Study Of Parachute Scale Effects

A study was conducted to determine the effects of changing scale upon drag coefficients, filling time, peak opening force, and stability for single, unreefed textile parachute canopies. The investigation was confined to Flat Circular, Extended Skirt, Ringslot, Ribless Guide Surface, Circular Flat Ribbon, and Conical Ribbon parachutes operating in the subsonic flow regime at altitudes below 20,000 feet. As an integral part of the study, a survey of the existing literature and test data, a compilation of all pertinent data, and recommendations for future experimental investigations were made. Scaling equations with associated 95-percent confidence intervals were developed for the drag coefficient of the Flat Circular and Extended Skirt parachutes through the use of multiple regression analysis which the indicates the significant variables and their functional forms. Because the available data was poorly distributed, the equations will have to be used circumspectly to avoid misleading conclusions.

This document serves as the third revision of the USAF Parachute Handbook which was first published in 1951. The data and information represent the current state of the art relative to recovery system design and development. The initial chapters describe representative recovery applications, components, subsystems, material, manufacture and testing. The final chapters provide empirical data and analytical methods useful for predicting performance and presenting a definitive design of selected components into a reliable recovery system.