Has someone taken an rc airplane and turned the wing upside down and flown it? It should be pretty easy to demonstrate.

RC airplanes have insane thrust to weight ratios, with enough thrust a brick can fly.

That said with my historic experience with single piston RCs if you didn’t compensate for the upside down flight with your ailerons you would nose dive.

Changing the angle of attack effectively changes the shape of the airfoil. No gotcha here either.

I'm not immediately convinced that "effectively changing the shape" is a coherent idea. The lift effect either crucially depends on the actual, unchanging shape of the aerofoil or it doesn't. Flying upside-down proves that it doesn't. Maybe all we're disproving is a straw-man of a "Bernoulli-ist" position, but we're disproving it all right.

EDIT: trying to think what you might mean by "effectively changing the shape". Do you just mean that an upside-down aerofoil is a reflection of the aerofoil the right way up? Because that's the entire point of the argument you seem to be trying to rebut.

If you are asserting that the angle of attack does not affect the lift, you are wrong.

A plane flying upside down is most certainly not using the same angle of attack as it does right side up. The real difference in performance is efficiency, the upside down plane is burning more fuel due to the increased drag from sub-optimal operation (a high angle of attack to overcome the optimization for right-side-up flying).

Note that a right-side-up wing can easily plummet by dropping its angle of attack. That is what it's doing while upside down to generate lift.

> If you are asserting that the angle of attack does not affect the lift, you are wrong.

I am certainly not asserting that, and I'm baffled how you could have formed the impression that I was.

You appeared to be attempting to rebut an argument in favour of the significance of angle of attack. We have another pointless internet misunderstanding on our hands.

I am replying to this:

"I usually just answer Socratically: "So how can (some) planes fly upside-down?" whenever I encounter the Bernoulli-adherents."

Which is a lazy and garbled gotcha attempt.

It is a lazy gotcha attempt. It is a lazy attempt at gotcha-ing someone who believes angle of attack ISN'T important. Unless you think a plane flying upside-down is somehow evidence AGAINST the importance of angle-of-attack?

Again: this entire pointless misunderstanding has arisen because you didn't see - apparently STILL HAVEN'T SEEN - which side of the debate the comment you replied to is arguing for.

Oh I see. You think the Bernoulli approach is independent of angle of attack? It's not.

I'm afraid it is most evident that you do not see. Forget trying to guess what I might or might not think about aerodynamics. Just see if you can follow the following recap of the conversation:

1) anvandare says aeroplanes can fly upside down. This is an argument AGAINST a putative person who argues that lift is entirely a function of aerofoil shape, ignoring angle of attack. In advancing this argument, anvandare implies that he DOES understand and contend that angle of attack is significant.

2) You say something unclear about "effective change of shape", apparently attempting to rebut anvandare, who, remember, contends that angle of attack is significant.

3) I say that what you said about "effective change of shape" is unclear, meaning I am rebutting you, meaning I agree with anvandare that angle of attack is significant.

4) You form the impression that I believe angle of attack is not significant, and tell me that if I believe angle of attack is not significant, then I am wrong.

Can you see where you have gone wrong there?

Having written all this, I'm come to the point of actually becoming quite concerned about your neurological state. If you've had a recent head injury or you're old enough that Alzheimers is a possibility, you need medical advice - you've failed to follow the simple thread of a conversation.

But the "true" explanation given above is that the engine pushes the horizontally accelerated air downwards (with respect to its own orientation). Wouldn't that also lead to the conclusion that upside down flight is impossible?

Because there is not up or down for the wing when its cutting through a fluid. It is not that we have seen planes flying intercontinental flights upside down.

And those upside down events do not happen at 10 feet above ground. There is plenty of fluid (air) above and below the aircraft and power (fighters jet engines are the most powerful ones on aircrafts) to be able to correct any up-downward force with flaps (basically walls to air)

This is nonsensical. Glider pilots (no engine!) fly aerobatics programs all the time, in planes with curved wings. If the pilot is a bit of a masochist, they could fly upside down for half an hour in still air given enough altitude. The various forms of air resistance will be greater and energy/altitude loss hence higher, but the wing will still be generating lift equal to the weight of the airplane.

> Because there is not up or down for the wing when its cutting through a fluid.

Except that there obviously is. Unless you ignore gravity.