The Textbook Myth

Most textbooks explain flight with the equal transit time theory: air splits at the wing's leading edge, and since the top surface is curved and longer, air on top must travel faster to meet the air below. Faster air means lower pressure, which means lift.

Sounds elegant. One problem: it is wrong. No physical law requires air above and below a wing to reunite at the trailing edge. High-speed photography shows air on top actually arrives first. The equal transit time model underestimates real lift by a wide margin. The actual physics is both simpler and more interesting than the textbook version.