EXTERNAL BALLISTICS

FIRST OFF

• 3 main ballistics
• Internal ballistics
• External ballistics
• Terminal ballistics
• Focusing on external ballistics

GEOMETRY RELATION

• A bullet is a type of arc
• If left long enough, becomes a parabola
• Shapes used in projectiles
• Spin angles

Using a standard G7 NATO projectile

Not based on angle, but twist rate
Common angle between 30-50 degrees

Slight angles, but to compensate for drag

ARCS AND PARABOLAS

• A bullet creates an arc to the target
• In a perfect world, it would make a parabola
• Also scope makes a secant

FACTORS

• Drag
• Wind speed and resistance
• Projectile shape
• Muzzle velocity
• Bullet grain (weight)
• Caliber and powder

BASE STANDARDS

• Standard G7 projectile
• .308 caliber
• No wind
• 150 grains
• 3000 FPS muzzle velocity
• Gravity is standard (30 pounds)

CALCULATIONS

• Equation for simple ballistics
• X=(Vsquared/G)*sin(2 theta)
• X=max distance
• V=muzzle velocity
• G=gravity
• Sin(2 theta)= angle of traj. *2

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ADVANCED BALLISTICS

• Drag coefficient
• Cd=Fd/(0.5PVsquaredA)
• Fd=force drag
• P=density of fluid
• V=velocity of object
• A=reference area
• Cd=drag coefficient
• Not reliable under speed of sound (~1278 FPS)

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ADVANCED BALLISTICS

• You need:
• Temperature
• Air pressure
• Humidity
• Altitude
• Wind angle/wind speed
• Zero range
• Shooting angle/slant height
• Drag function

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