[Dynamo]

Originally Posted by krap101

I talked to a really smart Aerospace PhD student (I'm a sophmore in aerospace), since I've been wanting a "scientific" answer for the aerodynamics of a twist barrel. He said that he believed that decreasing the turn rate of the spiral of the barrel wouldn't really affect the max fps of the barrel. I think it had something to do with the aerodynamics of a sphere, and something called the Karman vortex street. At a certain point, the velocity of the air will cause vortices to get thrown off unevenly, which will destabilize the bb.

http://en.wikipedia.org/wiki/K%C3%A1..._vortex_street

Although he wasn't 100%, and this isn't exactly his field, he's extremely smart, and I would side with him than just about anybody else.


Interesting video

YouTube - unstable velocity flow of air past cylinder with alternating direction

YouTube - karman vortex street

YouTube - Fluid Mechanics - Cool Science Experiment

interesting videos, unfortunately they don't really apply to a BB being propelled down a barrel. the gap between the BB and the barrel wall as well as the pressure differential between the air ahead of the BB and the air behind it pushing on it, as well as taking into account the BBs backspin are very important.