eric kathe

Wednesday, April 17, 2002 NDIA Guns&Ammo . . . 1

RAVE

N A New Species of Gun for theObjective Force

Eric KatheU.S. Army, TACOM-ARDEC Benét Labs

Watervliet Arsenal, NY

RAVEN


RAVE

NOutline

• RAVEN Concept• 35mm RAVEN Implementation• Experimental Results• Comments on Blast• Discussion of Results


RAVE

NPrior Art: DAVIS Gun

• Recoilless• Accurate• Capable of

High PressurePropulsion

• Drawbacks:– Inefficient– Weight– Back Blast &

Back “Bullet”


RAVE

NHow it works

• Initial operation as a closed-breech gun.

• Upon a delayed venting of the chamberRAVEN operates as a recoilless rifle.

• The limiting velocity of the rarefaction wavereleased by the venting will reduce oreliminate any degradation in projectilepropulsion.

• Analogy may be drawn to the rarefactionwave through the driver section of a shock-tube.


RAVE

NInertial “Blow-Back” Breech

• Intentional rupture of cartridge case.– Compatible with combustible case technology.

• Breech travel governed by same propellantpressure that drives the projectile.

• Recoil stroke to vent port and recoil massdetermine vent time.– Robust, reliable, potentially weaponizable . . .

but not the only path forward.


RAVE

NPicture of Test Fixture


RAVE

NOerlikon KD AA 35mm TP

• 1,175 m/s• 250 #s

1,100 Ns• 55 ksi

383 MPa• L 3.1m

• Mp = 0.55 Kg• Mc = 0.33 Kg• Mc/Mp = 0.60


RAVE

NCartridge Case Notch

The back of thecartridge casewas modified toincorporate arupture notch &accommodate anylon obturatorband.


RAVE

NInternal Workings of Test Fixture

Shear Plug

Firing PinActuator

FiringPinBushing

Nylon ObturatorBand Fit OverCase Head


RAVE

NBreech Operating Sequence


RAVE

NARES Test Range

Erie Proving Grounds, Port Clinton, OH


RAVE

NFirst Firing, 30 August 2001

• Firingevent


RAVE

NFirst Firing, 30 August 2001

• CaseHeadEjection

• CaseBodyEjection


RAVE

NFirst Firing Video


RAVE

NPrimary Recoil

The primary recoilrods, utilizingsimple copperplumbing tubingas crush tubesworked well.


RAVE

NNon-Venting Pressure Data

Inertial Blow-Back Breech

1135 m/s Muzzle Velocity 2-9-4


RAVE

NPressure Travel Time Curve

Inertial Blow-Back Breech


RAVE

NHeavy/Early RAVEN Pressure Data

1131 m/s Muzzle Velocity 2-3-5


RAVE

NSuperimposed Chamber Pressure

Light-Nominal-RAVEN vs. Non-Venting

1131m/s Vented vs 1135m/s NV


RAVE

NRarefaction Wave Head Identification

• LocalMinimum ofsecondderivative ofpressure traceis indicativeof wave headpassage.


RAVE

NRarefaction Wave Head Identification

• Intersection of exponential fits avoidssensitivity to smoothing drift.


RAVE

NPressure Travel Time Curve

Light-Nominal-RAVEN

Wave Front Chases Projo Down Bore.


RAVE

NSuperimposed Pressure Gradient

Heavy-Early-RAVEN vs. Non-Venting



RAVE

NMeasured Recoil Reduction

Two Base Lines:• 51% reduction vs closed breech• 58% reduction vs inertial breech


RAVE

NReduced Heat Transfer

• 20% Reduction in Temperature at Mouth ofChamber


RAVE

NReduced Heat Transfer

50%Reduction

OverMuzzleHalf ofBarrel


RAVE

NMuzzle Velocity

• The inertial breech may be anticipatedto reduce muzzle velocity due to energyimparted to breech.

• Theoretical (Lumped IB) Vs. Test [m/s]– Closed Breech, 1175 vs. 1175 (Matched)– Heavy Breech, 1130 vs. 1151– Light Breech, 1095 vs. 1100– Non Vent Breech, 1124 vs. 1121

CB: 334 Kg, HB: 35.9 Kg, LB: 20.9 Kg, NV: 31.8 Kg


RAVE

NComparison to Muzzle Brakes

• RAVEN exceeded the performance of a doublebaffle brake.

• Fitted with a G=1 brake, RAVEN is estimated tonearly halve the remaining M109 momentum.

272 Ns

467 Ns467 Ns467 Ns467 Ns

M109 Double BaffleBrake Estimate

59%


RAVE

NNo Nozzle Throat Erosion

• Metallographic analysis of the edge ofthe “valve seat” indicate a heat affectedzone approximately 5 µm deep.

• Zero Erosion Discerned• Prior concerns regarding

erosion may have beenoverstated.

• Remains to be seen how itwill perform with “hot”propellant.


RAVE

NPotential RAVEN Applications


RAVE

NComments on Back Blast

• Danger zone extent behind prior large caliber recoillessis similar to current TOW missiles.

Source: AMCP 706-238 RecoillessRifle Weapon systems on 105mmM27 (8 lbm charge) & FM 23-34TOW Weapon Systems.


RAVE

NMuzzle Blast

Legacy compatible Ultra-Light 120mmtank gun on a Block I FCS.

The CV90120-T tank has been developed to provide a lighter highly mobile main battle tank with 120mm high pressuresmoothbore 120mm gun, battlefield management and extensive defensive aids suite.The CV90120-T tank has been developed to provide a lighter highly mobile main battle tank with 120mm high pressuresmoothbore 120mm gun, battlefield management and extensive defensive aids suite.The CV90120-T tank has been developed to provide a lighter highly mobile main battle tank with 120mm high pressuresmoothbore 120mm gun, battlefield management and extensive defensive aids suite.


RAVE

N

ELEVATED TOW SYSTEM (ETS)ELEVATED TOW SYSTEM (ETS)

The mast mounted TOWThe mast mounted TOWsystem developed by Delco in conjunctionsystem developed by Delco in conjunctionwith with FalckFalck-Schmidt of Denmark provides a unique-Schmidt of Denmark provides a uniquebattlefield capability. Chassis mounted, it is abattlefield capability. Chassis mounted, it is ahighly mobile, armored TOW platform capable ofhighly mobile, armored TOW platform capable ofreconnaissance and engagement from defilade.reconnaissance and engagement from defilade.


RAVE

NGun on a Wing-Tip

Advances in compositecannon technology, firecontrol stabilization,and smart ammunitionmay work withrecoilless operation toprovide formidablearmament foroverwhelming lethality

U.S. P-51 with 106 mm Recoilless Rifle on each wingtip


RAVE

NConclusions

• RAVEN concept experimentally validated.• Dramatic reduction in measured recoil

momentum observed w/out compromise inprojectile propulsion.

• Substantial reduction in barrel heatingobserved.

Comments:• Recoil and Barrel Heating Reduction may prove Enabling

for Future Composite Guns.• Efficient Recoilless Operation Also Viable.

eric kathe

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