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ISO 9001 CertifiedBSI FS15149

PRESENTATION TO THE 38th NDIA GUNS & AMMO SYMPOSIUM

26 MARCH 2003

ADAPTATION OF AN M67 RECOILLESS RIFLEADAPTATION OF AN M67 RECOILLESS RIFLE TO FIRE WATER SLUGS TO FIRE WATER SLUGS

DAVID C. SMITH, BENET LABS PHONE: (518) 266-4741 EMAIL: [email protected]

DAVID A. NELSON, NAVEODTECHDIV PHONE: (301) 744-6850 x223 EMAIL: [email protected]

2/1926 MAR 03

ISO 9001 CertifiedFS15149

WHY A WATER CANNON?

• WATER CANNON IS A COMMON TOOL TO PROVIDE THESEFUNCTIONS IN EXPLOSIVE ORDNANCE DISPOSAL.

FUNCTION

LIED THREAT

ACCESS GENERAL DISRUPTION

PRECISION DISRUPTION

MAN PORTABLE Vantrepan Hydra-Jet

Magic Cube

Bootbanger Exit Charge Hydra-Jet

MDET

Shock Tube Wire Cutter Detonator Wire Cutters

SMALL VEHICLE

Vantrepan Bootbanger Exit Charge Hydra-Jet

Magic Cube

Bootbanger Exit Charge

MDET

Shock Tube Wire Cutter Hydra-Jet

MDET Detonator Wire Cutters

LARGE VEHICLE

Vantrepan Bootbanger Exit Charge Hydra-Jet

Magic Cube MDET

Bootbanger Exit Charge

Shock Tube Wire Cutter Bootbanger Exit Charge Hydra-Jet

MDET Detonator Wire Cutters

3/1926 MAR 03


M67 RECOILLESS RIFLE ADAPTATIONOBJECTIVES & REQUIREMENTS

• IN 2001, NAVEODTECH DIV BEGAN PROGRAMS TO REDUCE WEIGHTOF CURRENT WATER CANNON DEVICES.

• BENET LABS WAS CONTACTED TO SUPPORT CONCEPT OFADAPTING M67 RECOILLESS RIFLE TO FIRE WATER SLUGS.

• REQUIREMENTS:– DEVELOP A NUMERICAL ANALYSIS OF THE FLUID PRESSURE

CAPABILITY OF THE (M67) PRESSURE VESSEL.– DEVELOP A FIRST ORDER AXISYMMETRIC PRESSURE-TIME

ANALYSIS OF THE FLUID DURING THE BALLISTIC EVENT.– DEVELOP AN INTERIOR BALLISTIC ANALYSIS SHOWING

PRESSURE TIME CURVE OF THE PROPELLING CHARGE AND APREDICTION OF IMPULSE.

– DEVELOP A MODIFICATION DESIGN FOR THE 90 MM M67RECOILLESS RIFLE.

4/1926 MAR 03


CURRENT DESIGN M67 RECOILLESS RIFLE ADAPTATION

90 MM THIN WALLED TUBE -RIFLED – 1.4 M LONG

FORWARD GRIP ANDMONOPOD ASSEMBLY

REAR BIPOD/SHOULDERREST ASSEMBLY

VENTING BREECHASSEMBLY WITH FIRINGMECHANISM – INCLUDESSAFETY

AIMING OPTICS GROUP

5/1926 MAR 03


CONCEPT M67 RECOILLESS RIFLE ADAPTATION

TUBE - UNMODIFIED

REMOTE FIRING COMPONENTSEXISTING FIRING PIN CABLERELEASE - UNMODIFIED

NEW BRACKETS &SUSPENSION SYSTEMREPLACES HAND GRIPSAND BIBOD

EXPLODED VIEW NEXT SLIDE

6/1926 MAR 03


COMMERCIAL SOLENOID

MIL SPEC CABLE CONNECTORCOVER & BRACKET

EXPLODED VIEW M67 RECOILLESS RIFLE ADAPTATION

7/1926 MAR 03


WATER SLUG/PROJECTILEM67 RECOILLESS RIFLE ADAPTATION

EXISTING M590 CARTRIDGEWITH EXISTING M112 CASE &REAR PLATE OF M590WARHEAD

BRITTLE PLASTIC CONTAINEROF FLUID MOUNTED TO REARPLATE.

