Modeling of Aircraft Unsteady Aerodynamic Characteristics. Part 2: Parameters Estimated from Wind Tunnel Data PDF Download
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Author: National Aeronautics and Space Adm Nasa
Publisher: Independently Published
ISBN: 9781729346334
Category : Science
Languages : en
Pages : 46
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Book Description
Aerodynamic equations with unsteady effects were formulated for an aircraft in one-degree-of-freedom, small-amplitude, harmonic motion. These equations were used as a model for aerodynamic parameter estimation from wind tunnel oscillatory data. The estimation algorithm was based on nonlinear least squares and was applied in three examples to the oscillatory data in pitch and roll of 70 deg triangular wing and an X-31 model, and in-sideslip oscillatory data of the High Incidence Research Model 2 (HIRM 2). All three examples indicated that a model using a simple indicial function can explain unsteady effects observed in measured data. The accuracy of the estimated parameters and model verification were strongly influenced by the number of data points with respect to the number of unknown parameters. Klein, Vladislav and Noderer, Keith D. Langley Research Center RTOP 505-64-52-01...
Author: National Aeronautics and Space Adm Nasa
Publisher: Independently Published
ISBN: 9781729346334
Category : Science
Languages : en
Pages : 46
Get Book
Book Description
Aerodynamic equations with unsteady effects were formulated for an aircraft in one-degree-of-freedom, small-amplitude, harmonic motion. These equations were used as a model for aerodynamic parameter estimation from wind tunnel oscillatory data. The estimation algorithm was based on nonlinear least squares and was applied in three examples to the oscillatory data in pitch and roll of 70 deg triangular wing and an X-31 model, and in-sideslip oscillatory data of the High Incidence Research Model 2 (HIRM 2). All three examples indicated that a model using a simple indicial function can explain unsteady effects observed in measured data. The accuracy of the estimated parameters and model verification were strongly influenced by the number of data points with respect to the number of unknown parameters. Klein, Vladislav and Noderer, Keith D. Langley Research Center RTOP 505-64-52-01...
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781722379582
Category :
Languages : en
Pages : 28
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Book Description
A short theoretical study of aircraft aerodynamic model equations with unsteady effects is presented. The aerodynamic forces and moments are expressed in terms of indicial functions or internal state variables. The first representation leads to aircraft integro-differential equations of motion; the second preserves the state-space form of the model equations. The formulations of unsteady aerodynamics is applied in two examples. The first example deals with a one-degree-of-freedom harmonic motion about one of the aircraft body axes. In the second example, the equations for longitudinal short-period motion are developed. In these examples, only linear aerodynamic terms are considered. The indicial functions are postulated as simple exponentials and the internal state variables are governed by linear, time-invariant, first-order differential equations. It is shown that both approaches to the modeling of unsteady aerodynamics lead to identical models. Klein, Vladislav and Noderer, Keith D. Langley Research Center RTOP 505-64-52-01...
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Languages : en
Pages : 46
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Languages : en
Pages : 50
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Author: Vladislav Klein
Publisher:
ISBN:
Category : Oscillations
Languages : en
Pages : 46
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Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781720373018
Category :
Languages : en
Pages : 56
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This report summarizes the activities in unsteady aerodynamic modeling and application of unsteady aerodynamic models to flight dynamics. A public on briefing was presented on July 21, 1999 at Langley Research Center.Lan, C. EdwardLangley Research CenterAERODYNAMIC CHARACTERISTICS; FLIGHT CONDITIONS; UNSTEADY AERODYNAMICS; MATHEMATICAL MODELS; FUZZY SYSTEMS; FLOW DISTRIBUTION; CONVOLUTION INTEGRALS; NONLINEARITY; FOURIER ANALYSIS
Author: National Aeronautics and Space Adm Nasa
Publisher: Independently Published
ISBN: 9781723743511
Category : Science
Languages : en
Pages : 34
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Aerodynamic equations for the longitudinal motion of an aircraft with a horizontal tail were developed. In this development emphasis was given on obtaining model structure suitable for model identification from experimental data. The resulting aerodynamic models included unsteady effects in the form of linear indicial functions. These functions represented responses in the lift on the wing and tail alone, and interference between those two lifting surfaces. The effect of the wing on the tail was formulated for two different expressions concerning the downwash angle at the tail. The first expression used the Cowley-Glauert approximation known-as "lag-in-downwash," the second took into account growth of the wing circulation and delay in the development of the lift on the tail. Both approaches were demonstrated in two examples using the geometry of a fighter aircraft and a large transport. It was shown that the differences in the two downwash formulations would increase for an aircraft with long tail arm performing low-speed, rapid maneuvers.Klein, VladislavLangley Research CenterUNSTEADY AERODYNAMICS; AERODYNAMIC CHARACTERISTICS; AERODYNAMIC STABILITY; LONGITUDINAL STABILITY; LIFT; PITCHING MOMENTS; WIND TUNNEL TESTS; BODY-WING AND TAIL CONFIGURATIONS; WINGS; TAIL ASSEMBLIES; DOWNWASH; FIGHTER AIRCRAFT
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Category : Oscillations
Languages : en
Pages : 70
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Category : Aeronautics
Languages : en
Pages : 1102
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Category :
Languages : en
Pages : 30
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