flash tube stub to cl ear it of adh esivebefore the material dries .An other al ternative is to si m ply fill the'cu t -downcase with epoxy adhesive and, when it ha s set, drill outth e requ ired channel and flash tube opening with a 2-m il limeter-diameter bit. In fact, there is any numb er ofways to achieve the desired effect and, if the examplesgiven h ere sta rt you th in king and you come up wi th animproved method, so much the better.At this stage the correct operation of the LAW safetycatch and firin g m ech anism should be tested. Do thisby installing a t oy cap (of th e type used in children's 8-or 12-shot revolvers] in place of th e primer. This typeof cap is plasti c and is usually supplied in "circles" of 8or 12, which are packed 6 ci r cl es t o a box . Typicalbrand na mes are Super Disc and Am m o King. TheSuper Disc type i s made by Edison Gioca tt oli, 50019,Sesto Fioren t ino, Ita ly, and is imported by Toys R Us ,

Those used in tests were about 5 millimeters in diamete r (wi th a slightly wider top flange) and 5 milli metersdeep and were an excellent friction fit in the primer pocket. Note that they will stick up above the primer housingface slightly (about 1 to 2 millimeters) when installed.This type of plastic cap will be used later in the completed weapon . It is more than likely that there ateproper commercial primers or metal blanks of a suitable size and power that can be used instead. If you arefami lia r eno ugh w ith the field to make an intelligentselection, you might want to experiment. The only cautionary note I w ou ld s ound is that too powerful aprimer may well blow the igniter assembly [not to men-

LAW AND DISORDERu , . .o o - .2 8

ti o n t he prime r bl ock h ou sing an d rear co ver ) apra ther th an in i t iate the ro ck et pro pellan t . (Time cst raints an d the need to dodge a BATFsearch team loin g for th e LAWs we stole to experim en t wit h durth e writing of th is bookl et prevented us from testingpo ssi ble alt ernatives .) Anyway, toy caps can, in mparts of t he wo rl d, be obtained with greater easeless suspicion than primers.So pu sh t he cap ho me as far as it wi ll go, but dbother to force it. It will be compressed somewhat wthe cover is refitted. The design of the LAW firing psuch that there is no risk of the cap being forced agait (and therefore causing it to fire )during this procedu

No w replace the primer block in the housing and atthe cover plate. Tighten the cover screws alternately aple of turns at a time until the plate is secure. Ha vchecked that no one is staring down the rear of the tex tend th e tube, pull t he safety catch out to armweapon, and fire. Isn' t that little echoey "bing" satisfyiIf the weapon doesn' t fire, recock (close and exteand try again . If nothing ha ppens th is time, closetube down, check that the safety is on "safe," and disemble th e primer block hous i ng. f t h e cap baspierced or severely inden ted the firing system is oTry again with a fresh cap.If all was well, run through the procedure again aple of times. Get used to performing the co rrect misdrills. If you don't get any misfires, pretend. Overcany tendency to look down the tube and/or pointback of it at your own body when opening and clothe weapon, and practice not closing your eyes whendepress the firing button Confirm that the weaponot fire when the safety handle is pushed inThe next stage is to attach a new length of fl

tube to the stub on the prime r block and perforflash tube test.A replacement flash tube can be made from semir

RE RMING THE LAW 2


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plastic tubing, 5-m il limeter external diameter, 4-m illimeter internal diameter. The wall dia meter wil l therefore be 1 millimeter. These dimensions facilita te easyattachment to the stub. The type of tu be used is not critical, th e primary re qu irem ent being that it doesn t kinkseverely when gently bent through a curve.In tests we successfully used a length of outer insulation pul led fro m coaxial cable of th e type comm onlyus ed for CB and ham radio hookups. This has an in tern aldiameter of around 4 millimeters and an ext ernal diameter of around 5 millimeters.For th is tes t us e a 63.5-millimeter length of tube. Theprocedure is as follows:1. Place a safety match head in one end of the tube

and tape t up.2. Install a cap in the primer block.3. N ow force the open end of the new tube ov er th e

stub on th e primer block and push it home un til itis flush wi th the block body.4. Refit th e primer block (cap side inward!)and fasten

the cover pla te . When you are fittin g th e primerblock, t he area of fl ash tube that covers the flashtu be stub w ill m ake for a tight frict ion fit wi thinth e fl ash tu be chan nel. Subsequently locking itdown by th e c over plate ensures t ha t t he tub ingwill not simply blow off the stub when the capfires. Bend the tube Iorward and upward so that tis roughly central in the launcher, and secure it inthis position with tape or any expedient support.This replicates the angle through which the flashfrom the cap will have to trave l to fire the igniter.Test-fire the weapon fo llowing all previously men-

LAW AND ISOR ER... .30

tioned safety requ irements. The match head should iginstantaneousl y an d will (depending on the t ypeam ount of tape you used to seal the end of the flash tuprobably be propelled ou t of th e front of the laun cher.

