Can someone explain a High Speed Stall
02-08-2017, 08:01 PM
#26
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Remember that air acts like a fluid. The fluid needs to stay in proximity with the wing surface in order to create lift. Once that proximity begins to depart the wing, regardless of the cause a stall begins. Imagine water flowing over the wing generating lift. Suddenly there's an abrupt change of direction of the wing. The water is going one direction and the wing another. The distance between the flow of water and the wing surface increase until there's no longer "lift".
How does this apply to symmetrical wings that fly by angle of attack, not lift? Thanks.
02-09-2017, 01:38 AM
#28
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A wing will stall at any speed. What determines when a wing stall is the angle of attack of the wing to the relative wind coming at the wing. I don't know what it is for model aircraft but on a piper or Cessna it is in the neighborhood of 20 degrees angle of attack. It does no matter whether the plane speed is 50 knots or 150 knots when you exceed that angle of attack the air flow over the wing goes from a laminar flow to a turbulent flow with eddies and it then separates from the wing and lift is lost. I'm a certified flight instructor and I would do a steep turn with my student to demonstrate this and at 45 degrees of bank at 70 knots and then keep pulling the control back increasing our G force and pretty soon the stall horn would come on even though we were going 70 knots when the aircraft would normally stall at 43 knots.
02-11-2017, 05:19 PM
#29
To put it in plane language, a stall occurs when the angle of attack to too much, and the air going over the top of the wing curls in, filling the partial vacuum above the wing, destroying lift. Straight and level the weight of the plane is 1G. If the plane weights 10 lbs when wing only has to support 10lbs. In a high G turn, say 6 Gs, the wing has to support six times as much weight, 60 lbs, so more angle of attack is necessary to provide lift to support this "weight". The smaller the wing, the heavier the plane, the more angle of attack is necessary to hold the turn. Then too much angle of attack causes the stall. Usually a snap one may or the other because both wings usually don't stall at the same time.
