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Six-degree-of-freedom guidance and control-entry analysis of the HL-20The ability of the HL-20 lifting body to fly has been evaluated for an automated entry from atmospheric interface to landing. This evaluation was required to demonstrate that not only successful touchdown conditions would be possible for this low lift-to-drag-ratio vehicle, but also the vehicle would not exceed its design dynamic pressure limit of 400 psf during entry. This dynamic pressure constraint limit, coupled with limited available pitch-control authority at low supersonic speeds, restricts the available maneuvering capability for the HL-20 to acquire the runway. One result of this analysis was that this restrictive maneuvering capability does not allow the use of a model-following atmospheric entry-guidance algorithm, such as that used by the Space Shuttle, but instead requires a more adaptable guidance algorithm. Therefore, for this analysis, a predictor-corrector guidance algorithm was developed that would provide successful touchdown conditions while not violating the dynamic pressure constraint. A flight-control system was designed and incorporated, along with the predictor-corrector guidance algorithm, into a six-DOF simulation. which showed that the HL-20 remained controllable and could reach the landing site and execute a successful landing under all off-nominal conditions simulated.
Document ID
19930069740
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Powell, Richard W.
(NASA Langley Research Center Hampton, VA, United States)
Date Acquired
August 16, 2013
Publication Date
October 1, 1993
Publication Information
Publication: Journal of Spacecraft and Rockets
Volume: 30
Issue: 5
ISSN: 0022-4650
Subject Category
Space Transportation
Accession Number
93A53737
Distribution Limits
Public
Copyright
Other

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