some comments regarding performance potential for a new machine gun and ammunition concepts abe...
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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
0173-04
Basic Characteristics of Tubular Projectiles
• Low supersonic drag
• Light weight allows increased muzzle velocity
• High gyroscope stability
Flightdirection
0171-04
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
0174-04
Bow shock associated with “choking” and high drag
Note: Above shape is known as a Busemann Biplane andalso as an “internal” design
0172-04
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
0176-04
Aeroballistic Range Photographs/TCD-3M ~ 40
Near muzzle
20 feet down range
15 feet down range
300 feet down range
0175-04
0183-04
M103 case
Obturator/pusher
Tubular projectile
WSC MAR 76
0178-04
Potential Advantages of Tubular Projectiles
• Higher launch velocity (lighter weight)
• Shorter time of flight
• Near straight-line trajectory profile
• Simplified fire control
0170-04
0182-04
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
0180-04
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
0181-04
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
0169-04
DRDAR-ACW
0179-04
“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!”
0177-04
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