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...

Optimization Based Clearance of Flight Control Laws
Optimization Based Clearance of Flight Control Laws

Author: Andreas Varga

Publisher: Springer

Published: 2011-11-23

Total Pages: 453

ISBN-13: 3642226272

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This book summarizes the main achievements of the EC funded 6th Framework Program project COFCLUO – Clearance of Flight Control Laws Using Optimization. This project successfully contributed to the achievement of a top-level objective to meet society’s needs for a more efficient, safer and environmentally friendly air transport by providing new techniques and tools for the clearance of flight control laws. This is an important part of the certification and qualification process of an aircraft – a costly and time-consuming process for the aeronautical industry. The overall objective of the COFCLUO project was to develop and apply optimization techniques to the clearance of flight control laws in order to improve efficiency and reliability. In the book, the new techniques are explained and benchmarked against traditional techniques currently used by the industry. The new techniques build on mathematical criteria derived from the certification and qualification requirements together with suitable models of the aircraft. The development of these criteria and models are also presented in the book. Because of wider applicability, the optimization-based clearance of flight control laws will open up the possibility to design innovative aircraft that today are out of the scope using classical clearance tools. Optimization-based clearance will not only increase safety but it will also simplify the whole certification and qualification process, thus significantly reduce cost. The achieved speedup will also support rapid modeling and prototyping and reduce “time to market”.

Introduction to Aircraft Flight Mechanics
Introduction to Aircraft Flight Mechanics

Author: Thomas R. Yechout

Publisher: AIAA

Published: 2003

Total Pages: 666

ISBN-13: 9781600860782

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Based on a 15-year successful approach to teaching aircraft flight mechanics at the US Air Force Academy, this text explains the concepts and derivations of equations for aircraft flight mechanics. It covers aircraft performance, static stability, aircraft dynamics stability and feedback control.

Flight Stability and Automatic Control
Flight Stability and Automatic Control

Author: Robert C. Nelson

Publisher:

Published: 1998

Total Pages: 464

ISBN-13:

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This edition of this this flight stability and controls guide features an unintimidating math level, full coverage of terminology, and expanded discussions of classical to modern control theory and autopilot designs. Extensive examples, problems, and historical notes, make this concise book a vital addition to the engineer's library.

Flight-Determined, Subsonic, Lateral-Directional Stability and Control Derivatives of the Thrust-Vectoring F-18 High Angle of Attack Research Vehicle (Harv), and Comparisons to the Basic F-18 and Predicted Derivatives
Flight-Determined, Subsonic, Lateral-Directional Stability and Control Derivatives of the Thrust-Vectoring F-18 High Angle of Attack Research Vehicle (Harv), and Comparisons to the Basic F-18 and Predicted Derivatives

Author: National Aeronautics and Space Administration (NASA)

Publisher: Createspace Independent Publishing Platform

Published: 2018-05-31

Total Pages: 90

ISBN-13: 9781720525899

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The subsonic, lateral-directional, stability and control derivatives of the thrust-vectoring F-1 8 High Angle of Attack Research Vehicle (HARV) are extracted from flight data using a maximum likelihood parameter identification technique. State noise is accounted for in the identification formulation and is used to model the uncommanded forcing functions caused by unsteady aerodynamics. Preprogrammed maneuvers provided independent control surface inputs, eliminating problems of identifiability related to correlations between the aircraft controls and states. The HARV derivatives are plotted as functions of angles of attack between 10deg and 70deg and compared to flight estimates from the basic F-18 aircraft and to predictions from ground and wind tunnel tests. Unlike maneuvers of the basic F-18 aircraft, the HARV maneuvers were very precise and repeatable, resulting in tightly clustered estimates with small uncertainty levels. Significant differences were found between flight and prediction; however, some of these differences may be attributed to differences in the range of sideslip or input amplitude over which a given derivative was evaluated, and to differences between the HARV external configuration and that of the basic F-18 aircraft, upon which most of the prediction was based. Some HARV derivative fairings have been adjusted using basic F-18 derivatives (with low uncertainties) to help account for differences in variable ranges and the lack of HARV maneuvers at certain angles of attack.Iliff, Kenneth W. and Wang, Kon-Sheng CharlesArmstrong Flight Research CenterF-18 AIRCRAFT; ANGLE OF ATTACK; MAXIMUM LIKELIHOOD ESTIMATES; DIRECTIONAL STABILITY; CONTROL SURFACES; AIRCRAFT CONTROL; WIND TUNNEL TESTS; PARAMETER IDENTIFICATION; LATERAL STABILITY