On 2/3/2011 4:55 PM, John Doe wrote:
Is there such a calculation/formula? How can you tell what
propeller to use, how fast it should rotate, and how much weight
it can push along the ground?

Specifically... I would like to tell what sort and size of
propeller rotating at what speed, in calm air to push 100 or 200
pounds on smooth and level pavement with zero rolling resistance
to about 20 mph.

Thanks.




Here's a response off the top.
Try a 10HP motor running a four foot prop with a 3 or 4 inch pitch.
Make the prop out of a coupla spruce or pine planks glued together with
epoxy, and carve the shape with a few cardboard templates to keep the
thing aero balanced. Make sure it will statically balance before
spinning it up to say 3500 rpm. Good luck

Brian