How Do Airplanes Fly: The Textbook Fails 4 Tests

How do airplanes fly? The textbook answer says air over the curved top must race to meet the air underneath at the back edge. NASA's own aeronautics guide files that story under Incorrect Lift Theory, and we put it through 4 tests in a drawn wind tunnel. The equal-transit story fails 4 tests: a symmetric wing lifts, a flat paper plane flies, some low-drag wings have a longer bottom, and planes fly upside down. In this video: The textbook story (Longer Path / Equal Transit Time) and why so many of us learned it 4 tests it fails, from NASA's Incorrect Lift Theory page Smoke pulses in a wind tunnel: the air over the top reaches the back edge first (University of Cambridge) What really holds a plane up: the wing turns the air down, and the air pushes the wing up Bernoulli or Newton? NASA's answer is both Angle of attack, the lift equation and why twice the speed gives 4 times the lift The dark side: stalls, wing-tip vortices and induced drag Why jets cruise fast: at 35,000 feet the air is about 31% as dense as at sea level (our calculation from NASA's standard atmosphere model) Sources: NASA Glenn Research Center, Incorrect Lift Theory #1: https://www.grc.nasa.gov/www/k-12/Vir... University of Cambridge, How wings really work (2012): https://www.cam.ac.uk/research/news/h... NASA Glenn, Bernoulli and Newton: https://www1.grc.nasa.gov/beginners-g... NASA Glenn, Lift from Flow Turning: https://www.grc.nasa.gov/www/k-12/Vir... NASA Glenn, What is Lift?: https://www.grc.nasa.gov/www/k-12/Vir... NASA Glenn, Downwash Effects on Lift: https://www1.grc.nasa.gov/beginners-g... NASA Glenn, Incorrect Lift Theory #2 (skipping stone): https://www.grc.nasa.gov/www/k-12/Vir... NASA Glenn, Effects of Inclination on Lift: https://www1.grc.nasa.gov/beginners-g... NASA Glenn, The Lift Equation: https://www1.grc.nasa.gov/beginners-g... NASA Glenn, Earth Atmosphere Model (English units): https://www1.grc.nasa.gov/beginners-g... Sources checked 15 Oct 2026; the air-density ratio, the 1.8x speed figure and the speed-squared arithmetic are our calculations from the NASA models above. New money, tech and science explainers every week. Subscribe: @inkminute Chapters: 0:00 How do airplanes fly? 0:44 What does the textbook story say? 2:01 Does the story pass 4 tests? 3:26 Does the air really meet at the back? 4:41 So what really holds a plane up? 6:14 How does a wing turn the air? 6:54 What is the dark side of lift? 7:59 Why must jets fly so fast up high? 9:26 So how do airplanes really fly? #howdoairplanesfly #science #aerodynamics