Experimental and theoretical investigation of the reduction in parachute drag caused by forebody wake effects: data compilation and program summary
An experiment was conducted to evaluate approximate analytical methods for predicting the reduction in parachute drag caused by forebody wake effects. The drag of a 20/sup 0/ conical ribbon parachute was measured at several axial stations behind an ogive cylinder forebody with and without fins. The same parachute was tested in undisturbed flow (where wake effects were negligible) so that the effects of suspension line length on parachute drag could be separated from the drag losses caused by the turbulent wake. Total head pressure surveys were made across the forebody wake and integrated across the canopy skirt area to determine the effective dynamic pressure acting on the parachute. Experimental results confirmed the validity of the underlying physical model of the parachute/wake interaction: the ratio of parachute drag behind a forebody divided by wake-free parachute drag is equal to the ratio of effective dynamic pressure acting on the parachute divided by free-stream dynamic pressure. However, the inability of existing turbulent wake theoretical models to make accurate predictions of wake velocity distributions for arbitrary forebody shapes is a fundamental limitation of the drag-loss analysis. If wake velocity profiles are known, the empirical constants in the turbulent wake theoretical models can be adjusted and accurate estimates of wake-induced parachute drag loss can be obtained from existing theory.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (USA)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 6590249
- Report Number(s):
- SAND-81-0510; ON: DE83005364
- Resource Relation:
- Other Information: Portions of document are illegible. Printed copy available until stock is exhausted
- Country of Publication:
- United States
- Language:
- English
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