Ballistic coefficient
In ballistics, the ballistic coefficient (BC) 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. This is roughly the same as saying that the projectile in question possesses low drag, although some meaning is lost in the generalization. BC is a function of mass, diameter, and drag coefficient.
Where:
The formula for calculating the ballistic coefficient for small and large arms projectiles only is as follows:
Where:
The Coefficient of form (i) can be derived by 6 methods and applied differently depending on the trajectory models used: G Model, Bugless/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:
or
From standard physics as applied to “G” models:
Where:
This formula is for calculating the ballistic coefficient within the smalls arms shooting community, but is redundant with BCProjectile:
Where:
In 1537, Niccolò Tartaglia did some test firing to determine the maximum angle and range for a shot. His conclusion was near 45 degrees. He noted that the shot trajectory was continuously curved.
In 1636, Galileo Galilei published results in "Dialogues Concerning Two New Sciences". He found that a falling body had a constant acceleration. This allowed Galileo to show that a bullet's trajectory was a curve.
Circa 1665, Sir Isaac Newton derived the law of air resistance and stated it was inversely proportional to the air resistance. Newton's experiments on drag were through air and fluids. He showed that drag on shot increases proportionately with the density of the air (or the fluid), cross sectional area and weight of the shot. Newton’s experiments were only at low velocities to about 260 m/s (853 ft/s).
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Wikipedia