Energetic Materials Research and Testing Center
Mike Stanley, EMRTC
Introduction to Ballistics
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
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
Interior Ballistics
 Propelling charge design
 Projectile /Sabot design
 Barrel design
 Recoil system
 Wear
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.
Early cannon projectiles
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.
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
The first large bore howitzers were used in WWI and II
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
Modern Large Bore Cannon
Chamber
Breech
Primer
Shoulder
Charge
Projectile
Bore
Muzzle
How does propellant work?

BR    P    
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
Typical cannon propellant charge
Propellant
Primer
Ignitor
Interior Ballistics Computer Codes
Breechless guns
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.
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.
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
Projectile Dynamics
Projectile Acceleration =
a
proj

a r e c o il 
Net Force on Projectile
Projectile Mass
Pb a s e  P r e s  P a i r A b o r e
m proj g
Pb r e e c h  P r e s A b o r e
m r e c o il g
a
dv
 
x
dt
v
dx
 x
dt
ALGOR FINITE ELEMENT ANALYSIS
Dynamic Projectile and Sabot Analysis
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
Pressure Measurements
56,000
560,000
48,000
Actual Breech Pressure
IBHVG2 Preliminary Breech
IBHVG2 Adjusted Breech
480,000
Actual Impulse
IBHVG2 Impulse
40,000
400,000
32,000
320,000
24,000
240,000
16,000
160,000
8,000
80,000
0
0
0.005
0.01
0.015
Time (sec)
0.02
0
0.025
Impulse
Pressure (psi)
Test 1 Breech Pressure and Impulse
Test 1 Pressure Differential
4,500
IBHVG2 Difference
Actual Difference
Pressure Difference (psi)
3,000
1,500
0
-1,500
-3,000
-ΔP
-4,500
“Reverse Differential Pressure”
-6,000
0
0.005
0.01
0.015
Time (sec)
0.02
0.025
Why pressure waves are bad
Breech Failure Analysis
Causes

Poor conditioning of propellant


Charge loading

High loading density or non-uniform loading




Major energy contribution thereby varying pressure differential
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

Exterior Ballistics
 Flight Dynamics
 Pitch and Yaw
 Fin Stabilized
 Spin Stabilized
 Trajectory Analysis
Projectile with discarding sabot
Sabot Dynamics
Image Motion Compensation
Photography (Streak)
Flash X-Ray
 Diagnostic tool to look at projectile “in-flight”
 Can see pitch and yaw along with structural stability
Doppler Radar Analysis
Terminal Ballistics
 Impact Dynamics
 Penetration Depth
 Cratering
 Obliquities
 Fuzing
 Projectile Materials
 Target types
Projectile Penetration