Determination of the Aerodynamic Drag Force on a Parachute

摘要

The use of the Buckingham Pi theorem in dimensional analysis suggests that the aerodynamic drag force that is exerted on parachutes is a quadratic function of speed, but it cannot determine the drag coefficients because they must be determined experimentally. In this article, experimental data are presented and used in two different, but complementary, ways to demonstrate that the drag force is quadratic, and to determine the corresponding drag coefficients. Curve-fitting a second-degree polynomial to the collected data makes it possible to verify directly that the nature of the force is quadratic and to estimate drag coefficients. Predicted terminal speeds of the parachutes are also used to determine the drag coefficients. A comparison of the two sets of results indicates that the combined use of the methods helps improve the accuracy of the drag force obtained.