Originally Posted by
AlphaZuluRomeo
airtren
the "gaining of speed" is still important. It is part of the solution/recovery, and the change of AOA - bring the nose down - is a means to achieve just that.
Uho... Perhaps is the procedure not perfectly written. On the other hand, I disagree when you write "the change of AoA is a means to achieve a gain of speed" (if I understood correctly?)
It's the other way : the gain of speed is a mean to lower AoA (all other parameters equals). And lowering the AoA is what is important to avoid/exit a stall.
Your rephrasing of my text is still in line with what I meant, in the context of the presentation, so I will explain from a different angle. I will use material from that presentation, as what I referred to was in its context:
The change of "AoA" affects the lift coefficient CI, according to the
CI curve, as a function of AoA. (page 5 of that presentation).
The CI is a member of the "lift" equation - see bellow - and thus it affects the "lift":
Lift = 1/2 pSv**2Ci, (page 4 of that presentation)
(where: p = air density, S=wing surface, v=CAS, v**2 is square of CAS, Ci=lift coefficient)
Examining just from a pure Mathematics perspective, given that the S is a constant, the other two elements that affect (and will increase) the "lift" are the "p" and "square of v" (if they increase).
Furthermore, if theoretically and abstractly one can assume that AoA does not affect speed - so the speed stays constant - as CI cannot go above a Maximum Value, one may try to change AoA as much as he wants, but that (Max) CI, with an insufficient "v" (speed), and insufficient "p" may still result in insufficient "lift" and thus no return to normal flight.
So my point again is that the change of AoA affecting the CI alone, may not be sufficient to cause the return to normal flight.
It is rather the combined effect of the AOA on the CI, with the AoA effect on increasing the speed and thus the "square of v" that from a possible "speed" insufficiency in a "insufficient lift", to a "sufficient speed", which by resulting in a sufficient "lift" makes the a/c return to normal flight.
I can understand why the written presentation may attempt to reduce the aspects of recovery from Stall that may be look too acrobatic, because of the drastic changes of speeds, and altitude. But I can see how the verbal communication during the presentation, or a training session may be very explicit on the dramatics of the change of AoA to aggressive Nose Down, and letting the a/c in a Nose Down fall to gain sufficient speed, to change the AoA again, to level off, and transform the falling speed into horizontal speed, get sufficient "lift", to get to normal flight.
....
You say, the "gain of speed is a means to lower AOA".
I don't see how the "gain of speed" has necessarily a "lower AoA" consequence. Perhaps your elaborating would help.