New Extended Range Shoulder-Fired 40mm Grenade System · 2018-04-26 · Grenade mass [g] 400 500 600 700 800 900 Maximum range [m] ERLP (840m) Std LV (435m) XM320 (2.3kg) XRGL40 (5kg)

Extended Range40 mm

Outline

Introduction40 mm Systems

Objectives

Recoil EnergyLimitations

Calculations

External Ballistics

Propulsion SystemInternal ballistics

Pressure approximation

Muzzle velocity

ERLP propulsion

ERLP Specifications

Conclusions

1

New Extended Range Shoulder-Fired40 mm Grenade System

Danie Elsa Hennie Pieterseb Marius de Bruinc

aDept of Mech and Mechatronics Eng,Univ of Stellenbosch, South Africa

[email protected]

bRippel Effect Weapon Systems Pty (Ltd),Silver lakes, Pretoria, South Africa

[email protected]

cDenel Land Systems Western Cape, Denel Pty (Ltd),Somerset West, South [email protected]

22nd Small Arms and Cannons SymposiumDCMT Shrivenham, UK19–21 August 2008

Extended Range40 mm

Outline


Objectives


Calculations

External Ballistics



Muzzle velocity

ERLP propulsion

ERLP Specifications

Conclusions

2

Outline

1 Introduction40 mm Weapon SystemsDesign Objectives

2 Recoil Energy AnalysisFree recoil energy limitationsRecoil Energy CalculationsExternal Ballistics Calculations

3 Propulsion SystemInternal ballisticsPressure approximationMuzzle velocityFinal ERLP propulsion system

4 ERLP Design Specifications

5 Conclusions

Extended Range40 mm

Outline


Objectives


Calculations

External Ballistics



Muzzle velocity

ERLP propulsion

ERLP Specifications

Conclusions

3

IIntroduction

This section consists of:

Overview of 40 mm type ammunition.

Overview of 40 mm weapon systems.

Design objectives of new extended range 40 mmammunition.

Extended Range40 mm

Outline


Objectives


Calculations

External Ballistics



Muzzle velocity

ERLP propulsion

ERLP Specifications

Conclusions

4

40mm×46mm Standard Ammunition (Low Velocity)

High pressure chamber

Cartridge caseLow pressure chamber

Projectile

Vent holes

High/low pressure propulsion system

Muzzle velocity 76 m/sEffective range 375 m

Maximum range 430 m

Maximum pressure 13 MPa

Extended Range40 mm

Outline


Objectives


Calculations

External Ballistics



Muzzle velocity

ERLP propulsion

ERLP Specifications

Conclusions

5

40 mm Weapon Systems

http://en.wikipedia.org/wiki/M79_Grenade_launcher

M79

M203

http://en.wikipedia.org/wiki/M79_Grenade_launcher

Extended Range40 mm

Outline


Objectives


Calculations

External Ballistics



Muzzle velocity

ERLP propulsion

ERLP Specifications

Conclusions

6

40 mm Weapon Systems ...

http://www.heckler-koch.de

HK69 A1


AG36, XM320



Extended Range40 mm

Outline


Objectives


Calculations

External Ballistics



Muzzle velocity

ERLP propulsion

ERLP Specifications

Conclusions

7


http://www.hk-usa.com/le_agc_general.html

M4/XM320 and M16A2/XM320

L85A2/L17A2

http://www.hk-usa.com/le_agc_general.html

Extended Range40 mm

Outline


Objectives


Calculations

External Ballistics



Muzzle velocity

ERLP propulsion

ERLP Specifications

Conclusions

8


http://www.rippeleffect.com/

XRGL40

http://www.rippeleffect.com/

Extended Range40 mm

Outline


Objectives


Calculations

External Ballistics



Muzzle velocity

ERLP propulsion

ERLP Specifications

Conclusions

9

Design Objectives

The new Extended Range Low Pressure (ERLP™) 40 mmround was developed with the following objectives:

Extending the range as much as possible for tacticalreasons.

Keeping the recoil energy below 60 J in accordance withTOP3-2-504, when fired from the XRGL40™ or fromunder-barrel configurations such as the L85A2/L17A2so that a maximum of 100 rounds/day/man can befired.

Minimizing the propulsion pressure for weapon safetyand use in existing weapons.

Modifying the M118 based cartridge case to preventaccidental loading in weapons where it may be unsafe.

Extended Range40 mm

Outline


Objectives


Calculations

External Ballistics



Muzzle velocity

ERLP propulsion

ERLP Specifications

Conclusions

10

IIRecoil Energy Analysis


Maximum recoil energy limitations.

Different weapon system mass parameters.

Recoil energy formulas.

