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Parks College

Parachute Research Group

Ram-Air Parachute Deployment Study

Mr. Roberto Montanez, Dr. Jean Potvin, and Mr. Gary Peek

Presented at the 1997 PIA Symposium and at the 14th AIAA Aerodynamic Decelerator Systems Conference

The Parks College Ram-Air Parachute Study is a multi-year experimental program designed to provide parachute riggers, researchers and designers with a public database on the inflation of slider-reefed ram-air parachutes.

The Riser Force Study is collecting data from deployments of several sport parachutes. The instruments used include electronic devices to measure deployment altitude and pre-deployment speed, and opening forces acting on the risers, as well as a belly-mounted video camera and a mechanical accelerometer.

The emphasis is over performing at least 20 jumps on each parachute to obtain accurate measurements of canopy spreading time, jumper maximum deceleration and time history of the loads applied on the risers. So far over 250 instrumented jumps have been performed by two of the investigators (Gary Peek and Jean Potvin) at drop zones in the St. Louis, Missouri area.

Some trends so far observed:

Fall rates for different skydiving activities are found to be in the 100-160 mph range (sea-level adjusted air speed).

The maximum jumper deceleration associated with deployments that follow free falls appears to average 4 to 6 g's (similar decelerations can be obtained by jumping from a chair and landing without body flexing); decelerations associated with "clear and pull" jumps are in the 1-2 g range.

Opening loads applied on the left- and right-risers are rarely symmetrical; in most jumps, one side bears the brunt of the opening shock. Moreover, the rear risers undergo larger loads than the front risers. Here are graphs of the riser loads.

From jump to jump, the maximum deceleration of the parachute/jumper system rarely exceeds 25-percent of its average. This means that parachutes that open "hard" on average will feature more variations in opening shock (i.e. more inconsistent openings).

More information on the results of this continuing study can be found in these reports (and are available on request) from Dr. Jean Potvin.

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

G. Peek, "Skydiving Fall Rate: A Research Project Investigating Skydiving Freefall Speeds Using a Microprocessor-based Barograph (Recording Altimeter)"; unpublished.

J. Potvin, R. Montanez and G. E. Peek; "The Parks College Ram-Air Parachute Deployment Study: A Status Report"; Proceedings of the AIAA 14th Aerodynamics Decelerator Systems Technology Conference; paper AIAA-97-1426.

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