Calculate speed
 

Does anyone know or remember the fromula for calculating the speed of an airplane. I had it written down a few years ago but can't seem to find it. I remember using it once a few years ago and I remember that we marked off 500 ' and then we did the math but I can't rember the formula....Thanks

RE: Calculate speed
 

The formula is:- MPH = RPM x PROP PITCH x 0.00094.

This gives the absolute maximum theoretical speed of the airplane in straight and level, no wind assisted flight. This does not take into account any prop inefficiencies or airplane drag.

A few people on this Forum should apply this formula to their speed claims.

Ed S

RE: Calculate speed
 

Yeh , I use it quite often when a gun isn't around. Lets say your runway is 700ft long and your plane flys it in 6 seconds (roughly)

700 ft div by 6 seconds = 116 ft per second

116 x 60 x 60 = 417600

417600 div by 5280 = 79mph


The 60 60 thing is 60 seconds in a minute and 60 minutes in an hour and the 5280 is the mile.