If the match lights, your choice of t ubing and caok ay and the system will in i t iate the improvised igndescribed later. If the match doesn t light, check for a sin the flash tube where it exits the primer block housThe flash tube will split he re i f the tube was ki nked baduring firing. Try a stiffer type of tubing or a differentWe will now leave th is aspect o f th e fi ring syst em fwhile and move on to the rocket itself.

TH RO KETT his sect ion gives detail s on constructin g a repla

ment rocket for th e LAW. The rocke t is a nominal 66mround as per the or igin al, alb eit of li ghter cons t ructand with fixed fin s.

Basic rinciplesRockets (and jet s, for that matter] fly in accordawit h N ewton's th ird law (ho w appropriate) of motiw h ich states that for ev ery action there is an equalopp osite reaction . He re that means that a force equath a t produced by gases (fr om the burn ing propellaescaping through the exhaust n ozzle is exerted inopposi te direction, th ereby dr iving t he rocke t forwaThe rocket's movement is not dependent on a buildugas pressure behind it.

The power source used here is based on the D12-0D12-P type of flying model rocket en gine, avail able fmost toy and model shops. It wi ll be used to powrocket consisting of the following parts:1. Nose cone (NC): One plastic flying mo de l rockekit, nose cone type PNC-BOK modified as

REARMI: JG THE L W 3


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descri bed;orimpr ovi sedcone ofsimil ar dimensions (seefig.91

2. Nose inser t(NIl:Plastic flyingmodel rocket k it,type PNC -80BBor wood,plastic,orlight m etalimprovisation (som epla st ic caps from ae ros olspraysare sui table,asare variousplasticsoftdrinkbottlesif cut down to the correctdia meterI

3. Bodytube BTl:Hard plasticor fiberglasstubing orflying mo delrocketbodytu bing,41 .6-millimeteroutsidediameter,40.S-mi llim eter internal diameter,273 millimeterslong.

4. Enginemount assembly (EM):flying modelrockettype EMOSOSS/ 60 lor im provis e fro m illustrationbelow).

S. Stabilizing fins (SF):Six fins metal ,plastic orwood,95.3 millimeters long,1.6to2.4m illimetersthick (dependingon material used},11millimetershigh,shaped asperFigures16and 17.

Nose ConeAssemblyCut offthe lower (insert)part ofthe longer ofthe two

plastic nose con esas indicated in Figure9, taking carenot to damage the remainder of the cone. This willleaveyou with anose cone ofthe dimensions shown inFigure10. Now pack the inside ofone end ofthe bodytube with epoxy adhesive to adepth ofabout 70mil limeters and apply epoxy to the front of the cut-downnose cone to asimilar depth. Insert the nose cone intothe body tube as far as it will go and wipe away anyexcessadhesive.

Using aspirit level and blocks check and adjust theconeuntil it isperfectly centered. Secure the joint withplasticelectrical tape andset the assembly asidetodry.

When the tubeand con eassem blyhasdried,theninsert can beinstalledin tothe open frontofthe placone.For " dry "fi r ingsth efr ict ionfit will su ff icexp losiveco mpon ents ar e to be ins ta lled ,the jshould besealedwi th athin layerofepoxy.

ENGINE MOUNT

FIGURE 9:Nose cone

CUTHERE ( J 70MM A Adhesil 207 MM I \ A

65 MM I 40.5 ~MMMM

FIGURE 10: Inserting nose cone into body tubeA Adhesive

The engine mount can nowbeinstalled. This isaing model rocket kit type EM -SOS5! 60 ,or i t maimprovised as per Figure 14. T hemount shoul

LAW ND ISOR ER REARMING THEL W32 3


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n :t===}.-wFIGURE 11: Aligning the nose cone

SL Spirit level W Wood blocksI MM I

102 MM FIGURE 12: Nose insert

25.4 MMI I

[[)FIGURE13: Installing the nose insert

installed in th e body tube so that the en d of the m etalengine holder on th e mo unt pro trudes ab out a quarterin ch (6.4 mm ) bey on d t he end of t h e body tu be . T heother end of th e sprung metal holder actually penetratesthe en gine tu be, whe re it act s as an engine stop . Theholder is held in p lace by the plast ic retainer PR). This isa length of plastic or ru bber tubin g forming a t igh t fricti on fit over the engine holder and tube.

