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An analytical technique for approximating unsteady aerodynamics in the time domainAn analytical technique is presented for approximating unsteady aerodynamic forces in the time domain. The order of elements of a matrix Pade approximation was postulated, and the resulting polynomial coefficients were determined through a combination of least squares estimates for the numerator coefficients and a constrained gradient search for the denominator coefficients which insures stable approximating functions. The number of differential equations required to represent the aerodynamic forces to a given accuracy tends to be smaller than that employed in certain existing techniques where the denominator coefficients are chosen a priori. Results are shown for an aeroelastic, cantilevered, semispan wing which indicate a good fit to the aerodynamic forces for oscillatory motion can be achieved with a matrix Pade approximation having fourth order numerator and second order denominator polynomials.
Document ID
19810002914
Acquisition Source
Legacy CDMS
Document Type
Technical Publication (TP)
Authors
Dunn, H. J. (NASA Langley Research Center Hampton, VA, United States)
Date Acquired
September 4, 2013
Publication Date
November 1, 1980
Subject Category
Structural Mechanics
Report/Patent Number
L-13255
NASA-TP-1738
Accession Number
81N11422
Funding Number(s)
PROJECT: RTOP 505-34-33-02
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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