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Physics, Astronomy & Cosmology / Flying in ground effect
« on: 17/01/2008 22:43:54 »
Yes, when a wing moves through the air, the air moving over the top, goes faster than the air on the bottom. Hence a low pressure is created on the top & a high pressure on the bottom. That difference in air pressure causes the air to “lift” or push the wing up.
The air on the bottom moves towards the tip of the wing, then up & over producing wingtip vortices (turbulence). That is drag. When flying within the 1 to 1.5 distance of the wing span, above the ground, the vortices get disturbed and “straighten out” due to the venturi effect, hence less drag, and in increase of lift due to the “cushion” of air, which is an increase of air pressure, hence more lift. At half the wingspan, you really notice it. At low speeds, the angle of attack of the wing is greater, speeding up the air over the top.
The air on the bottom moves towards the tip of the wing, then up & over producing wingtip vortices (turbulence). That is drag. When flying within the 1 to 1.5 distance of the wing span, above the ground, the vortices get disturbed and “straighten out” due to the venturi effect, hence less drag, and in increase of lift due to the “cushion” of air, which is an increase of air pressure, hence more lift. At half the wingspan, you really notice it. At low speeds, the angle of attack of the wing is greater, speeding up the air over the top.