Dr. Christopher S. Baird

How do airplanes fly upside down if it's the shape of the wings that make them fly?

Category: Physics      Published: December 17, 2012

The way a wing is tilted is the main thing that makes a plane fly, and not the wing's shape. The angle of attack is the angle between the axis of the wing and the direction of incoming air. Public Domain Image, source: Christopher S. Baird.

The shape of the wings is not the main reason that airplanes fly. Rather, the angle of attack for the wings is what creates most of the lift, as laid out in the book "Flight Physics" by Egbert Torenbeek and H. Wittenberg. The role angle of attack plays in flight is explained in detail by NASA's education website. If the top of the wing is more curved than the bottom of the wing, then air pressure does indeed decrease over the wing and help to suck up the wing. But this is not the main effect. When a wing is tilted with the leading edge up relative to the incoming wind, the air tends to pile up under the wing, causing high pressure that pushes the wing up. The wing is riding on top of a bubble of dense air. This is the same reason kites fly. Even a perfectly flat-winged airplane can fly if it tilts its wings. You can literally get a brick to experience lift with a strong enough motor and the right orientation of the brick. Stunt planes that are meant to fly upside down have symmetrical wings. They don't rely at all on wing shape for lift. To fly upside down, a stunt plane just tilts its wings in the right direction.