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Parks College

Parachute Research Group

In-Flight Study of the Pressure Distribution Near the Surfaces of an Inflating Ram-Air Parachute

Dr. Jean Potvin and Mr. Gary Peek

Presented at the 16th AIAA Applied Aerodynamics Conference

Recent progress in the mathematical description of the inflation of ram-air parachutes has been made through the use of computer simulations. Given the highly complex and unsteady nature of parachute inflation, these computer simulations are still in a development stage since they use drastic approximations to meet the limitations of current algorithms and computers. Ultimately, the use of such approximations can only be validated by experiment. Unfortunately, current parachute inflation databases are not detailed enough to provide the information needed. The main objective of this experiment is to provide researchers with measurements of the pressure distribution inside, below and above the surfaces of a ram-air parachute inflating during a live drop.

The experiment consists of measuring the pressure differences between various locations inside and outside the cells of ram-air parachute. The measurements are performed with solid state pressure sensors sewn in the parachute's next-to-center cell and connected to several pressure taps located inside the cell or on the top an bottom skin of the canopy. The transmission of power and data to and from the pressure sensor is accomplished by wires which are finger-trapped in the parachute's suspension lines, amplified/scaled by circuits mounted on the risers, and connected to a data acquisition system carried by the test parachutist. The pressure sensor array has been designed so that the parachute can be folded and deployed in the manner intended by the manufacturer. This system has also been designed to survive a large number of packings and deployments of the parachute. Here is an overall diagram of the system.

The experiment is in progress. Full results will be released in the future.

Until that time, we will make available graphs of some of the raw data collected, like this graph. This is a graph of the pressure differentials between different parts of the parachute during deployment. (Notice that the points on this graph are referenced only to the voltage from our data acquisition system and are not in actual pressure.)

We have not yet begun the testing of pressure during flight, but will at some point have data on this also.

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