According to a widely circulated explanation for flight—in particular, for the lift force1—air meets the front surface of a wing and splits into streams flowing over the top and under the bottom and meeting just at the back of the wing (Fig. 1). Thus, if the wing is cambered so that the top route is longer than the bottom route, air flowing over the top moves faster than air flowing under the bottom. By Bernoulli's principle, the pressure on the top surface is lower than the pressure on the bottom surface. Let there be lift!

Would that it were so. The explanation is not only incorrect, it's dangerously so. For it reaches a correct conclusion, that there is lift, using incorrect reasoning. The correctness of the conclusion means that even gaping holes in the reasoning pass unnoticed. Who wants to unpick an argument whose conclusion seems confirmed...

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