When it is n ot n ecessary to recover an d reuse therocket, an alternative engine-mounting technique can beus ed. Simply use a balsa wood cylinder with an exte rnaldia m eter th at m akes for a fricti on fi t in si de the bodytube, the rear end of which is drilled centrally to accomm odate the engine. This drilled housing should be shorter than th e engin e length by about a quarter in ch. Bothbalsa insert an d engine are secured with epoxy.

ENGINESPropulsion is provided by a DI 2 0- or DI I -P-type flying model rocket engine, m odified by caref ull y drillingthrou gh the propellant of the engine centrally from the

nozzle opening to t he o the r end with a l /8 -inch (31.8mml diameter rill bit and then (in the case of th eD12-0engine] plugging th e open en d of th e engine case wi thepoxy. Save the propel lant powder produced during thedrilling; it will be used later.

STABILIZING FINSThe fins are attached one at a time in the positions indicated in Figures 16 and 17 with epoxy adhesive lin the caseof fiberglass or heavy card body parts] or, i f using m etalparts, a spot weld, braze, or solder in th e position shown.Care should be t aken to ensure t hat the fin s are perfec tly straight. Once at tached they can be strengthen edby runn ing a thin bead of epoxy al ong each side of the

LAW A'-:D SOR ER REARMING THE LAW34 35


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64 MM HO

E1

R

- FRONTVIEW OFCR

i . ' 'H I ,. '-._'.' i HI .pt!\ , I6 4MM

FIGURE 14: DiagramofenginemountIT Engine tube: stiff card, 70 mm long; internaldiameter, 24 rnrn:

externaldiameter, 25.4 mmCR Centralizingrings: tworingsmadeofstiffcardorplastic, 6.35mm

deep, internal diameter allowing friction f it on ET, externaldiameterallowing frictionfit in40.5 mmbody lube

EH Engineholder :length ofspring steel,3 mm wide, .Smmthick, 70mm longwith the last63.5 mm ofeachendbent ata 9o-degreeangle.

SP Stop piece: wooden or metal disk, 6.35 mm thick, diameterfaeil tati ngfriction fit in IT

PR Plasticretainer: plastic tubing,25.4 mmlong,diameterallowingafrictionoverEHand IT

HO Hole: locatedas shown to facilitate upward movement of EH forengine installationE Positionof engine

LAW AND ISOR R36

VIEW FROM ABOVECR CR

FIGURE 15:Enginehol der

70MMI I

ENGINE HOLDERVIEWFROMSIDEattachment point. Fin alignment guides are availablecommercially from flying model rocket suppliers.

Note that in the case of metal body parts the fins areattached with only a s ingle spot weld or braze. Thisallows for subsequent m inor straightening.Once the fins are at tached, check to be sure that the:

rocket can actually be inserted into the tube withouthang-ups. Load the rocket, fins first, into the front of theclosed tube. As it is th e rearmost (inner) tube that hasthe smaller diameter, it is this one in which you arechecking for finclearance.

wA

- -'1 MM

FIGURES 16 AND 17; Findimensionsand positioning A Epoxyadhesive w Spotweld

REARMING THELAW 37


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If the fins catch on the innerm ost tube, remove therocket and me asure th e h eigh t of eac h fin . If an y a resl ightly hi gher than the others , sand or fil e th e ir topedges ve ry carefully to bring al l th e fins to th e sa m eh eight an d th en continue un til th e overall he ight ofthe fi ns (diame ter of the fin assembly)is such that therocket can be inserted all the way in to th e tube with ou t difficulty.

TH IGNIT R

The heart of the improvised igni te r described here isthe nozzle from a tube of silicone sealer [bath or windowsealer )or some sim ilar improvi sat ion. It is via this andthe flash tube that the flash from th e cap or primer willbe communicated to the engine propellant.Step on e is to cu t the nozzle in h alf and then cut offthe tip at a point from the end that will give an openingof abou t 2 m illime ter s. Sand o r t rim the outs ide of th enozzle end, as required, to give an external diameter thatprovides th e nozzle ti p with a friction fi t in the enginenozzle to a depth of about 10 millimeters.A nozz le hous ing can now be prepared from a used Dseries engine, per the diagram on th e facing page Ifig. 19).The holder is simply th e nozzle end of a D-series engine .Th e engi ne no zzle hole is widen ed from th e inside toprovide a fri ct ion fit for the plastic nozzle in such a ma n ner that w ith the plastic nozzle inserted from th e insideof the clay nozzle, th e last 10 millimeters or so of it protru des beyond t he card rim as shown in Figure 19. Theplastic no zzle is t hen secured and the clay nozzle reinforced with epoxy adhesive.

