1. Some Comments Regarding Performance Potential for a New Machine Gun and Ammunition Concepts
Abe Flatau
Consultant

2. 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

3. 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.

4. 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.

5. 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.

6. Aerodynamicist’s Golden Rule
“Assume Everything, But the Responsibility.”

7. Current and Proposed Heavy Machine Gun Systems
Wt (lb) V0(ft/sec)
US mm(.50cal) ,800
US mm(.60cal)
US mm(.65cal) ,000
Soviet mm(.57cal) ,511
US mm M ,380

8. 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

9. Relatively New Technologies (Since Browning .50 Cal was Accepted)
Aeroballistic
Interior Ballistics
Materials (high strength & light weight)
Computer Aided Design

10. Projectiles Tubular w/ Incendiary Pusher/obturator Multipurpose
Consumable
Conventional w/ HE Charge
SLAP

11. 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

12. Packing Density
WWII Propeller Aircraft
Jet Fighter

13. 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.

14. Full-bore Tubular Projectile Configuration
Air flow
Lip angle
Rotating band
Crimp groove
Boattail
Convergent area
Throat
Divergent area

15. Basic Characteristics of Tubular Projectiles
Flight
direction
Low supersonic drag
Light weight allows increased muzzle velocity
High gyroscope stability

16. External Flow Characteristics of Tubular Projectiles
High Mach Number
Low Mach Number
M  1.9
Direction of flight
Swallowed flow
No bow shock on or in front of nose
Low drag
Choked flow
Bow shock
High drag

17. Bow shock associated with “choking” and high drag
Note: Above shape is known as a Busemann Biplane and also as an “internal” design

18. Before high drag condition
Schlieren Photographs of TCD-3 WSCO Supersonic Wind Tunnel Variable Mach Number Operation
M  3.0
M  2.5
M  1.6
M  2.0
Before high drag condition
High drag condition

19. Aeroballistic Range Photographs/TCD-3
M ~ 40
Near muzzle
20 feet down range
15 feet down range
300 feet down range

20. Tubular projectile M103 case
Obturator/ pusher
M103 case
WSC MAR 76

22. Potential Advantages of Tubular Projectiles
Higher launch velocity (lighter weight)
Shorter time of flight
Near straight-line trajectory profile
Simplified fire control

23. Kinetic Energy vs. Range
500
1000
1500
2000
Range, meters 40 30 25 20 15 10 5
Kinetic energy, ft-lb  103
0.5 sec
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Size Weight, lb Vo, ft/sec
0.65 cal
14.5 mm api
0.50 cal. apm
20 mm M

24. T-0.65 Caliber vs. 0.50 Caliber Caliber Weight, lb T-0.65 0.0794
5000
4000
3000
2000
1000
Velocity, ~ft/sec
Range, ~meters
0.5 sec
1.0
1.5
2.0
2.5
3.0
4.0
0.7 sec
2.8

25. Representative Trajectory Profiles
.50 cal. AP:  = 2, V0 = 2800 FPS
.60 cal. TCD-7:  = 0.6, V0 = 5000 FPS
500
1000
1500
2000 40 30 20 10
Horizontal range, ~meters
Height, meters
Vi.65 cal = 1028 FPS
t = 2.60 sec
and
Vi.50 cal = 815 FPS
t = 4.50 sec

26. 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
DRDAR-ACW

28. “That’s how Research and Development put the pressure on
“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!”