Quote:
Originally Posted by peterb
What sort of effect does a head or tail wind have on a projectile?
Cheers, Pete

In Chapter 7 of Robert McCoy's book "Modern Exterior Ballistics" the math is given to calculate the effect of head and tail wind. He gives the example of an M2 ball bullet (3006 @ 2800 fps) with a 10 mph tail wind and demonstrates that causes the point of impact at 600 yards to be raised by 0.7 inches relative to not having a tail wind.
Basicly a tail wind decreases the time of flight by slightly reducing the drag on the bullet. That affects the drop simply from reducing the time the acceleration of bravity (32 ft/sec^2) is applied to the bullet before impact. A head wind likewise increases the time of flight lowering the point of impact.
Many ballistic computer programs are based on McCoy's work and include the effect of the head and tail wind components in the calculations. You can check if your's does by including a head or tail wind in the calculation (if the software has a place to enter a 0 or 180 degree wind) and see if it causes the expected small change in the calculated drop. You can then check the effect on your particular bullet/velocity/atmosphere at various ranges. Drop however is related to the square of the time of flight while croswind effects are linear with the time of flight.
Head and tail wind effects are generally much smaller than crosswind effects at practical ranges but do increase with range more than crosswind effects. If you're worried about it let your ballistic computer show you the effects.