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Plane weight to engine size

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Plane weight to engine size

Old 03-18-2003, 12:10 AM
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jdwiflyrc
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Default Plane weight to engine size

Hello,

Is there a rule of thumb formula to figure engine size to plane weight and does this work for all gas, four stroke and 2 stroke engines.

All help will be appreciated.

Thanks, John
Old 03-18-2003, 02:52 AM
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Geistware
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Default Plane weight to engine size

You need to first determing what weight you need to balance your plane (range) then you need to select an engine that can produce as much thrust as your plane weights.

Remember, for low wing loadings (gliders and sport aircraft) you can go with less thrust and for performance (aerobatics and pylon racers) you may want to go with a little more thrust
Old 03-19-2003, 02:31 AM
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jdwiflyrc
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Default Engine to plane weight

Hello and thanks for that answer.

Now how do you determine engine thrust.

Thanks, John
Old 03-19-2003, 05:53 AM
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CafeenMan
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Default Plane weight to engine size

There are rules of thumbs for types of aircraft - not for aircraft overall.

For example a good .40 trainer has about 700 inches of wing. That's way too much wing for a .40 sport plane.

So to answer your question, no there isn't a generic rule of thumb. You have to include the kind of plane you're talking about as part of the question.
Old 03-19-2003, 06:13 AM
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MAJSteve
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Default Plane weight to engine size

I usually use .1 cubic inch for every pound of finished weight. Therefore a 4 lb plane would have a .40, a 6 lb a .60, and an 18 lb plane a 1.8. If its a weak engine or propped wrong, it might be marginal.

Depending on the engine, this may be adequate to good performance, it will not give unlimited vertical. A rule of thumb for this is that the engine should produce AT LEAST as much thrust as the plane weighs full of fuel. There's no lift so the prop has to carry the whole weight PLUS the extra needed for climb or hover.
Old 03-21-2003, 05:24 AM
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Whirley Bird
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Default Re: Engine to plane weight

Originally posted by jdwiflyrc
Hello and thanks for that answer.

Now how do you determine engine thrust.

Thanks, John
John,
I'm beat and it's late.
Look for a PM tomorrow and i'll let you know how we measured thrust on both full size gyros,hang gliders and RC aircraft
Do you have a plane and engine now?
Old 03-21-2003, 10:39 AM
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jdwiflyrc
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Default Thrust

YES,

more of each than I need. I acquired a large shoestring recently and trying to come up with an engine for it.

Thanks, John

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