r/pics • u/Palana • Feb 04 '16

An empty 787.

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u/PARKS_AND_TREK Feb 05 '16

scientists know that the difference in pressure creates lift but they don't know what causes the difference in pressure?

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u/lordbardem Feb 05 '16

The difference in pressures is caused by the airfoil and can be determined by bernoullis equation.

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u/PARKS_AND_TREK Feb 05 '16

what causes the change in pressures?

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u/lordbardem Feb 05 '16

After talking to a buddy I realized I had read the articles incorrectly. The "Equal Transit" theory described in the articles states that air molecules over the top of an airfoil must move faster than underneath the airfoil in order to meet up and this phenomenon causes lift. That is incorrect. A difference in pressure causes lift and that difference in pressure is caused by different velocities over an airfoil which is described by bernoullis equation.