Now attach the nozzle assembly to the engine packwith m ask ing tape. Pierce the tape at the holder notchspotan d install the engine/igniter assembly in the rocket, orient ing the assembly correctly so that th e engineholder fits in the notch properly.

38 LAW AND ISOR ER

(

FIGURE 18:\ (- ..IIIII ,'. r . 'I'!;i I ,',t> 1,

N V I

~ t l ; n r ~ l i ; : il l.,

VIEWFROMACB

ICURE19: NozzlehousingEN Enginenotch(4x 4x 4mm

notchtoaccommodateendof CH

engineholder) CN Clay nozzle CB Ca rd body I ENCH Centralhole }\B I IN Plasticnozzle

> i PN13

CROSS SECTION

REARMING TH L W... . 3


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CB"CN .CH

T8T

NH LIN_ ' . EPHN . . PR I EH SPFIGURE 20: Igniter in cross section

CR Centering ringsCB Card body BT Body tube (rocket body)(on cut off engine nozzle) PR Plastic retainerCN Clay nozzle EP EngineCH Cen/ral hole EH Engine holderIN Improvised nozzle SP Stop pieceNH Nozzle holder ET Engine tubeHN Holder notch (engine notch)

Install the rocket in the tube (fin end first, from thefront of the closed tube so that the open end of theimprovised nozzle is more or less flush with the hack ofthe tube .Next cu t a 63.S-m illimeter piece of improvised flashtube) push one end over the flash tube stub on the primerblock, an d install the primer block in its housing. Nowtrim the free end of the tube to a length (typically about57 m.illimeters] that facilitates its insertion (fully) butwithout undue force) into the improvised igniter nozzlewith as shallow a curve as possible (the idea being thatthere are no sharp kinks in the flash tube) .Having determined the correct length of flash tuberequired [which will vary slightly depending on exactlywhat type of material you have used], remove the rocket

LAW AND ISOR R40 . . . .. . . . . . u , .

and ta ke out the engine/nozzle assembly. Remove theprimer block and flash tube also but do no t disassembl e.Now pour th e p rope ll an t powder sav ed from th eengine-drilling process in to the nozzle, tapping the nozzle to en co u rage some of the po wder t o fall in to t h eengine pack. Add powder un til th e nozzle itself is almostfilled. Press the end of the tube down firmly into the center of the powder, turning it slightly as requi red to obtaina friction fit . Secure the tube with epoxy adhesive at thetop of the nozzle as shown.An alt ernat ive ign iter nozzle can be improvised fromtwo of the plastic igniter holders wh ich are supplied withthe engines. These are drilled cen trally an d secured backto-back wi th Superglue or epoxy adhesive lor they can besecured with epoxy adh esive first and th en dril led afterdry ing]. One end is inserted into th e engin e nozzle; theother has the lower end of the flash tube pushed over it .

PB

P

TSrr

FIGURE21: The completed igniter assemblyCH Central hol e NH : I 02.zle holderEH Engine holder (engine tube HN Holder notch (toand centralizing rings not accommodateshown) end of engine holder)EN Engine nozzle FT Flash tubeIN Nozzle (conta ining propellant FrS Flash tube stub

powder) PB Primer blockA Adhesive P Primer (cap)T Tape

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TR NSIT SAFETYAll that remains to be done now is to attach a simpleimprovised transi t safety (round lock). There are severalalternatives possible here but a simple and effectivet echn ique is to wrap stiff wire around the nozzle holder aco uple of ti m es a nd secure it with epoxy. T he wire i sthe n bent up an d out of the tr ansit safety hole du ri ngend-cap rep laceme nt (looping the free end of the wire totake the safety pin ).

FIN L RE RMINGFinal rearmin g in vo lves in s t allin g th e engine jigniter/ flash tu be assembly in the rocket (ensur ing that

th e engine holder is re ta ining the engine correct ly) andthen loading the rocket into the launcher, fin first, fromthe fron t of laun cher. f an improvised explosive round isloaded, this procedure sh ou ld be under taken wi th thelaun cher on the ground.

