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Interpretation of Vehicle Tumbling Predictions from 6-DOF Entry and Descent SimulationBlunt body entry vehicles are subject to dynamic instability during terminal descent. This often manifests as limit cycle oscillations in total angle of attack, but can diverge into tumbling behavior under certain conditions. For the Mars Sample Return Earth Entry Vehicle (MSR EEV), there is a constraint on the orientation of the sample tubes so backward impact is impermissible. Past missions have chosen to deploy parachutes to preclude tumbling, but active events after release of MSR EEV have been ground-ruled out with the intent to maximize system reliability. Prevention of tumbling during subsonic descent is a design driver for MSR EEV. During preliminary design of the MSR EEV, six degree-of-freedom numerical simulations indicated an unacceptably high probability of tumbling for a 60degree sphere-cone forebody geometry, which necessitated a design change. Decreasing the forebody angle was expected to improve dynamic stability, but would also adversely impact mass, aeroheating, and manufacturing risk. Hence there was strong motivation to understand the physical drivers for the onset of tumbling, and to determine: (a) whether the causes of tumbling are representative of physically realizable vehicle entry configurations and (b) what changes can be made to existing design and analysis practices to ensure a stable vehicle.
Document ID
Acquisition Source
Ames Research Center
Document Type
Jacob Needels
(Neerim Corporation Hampton, Virginia, United States)
Peter Gage
(Neerim Corporation Hampton, Virginia, United States)
Jeffrey Hill
(Ames Research Center Mountain View, California, United States)
Date Acquired
June 8, 2021
Subject Category
Aircraft Stability And Control
Aeronautics (General)
Meeting Information
Meeting: 18th International Planetary Probe Workshop
Location: Virtual
Country: US
Start Date: June 17, 2021
End Date: August 10, 2021
Sponsors: Analytical Mechanics Associates (United States)
Funding Number(s)
Distribution Limits
Public Use Permitted.
Technical Review
NASA Peer Committee
Entry Vehicle
Flight Mechanics
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