ORIGINAL: nitro junky
IF your just looking to get a close speed ( RPM X Pitch X .000947 = speed) IT'S NOT perfect but it is pretty close. I have a radar gun that we have compared this to and it is usually with in 5 MPH of the radar gun on a flat level fly by.
That would be what the ThrustHp program does. So my speed would be about 105 mph. Does that seem about right for the plane? I will clock it over our 400 ft field next time I am out to get more accurate reading.