The theory of flight is complex, even to the point of take-off. However, it is essential to remember that it is the theory that provides the lift to keep an a/c airborne. If you took away the theory, even for a moment, the thing would plummet like a stone.
Again, pencil and paper would be useful, but please use your imagination to follow me through....
Imagine a basic aerofoil shape, in cross-section, and I'll explain how it is all to do with the pressure differences between the top and the bottom of the wing. (Some people think pressure difference is the reason why a cricket ball swings through the air, but in fact that is just sheer fluke).
Ok, so the top of the wing has a nice STEEP curve, so let us call that S for steep. But the bottom of the wing has a much more SHALLOW curve so I'll label that S for shallow. Now if you imagine two identical particles of air travelling towards the wing, one I will call A and the other one I'll call...... A as well.... because they're identical.
Right, now these two particles of air are going to be divided when they hit the leading edge of the wing (which is in the front, so let me label that point F for FRONT.) However, they have to meet up again at the rear of the wing (which is where the FLAPS are.. so let us call that F for FLAPS).
So.. particle A has to pass over S to point F, in the same time that it takes particle A to pass over S to point F. But... one of those particles has to travel a greater distance to get from point F to point F, than the other. Which is it? Is it particle A or particle A?
I think MOST of you got it spot on.. it is of course particle A.
OK, so now we know that particle A has to pass over S to point F in exactly the same time as it takes particle A to pass over S to point F. But particle A has a greater distance to travel than particle A, so how does it achieve the same time?
NO! Cornish Jack it does NOT set off earlier!!!!
If you lot are not going to take this seriously, then I won't waste any more of your time. Goodbye
with acknowledgements to "Roy Mallard" - Other Peoples Lives