8/1926 MAR 03


ANALYSIS M67 RECOILLESS RIFLE ADAPTATION

0

100

200

300

400

500

600

700

0.0000 0.0010 0.0020 0.0030 0.0040 0.0050 0.0060 0.0070

Time (s)

Pre

ssur

e (b

ars)

PRESSURE-TIME OFM590 CARTRIDGE IN M67 RECOILLESS RIFLE

NOVA CODE

BRLRR CODE

9/1926 MAR 03



ELASTIC STRENGTH PRESSURE OF M67 RECOILLESS RIFLE

-5000

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

0 5 10 15 20 25 30 35 40 45 50

Distance from Rear Face of Tube (RFT) (in)

Pres

sure

(ps

i)

Interior Ballistic(Nova)Elastic StrengthPressureMax Fluid Pressure

10/1926 MAR 03



• CFD MODELING– FLUENT USED TO COMPUTE NEAR WALL PRESSURE

• 2-PHASE VOLUME OF FLUID (VOF) MODEL.• COMPRESSIBLE AIR AND INCOMPRESSIBLE WATER• TURBULENCE MODELED WITH K-E MODEL

– VELOCITY PROFILE ON PISTON FACE• NOVA GENERATED VELOCITY VS. TIME PROFILE APPLIED TO

M590 PISTON FACE– MOVING DYNAMIC MESH (MDM) USED TO HANDLE PISTON

MOTION.• SLIDING, NON-CONFORMAL INTERFACE AT BARREL WALL

AND OUTSIDE BARREL.• MESH DESTROYED AT PISTON FACE AND TARGET.

– UNSTEADY, SEGREGATED, IMPLICIT SOLVER.

11/1926 MAR 03



M67 Barrel

Water Slug

M590 Piston

Velocity ProfileOn Face (GridDestructionFace)

Compressible Air

SlidingInterface

Grid DestructionFace

12/1926 MAR 03



Volume FractionWater

13/1926 MAR 03



Pressure

14/1926 MAR 03



Velocity

15/1926 MAR 03


DESIGN CONCLUSIONS M67 RECOILLESS RIFLE ADAPTATION

• THE M67 CAN BE MODIFIED TO FIRE WATER SLUGS AT OR ABOVE1000 FPS EXIT VELOCITY. (1200 FPS PREDICTION)

• THE MODIFICATIONS APPEAR TO RESULT IN A SYSTEM WITH NOAPPARENT SAFETY HAZARDS (EXCEPTION – NEXT BULLET)

• THE INTERIOR BALLISTICS AND FLUID ANALYSIS INDICATE THATTHE MODIFIED M67 HAS A MINIMAL RISK OF FAILURE. POSSIBLETHAT WATER HAMMER COULD OCCUR AS THE WATER SLUG EXITSFROM THE BARREL.

• THE COMPUTATIONAL FLUID DYNAMICS MODELS AREINCONCLUSIVE FOR PRESSURES AT SHOT EXIT. IF THEPRESSURES ARE CLOSE TO THE LEVELS SHOWN BY THEANALYSIS, FAILURE OF THE GUN TUBE MAY OCCUR.

16/1926 MAR 03


FINAL TEST SET UP M67 RECOILLESS RIFLE ADAPTATION

17/1926 MAR 03


EFFECTIVENESS TESTING(DISRUPTION)

18/1926 MAR 03


NAVY EOD WATER CANNON CONCLUSIONS

• BENET MODELING OF M67 AND ANALYSIS OF OTHER (WATERDRAGON) SYSTEMS COMBINED WITH NAVEODTECHDIV TESTSINDICATE:– LIGHTER SYSTEMS ARE FEASIBLE (M67 RECOILLESS)– LIGHTER SYSTEMS CAN PERFORM SAME FUNCTIONS AS

CURRENT SYSTEMS.– MORE EFFICIENT MATERIALS AND DESIGN TECHNIQUES CAN

CREATE SYSTEMS WITH SIMILAR DURABILITY AT ONLYMODERATE COST INCREASES.

90 mm (H)

2-inch Cannon

19/1926 MAR 03


WATER CANNONFUTURE DEVELOPMENT

• NAVEODTECHDIV HAS DEVELOPED CONCEPT FOR ‘MEDIUMDIRECTED ENERGETIC TOOL (MDET) AS NEXT GENERATIONPROGRAM & RETAINED BENET TO SUPPORT DESIGN EFFORTS

PRESENTATION TO THE 38th NDIA GUNS & AMMO … · PRESENTATION TO THE 38th NDIA GUNS ... PHONE:...

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