Experimental Investigation of Parachute Canopies with Rectangular Parallelepiped Geometries

A series of wind-tunnel experiments were conducted in which the drag characteristics and inflated geometry of model parachute canopies with rectangular parallelepiped geometries (polyhedron) were examined. The model-canopy layouts were the same as cross canopies with the adjacent sides completely attached together. All models had a base dimension of 0.2 m, and aspect ratios ranged from 0.2 to 1.2. The models did not have a central vent or any other geometric porosity. The data show the inflated geometry of the canopy differs from the constructed geometry with the smallest change occurring at a constructed aspect of 0.8 and the variation becomes larger for increasing or decreasing constructed aspect ratios. The data also indicate the aerodynamic drag coefficient, based on the projected area, has a maximum value of approximately one for the constructed aspect ratio of 0.3 corresponding to an inflated aspect ratio of 0.53. The drag coefficient is less for smaller and larger aspect-ratio models. If scaled by the canopy surface area drag of the rectangular parallelepiped canopies is lower than flat circular canopy designs. These findings are consistent with the past findings on other flexible parachute canopies and rigid bluff bodies.