>snip Leo Hill wrote: > > Am I to understand that my high school science teacher > was wrong when he stated that the reasons planes fly > is because of the low pressure area on the top of the > wing lifts the plane. > end of snip Since I was a high school physics teacher, a private pilot, and an aircraft builder I think I should offer my observations here. My aircraft was a low wing model and had fabric covered wings. Although the fabric on the wings was drum tight I used to notice that the fabric on the top surface of the wing bulged upward between the ribs when in flight. When the sun was low on the horizon and I had one wing pointed toward the sun this bulging was quite noticeable, and almost alarming, considering that the fabric was rib stitched onto the wing. Obviously the fabric was bulging upward because there was reduced pressure above the wing and the air *inside* the wing, which was at ambient pressure, was bulging the fabric upward. On one occasion I asked the pilot of another aircraft to tuck in under me in flight and tell me if he could see similar bulging in the bottom surface of the wing. He reported that if there was any deformation there it was not noticeable to him. From these observations I concluded that the aircraft was being held in the air by the pressure differential between the air *inside* the wing and the air above the wing. Of course the reduced pressure above the wing was predicted by Bernoulli. When you apply Conservation of Momentum principles to aircraft flight you see that there must be a down-wash of air as a result of the passage of the airplane. But I think this down-wash is a *result* of the flight of the aircraft, not a *cause* of the lift. In a similar vein, do we say that a boat is thrust forward because of the stream of water rushing rearward from the propellor? No, the water rushing rearward is an effect, and the boat thrusting forward is another simultaneous effect, of the forces at play on the surfaces of the propellor. ...my rather long, and perhaps naive, two cents. Glen Zwicker M/V Glen-L Yukon (under construction) P.S. I think it was Antoine de Saint Axupery who said, while watching an airplane become airborne, "...and the miracle of flight began". Perhaps we should let him have the last word.