ORIGINAL: Gray Beard
If you do a search here you will find a number of threads on P-Factor. According to my books it is the vortex effect from the air flow of the prop hitting the tail feathers. In MAN they have shown it with drawings. But that is just my understanding of it from what I have read. The left drift of a plane is most often mentioned as torque though but how much torque does one of our little engines really have. My two meter pattern planes are long enough that the P-Factor has no effect at all, they will just run out straight every time.
Seamus?? I would think so but I'm no engineer so can't say for sure. Makes sense though doesn't it?
I'm with you on the spiral airflow hitting the vertical fin; not with you on P-factor. As to torque, I think it is just easier to rationalize it from that perspective. If the propeller represented on the right side of the spinner is decending into the forward airstream at high angles of attack it creates more thrust relative to the other half. That asymetry will "torque" the airframe around the vertical axis. I think that is what folks are referring to when they use the word torque. But still, I don't see that happening on take-off roll because the thrust is aligned fine as soon as the tail lifts I guess. Spiral airflow, on the other hand is there at all angles of attack and I would think shows up pretty good at take-off roll when it represents the bulk of the flow over surfaces etc. but then gets increasingly watered down in terms of its ability to effect anything as airspeed increases (ie. and we release that initial rudder input).
Anyway, I could be wrong. I should be more sure of myself before I comment actually. If I get some extra time maybe I'll refresh and read on it. Cancel that. If I get some extra time I'm going flying!
Thanks for your response!
Tom