# Pressure Distribution Pattern around Wing

it is clear that the overall integrated pressure on the top of the wing is less than the overall pressure at the bottom of a wing in order to produce a net nonzero lift force. Based on the attached figure below (AoA going from small to large), it seems that, for low and medium angles of attack, the pressure both at the top and bottom surfaces of the wing is lower than the free stream atmospheric pressure. The arrows' directions, from what I understand, are pressure gradients pointing toward higher pressure area, correct? When the angle of attack is sufficiently large, the pressure on the wing's bottom surface is higher than the free stream pressure (positive pressure coefficient)...Is that correct?

Whenever the local pressure is lower than atmospheric pressure, I think air would rush to that area so air would be moving from far above the wing towards the wing top surface (same for bottom wing surface when the pressure coefficient is negative). Is that what happens? Thanks.

• You may find the website How it flies interesting. – Manu H Dec 29 '18 at 22:32
• "it is clear that the overall integrated pressure on the top of the wing is less than the overall pressure at the bottom of a wing in order to produce a net nonzero lift force." This does not take into account that the wing produces downwash at the rear of the wing to press the air flowing across the wing down, and this downward pressure pushes the wing up. The flow across the wing gets less and less smooth as the AoA increases, up to the point where the wing stalls from the loss of downwash/loss of lift. – CrossRoads Dec 31 '18 at 2:02
• @CrossRoads: When looking from the point of view of solving the Navier-Stokes equations, the downwash is the inevitable effect of the pressure distribution on the wings. So "take into account the downwash produced by the wing" is actually the same as "overall integrated pressure on top is less than bottom". You can design a wing where the overall integrated pressure is equal and you will find zero downwash or one where it is more and you will find upwash. – slebetman Apr 12 '19 at 6:46