Thank you stressmerchant and Jhieminga: I will try to look up these documents.
The problem I see with wind-tunnel testing is it would not duplicate the air's curvature in a turn... The vertical I refer to is always to the fuselage. Even low speed sustained turning could be close to a 80- 90° bank, as pilots can keep the ailerons deflected during the turn, this to increase bank angle beyond "normal" parameters (catching the wing drop, in effect),.. And low speeds is the area of maximum prop load. So variations vertical to the fuselage, or close to it, can be assumed here for simplicity, even during low speed sustained speed turns.
The effect on the prop I would see is that, in a low wing position, the prop's exit spiral is, by necessity, "split" into above wing or below wing airflows. Increasing the engle of attack, while curving the incoming air upward, might causethat "split" to change in its above-below wing distribution, some of the "below wing" air "shifting" to above the wing. If that proportion of change is significant, this air would then be forced into a kind of "dogleg" path, which would lenghten its path, and so accelerate this portion of the air, depressurizing the corresponding area of thrust within the prop disc (in this case the below wing area).
The basic reason why I am asking this is that 25 years of reading WWII fighter combat accounts has me convinced that the prop, in these particular low-wing types, is "turn averse" to a significant extent. All you hear about, constantly, is the use of reducing the throttle, not using full power in combat, using less than full power in combat, except strictly for straight lines. Even more significant, increasing the throttle to increase the turn rate is never mentionned, not even once (given the thousands of accounts I have read, I find this absolutely astonishing)... There are numerous accounts that are cristal-clear about lowering power to increase the turn rate at extremely low speeds, very near the ground... All this implies prop power is turn-averse to a certain extent, especially at low speeds: To be turn-averse, there must be an uneven (opposite to turn) bias within the prop disc... The arrival of jets in 1945 radically changed this power-averse pilot behaviour, which is yet another clue. The behaviour of front-line pilots regarding power management bears no resemblance at all between the jet era and the prop era: Prop era pilots always behave as if their aircrafts had too much power, and that this was detrimental to combat maneuvering, no matter how low the speed or altitude, and especially at low speed and altitudes...
The general impression I get from known propeller effects is that their aversion to turn is only mild and yaw-related, but nothing about vertical to fuselage turn-aversion. Hence my question.
Gaston
Last edited by Gaston444; 3rd Mar 2020 at 00:45.