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Body-freedom flutter of a 1/2-scale forward-swept-wing model, an experimental and analytical studyThe aeroelastic phenomenon known as body-freedom flutter (BFF), a dynamic instability involving aircraft-pitch and wing-bending motions which, though rarely experienced on conventional vehicles, is characteristic of forward swept wing (FSW) aircraft was investigated. Testing was conducted in the Langley transonic dynamics tunnel on a flying, cable-mounted, 1/2-scale model of a FSW configuration with and without relaxed static stability (RSS). The BFF instability boundaries were found to occur at significantly lower airspeeds than those associated with aeroelastic wing divergence on the same model. For those cases with RSS, a canard-based stability augmentation system (SAS) was incorporated in the model. This SAS was designed using aerodynamic data measured during a preliminary tunnel test in which the model was attached to a force balance. Data from the subsequent flutter test indicated that BFF speed was not dependent on open-loop static margin but, rather, on the equivalent closed-loop dynamics provided by the SAS. Servo-aeroelastic stability analyses of the flying model were performed using a computer code known as SEAL and predicted the onset of BFF reasonably well.
Document ID
Document Type
Contractor Report (CR)
Chipman, R.
(Grumman Aerospace Corp. Bethpage, NY, United States)
Rauch, F.
(Grumman Aerospace Corp. Bethpage, NY, United States)
Rimer, M.
(Grumman Aerospace Corp. Bethpage, NY, United States)
Muniz, B.
(Grumman Aerospace Corp. Bethpage, NY, United States)
Date Acquired
September 4, 2013
Publication Date
April 1, 1984
Subject Category
Aircraft Stability And Control
Report/Patent Number
NAS 1.26:172324
Accession Number
Funding Number(s)
Distribution Limits
Work of the US Gov. Public Use Permitted.
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