Download or read book Parameter Estimation Methods for High Angle of attack Aerodynamic Modelling written by Jordan Leung and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, extensive research has been performed in post-stall aerodynamic model development to facilitate the use of simulator-based stall recovery training for commercial pilots. To develop these aerodynamic models, the parameters within a postulated model structure are often estimated from flight test data in a process referred to as aircraft parameter estimation. However, the complex dynamics involved in stall poses some notable challenges to the parameter estimation procedure. This thesis presents and investigates a variety of parameter estimation methods that yield more accurate estimates than traditional techniques when applied to stall modelling problems. Specifically, these methods look to reduce parameter biases that occur during post-stall modelling problems due to the presence of large model deficiencies. The presented methods are applied to both simulated and real aircraft flight data to demonstrate the improvements seen over traditional aircraft parameter estimation methods.
Download or read book Aerodynamic Parameters of High Angle Of Attack Research Vehicle Harv Estimated from Flight Data written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-02 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerodynamic parameters of the High-Angle-of-Attack Research Aircraft (HARV) were estimated from flight data at different values of the angle of attack between 10 degrees and 50 degrees. The main part of the data was obtained from small amplitude longitudinal and lateral maneuvers. A small number of large amplitude maneuvers was also used in the estimation. The measured data were first checked for their compatibility. It was found that the accuracy of air data was degraded by unexplained bias errors. Then, the data were analyzed by a stepwise regression method for obtaining a structure of aerodynamic model equations and least squares parameter estimates. Because of high data collinearity in several maneuvers, some of the longitudinal and all lateral maneuvers were reanalyzed by using two biased estimation techniques, the principal components regression and mixed estimation. The estimated parameters in the form of stability and control derivatives, and aerodynamic coefficients were plotted against the angle of attack and compared with the wind tunnel measurements. The influential parameters are, in general, estimated with acceptable accuracy and most of them are in agreement with wind tunnel results. The simulated responses of the aircraft showed good prediction capabilities of the resulting model. Klein, Vladislav and Ratvasky, Thomas R. and Cobleigh, Brent R. Langley Research Center...
Download or read book Inclusion of Unsteady Aerodynamics in Longitudinal Parameter Estimation from Flight Data written by M. J. Queijo and published by . This book was released on 1979 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Identification of Aircraft Stability and Control Coefficients for the High Angle of Attack Regime written by W. E Hall (Jr) and published by . This book was released on 1974 with total page 257 pages. Available in PDF, EPUB and Kindle. Book excerpt: A central problem of the stall/post-stall flight regime is the identification of nonlinear aerodynamic coefficients whose adverse characteristics may produce severe handling quality degradation. This identification problem is twofold: determination of the nonlinear aerodynamic models and estimation of the coefficients of these models. An integrated parameter identification procedure based on maximum likelihood methods is presented to resolve these problems with verification results based on a nonlinear six-degree-of-freedom digital aircraft simulation. The identification procedure consists of the sequential application of a model determination algorithm and a maximum likelihood identification method. Input design and measurement system specification techniques are combined with this application to form the integrated parameter identification process. The model determination algorithm is based on least squares subset regression techniques. This structure and parameter estimation procedure is applied to the response of an advanced fighter. Results of the application of the identification procedure to these data have shown that the model structure and parameters of the nonlinear regime can be successfully identified, even in the presence of high levels of process and measurement noise. It is further shown that the estimates obtained from a data length with a given input can be used to successfully predict the response of the aircraft to another input in the same flight regime. The procedures established and verified are highly flexible and may be readily applied to modeling other classes of nonlinear vehicles from test data.
Download or read book Aircraft Aerodynamic Parameter Estimation from Flight Data Using Neural Partial Differentiation written by Majeed Mohamed and published by Springer Nature. This book was released on 2021-02-23 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents neural partial differentiation as an estimation algorithm for extracting aerodynamic derivatives from flight data. It discusses neural modeling of the aircraft system. The neural partial differentiation approach discussed in the book helps estimate parameters with their statistical information from the noisy data. Moreover, this method avoids the need for prior information about the aircraft model parameters. The objective of the book is to extend the use of the neural partial differentiation method to the multi-input multi-output aircraft system for the online estimation of aircraft parameters from an established neural model. This approach will be relevant for the design of an adaptive flight control system. The book also discusses the estimation of aerodynamic derivatives of rigid and flexible aircraft which are treated separately. The longitudinal and lateral-directional derivatives of aircraft are estimated from flight data. Besides the aerodynamic derivatives, mode shape parameters of flexible aircraft are also identified in the book as part of identification for the state space aircraft model. Since the detailed description of the approach is illustrated through the block diagram and their results are presented in tabular form with figures of parameters converge to their estimates, the contents of this book are intended for readers who want to pursue a postgraduate and doctoral degree in science and engineering. This book is useful for practicing scientists, engineers, and teachers in the field of aerospace engineering.
