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Book Modelling of Unsteady Aerodynamic Characteristics for Aircraft Dynamics Applications at High Incidence Flight

Download or read book Modelling of Unsteady Aerodynamic Characteristics for Aircraft Dynamics Applications at High Incidence Flight written by Nikolay Abramov and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A traditional representation of aerodynamic characteristics based on the concept of aerodynamic derivatives fails to be accurate at high angles of attack due to significant dynamic effects generated from separated and vortical flow. As the possibility of performing controlled flight at high angles of attack has already become a common requirement for modern combat aircraft, the problem of an adequate model for aerodynamic loads at high incidences is the issue of the day. This thesis presents a phenomenological approach to modelling of unsteady aerodynamic characteristics at high angles of attack. In this approach aerodynamic characteristics are considered as a combination of two components having different characteristic time scales which describe the contribution to the total aerodynamic load from the different flow structures. It is assumed that all dynamic properties of the flow are amassed in the' slow' component. To describe its behaviour specially designed nonlinear differential equations are used. Depending on the parameters, this model can reproduce both 'weak' and 'strong' nonlinear effects including static hysteresis. A special identification technique has been developed for the estimation of the model parameters using dynamic wind tunnel test data.

Book Special Course on Aircraft Dynamics at High Angles of Attack Experiments and Modelling

Download or read book Special Course on Aircraft Dynamics at High Angles of Attack Experiments and Modelling written by North Atlantic Treaty Organization. Advisory Group for Aerospace Research and Development. Fluid Dynamics Panel. Special Course and published by . This book was released on 1991 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This report consists of lecture notes of an AGARD Fluid Dynamics Panel Special Course. These notes provide the latest information on the development and use of dynamic experiments in wind tunnels from several of the NATO nations. They address current oscillatory and rotary test techniques, experimental results for typical configurations, and the use of these data for flight mechanics applications. Subject included are: dynamic lift, wing rock, fluid dynamics of rotary flows, mathematical modelling, non-linear data representation, vortex manipulation for control enhancement, and correlations of predictions based on rotary and oscillatory wind-tunnel and flight-test results. The complete course notes are contained in two volumes. The main part of the notes is contained in AGARD Advisory Report 265 (ADA235179). The present volume includes papers on: Unsteady aerodynamics of slender wings; Dynamic stall effects and applications to high performance aircraft; Oscillatory test techniques; Large amplitude oscillations; Oscillatory data for typical configurations; and Forebody vortex control."--Stinet.

Book Aerodynamic Modeling for Aircraft in Unsteady Flight Conditions

Download or read book Aerodynamic Modeling for Aircraft in Unsteady Flight Conditions written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-27 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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...

Book Modeling of Aircraft Unsteady Aerodynamic Characteristics Part 3 Parameters Estimated from Flight Data Part 3 Parameters Estimated from Flight Data

Download or read book Modeling of Aircraft Unsteady Aerodynamic Characteristics Part 3 Parameters Estimated from Flight Data Part 3 Parameters Estimated from Flight Data written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-05 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: A nonlinear least squares algorithm for aircraft parameter estimation from flight data was developed. The postulated model for the analysis represented longitudinal, short period motion of an aircraft. The corresponding aerodynamic model equations included indicial functions (unsteady terms) and conventional stability and control derivatives. The indicial functions were modeled as simple exponential functions. The estimation procedure was applied in five examples. Four of the examples used simulated and flight data from small amplitude maneuvers to the F-18 HARV and X-31A aircraft. In the fifth example a rapid, large amplitude maneuver of the X-31 drop model was analyzed. From data analysis of small amplitude maneuvers ft was found that the model with conventional stability and control derivatives was adequate. Also, parameter estimation from a rapid, large amplitude maneuver did not reveal any noticeable presence of unsteady aerodynamics. Klein, Vladislav and Noderer, Keith D. Langley Research Center RTOP 505-64-52-01...

Book Modeling of Aircraft Unsteady Aerodynamic Characteristics Part 2 Parameters Estimated from Wind Tunnel Data

Download or read book Modeling of Aircraft Unsteady Aerodynamic Characteristics Part 2 Parameters Estimated from Wind Tunnel Data written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-10-28 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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...

Book Modeling of Aircraft Unsteady Aerodynamic Characteristics

Download or read book Modeling of Aircraft Unsteady Aerodynamic Characteristics written by Vladislav Klein and published by . This book was released on 1994 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 degree 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.

Book On the Formulation of the Aerodynamic Characteristics in Aircraft Dynamics

Download or read book On the Formulation of the Aerodynamic Characteristics in Aircraft Dynamics written by Murray Tobak and published by . This book was released on 1976 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: The theory of functionals is used to reformulate the notions of aerodynamic indicial functions and superposition. Integral forms for the aerodynamic response to arbitrary motions are derived that are free of dependence on a linearity assumption. Simplifications of the integral forms lead to practicable nonlinear generalizations of the linear superposition and the stability derivative formulations. Applied to arbitrary nonplanar motions, the generalization yields a form for the aerodynamic response that can be compounded of the contributions from a limited number of well-defined characteristic motions, in principle reproducible in the wind tunnel. Further generalizations that would enable the consideration of random fluctuations and multivalued aerodynamic responses are indicated.

