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Old 29th Oct 2014, 16:44
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pattern_is_full
 
Join Date: Jan 2008
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barit1 ....The combination of "torque" (actually the propwash vortex pressing the LH side of the fin)....
Not really - they are two different (and real) effects.

The force (torque) the engine applies to the crankshaft and prop to spin them clockwise also applies a counterclockwise rolling force to the engine and what it is attached to (the rest of the aircraft). Basic Newtonian "equal and opposite" reaction.

Easy to see this in a helo that loses its tail rotor. Free of ground friction and a countervailing yaw force, the engine torque spins the airframe as well as the main rotor.

The force is equal and opposite, but the acceleration (speed of rotation) is proportional to the mass of each object (and the prop/rotor masses a lot less than the airframe, so spins a lot faster). F=M*A > F/M = A

On the ground (takeoff roll), the counterclockwise rolling force is translated into downforce on the left main gear, trying to dig it in, and thus adding drag on the left side (left-turning tendency).
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