Ballistic coefficient

In ballistics, the ballistic coefficient (BC, C_b) of a body is a measure of its ability to overcome air resistance in flight. It is inversely proportional to the negative acceleration: a high number indicates a low negative acceleration—the drag on the body is small in proportion to its mass. BC can be expressed with the units kilograms per square meter (kg/m2) or pounds per square inch (lb/in2) (where 1 lb/in2 corresponds to 703.069581kg/m2). where: Cb,Physics, ballistic coefficient as used in physics and engineering m, mass A, cross-sectional area Cd, drag coefficient density characteristic body length The formula for calculating the ballistic coefficient for small and large arms projectiles only is as follows: where: Cb,Projectile, ballistic coefficient as used in point mass trajectory from the Siacci method (less than 20 degrees). m, mass of bullet d, measured cross section (diameter) of projectile i, coefficient of form The coefficient of form, i, can be derived by 6 methods and applied differently depending on the trajectory models used: G model, Beugless/Coxe; 3 Sky Screen; 4 Sky Screen; target zeroing; Doppler radar. Here are several methods to compute i or Cd: where: or A drag coefficient can also be calculated mathematically: where: Cd, drag coefficient. density of the projectile. v, projectile velocity at range. π (pi) = 3.14159... d, measured cross section (diameter) of projectile or From standard physics as applied to "G" models: where: i, coefficient of form. CG, drag coefficient of 1.00 from any "G" model, reference drawing, projectile. Cp, drag coefficient of the actual test projectile at range. This formula is for calculating the ballistic coefficient within the small arms shooting community, but is redundant with Cb,Projectile: where: Cb,Smallarms, ballistic coefficient SD, sectional density i, coefficient of form (form factor) In 1537, Niccolò Tartaglia performed test firing to determine the maximum angle and range for a shot. His conclusion was near 45 degrees.