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Tip speed of a Prop

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Aerodynamics Discuss the physics of flight revolving around the aerodynamics and design of aircraft.

Tip speed of a Prop

Old 06-09-2005, 07:44 PM
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Buzz Lightyear
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Default Tip speed of a Prop

Hi

Can someone please let me know how to calculate the tip speed of a prop.

Thanks

Buzz
Old 06-09-2005, 08:20 PM
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HighPlains
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Default RE: Tip speed of a Prop

The square root of the sum of the squares

The simple answer is to calculate just the tip speed due to rotation, but is incorrect. You can find plenty of online calculators that do just that. That requires measurement of rpm, with prop diameter and using pi to calculate the distance traveled by the tip.

But the real answer requires knowing forward speed as well, since the prop tip is traveling a helical spiral through the air. Thus - the square root of the sum of the squares – take the rotational speed and the forward speed, square both terms, add, and take the square root. Make sure both numbers are the same units.

For model airplanes, the engines unload too, so the ground rpm is lower than the actual rpm in the air.

Then if you want to know the percentage of the speed of sound the tip is traveling, you need to factor in temperature too.
Old 06-09-2005, 08:27 PM
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Buzz Lightyear
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Default RE: Tip speed of a Prop

I should have thought of that!!!!!!!!!!

I have found the formula

Thanks

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