This is a merge request for two P-factor posts:
- What's P-Factor and why does it occur?
- What is P-Factor in Propeller Aerodynamics? [Duplicate Closed]
Both questions are identical, with the now-closed question having answer(s) worth preserving and promoting (getting to the closed question is not straightforward).
IIRC (although can't find it easily now on Meta.SE), merging doesn't have to be new → old -- the older question doesn't have an accepted answer, and merging the newer → older would result in the accepted answer being unaccepted, so I'd say merge old → new to preserve the accepted status (not necessarily though, you decide the direction based on the guidelines available).
I didn't flag it because it's too long by >200 characters and might need discussion/explanation.