Accession Number : ADP005891

Title :   Measurements of Aerodynamic Forces on Unsteadily Moving Bluff Parachute Canopies,

Corporate Author : LEICESTER UNIV (UNITED KINGDOM)

Personal Author(s) : Cockrell, D. J. ; Harwood, R. J. ; Shen, C. Q.

Report Date : JUN 1987

Pagination or Media Count : 8

Abstract : Equations which describe the unsteady motion of bluff bodies through fluids contain certain components, termed added mass coefficients, which can be determined only by experiment. From the solutions to such equations the ways in which the shapes of parachute canopies influence the frequency of their oscillatory motion in pitch and their corresponding damping rates are required. Although a full-scale parachute canopy descends through air, oscillating in pitch as it does so, experiments necessary to determine these added mass coefficients have been performed underwater, using for this purpose a large ship tank from the towing carriage of which the model parachute canopies were suspended. These experiments showed that the added mass coefficients for bluff parachute canopies differed appreciably from their corresponding potential flow values. The latter were obtained from the analysis of inviscid fluid flow round regular shapes which were representative of those parachute canopies. The significance for the prediction of the parachute's dynamic behavior in pitch of these differences is outlined.

Descriptors :   *PARACHUTE CANOPIES, AERODYNAMIC FORCES, OSCILLATION, PITCH(MOTION), DAMPING, MASS, COEFFICIENTS, MODEL TESTS, TOWING, EXPERIMENTAL DATA, DATA ACQUISITION, UNDERWATER, GREAT BRITAIN.

Subject Categories : Aerodynamics
      Gliders and Parachutes

Distribution Statement : APPROVED FOR PUBLIC RELEASE