The Parks College Parachute Research Group

by Gary Peek


Re-printed from the St. Louis Aviation Journal


Introduction

For most skydivers, technical knowledge about how their parachutes work simply means going to the airport knowing enough to stay safe. But for a team of skydivers in the St. Louis area, that knowledge alone is not enough. Jean Potvin, a physics instructor at St. Louis University-Parks College, and Gary Peek, a computer and electronics consultant, have formed the Parks College Parachute Research Group (or PRG) to answer questions about how parachutes open and fly. Some of the questions they hope to answer are: "By exactly how much does opening shock change with canopy size and wing loading?", "What is the pressure balance between the inside and outside of a parachute?", "How fast is the parachute unfolding process right after it comes out of container?", "and how is this determined by the parachutes packing style?" To answer these questions, and to push the limits of our knowledge a bit further, these skydivers along with the help of students at St. Louis University have been developing computer models of parachute inflation as well as performing wind tunnel experiments and instrumented test jumps to validate such models. To carry out the experimental portion of this research, these investigators have developed some unique and interesting test equipment and procedures to capture the data associated with these studies. The long term goal of the PRG is ultimately to provide the military and the parachute industry with better design tools that will reduce the cost of prototyping and testing new canopies.

The Group's Beginnings

Jean Potvin first got interested in parachuting as a sport rather than a research project. Being a physicist, he naturally got interested in the theoretical aspects of the physics and aerodynamics of ram-air parachutes and found that the inflation computer models used by researchers lacked the accuracy needed by the designers of our modern gear. (No wonder, since such models had been initially created for the description of the inflation of round parachutes!) In 1994 Potvin began devising a new model more specific to sport ram-air parachutes and, in order to validate this model, began jumping with a helmet-mounted aerobatic aircraft G-meter and video camera to record maximum opening force and canopy inflation times. During this same period, Gary Peek was doing some research in another area of skydiving. In 1990 he became interested in improving formation skydives by learning more about fall rate, and began working on a device that could periodically record the altitude during a jump and calculate freefall speed. Devices like these are called "barographs", and some older style mechanical barographs have been used in aviation altitude record attempts for many years. By using some newer technology, Peek developed a barograph that is small and lightweight, and can be worn on a skydiver's wrist.

Joining Forces

These two skydivers knew little about each other's work because they normally jumped at two different drop zones in the St. Louis area, and were both quite busy with their individual work. It was not until they participated together in an exhibition jump at Parks College, (which was arranged by a former student of Potvin's that often jumped with Peek), that their conversation turned to their respective research projects. It was then that they finally realized that they had a lot in common, and would benefit greatly by working together. Almost immediately, their work as a team began. Potvin's mathematical knowledge quickly provided a method for improving Peek's barograph, which continues to be used by the Group to determine airspeeds during parachute deployment. Potvin also told Peek of his interest in using an electronic device that would allow him to record signals from force and pressure sensors mounted on risers as part of his parachute opening force research. Peek realized that a simple data recording device could be made with the same technology that he had incorporated into his most recent barograph design, so at his suggestion, Potvin purchased the components necessary to build the device. Peek quickly put it all together, and after a small programming modification, they were collecting jump data with the Group's first data acquisition system made specifically for research jumpers. Since that time, the Group has made over 300 instrumented test jumps, and Peek has since designed and built a much more sophisticated system that can collect and store data at a faster rate and from more sensors.

Current Projects

The Group has been working on various projects utilizing the large subsonic wind tunnel at Parks College, including a study of the unfolding and inflation of a scale model parachute.

Other funded projects include:

In conclusion

As the number of applications for ram-air parachutes increases due to the constantly evolving sport market, and because of increased interest by civilian and military government agencies, there will be an expanding demand for more accurate knowledge about the inner workings of parachutes. The Parks College Parachute Research Group plans to continue to provide some of the needed new knowledge required by these new and novel applications. More information as well as photographs from these various projects can be found on the Group's web site at http://www.pcprg.com



Gary Peek is a Commercial Pilot, Master Parachute Rigger, and skydiving Instructor/Examiner. His articles on skydiving have been published in Parachutist, the official publication of the United States Parachute Association.

If you would like more information about parachute rigging services or skydiving you may contact Gary at (636) 946-5272 or email: peek@pcprg.com