Abstract

The motion of an American football in a forward pass is discussed in this paper. It was investigated by using wind-tunnel aerodynamic data in a numerical integration of the full nonlinear equations of motion, and by application of the small-angle theory for the atmospheric motion of an axisymmetric spinning body. The numerical simulations agree with certain observed features such as the range, flight duration, and ratio of the spin and precession frequencies. The analytic results reveal functional dependences of the flight parameters on the aerodynamics and give insights into the physical effects that occur. Both approaches show a feature that is known as ‘drift’ in the science of ballistics, namely that a long, highly arched trajectory of a spinning body does not lie in a vertical plane, but rather turns slightly to the left or right, depending on the direction of the spin vector and on the magnitudes of the aerodynamic loads. Verf.-Referat