From:	Mongoose m0ng005e@*********.com
Subject:	Ballistics (was: Two firearms at once)
Date:	Mon, 8 Mar 1999 17:48:01 -0600

:-From: Adam Getchell <acgetchell@*******.edu>
:>> snip some physics<<
:Adam,
: Just a quick question, where does the spin generated by the rifling
fit
:into all this? I "know" from shooting both rifles and smoothbores, as
well
:as baseball and football, that spinning the projectile adds both range
and
:velocity. Why? And please, talk down for those of us who are physicsly
:impaired;-]
:
:hivemind
:
:



Basically, spinning things keep spinning they way they were spun, and
that's good if you want to keep the bullet pointing the direction it was
fired.


For this same reason a good (American) football throw has a "spiral"-
without the spin, the bullet tumbles randomly. Aerodynamic drag and lift
both figure in. If the bullet tumbles, its not point first, increasing
drag and decreasing velocity, which hurts range and damage.
Random tumble would add also a random "lift" in a random direction-
which affects accuracy. The bullets path would be like that of a baseball
pitchers Knuckle ball, which is thrown without spin- it is unpredictable.
This is actually the reason rifling was developed- muskets were quite
inaccurate past 20m, due to the balls random spin.


Mongoose