Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

Calculate speed

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Old 01-27-2005, 11:26 AM
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DLT
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Default 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
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Old 01-27-2005, 01:06 PM
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Ed Smith
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Default 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.

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Old 01-27-2005, 03:02 PM
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Cyclic Hardover
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Default 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.
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