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Photogrammetric Analysis of CPAS Main ParachutesThe Crew Exploration Vehicle Parachute Assembly System (CPAS) is being designed to land the Orion Crew Module (CM) at a safe rate of descent at splashdown with a cluster of two to three Main parachutes. The instantaneous rate of descent varies based on parachute fly-out angles and geometric inlet area. Parachutes in a cluster oscillate between significant fly-out angles and colliding into each other. The former presents a sub-optimal inlet area and the latter lowers the effective drag area as the parachutes interfere with each other. The fly-out angles are also important in meeting a twist torque requirement. Understanding cluster behavior necessitates measuring the Mains with photogrammetric analysis. Imagery from upward looking cameras is analyzed to determine parachute geometry. Fly-out angles are measured from each parachute vent to an axis determined from geometry. Determining the scale of the objects requires knowledge of camera and lens calibration as well as features of known size. Several points along the skirt are tracked to compute an effective circumference, diameter, and inlet area as a function of time. The effects of this geometry are clearly seen in the system drag coefficient time history. Photogrammetric analysis is key in evaluating the effects of design features such as an Over-Inflation Control Line (OICL), Main Line Length Ratio (MLLR), and geometric porosity, which are varied in an attempt to minimize cluster oscillations. The effects of these designs are evaluated through statistical analysis.
Document ID
20110011458
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Ray, Eric
(Jacobs Technologies Engineering Science Contract Group Houston, TX, United States)
Bretz, David
(Barrios Technology, Inc. Houston, TX, United States)
Date Acquired
August 25, 2013
Publication Date
May 23, 2011
Subject Category
Spacecraft Design, Testing And Performance
Report/Patent Number
JSC-CN-23207
Meeting Information
Meeting: 21st AIAA Aerodyanamic Decelerator Systems
Location: Dublin
Country: Ireland
Start Date: May 23, 2011
End Date: May 26, 2011
Sponsors: American Inst. of Aeronautics and Astronautics
Funding Number(s)
WBS: WBS 644423.06.31.04.03.10
Distribution Limits
Public
Copyright
Public Use Permitted.
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