A New Approach to the Determination of the Steady-State Inflated Shape and Included Volume of Several Parachute Types

摘要

A new approach is presented to obtain the steady-state inflated shape of the gore mainseam and the canopy volume of flat circular, 10 percent extended skirt, elliptical, hemispherical, 16 percent porous ring slot, 24 percent porous ribbon in 12- and 16-gore configurations and cross-type parachutes. The canopies are demonstrated to closely elliptical in cross section. The axis ratios of the ellipses are derived from photographic coverage of wind-tunnel tests of models of each type of parachute. Wind-tunnel tests were conducted at various velocities from 17 mph to 200 mph using flat parachute models of approximately 40-inch diameter and shaped gore models of approximately 26-inch inflated diameter. Axis ratios, scale factors, and methods of computing the coordinates of the inflated canopy shape are presented. A new approach to the steady-state volume of the parachute, which includes the volume of the billowed gore and an air volume ahead of the skirt hem of the canopy, is given. The results of this investigation are particularly applicable to studies of canopy stress analysis and determination of the volume of air, which must be collected during canopy inflation process for use in the calculation of opening-shock force. (Author)