Determination of Stability and Control Derivatives from the NASA F/a-18 Harv from Flight Data Using the Maximum Likelihood Method
Determination of Stability and Control Derivatives from the NASA F/a-18 Harv from Flight Data Using the Maximum Likelihood Method

Author: National Aeronautics and Space Adm Nasa

Publisher:

Published: 2018-11-07

Total Pages: 102

ISBN-13: 9781730938672

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This report is a compilation of PID (Proportional Integral Derivative) results for both longitudinal and lateral directional analysis that was completed during Fall 1994. It had earlier established that the maneuvers available for PID containing independent control surface inputs from OBES were not well suited for extracting the cross-coupling static (i.e., C(sub N beta)) or dynamic (i.e., C(sub Npf)) derivatives. This was due to the fact that these maneuvers were designed with the goal of minimizing any lateral directional motion during longitudinal maneuvers and vice-versa. This allows for greater simplification in the aerodynamic model as far as coupling between longitudinal and lateral directions is concerned. As a result, efforts were made to reanalyze this data and extract static and dynamic derivatives for the F/A-18 HARV (High Angle of Attack Research Vehicle) without the inclusion of the cross-coupling terms such that more accurate estimates of classical model terms could be acquired. Four longitudinal flights containing static PID maneuvers were examined. The classical state equations already available in pEst for alphadot, qdot and thetadot were used. Three lateral directional flights of PID static maneuvers were also examined. The classical state equations already available in pEst for betadot, p dot, rdot and phi dot were used. Enclosed with this document are the full set of longitudinal and lateral directional parameter estimate plots showing coefficient estimates along with Cramer-Rao bounds. In addition, a representative time history match for each type of meneuver tested at each angle of attack is also enclosed. Napolitano, Marcello R. Unspecified Center...

Determination of the Stability and Control Derivatives of the NASA F/A-18 Harv Using Flight Data
Determination of the Stability and Control Derivatives of the NASA F/A-18 Harv Using Flight Data

Author: National Aeronautics and Space Administration (NASA)

Publisher: Createspace Independent Publishing Platform

Published: 2018-07-17

Total Pages: 124

ISBN-13: 9781723022715

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This report documents the research conducted for the NASA-Ames Cooperative Agreement No. NCC 2-759 with West Virginia University. A complete set of the stability and control derivatives for varying angles of attack from 10 deg to 60 deg were estimated from flight data of the NASA F/A-18 HARV. The data were analyzed with the use of the pEst software which implements the output-error method of parameter estimation. Discussions of the aircraft equations of motion, parameter estimation process, design of flight test maneuvers, and formulation of the mathematical model are presented. The added effects of the thrust vectoring and single surface excitation systems are also addressed. The results of the longitudinal and lateral directional derivative estimates at varying angles of attack are presented and compared to results from previous analyses. The results indicate a significant improvement due to the independent control surface deflections induced by the single surface excitation system, and at the same time, a need for additional flight data especially at higher angles of attack. Napolitano, Marcello R. and Spagnuolo, Joelle M. Unspecified Center AIRCRAFT CONTROL; AIRCRAFT STABILITY; ANGLE OF ATTACK; F-18 AIRCRAFT; FLIGHT TESTS; LATERAL STABILITY; LONGITUDINAL STABILITY; MAXIMUM LIKELIHOOD ESTIMATES; PARAMETER IDENTIFICATION; AIRCRAFT MANEUVERS; CONTROL SURFACES; EQUATIONS OF MOTION; MATHEMATICAL MODELS; THRUST VECTOR CONTROL...

Determination of the Stability and Control Derivatives of the F/A-18 Harv from Flight Data Using the Maximum Likelihood Method
Determination of the Stability and Control Derivatives of the F/A-18 Harv from Flight Data Using the Maximum Likelihood Method

Author: National Aeronautics and Space Adm Nasa

Publisher: Independently Published

Published: 2018-12-29

Total Pages: 28

ISBN-13: 9781792079962

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The research being conducted pertains to the determination of the stability and control derivatives of the F/A-18 High Alpha Research Vehicle (HARV) from flight data using the Maximum Likelihood Method. The document outlines the approach used in the parameter estimation (PID) process and briefly describes the mathematical modeling of the F/A-18 HARV and the maneuvers designed to generate a sufficient data base for the PID research. Napolitano, Marcello R. and Spagnuolo, Joelle M. NASA-CR-191216, NAS 1.26:191216 NCC2-759...

Estimation of the Longitudinal and Lateral-Directional Aerodynamic Parameters from Flight Data for the NASA F/A-18 Harv
Estimation of the Longitudinal and Lateral-Directional Aerodynamic Parameters from Flight Data for the NASA F/A-18 Harv

Author: National Aeronautics and Space Adm Nasa

Publisher:

Published: 2018-10-28

Total Pages: 52

ISBN-13: 9781729339169

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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...

Extraction of Lateral-Directional Stability and Control Derivatives for the Basic F-18 Aircraft at High Angles of Attack
Extraction of Lateral-Directional Stability and Control Derivatives for the Basic F-18 Aircraft at High Angles of Attack

Author: National Aeronautics and Space Administration (NASA)

Publisher: Createspace Independent Publishing Platform

Published: 2018-07-03

Total Pages: 42

ISBN-13: 9781722225872

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The results of parameter identification to determine the lateral-directional stability and control derivatives of an F-18 research aircraft in its basic hardware and software configuration are presented. The derivatives are estimated from dynamic flight data using a specialized identification program developed at NASA Dryden Flight Research Center. The formulation uses the linearized aircraft equations of motions in their continuous/discrete form and a maximum likelihood estimator that accounts for both state and measurement noise. State noise is used to model the uncommanded forcing function caused by unsteady aerodynamics, such as separated and vortical flows, over the aircraft. The derivatives are plotted as functions of angle of attack between 3 deg and 47 deg and compared with wind-tunnel predictions. The quality of the derivative estimates obtained by parameter identification is somewhat degraded because the maneuvers were flown with the aircraft's control augmentation system engaged, which introduced relatively high correlations between the control variables and response variables as a result of control motions from the feedback control system. Iliff, Kenneth W. and Wang, Kon-Sheng Charles Armstrong Flight Research Center RTOP 505-68-50...