John T,
It is preferable, while training to the requirements of specific Types, to make sure that the underlying explanations are not over-simplified to the point of being unhelpful and, perhaps, counterproductive.
I agree.
Probably preferable to concentrate on the interaction of the aeroplane and the surrounding air flow rather than wherever the ground might be .. other than if ground contact is an imminent risk, we probably can afford not to worry unduly about where the ground might be whilst endeavouring to get the aeroplane back into controlled flight ?
Agreed. I was talking about a specific scenario where the airplane was in a basic 1G stall. If the airplane starts descending towards the ground, the nose needs to be lowered so as to reduce the angle of attack.
I understand the descriptions I was using sound 'unconventional'. I wouldn't teach someone to recover from a stall by talking about the ground and not about the aerodynamic aspects such as angle of attack, etc.
Depends on what degree of control you might have in the particular circumstances. However, presuming that the input produces yaw .. that produces slip and too much slip may precipitate a significant departure. Probably not a good technique as a general consideration ?
Exactly! And that's what I'm trying to convey - that using rudder in that situation isn't conducive to efficient stall recovery.
If the former problem occurs, the nose might rapidly point more directly towards the ground. Just what aerodynamic benefit arises from having the nose point away from the ground ?
No benefit! I'm not sure if you misunderstood what I wrote or not. I think we're thinking similarly - I'm just approaching it from a different angle.
If you were to use elevator instead - you will point the nose towards the ground,
While that may be an effect, it also will have the primary, and desirable, effect of reducing alpha. How is the ground relevant to the aerodynamic concerns ?
Yes. I've always been teaching that if you're in a stall you need to reduce alpha, and that the primary method of doing that is by pitching down.
What I was meaning with regard to the ground in this case is that your velocity vector is pointing towards the ground, so pointing the nose towards the ground (towards the direction that you're going) will reduce the angle of attack.
Maybe I just had a weird way of saying it - I wanted to point out that putting in 'top-rudder' at the point of stall in an effort to stop a wing drop produces undesired effects.
However, one needs to be considerate of the particular Type's pitching moment characteristic - some aeroplanes have nasty spots where the elevator's capability to produce pitching motions is compromised greatly.
Agreed. That would be discussed in that type's training then.
If you're at the critical angle of attack, you can unload the wing by ... increasing angle of attack
Perhaps you can provide further amplification on this suggestion ?
I don't
suggest this as being something I would teach as part of stall training but what happens to the coefficient of lift when you're at the critical angle of attack and reduce alpha? It decreases. What happens when you increase alpha? It decreases. I was specifically talking about the wing loading when the airplane is significantly past the critical angle of attack (stalled). Obviously increasing alpha beyond the stall is the opposite of what should be taught in stall recovery.
By pitching down, while at 45 degrees of bank, you will move the longitudinal axis back towards the initial heading.
And the effect of that might be ?
Nothing really gained in my opinion. But for the pilots who are anal about heading control in stalls I thought it might make them see things differently - the same ones that practice the 'falling leaf' stall and think it's doing good for the student. I don't quite share their philosophy.