"Cliff" wrote in message
...
On Thu, 14 Jul 2005 19:28:11 -0700, "PrecisionMachinisT"
wrote:

Never forget that a simple 'propellor' is nothing more than a simple
screw.........

There is lift to be considered.
The simple sheet metal ones differ I think G.

Cliff is right. A water propellor, better known as a screw, IS a screw. It
works in an incompressible medium.

But an air propeller is better viewed as (and actually IS) two wings
operating in rotary fashion.

LLoyd