Book Unsteady Aerodynamics Fundamentals and Applications of Aircraft Dynamics Conference Proceedings of the Joint Symposium of the Fluid Dynamics and Flight Mechanics Panels Held in Goettingen Federal Republic of Germany on 6 9 May 1985

Download or read book Unsteady Aerodynamics Fundamentals and Applications of Aircraft Dynamics Conference Proceedings of the Joint Symposium of the Fluid Dynamics and Flight Mechanics Panels Held in Goettingen Federal Republic of Germany on 6 9 May 1985 written by ADVISORY GROUP FOR AEROSPACE RESEARCH AND DEVELOPMENT NEUILLY-SUR-SEINE (France) and published by . This book was released on 1985 with total page 625 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dynamic behavior of aircraft in high performance maneuvres is greatly affected by various unsteady flow phenomena, particularly at high angles of attack, where extensive regions of separated flow and several systems of symmetric vortices are often present. Such flows, already rather complex in steady flight, become even more involved in oscillatory or high rate-of-turn flight, where the time lags associated with the various vortical and separated flows become a significant factor affecting profoundly both the static and the dynamic aerodynamic parameters of the aircraft. A good understanding of unsteady aerodynamics is also important for design of advanced flight control systems, prediction of wing structural and maneuvre loads and buffet prediction. This symposium examined recent advances in the methods for experimental and computational prediction of non-linear flow phenomena in unsteady aerodynamics and of stability parameters required to describe adequately the dynamic behavior of aircraft will special emphasis on high-angle-of-attack situations. The major program topics were: (1) Unsteady aerodynamics, (2) Dynamic stability parameters, and (3) Applications to aircraft Dynamics. In the first part, topics such as unsteady boundary layers, unsteady separation and stall, buffeting and unsteady airloads were discussed. The second part covered wind-tunnel and flight-test techniques, with special emphasis on the measurement of non-linearities, aerodynamic cross-coupling, hysteresis and time-dependent effects. In part three, various applications of the above to the actual prediction of aircraft dynamics were described, including topics such as mathematical modelling, bifurcation theory, prediction of wing rock, advanced control systems, etc.

Book Modeling of Aircraft Unsteady Aerodynamic Characteristics

Download or read book Modeling of Aircraft Unsteady Aerodynamic Characteristics written by Vladislav Klein and published by . This book was released on 1994 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Select Means for Determining Unsteady Aerodynamic Response Characteristics from Static Data

Download or read book Select Means for Determining Unsteady Aerodynamic Response Characteristics from Static Data written by Gregory A. Addington and published by . This book was released on 2000 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent analysis has shown that nearly every high-performance tactical aircraft in the inventory of American and allied air forces has experienced some sort of unexpected controlled-flight departure in the early stages of flight testing. Most, if not all, of these in-flight departures had characteristics which lead to the conclusion that they were the result of critical state encounters. Critical states are discrete flight mechanical state vector values where the aerodynamic response loses its analytic dependence on one or more of the variables in that state vector. Critical states manifest themselves as discontinuities in either magnitude or slope in static force and moment data, and as dynamic responses which may be nonlinear with respect to either geometric parameters and/or time. This report presents two analysis procedures which have shown promise in the detection of critical states. First, spectral analysis of data ensembles acquired during wind tunnel tests of two 65 degree delta wings has shown that changes in these spectra signal the presence of some critical states. Further, the nature of these spectra have in some instances provided insight into the nature of the dynamic response. The second analysis procedure involves comparing the static experimental data to a simple potential-flow-based numerical model. It was found that when the experimental dataset diverged from the numerical simulation, critical states were present. Both of these analysis procedures required no additional data to be acquired and minimal analytical effort. Therefore, they provide a cost-effective means for adverting the effects of critical states during early air vehicle test-and-evaluation programs.

Book Special Course on Aircraft Dynamics at High Angles of Attack Experiments and Modelling

Download or read book Special Course on Aircraft Dynamics at High Angles of Attack Experiments and Modelling written by North Atlantic Treaty Organization. Advisory Group for Aerospace Research and Development. Fluid Dynamics Panel. Special Course and published by . This book was released on 1991 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "This report consists of lecture notes of an AGARD Fluid Dynamics Panel Special Course. These notes provide the latest information on the development and use of dynamic experiments in wind tunnels from several of the NATO nations. They address current oscillatory and rotary test techniques, experimental results for typical configurations, and the use of these data for flight mechanics applications. Subject included are: dynamic lift, wing rock, fluid dynamics of rotary flows, mathematical modelling, non-linear data representation, vortex manipulation for control enhancement, and correlations of predictions based on rotary and oscillatory wind-tunnel and flight-test results. The complete course notes are contained in two volumes. The main part of the notes is contained in AGARD Advisory Report 265 (ADA235179). The present volume includes papers on: Unsteady aerodynamics of slender wings; Dynamic stall effects and applications to high performance aircraft; Oscillatory test techniques; Large amplitude oscillations; Oscillatory data for typical configurations; and Forebody vortex control."--Stinet