FIGUR : View of end capshowi ng position of transit safety holeTSH

FIG URE 3: Wire transit safetyattached to igniter nozzle holderEC End capTSH Transit safety holeW WireNH Nozzle holder

LAW AND ISOR ER. . . . a , - .4

Lastly, a fresh cap is installed in the pr imer blockth e primer block and its housin g cover fit ted.TEST-FIRING

Al th ough the device described here has been fmany ti mes without problem , it is not beyondrealm of possibility th at you have screwed yours upt hat M u rphy is abou t , so always make a te st -wearing goggles, gloves, and a substan tial jacket. Tlatter requi rement sounds odd, bu t i f you have failefollow th e ins truct ions carefu lly and end up wi tround that hangs up in the tube, the launcher willvery hot .Make sure the area to the front and rear of th e tubcl ear. Rem em ber th at th e sys tem fi res fr om an obreech, so the risk of the tube actually exploding due buildup of pressure is negligible .

Ch eck the t ube th oroughly for dam age after th is tfire and all subsequent firings, an d no te tha t th e rocen gin e js ] wi ll ofte n l ea ve a deposit in the tu be thun less cleaned away, will in terfere wi th th e subsequinsertion of another rocket.There is some backblast when the rockets used herefired as described. It is minimal, however, and goggles provide adequate protection against smoke being blointo the eyes. f you in tend to experiment with alterndesigns, propellant types, or eng in e con figurationsimprovised perspex blast shield should be fitted aroundfront of the LAW tube until th e ABOL qu ali ties ofexperimental system are determi ned.

DISCARDING SABOTSUBCALI BER SYSTEMOpting for a subcaliber rocket and a simple

carding sabot assembly provides an even more raroute to rearming your LAW. Several suitable roc

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kits are available , an d the only modification theyrequire is a reduction in fin diameter to allow for asliding fit within the rear of the LAW tube. The forwardlaunch lug should be at tached to such rockets, as pe rthe ki t ins tructions , but at least 25.4 millimeters fromthe front of the body tube.The discarding sabot can be made from a cylindricalpiece of balsawood, 25.4 millimeters in length and withan external diameter that allows for a sliding fit withinthe tube. The cylinder is bored out centrally to a diame ter that provides a tight friction fit for the rocket bodyand then cut vertically into two halves. A short (3.2millimeter) pin i s driven into the center of each resultingface on one of th e halves only. The other balsa half isth en aligned correctly and pressed onto them. Finally,the resulting holes in the second balsa hall are enlargedslightly to ensure that the pins move freely in them.During loading the two halves are positioned aroundthe rocket, just in front of the launch lug, thus forming acollar of the correct external diameter. When, uponfiring, this part of the rocket exits the tube, the assemblywill simply fall away.

LAUNCH ROD AND INSERT SYSTEMHere a soft wood insert 6S millimeters in diameter

and 9.S millimeters thick is prepared by drill ing out ahole 25.4 millimeters in diameter from its center andcutting a slot 12.7 millimeters deep and 6.4 millimeterswide from the center hole to any point on the outer rim.The rocket to be fired is now placed centrally over thecenter hole and oriented so that the front launch lug onthe rocket is at least 6.4 millimeters to the left or right ofthe slot. Ink the end of the long-type Estes launch rod [orsome sturdier improvisation of similar dimensions) andcarefully place it through the launch lug until it contactsthe insert. Drill the point thus marked by the ink to a

44 L W ND O SOKDER

diameter that provides a tight friction fit for the enthe launch rod. Putting a drop of Superglue in theprior to fitting the rod will keep t secure . Open the Ltube and position the insert in the rear of i t. Markfront of the launch rod where it exits the front oftube. Remove th is excess length to a point more orflu sh with the front of the tube.To use the system, install an engine and ignassembly in the rocket as previously described, andload the rocket into the tube and fit th e primer bland so on. Finally, feed the launch rod in to the bacthe LAW and through the launch lug an d, ha voriented the slot so that it covers the flash tube, pthe insert as far into the back of the tube as it wiwithout using undue force. Check the front of the rofor a more-or-less central position in the tube, and adas required by applying more pressure to the appropside of the insert.

Many of the smaller rocket ki ts are designed toC-type engines. Greater ranges and/or payloads caachieved, however, by not fitting the supplied engmount assembly to such rockets and instead installiD -type engine directly in to the rocket bodysection. This can be achieved by removing enough of

outer part of the card engine body to provide for afriction fit. In tests the Alpha III kit was successfmodified in this manner and used with the discarsabot system described previously.