Download or read book Estimation of the Longitudinal and Lateral Directional Aerodynamic Parameters from Flight Data for the NASA F A 18 Harv written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-06 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: This progress report presents the results of an investigation focused on parameter identification for the NASA F/A-18 HARV. This aircraft was used in the high alpha research program at the NASA Dryden Flight Research Center. In this study the longitudinal and lateral-directional stability derivatives are estimated from flight data using the Maximum Likelihood method coupled with a Newton-Raphson minimization technique. The objective is to estimate an aerodynamic model describing the aircraft dynamics over a range of angle of attack from 5 deg to 60 deg. The mathematical model is built using the traditional static and dynamic derivative buildup. Flight data used in this analysis were from a variety of maneuvers. The longitudinal maneuvers included large amplitude multiple doublets, optimal inputs, frequency sweeps, and pilot pitch stick inputs. The lateral-directional maneuvers consisted of large amplitude multiple doublets, optimal inputs and pilot stick and rudder inputs. The parameter estimation code pEst, developed at NASA Dryden, was used in this investigation. Results of the estimation process from alpha = 5 deg to alpha = 60 deg are presented and discussed. Napolitano, Marcello R. Ames Research Center...
Download or read book Parameter Estimation Techniques and Applications in Aircraft Flight Testing written by and published by . This book was released on 1974 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aerodynamic Parameters of High Angle of Attack Research Vehicle HARV Estimated from Flight Data written by and published by . This book was released on 1990 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling of Aircraft Unsteady Aerodynamic Characteristics Part 3 Parameters Estimated from Flight Data written by and published by . This book was released on 1996 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book NASA Technical Paper written by and published by . This book was released on 1990 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book STEP and STEPSPL Computer Programs for Aerodynamic Model Structure Determination and Parameter Estimation written by and published by . This book was released on 1986 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Estimation of Aircraft Nonlinear Unsteady Parameters From Wind Tunnel Data written by Vladislav Klein and published by . This book was released on 1998 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modelling Aircraft Dynamics written by C. A. Martin and published by . This book was released on 1988 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: A review has been made of the approaches currently under development for the modelling of aircraft flight dynamics at high angles-of-attack. The review is based on current research literature and on discussions held during an overseas visit carried out for the purpose of technical updating in the areas of flight dynamic modelling and parameter estimation. Keywords: Flight dynamics; High angle of attack; Mathematical models; Flight tests; Parameters; Data reduction; Australia. (SDW).
Download or read book NASA Technical Note written by and published by . This book was released on 1974 with total page 936 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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...
Download or read book High Angle of Attack Aerodynamics written by Josef Rom and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aerodynamics of aircraft at high angles of attack is a subject which is being pursued diligently, because the modern agile fighter aircraft and many of the current generation of missiles must perform well at very high incidence, near and beyond stall. However, a comprehensive presentation of the methods and results applicable to the studies of the complex aerodynamics at high angle of attack has not been covered in monographs or textbooks. This book is not the usual textbook in that it goes beyond just presenting the basic theoretical and experimental know-how, since it contains reference material to practical calculation methods and technical and experimental results which can be useful to the practicing aerospace engineers and scientists. It can certainly be used as a text and reference book for graduate courses on subjects related to high angles of attack aerodynamics and for topics related to three-dimensional separation in viscous flow courses. In addition, the book is addressed to the aerodynamicist interested in a comprehensive reference to methods of analysis and computations of high angle of attack flow phenomena and is written for the aerospace scientist and engineer who is familiar with the basic concepts of viscous and inviscid flows and with computational methods used in fluid dynamics.
Download or read book NASA Technical Paper written by United States. National Aeronautics and Space Administration and published by . This book was released on 1979 with total page 582 pages. Available in PDF, EPUB and Kindle. Book excerpt:
