Air pressure forces act on the whole aircraft system(The relations of the pressure differences)
The air pressure of 1 bar acts with about 10 tons a 1 m². The wing area of a glider has about 10m², its mass is for example 333 kg. To make it easier to illustrate, a pressure difference of 1/333 bar on the wing is sufficient to keep the aircraft in the air.
This means an atmospheric pressure at the bottom of 1000 mbar (z. B. at high speeds) faced to a vacuum of 997 mbar on the topside. As often assumed the lift of 1/3 from above and 2/3 from below leads to pressure differences of 1 001 mbar below (1 mbar overpressure so ~) and 998 mbar above (ie only ~ 2 mbar vacuum). Often the impression will given that flying needs high pressure and suction forces (vacuum) which is hereby rectified.
(Example of a Standard Class glider at best glide at 100km / h)
With a wing loading of about 32kg / m², 12 m² wing area, airspeed of 28m / s and 15m wingspan (overflown area = 432m² / s) approx 65 kg / s of air is accelerated at a speed of 2x 2.625 m / s (bottomside + topside). This results in a counter-force to the gravity of approximately 3400 N (~ 340 kg). This force is the immediate response (pulse) on the accelerated downward air mass.
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