RCU Forums - View Single Post - Should a prop driven aircraft actually be symmetrical?
Old 04-07-2003 | 06:46 PM
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banktoturn
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Default Should a prop driven aircraft actually be symmetrical?

CafeenMan,

In principle, probably not. The fact that the prop constantly exerts a rolling torque on the airframe means that, in principle, you should have some compensation. In fact, you do. When you first fly your plane, you trim the ailerons, and that pretty well takes care of it. It probably makes more sense to take care of the torque this way than by trying to build a correction into the wings.

There are other asymmetries. The prop exerts torque on the airframe in a few other ways. Probably the main one is yaw as a result of propwash impinging on a vertical stabilizer that is not symmetric above and below the thrust line. This is most noticeable during takeoff, and can be minimized by balancing the vertical stabilizer above and below the thrust line. The gyroscopic forces due to the prop ( & other spinning mass ) and the 'P-factor' are also present, but probably negligible.

Overall, I think that trimming, and a few expediencies like adjusting the thrust angle of the engine on some planes, are adequate solutions to the inherent asymmetries.

banktoturn