1. Introduction to Ballistics
Energetic Materials Research and Testing Center
Mike Stanley, EMRTC
Introduction to Ballistics

2. What is Ballistics?
Ballistics is the science of launching projectiles using propellant or gunpowder
Includes both interior and exterior ballistics
Interior ballistics includes everything that happens inside the gun barrel
Exterior ballistics includes everything that happens outside the barrel
Terminal Ballistics is what happens when the projectile hits the target

4. When did ballistics begin?
Ballistics began with the invention of the first muzzle loading cannons in the 1200’s A.D.
Ever since, people have been trying to maximize the velocity, accuracy, and rate of fire for guns
The first handheld guns were muzzle loading rifles and were developed in the 1400’s
The first cannons and rifles were smoothbores
Rifling was introduced in the late 1600’s

5. Interior Ballistics Propelling charge design Projectile /Sabot design
Barrel design
Recoil system
Wear

6. First Propellant, Black Powder
Black powder, also known as gunpowder is a mixture of potassium nitrate, sulfur, and charcoal.
It originated in China around the tenth century and was used in fireworks and signals.
Black powder is the oldest form of a ballistic propellant and it was used with early muzzle-type firearms.
Black powder was eventually replaced by cleaner burning smokeless powder.

7. Early cannon projectiles

8. Early Smokeless Powders
In 1888, Albert Nobel invented a dense smokeless powder explosive called ballistite.
In 1889, Sir James Dewar and Sir Frederick Abel invented another smokeless gunpowder called cordite.
Cordite was made of of nitroglycerin, guncotton, and a petroleum substance gelatinized by addition of acetone.

9. Modern Propellants Modern propellants are nitrocellulose based
Include nitroglycerine, nitro guanidine, and nitrocellulose
Also include flash suppressants, deterrent layers, and layered burning
Modern propellants also are configured into many shapes and sizes from ball propellant, to solid sticks

10. The first large bore howitzers were used in WWI and II

12. Caliber The caliber of the gun is usually the diameter of the bore
Most guns are maximized for length, based on the velocity of the normal weight projectiles
120 calibers

13. Modern Large Bore Cannon
Breech
Bore
Shoulder
Projectile
Charge
Primer
Muzzle
Chamber

14. How does propellant work?
where BR is Burn Rate
β and α are found empirically
ζ (zeta) is the burn augmentation factor that accounts for energy from grain fracture and inconsistent grain burning
υ is the projectile velocity

15. Typical cannon propellant charge
Ignitor
Propellant
Primer

16. Interior Ballistics Computer Codes

17. Breechless guns

19. Davis Gun 16-inch gun: 40’ long, 16” diameter barrel
Portable: 40’ long x 10’ wide trailer
Firing positions from horizontal to 2° beyond vertical
Launch weights up to 2000 lbs.

21. Hypervelocity Gun Systems
Hypervelocity is defined as velocities over 2 Km/s. The guns range in length from 80 to 100 calibers which provides a relatively “soft” launch platform
Accelerations up to 200,000 g’s.
State-of-the-art computer codes are used to analyze the interior ballistics to optimize the propellant loads and charge configurations, and the acceleration and subsequent stress loads within the projectile itself.

22. EMRTC Two-Stage Light Gas Gun
The two stage light gas gun is propellant driven with an 8 inch diameter pump tube and can launch small fragments and projectiles up to 150 grams in weight
Helium driven
Velocities up to 22,000 fps
1.5 inch bore

23. Projectile Dynamics

24. ALGOR FINITE ELEMENT ANALYSIS Dynamic Projectile and Sabot Analysis

25. Sabot Sabot is French for wooden shoe
Sabots were used in cannons to provide a gas seal so the cannon ball would have more velocity
Sabots are used when the projectile is smaller than the bore
Sabots allow you to fire larger bore guns with greater chamber capacity which means more velocity

26. Pressure Measurements
Time (sec)
Pressure (psi)
Impulse
Test 1 Breech Pressure and Impulse
0.005
0.01
0.015
0.02
0.025
8,000
80,000
16,000
160,000
24,000
240,000
32,000
320,000
40,000
400,000
48,000
480,000
56,000
560,000
Actual Breech Pressure
IBHVG2 Preliminary Breech
IBHVG2 Adjusted Breech
Actual Impulse
IBHVG2 Impulse

27. Test 1 Pressure Differential
Time (sec)
Pressure Difference (psi)
Test 1 Pressure Differential
0.005
0.01
0.015
0.02
0.025
-6,000
-4,500
-3,000
-1,500
1,500
3,000
4,500
IBHVG2 Difference
Actual Difference
-ΔP
“Reverse Differential Pressure”

28. Why pressure waves are bad

30. Breech Failure Analysis
Causes
Poor conditioning of propellant
Major energy contribution thereby varying pressure differential
Charge loading
High loading density or non-uniform loading
Choked gas flow
Accelerated propellant grains
Inconsistent flame fronts
Poor ignition
Center initiated or inconsistent initiated charges cause longitudinal pressure wave to form in the chamber
Grain fracture

31. Exterior Ballistics Flight Dynamics Pitch and Yaw Fin Stabilized
Spin Stabilized
Trajectory Analysis

32. Projectile with discarding sabot

33. Sabot Dynamics

34. Image Motion Compensation Photography (Streak)

36. Flash X-Ray Diagnostic tool to look at projectile “in-flight”
Can see pitch and yaw along with structural stability

38. Doppler Radar Analysis

41. Terminal Ballistics Impact Dynamics Fuzing Projectile Materials
Penetration Depth
Cratering
Obliquities
Fuzing
Projectile Materials
Target types

43. Projectile Penetration