2/28/2023 0 Comments Parts of an airfoil$$\Delta P = 0.5 \times 1.225 \times (40^2 - 30^2) = 429 Pa$$Ĥ29 Pa is 4.29 grams per square cm or 0.06 pounds per square inch, so it's completely insignificant. Google gives the density of air at ground level as 1.225 kg/m3. This means that more curvature translates to more lift. This curvature generates the pressure difference and the lift. Basically, the introduction of the airfoil makes the flow curved. Fig:10B Pressure distribution around the airfoil. Rewriting the equation to make it more useful for our purposes gives: Fig:10A On the bottom pressure should increase as we move toward the airfoil. Although this really only applies to incompressible fluids, and air is obviously compressible, the article suggests it would be a reasonable approximation for low speeds. If an approximate answer would be OK then you could could use Bernoulli's equation as described in. A longer slightly more staid article is at Incidentally, there's a good NASA article on this subject at and it even includes a Java applet for you to play with the details of the wing. Once again I can't give you exact figures - I must admit I thought ballpark figures would be easy to calculate, but Google has failed me. The lowered pressure above the wing will indeed tend to pull the skin off the wing, or more precisely the air within the wing that is at normal atmospheric pressure will try to push the skin off. The pressure difference between the top and bottom of the wing is quite real, though note that on the top of the wing it's not a vacuum as the pressure doesn't decrease that much. Maybe this is why exact figures seem not to be quoted. I suspect the exact figures are rather variable and probably depend on whether the plane is climbing, descending, banking, etc and will also vary from plane to plane. I've never seen actual figures but, in general, articles I've seen about flight state that "most" lift is generated from the angle of attack and relatively little from the Bernoulli effect.
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