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h iS section is included as an appendix, asneither the author nor the publisher reallywants you to run around firing off live war-heads. You're probably going to get intoenough shit for firing the nonexplosive

rounds anyway The following illustrations show variousways in whi ch an explosive warhead might be detonatedupon impact. The designs are useful for incorporationinto various other types of missile systems that youshouldn't be messing with either Don't experiment

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with th em in conjunction wi t h explosive materialsunless you have a solid grasp of the field and the applicable industry-standa rd safety procedures.

MEC NIC LA copper shear wire 51 passes through the housing HIand body of the striker (ST). On impact, the pressure plate(PPJ is forced into the housing, shearing th e wire andallowing the striker pin P] to hit the percussion cap (PC).The striker pin is held clear of the percussion cap by a

creep spring (5). On impact, pressure on the pressurePC

FIGURE24: Shear pin

ST

5PC pp 5

FIGURE 25 : Creep springpressure

PP

LAW AND ISOR ER............................................... ....................................................... ...........48

D

H

SP

s+PC

FIGURE26: Diaphragm FIGURE 27: Creep spring-ine

plate PPJ overcomes the resistance of the spring andstriker pin hits the cap PCJ.The striker is at t ached to a convex disk of flexmetal forming a diaphragm (D ). Upon impactdiaphragm deforms, reversing in sh ape and drivingstriker pin SP) against the cap (PC). A varia tion suitafor fast-moving warheads/missiles/bombs has the facthe diaphragm covered except for two sm all chann[ust before impact the ai r is compressed in to these chnels, acting upon the diaphragm as per direct im pwith the solid ta rget.A h eavy striker (HS)is held clear of the cap (PC) bcreep spring (5). On impact, inertia the tendencysomething that is moving to want to keep moving wit is suddenly halted] acting upon the striker causes iovercom e the resistance of th e spring, allowing the ster pin to hit the cap.

The striker is retained by a thin metal flange or lipOn impact, inertia causes the striker to bend the retainsurfaces, allowing the striker pin SP) to hit the cap PC

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ELEORI CALA h ea vy con t ac t (HCI is

connected to one side of th ecircuit; the contact plate {CPIis conn ected to the other. Theheavy contact is retained byinsu la ted sp run g jaw s SIIUpon im pact, iner t ia forcesHC th rough the jaw s andonto the contact plate, thereby completing the circuit.The electrical swi tch comp rises two thin pl a tes {PI FIGU RE 28:insta lled close together. On Disk/flange retentionimpact the point of a metalrod MR) is thrust through TO B lTERYthe two plates, thereby completing the circuit.The switch is fitted to thefront of the warhead inside a Hecrushable cover. On impactthe two thin plates (TP) are ,forced together, thereby com _L 'J 1 1I: : L..:Ipleting the circuit. DETON TOR CP

SJFIGURE 29: Inertia switch

-p . . . TO B TIERY"P t O DETON TOR

, , \. TO B TIE Y. . . . . - MR TP XI ( TO DETONATOR

FIGURE 30: Thrust rod FIGURE 31: Nose-switch

LAW A:-;O OJ5 ?DfR50 u - .

ake care when loading a rocket with aimprovised warhead. Remember theanarchist's song, IIIf I drop this I'm fuckdead de dum, de dum . . .

Many thanks to "Nick," without whose help thisject wouldn't have been possible. Good luck withappeal, Nick, see you next visiting day.

Message to readers of Bic Farral l/s book ackyRocketry:Bic has asked me to point out that the car

..... .. ....................... ............. ............................................... 5


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shaped engine tubes on pages 7 and 49 are the result ofh is inability to d efeat the computer graphics packagem onster from hell prior to publication. Yes, the tubesshould be symmetrical. On a related note

Rocket an Is Jailed for our Years

A lovesick businessman whonailed a five-barrelled homemade rocket launc her to a tree intending toambush his ex-laver s new boyfriendhas been jailed for four yearsX fir s t told the court that herigged up the device to fire rocketsinto thunderclouds as an experiment.. . [then] changed his story and saidthe device was actually a suicideweapon . The judge described thecase as very strange and said the(suicide) claim was manifestlyuntrue and wholly implausible. J

The moral of this true story? Christ knows, but i tmade me laugh.

Law and Disorder: Rearming the M72 LAW

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Transcript of Law and Disorder: Rearming the M72 LAW