Parks College Parachute Research Group

Experimental Validation of the Ideal Parachute Model: A Status Report

J. Potvin and G. Peek - Parks College Parachute Research Group

Presented at the 15th AIAA Aerodynamic Decelerator Systems Conference, Toulouse, France, June 9-11, 1999




Abstract

We report on the continuation of an effort aimed at validating the predictions of a model of parachute inflation called the Ideal Parachute Model (or IPM), using the results of instrumented jumps collected by the Parks College Parachute Research Group. The focus is in using this information to validate weight-, size- and initial speed-scaling formulas that can be extracted from the IPM as it applies to slider-reefed ram-air parachutes. After reviewing the basics of the Ideal Parachute Model and its predicted scaling laws, we present an update of the database which has been increased to include the results of a new test jump program carried out in collaboration with Performance Designs Inc. We then report on the experimental validation itself, focusing on the following aspects:

1) maximum opening shock versus overall parachute size scaling (nominal/average openings and line-dumped openings -- they have a different size scaling relation);

2) maximum opening shock versus slider inertia scaling;

3) experimental time of maximum shock versus theoretical time of maximum shock.

Acknowledgements

The authors thank Mr. B. Coe and Mr. W. Downey from Performance Designs Inc. for their aeronautical expertise. They are also grateful to Performance Designs for providing financial support as well as loaning and rigging the test canopies for this project.

References

1. Perschbacher, T. and Potvin, J.; "The Improved Ideal Parachute Model and its Application to the Study of Inflation Dynamics of Slider-reefed ram-air and round parachutes"; this conference; AIAA-99-zzzz.

2. Potvin, J.; "Deployment Model for Slider-Reefed Ram-Air Parachutes"; AIAA-95-1564.

3. Potvin, J.; "Testing a New Model of Ram-Air Parachute Inflation"; The Aeronautical Journal, Vol. 101, pp. 299-313, 1997.

4. Lingard, J. S. ; "A Semi-empirical Theory toPredict the Load-time History of an Inflating Parachute"; AIAA-84-0814.

5. Garrard, W.L.; "Application of Inflation Theories to Preliminary Parachute Force and Stress Analysis"; AIAA-91-0862.

6. Goodrick, T. F.; "Scale Effects on Performance of Ram Air Wings"; AIAA-84-0783.

7. Lingard, J. S.; "Ram-Air Parachute System Design"; 2nd ADS Technology Seminar; 13th AIAA Aerodynamic Decelerator Systems Conference and Seminar, Clearwater Beach, Florida, 15 May, 1995. Unpublished.

8. Potvin, J., Montanez, R. and Peek, G. ; "The Parks College Ram-Air Parachute Deployment Study: a Status Report". AIAA-97-1426.

9. Potvin, J., Montanez, R. and Peek, G. ; "The Parks College Ram-Air Parachute Deployment Study". Proceedings of the 1997 Parachute Industry Association International Symposium, Houston, TX, February 9-13, 1997.



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