"Skywise" wrote in message
...
Then how do you explain how well a simple flat disk such as a CD will
fly? It certainly has no airfoil shape.

They don't. At least none of the CD's that I've ever thrown went
very far. They all roll immediately and change direction.

They fly as well as a frisbee (kleenex, q-tip, big deal) that has similar
size and mass distribution.

You can improve things at that scale somewhat by adding more mass around the
edge to stabilize it, but as anyone who's tried to toss a small 5" or so
frisbee knows, they really don't fly that well at that size, even when they
are designed as a frisbee rather than a CD.

IMHO, there are two key elements to frisbee aerodynamics: the mass and its
distribution (providing stability); and straight-up Newtonian deflection for
lift.

It's possible that there's a smidgen of airfoil effect due to some oddity of
airflow around the disc (air damming up at the front or something like
that), and of course there are a number of specialty discs (used in golf,
ultimate, etc.) that have specific aerodynamics built in that affect the
course of the disc. But otherwise, I would be surprised to find a frisbee
is a heck of a lot different, lift-wise, from your hand stuck out the window
of a car.

Pete