Calculation of maximum allowable muzzle velocity.

Simple external ballistics model.

Calculation of maximum allowable range.

Maximum recoil energy is the main design constraint

Extended Range40 mm

Outline


Objectives


Calculations

External Ballistics



Muzzle velocity

ERLP propulsion

ERLP Specifications

Conclusions

11

Free recoil energy limitations for shoulder fired weapons

Limitations on

Free recoil energy number of rounds

0 J to 20 J Unlimited firing

20 J to 40 J 200 rounds/man/day



Greater than 80 J No shoulder firing

Test Operations Procedure (TOP) 3-2-504, “U.S. Army SafetyEvaluation of Hand and Shoulder Weapons”.

K. Blankenship, et al. “Shoulder-Fired Weapons with High RecoilEnergy:Quantifying Injury and Shooting Performance”. USARIEMTechnical Report T04-05, 2004.

M79 as reference has recoil energy of about 40 J

Extended Range40 mm

Outline


Objectives


Calculations

External Ballistics



Muzzle velocity

ERLP propulsion

ERLP Specifications

Conclusions

12

Weapon Systems Properties

Total Barrel

Empty mass length

Weapon system [ kg ] [ mm ]

HK69 A1 2.2 356

XM320 (Stand Alone) 2.3 215

M79 2.7 356

M4/XM320 4.4 215

XRGL40 5.0 356+

L85A2/L17A2 5.3 215

M16A2/M203 5.4 250

M16A2/XM320 5.7 215

Extended Range40 mm

Outline


Objectives


Calculations

External Ballistics



Muzzle velocity

ERLP propulsion

ERLP Specifications

Conclusions

13

Recoil Energy calculations

Free recoil energy E

E = 12mW

[(mP +αmg

mW

)ve]2

(1)

with: mW = weapon mass [kg]mP = projectile mass [kg]mg = propellant gas mass [kg]ve = projectile muzzle velocity [m/s]vg = propellant gas velocity [m/s]α = vg/ve ≈ 1.75 (contribution of exit gasses)

The muzzle velocity ve for a given recoil energy E

ve =√

2mWEmP +αmg

(2)

Extended Range40 mm

Outline


Objectives


Calculations

External Ballistics



Muzzle velocity

ERLP propulsion

ERLP Specifications

Conclusions

14

190 195 200 205 210 215 220 225 230Grenade mass [g]

70

80

90

100

110

120

130M

axim

um

muzz

le v

elo

city

[m

/s]

Std LV

ERLP

XM320 (2.3kg)

XRGL40 (5kg)

Maximum muzzle velociy for E = 40J to 60J

ERLP

200 g projectile with 120 m/s muzzle velocity

Extended Range40 mm

Outline


Objectives


Calculations

External Ballistics



Muzzle velocity

ERLP propulsion

ERLP Specifications

Conclusions

15

External Ballistics Calculations

x

y½ρCd Av2

mG g

v

v0

θ0

Simplified 2D external ballistics model[xy

]= − ρCdAv

2mG

[xy

]−[

0

g

](3)

with: ρ = air density = 1.2 kg/m3

Cd = drag coefficient = 0.20 to 0.23A = sectional area = 0.022π m2

g = gravitation = 9.81 m/s2

v =√x2 + y2 (4)

Initial values: x0 = 0 m, x0 = v0 cosθ0 m/sy0 = 0 m, y0 = v0 sinθ0 m/s

Extended Range40 mm

Outline


Objectives


Calculations

External Ballistics



Muzzle velocity

ERLP propulsion

ERLP Specifications

Conclusions

16

190 195 200 205 210 215 220 225 230Grenade mass [g]

400

500

600

700

800

900

Maxim

um

range [

m]

ERLP (840m)

Std LV (435m)XM320 (2.3kg)

XRGL40 (5kg)

Maximum range for E = 40J to 60J

ERLP

Maximum range of 840 m and effective range of 800 m.

Live firings with radar measurements has given a maximumof 890 m.

Extended Range40 mm

Outline


Objectives


Calculations

External Ballistics



Muzzle velocity

ERLP propulsion

ERLP Specifications

Conclusions

17

IIIPropulsion System Analysis


Investigate the internal ballistics properties of system

Establish changes to reduce maximum pressure

Extended Range40 mm

Outline


Objectives


Calculations

External Ballistics



Muzzle velocity

ERLP propulsion

ERLP Specifications

Conclusions

18

Internal ballistics

PA α

x

Simplified internal ballistics model

x = PAm′ m′ =m

(1+ r

2

R2tan(α) tan(α+ β)

