Re: Flight again (was Re: The Lizard of Oz)

["James R. Cunningham" <jrccea@bellsouth.net>]

David Marjanovic wrote:

> , and non-pygostylians had reasonably long tails
> that put the center of gravity in a more stable position.

I must be misunderstanding your concept here.  It sounds like you're saying that
moving cg aft with respect to the center of lift is stabilizing, but moving it
forward is stabilizing, and moving it aft is destabilizing.  Again, I must be
misinterpreting what you said.

> Good argument. But the fuzz seems not to slow down the tennis balls
> significantly,

Fuzz allows you to speed the ball up significantly because the geometry of the
court and net is such that you can't apply a great deal of speed to the ball
unless you also apply some spin to help bring the ball down.  You can't put as
much power on a defuzzed ball because it will go long (though it does so at a
VERY respectable speed).  However, if you aren't interested in getting the ball
into the court -- you can hit a worn, new ball much faster than a fresh ball.

> and the effects of spin-induced drag -- flying in curves and
> such -- can be achieved equally well with a smooth soccer ball.

I think you're omitting differences in size, speed, Reynolds number, and seam
patterns.  I can testify from personal experience (average about 20-30 hours a
week for 5 years) that spin-induced drag does not work as well when the tennis
ball is smooth.

Cheers,

Jim