Some Comments Regarding Performance Potential for a New Machine Gun and Ammunition Concepts

Abe Flatau

Consultant

General Outline

• Summary

• Introduction

• Brief Technical Overview

• Ammunition

– Emphasis on lightweight, high V0, very low drag projectiles = high kinetic energy to deposit on target

• Brief Comparison of Trajectory Profiles

– Proposed vs. current

Conclusion

• It is strongly recommended that the key technologies be brought together to result in a modern, high performance, effective machine gun system that is a superior weapon in the field.

Summary

• Conceiving, developing and fielding a weapon system is not an easy task.

• Perhaps that is why we shy away from replacing tried and tested systems that have been used for almost the past century.

• This brief presentation points out some of the advances in technology that can be applied to a new high performance machine gun system.

Comments on .50 Cal Heavy Machine Gun

• Technology from the end of WWI (1918).

• Cartridge volume is limited. No significant increase in performance.

• Saboted Light Anti-Material Penetrator (SLAP) performance limited.

• Overall gun-ammo system limited for performance upgrade.

Aerodynamicist’s Golden Rule

“Assume Everything, But the Responsibility.”

Current and Proposed Heavy Machine Gun Systems

Wt (lb) V0(ft/sec)

• US 12.7mm(.50cal) 0.1014 2,800

• US 15.24mm(.60cal)

• US 16.51mm(.65cal) 0.0794 5,000

• Soviet 14.5mm(.57cal) 0.1391 3,511

• US 29mm M246 0.2267 3,380

Characteristics of Well Designed Tubular Projectiles

• High muzzle velocity +Low drag shape =

High kinetic energy + short time of flight = relatively flat trajectory = high hit probability

Performance bonus = high gyroscopic stability = anti-ricochet

Relatively New Technologies(Since Browning .50 Cal was Accepted)

• Aeroballistic

• Interior Ballistics

• Materials (high strength & light weight)

• Computer Aided Design

Projectiles

• Tubular w/ Incendiary

– Pusher/obturator

• Multipurpose

• Consumable

• Conventional w/ HE Charge

• SLAP

Interior Ballistics

• Compacted propellant

– (Proprietary designs and concepts)

• Ignition Techniques

• Lightweight projectile

• Mass (M) + High muzzle velocity (V) = High kinetic energy (1/2MV2)

• Equates to: Shorter time of flight to a given distance + some aerodynamic lift combined with low-aerodynamic drag = a relatively flat trajectory

Packing Density

• WWII Propeller Aircraft

• Jet Fighter

Conclusion

• It is strongly recommended that the key technologies be brought together to result in a modern, high performance, effective machine gun and ammunition system that is superior to other gun-launched weapons in its general class.

Full-bore Tubular Projectile Configuration

Airflow

Lip angleRotatingband

Crimpgroove Boattail

Convergentarea Throat Divergent

area

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Basic Characteristics of Tubular Projectiles

• Low supersonic drag

• Light weight allows increased muzzle velocity

• High gyroscope stability

Flightdirection

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External Flow Characteristics of Tubular Projectiles

Swallowed flow

• No bow shock on or in front of nose

• Low drag

Directionof flight

High Mach Number Low Mach Number

M 1.9

Choked flow

• Bow shock

• High drag

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Bow shock associated with “choking” and high drag

Note: Above shape is known as a Busemann Biplane andalso as an “internal” design

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Schlieren Photographs of TCD-3 WSCO Supersonic Wind Tunnel Variable Mach Number Operation

Before high drag condition High drag condition

M 3.0 M 2.5

M 1.6M 2.0

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Aeroballistic Range Photographs/TCD-3M ~ 40

Near muzzle

20 feet down range

15 feet down range

300 feet down range

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M103 case

Obturator/pusher

Tubular projectile

WSC MAR 76

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Potential Advantages of Tubular Projectiles

• Higher launch velocity (lighter weight)

• Shorter time of flight

• Near straight-line trajectory profile

• Simplified fire control

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Kinetic Energy vs. Range

0 500 1000 1500 2000Range, meters

40

30

25

20

15

10

5

0

Kin

etic

en

erg

y, f

t-lb

1

03

0.5 sec

0.5 sec0.5 sec

0.5 sec

1.01.0

1.0

1.5

1.5

1.5

1.52.02.0

2.02.5

2.5

2.5 3.03.5 4.0

Size Weight, lb Vo, ft/sec

0.65 cal. 0.07940 5000

14.5 mm api 0.1391 3511

0.50 cal. apm2 0.1015 2800

20 mm M246 0.2267 3380

T-0.65 Caliber vs. 0.50 Caliber

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Caliber Weight, lb

T-0.65 0.0794

0.50 0.1014

5000

4000

3000

2000

1000

0

Vel

oci

ty,

~ft

/sec

0 1000 2000 3000Range, ~meters

0.5 sec

1.0

1.5

2.0

2.53.0

4.0

0.7 sec1.0

2.0

2.8

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Representative Trajectory Profiles

0 500 1000 1500 2000

40

30

20

10

0

Horizontal range, ~meters

Hei

gh

t, m

ete

rs

Vi.65 cal = 1028 FPSt = 2.60 sec

andVi.50 cal = 815 FPS

t = 4.50 sec

.50 cal. AP: = 2, V0 = 2800 FPS

.60 cal. TCD-7: = 0.6, V0 = 5000 FPS

Summary of .65 Caliber Tubular Projectile Characteristics

• Significant increase in kinetic energy over .50 caliber

• Terminal ballistics far superior to .50 caliber AP

• Flatter trajectory than .50 caliber

• Shorter time of flight than .50 caliber

• Greater range than .50 caliber

• Low weight system/low cost ammunition

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DRDAR-ACW

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“That’s how Research and Development put the pressure on. First they hustle you to promise them results. Then they hustle you some more to promise them results in our lifetime!”

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