)(5)

with: P = pressure [ Pa ]A = barrel projected area [ m2 ]R = barrel radius [ m ]r = projectile radius of gyration [ m ]α = barrel helix angle [ rad ]β = friction angle (tanβ = µ) [ rad ]m= projectile mass [ kg ]

Extended Range40 mm

Outline


Objectives


Calculations

External Ballistics



Muzzle velocity

ERLP propulsion

ERLP Specifications

Conclusions

19


V0 A

From ideal gas laws assume no heat transfer, no leakagesand that propellent is fully burnt. Approximate pressure asa simple blowdown system

P(x) = P0

(V0

V0 +Ax

)γ(6)

with: P0 = initial pressure [ Pa ]P = pressure [ Pa ]V0 = initial volume [ m3 ]A = barrel projected area [ m2 ]γ = heat capacity ratio (change to compensate for losses)

Extended Range40 mm

Outline


Objectives


Calculations

External Ballistics



Muzzle velocity

ERLP propulsion

ERLP Specifications

Conclusions

20

Muzzle velocity

Equation of motion of projectile from (5) and (6)

d2xdt2

= vdvdx= P0Am′

(V0

V0 +Ax

)γ(7)

Integrate with respect to velocity v, then

v2e =

2P0V0

m′(γ−1)

[1−

(1+Axe

V0

)1−γ](8)

with: ve = muzzle velocityxe = barrel travel distance

Equation (8) can be used to calculate the influence of lowpressure chamber volume and the effect of a shortenedbarrel.

Extended Range40 mm

Outline


Objectives


Calculations

External Ballistics



Muzzle velocity

ERLP propulsion

ERLP Specifications

Conclusions

21

1.0 1.5 2.0 2.5 3.0V�0 /V0

0.4

0.5

0.6

0.7

0.8

0.9

1.0P

�

0/P0

0.59

�=1.297

xe =0.3m�(V�0�V0 )/A

A0 =13.380cm2

V0 =20.795cm3

M79 with LV cartridge

ERLP

Doubling of low pressure chamber volume reduces peakpressure by about 40%.

Extended Range40 mm

Outline


Objectives


Calculations

External Ballistics



Muzzle velocity

ERLP propulsion

ERLP Specifications

Conclusions

22

0.50.60.70.80.91.0x�e /xe

0.90

0.92

0.94

0.96

0.98

1.00v

�

e/v e

0.94

XM

320

Velocity reduction compared to M79

Muzzle velocity of short barreled underslung weapons is95% compared to that of the M79 reference.

Extended Range40 mm

Outline


Objectives


Calculations

External Ballistics



Muzzle velocity

ERLP propulsion

ERLP Specifications

Conclusions

23

Final ERLP propulsion system

Based on the M118 cartridge.

The low-pressure chamber volume was doubledcompared to the M406 round with M118 cartridge.

Different propellents were tested and the finalconfiguration has a maximum pressure of 12 MPa to14 MPa.

Optimization of the high pressure chamber and ventholes is still in progress.

Extended Range40 mm

Outline


Objectives


Calculations

External Ballistics



Muzzle velocity

ERLP propulsion

ERLP Specifications

Conclusions

24

IVERLP Design Specifications

Projectile mass 200 g

Muzzle velocity 120 m/s (short barrel: 115 m/s)

Maximum range 840 m (short barrel: 800 m )

Effective range 800 m

Maximum pressure 12–14 MPa

Cartridge length 51 mm (Safety & performance)

Obturator (Efficiency)

Extended Range40 mm

Outline


Objectives


Calculations

External Ballistics



Muzzle velocity

ERLP propulsion

ERLP Specifications

Conclusions

25

40mm x 46mm Standerd Velocity HE

40mm x 51mm Extended Range (ERLP)

Extended Range40 mm

Outline


Objectives


Calculations

External Ballistics



Muzzle velocity

ERLP propulsion

ERLP Specifications

Conclusions

26

VConclusions

We have designed and verified an extended range 40 mmsystem that has met all our objectives.

The ERLP round has an effective range of 800 m.

The recoil energy is below 60 J for weapons with a massof 5 kg or more.

The recoil energy can be dangerously high from lighterweapons. This necessitates that the ERLP round beprevented from being loaded into such weapons.

Existing weapons require modification to fire the round.

The propulsion system resulted in a pressure of12-14 MPa, which is in the same range as the standardlow-velocity 40 mm systems, thereby not reducing thefatigue life of the chamber or barrel of existingweapons.

More than 400 shots have been fired successfully

Documents

New Extended Range Shoulder-Fired 40mm Grenade System · 2018-04-26 · Grenade mass [g] 400 500 600 700 800 900 Maximum range [m] ERLP (840m) Std LV (435m) XM320 (2.3kg) XRGL40 (5kg)