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Old 03-19-2003, 06:13 AM
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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.