ORIGINAL: lordmerren
ORIGINAL: da Rock
What most models have right thrust for:
6. Side thrust: Fly away from you, into any wind and pull vertical.
... A: Model continues straight up; No adjustment.
... B: Model veers left; Add right thrust.
... C: Model veers right; Reduce right thrust
This is a very often repeated test included in flight tests for trimming model flight. It shows that for most, the thrust is a response to an aerodynamic action called p-effect. P-effect is a result of the prop pulling better on one side than the other. It happens when the airplane pitches up or down. As you see from the trimming advice above, it happens, and changing the thrust cures it.
It's funny, but there is no test for p-effect in any other direction.................... left for example, or down.
The trimming advice above suggests adding more right thrust , or reducing right thrust. Neither will have any effect at all on P-factor.
Only down thrust will reduce P-factor.
Lm
There are two results. One resists the effect and the other alters it. Change the angle at which the prop encounters the slip and the direction of the result of the p-effect is changed. Change the angle of the thrust and it counters the force. Two different reasons for the effect.
As for down thrust.......... P-effect isn't actully up or down. Our description of it usually is, and therein lies the rub. P-effect actually happens when the plane is yawed. And it'll then cause an up or down force instead of the left right force it causes when the pitch axis is affected. So there isn't just one way (or direction) that reduces p-effect. The direction that reduces it is a direct function of what change of axis induces the effect.