The Parks College Parachute Research Group
by Gary Peek
Re-printed from the St. Louis Aviation Journal
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
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.
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.
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:
- A study of the opening shock for various sizes of a single parachute design.
This project, which is sponsored by a major sport parachute manufacturer,
involves measuring the load sustained by each parachute riser during deployment,
inflation, and glide.
- A study of the pressure environment inside and outside of an inflating
parachute. This project is sponsored by the U.S. Department of the
Interior Bureau of Land Management smokejumpers, and involves installing
pressure sensors in the standard issue BLM parachute.
- The development of computer models and their testing in wind tunnel
experiments and actual cargo airdrops. This project is sponsored by the
U.S. Air Force and the U.S. Army.
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
If you would like more information about parachute rigging services
or skydiving you may contact Gary at (636) 946-5272 or email: email@example.com