Re: [Phys-l] Final velocity of bullets

[Brian Whatcott <betwys1@sbcglobal.net>]

At 12:43 PM 1/23/2007,  Oren, you wrote:
...
>  does a bullet reach terminal velocity before or
> after the air friction stops the bullet from spinning and then produces
> the tumbling?
>
> Oren Quist, South Dakota State

I cannot speak directly to the question. I recall that the
 ogival bullet nose or round nose for that matter, is
advantageous from the point of view of low drag coefficient.

But this shape has a center of gravity aft of the center of
pressure, so it is only the spin that holds the bullet "on point"
 as it were. The spin substitutes precession, nutation and
(sometimes) a helical initial trajectory for tumbling.
It is perhaps for this reason (I cannot recall clearly) that
some competition bullets have square noses.

Bullets with hollow tails (rather than hollow noses) or better,
 boat tails can also help dynamic stability by placing the
CofG further forward.



Brian Whatcott    Altus OK    Eureka!