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HFL-10 lifting body flight control system characteristics and operational experienceA flight evaluation was made of the mechanical hydraulic flight control system and the electrohydraulic stability augmentation system installed in the HL-10 lifting body research vehicle. Flight tests performed in the speed range from landing to a Mach number of 1.86 and the altitude range from 697 meters (2300 feet) to 27,550 meters (90,300 feet) were supplemented by ground tests to identify and correct structural resonance and limit-cycle problems. Severe limit-cycle and control sensitivity problems were encountered during the first flight. Stability augmentation system structural resonance electronic filters were modified to correct the limit-cycle problem. Several changes were made to control stick gearing to solve the control sensitivity problem. Satisfactory controllability was achieved by using a nonlinear system. A limit-cycle problem due to hydraulic fluid contamination was encountered during the first powered flight, but the problem did not recur after preflight operations were improved.
Document ID
Acquisition Source
Legacy CDMS
Document Type
Technical Memorandum (TM)
Painter, W. D.
(NASA Flight Research Center Edwards, CA, United States)
Sitterle, G. J.
(NASA Flight Research Center Edwards, CA, United States)
Date Acquired
September 3, 2013
Publication Date
January 1, 1974
Subject Category
Report/Patent Number
Accession Number
Funding Number(s)
PROJECT: RTOP 756-48-01-00
Distribution Limits
Work of the US Gov. Public Use Permitted.
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