Aerodynamics Flashcards
1
Q
Centre of Pressure
A
the point where the aerodynamic forces act after adding them up (towards tip of bullet)
2
Q
centre of mass/ centre of gravity
A
where the bullet balances its weight
3
Q
what is the angle of attack
A
the angle between the longitudinal axis and the trajectory
4
Q
why do you add spin to a bullet
A
for gyroscopic stability
5
Q
what is drag coefficient
A
Fd = 1/2 Cd A V2 rho
6
Q
Ballistic coefficient
A
Cb = Cg / Cd x m/ d2
7
Q
1kg = ? grains
A
15400
8
Q
Spin rate
A
Muzzle velocity / twist rate
9
Q
green hill formula
A
T= (C x d2) / L
for muzzle velocities under 860 m/s then C = 150
for muzzle velocities over 860 m/s then C = 180
