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Old 02-08-2006 | 12:31 PM
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DKjens
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Default RE: Lets discuss P-Factor

OK, I've made a (poorly drawn) illustration of why I disaggree. This illustrates two rotor/propellor discs.

The disc to the right illustrates a helicopter rotor in hover with a constant pitch (AOA) of +6 deg, and the air hitting the rotor at 90 degrees. A change in pitch is applied through the cyclic. This input adds 5 deg of pitch at 12 o'clock and reduces 5 deg of pitch at 6 o'clock. If gyroscopic precession did not occur, the disc would start tilting towards us, but because of GP, the applied force takes effect 90 deg later, and actually tilts the disc to the left.

The disc to the left is a propellor, with 6 deg of pitch (AOA) at the tips. If the oncoming air direction is changed is illustrated, would it not have the same effect on the AOA that the tips meets the air, as the rotor disc to the right. The books say that this causes the disc to tilt away from us, but if GP is applied, just like on the other disc, the disc on the left would tilt to the right, which would mean applying a pitch up force on the airplane.

I am sorry if I seem/am thick headed, but I really don't see a difference in these two scenarios.

DKjens
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