Hi xerj

Pitching a clockwise spinning (seen from the cockpit) prop forward
will result in a yaw to the left, pitching it up will result in a
right yaw. Correct so far?

I believe it would be the other way round. Nose down will induce a yaw
to the right, nose up will induce yaw to the left. On the other hand,
yaw movement to the left will induce nose down and yaw to the right
will induce a nose up moment.

All this can be determined by the so called "rule of the right hand":
Extend the thumb, index finger and middle finger of your right hand in
a orthogonal manner. The thumb represents the vector of the initiated
rotary movement, e.g. pointing to the left for nose down. The index
finger represents the vector of the gyroscopic rotation (in this case
pointing in your flight direction - the vector of the propeller
rotation) while the middle finger gives you the vector of the rotary
force induced by the gyroscopic forces, pointing down meaning a
rotation or yaw to the right. (Rotation vectors assume a clockwise
movement when looking in the direction of the vector)

Whether all this is generally noticeable in a GA plane with a piston
engine and propeller I don't know. I suppose it was a big problem with
rotation engines of the very early days, where the whole cylinder block
rotated with the propeller, while the crank shaft was stationary and
mounted to the airplane.

However, why does a yaw to the right cause a pitch up, and a yaw to
the left cause a pitch down? I thought it would be the other way,
given that a yaw to the right means applying a force to the left of
the prop disc, which would result in the precession force being
applied 90 degrees later meaning that it would pitch DOWN. What am I
missing?

I don't know about this explanation. Why should a force be applied 90
degrees later?

regards,
Friedrich

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