Basically a plane being restrained will have a lower RPM compared to one that has unloaded in the air which will have a higher Rpm. I would consider that unless you are hovering, you will get higher RPM's and speed in the air.
ORIGINAL: rw Guinn
at 100% efficiency (1.0 in the above formula) a 6" pitch (10X6, 11x6, etc( would move 6 inches forward every full revolution. 10000rpm=60000 inches/minute,or 5000 feet/minute or about a mile/minute, or 56.8 MPH (Which is what that formula gives). Obviously not the case, as most of my 40 size Big Stik will do well over 60 MPH flat out, and certainly better than a .85 efficiency will give ( which is 48 MPH-assuming a slick model, which the stik is certainly NOT). but then, the airplane moving thru the air is NOT a static case, as the mere "pitch" would indicate. Although a prop is called an "airscrew", its action is considerably more complex than that.