Parks College Parachute Research Group

Glide Performance Study of Standard and Hybrid Cruciform Parachutes

J. Potvin, J. Papke, E. Brighton, T. Hawthorne and G. Peek
Park College Parachute Research Group
Saint Louis University
St. Louis, MO, 63103

R. J. Benney
Airdrop Technology Team
U.S. Army Natick Soldier Center
Natick, MA 01760-5017

Presented at the 17th AIAA Aerodynamic Decelerator Systems Technology Conference and Seminar, Monterey, CA, May 19 -22, 2003, Paper AIAA-2003-2160




Abstract

This paper presents the first results of a performance study of gliding cruciform and hybrid cruciform parachutes. The study was performed by dropping simultaneously one GPS-instrumented cruciform canopy rigged for glide, together with a non-gliding, "reference" parachute also GPS-equipped. The latter was allowed to drift freely with the wind, thereby yielding a measurement of the actual wind column encountered by the glider. After discussing wind effect removal from the gliding parachute velocity, we present the following flight performance data: glide ratio for a variety of suspension line trim settings, turn rates, and response to control inputs in the presence of the wind. For the sake of comparison, glide data was also acquired on a half-scale C-9 parachute and a 26ft GQ Security conical steerable parachute. In summary, although gliding at much steeper angles than parafoils, cruciform parachutes have glide ratios that are only slightly smaller than that of slotted hemispherical parachutes modified for gliding. On the other hand, cruciform parachutes can have quicker turn rates than round chutes. But because their lateral drag is large and forward speed similar to that of the wind, these parachutes have a limited turning ability into unsteady winds. As a result, complete turning will require time-dependent steering tailored to the actual winds encountered.



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