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Old 05-27-2011, 01:29 AM   #8 (permalink)
Join Date: Sep 2009
Location: New Kensington PA
Posts: 69

Big Blue - '94 Ford F-150 shortbed
90 day: 15.71 mpg (US)

Mexico Nuevo - '84 Honda V45 Sabre
90 day: 36.67 mpg (US)
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1. The way it was explained to me, back in flight training, is that if you "do the math": calculate the total amount of lift from "accelerated air" (Bernoulli) vs the total amount of lift derived from forcing air down (F=MA), you'll wind up with the same number.

2. The air flowing over the upper wing surface is indeed traveling (relative to the airplane) in excess of the surrounding undisturbed air. This is why when planes transition to the "transonic" region of flight (some localized areas of sub- and supersonic flow), they generally go supersonic first on the upper wing surface, causing mainly undesirable flight characteristics (google "Mach tuck.")

2a. Airplanes designed for "high-subsonic" cruise speeds generally have rather convoluted airfoils due to the phenomenon discussed in "2" stave off transonic effects as long as possible.

3. The air pressure atop the wing is indeed lower than beneath it. At the tips, the high-pressure air tries to work its way over to the top of the wing, producing "wingtip vortices," which are really cool to look at (when they're visible) and/or disturbing to contemplate (when they aren't visible and you're following a "heavy" for landing.)
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