No One Can Explain Why Planes Stay in the Air Do recent explanations solve the mysteries of aerodynamic lift? February 1, 2020
 On a strictly mathematical level, engineers know how to design planes that will stay aloft. But equations don't explain why aerodynamic lift occurs.
 There are two competing theories that illuminate the forces and factors of lift. Both are incomplete explanations.
 Aerodynamicists have recently tried to close the gaps in understanding. Still, no consensus exists.
In December 2003, to commemorate the 100th anniversary of the first flight of the Wright brothers, the New York Times ran a story entitled “Staying Aloft; What Does Keep Them Up There?” The point of the piece was a simple question: What keeps planes in the air? To answer it, the Times turned to John D. Anderson, Jr., curator of aerodynamics at the National Air and Space Museum and author of several textbooks in the field.
What Anderson said, however, is that there is actually no agreement on what generates the aerodynamic force known as lift. “There is no simple oneliner answer to this,” he told the Times. People give different answers to the question, some with “religious fervor.” More than 15 years after that pronouncement, there are still different accounts of what generates lift, each with its own substantial rank of zealous defenders. At this point in the history of flight, this situation is slightly puzzling. After all, the natural processes of evolution, working mindlessly, at random and without any understanding of physics, solved the mechanical problem of aerodynamic lift for soaring birds eons ago. Why should it be so hard for scientists to explain what keeps birds, and airliners, up in the air?
Adding to the confusion is the fact that accounts of lift exist on two separate levels of abstraction: the technical and the nontechnical. They are complementary rather than contradictory, but they differ in their aims. One exists as a strictly mathematical theory, a realm in which the analysis medium consists of equations, symbols, computer simulations and numbers. There is little, if any, serious disagreement as to what the appropriate equations or their solutions are. The objective of technical mathematical theory is to make accurate predictions and to project results that are useful to aeronautical engineers engaged in the complex business of designing aircraft.
continues at scientificamerican.com
Ed Regis has written 10 science books, including Monsters: The Hindenburg Disaster and the Birth of Pathological Technology (Basic Books, 2015). He has also logged 1,000 hours flying time as a private pilot. Credit: Nick Higgins
