Most aerospace curricula around the world have distinct levels of courses dealing with the subject of aircraft performance, stability, and control. The very first course usually deals with the performance of the aircraft in relation to its design parameters using appropriate equations of equilibrium under different flight conditions. In a second course on aircraft flight dynamics, the emphasis is on studying the effect of various design parameters on the stability of the aircraft; an important exercise here being the derivation of the equations of six degrees of freedom (6 DOF) motion of a rigid airplane, followed by the modal analysis of aircraft behavior, usually in low-angle-of-attack cruise flight using a linearized model and aero-control derivatives. To some extent, this course may also introduce the topic of flight control law design using linearized (state space, transfer function) models and linear control theory. An advanced level course on flight dynamics could deal with simulation aspects gradually developing into using advanced control theory to flight control design problems. Several excellent books covering aspects of flight modeling, simulation, and control based on a systems and control perspective are presently available. However, most books, but for some cursory material on nonlinear phenomena, tend to focus exclusively on linearized flight dynamics using linear systems and controls analysis tools. Another question, a very pertinent one, most often asked by students of flight dynamics is how good the simulations using the linear models are when compared to real-life flight maneuvers.
Exclusively focusing on modeling, simulation, and control aspects of aircraft flight dynamics, this book is an attempt to introduce readers to a systematic approach to “what to do with aircraft models?”—typically, coupled 6 DOF dynamic models with fairly extensive nonlinear aerodynamic mod�els without making any simplification or sacrifice of rigor, which is usually the cause of most confusion in dealing with the subject, this book directly delves into the analysis and simulation of the full-order equations of aircraft motion. Three aircraft models available in the public domain, two of
them being models for high- and low-angles-of-attack dynamics of F-18 and another one for studying the roll coupling behavior of airplanes, are used as illustrative examples. Beginning from setting up simulations of simple flight conditions, viz. level flight, landing, take-off, vertical loop in longitudinal plane, and horizontal turn, simulations are extended further to investigate the nonlinear behavior of the aircraft resulting from the onset of instability. Bifurcation analysis and continuation theory-based methodologies for investigation and prediction of aircraft nonlinear flight dynamics and nonlinear control techniques for devising the recovery strategy of airplanes from loss-of-control scenario are presented. The performance of aircraft models has been treated as an integral aspect in this presentation and computed simultaneously with trim and stability under different constrained flight conditions. The analysis of constrained maneuvers in this manner also reveals various control interconnect laws (schedules) required to fly the aircraft in specific state-constrained flights. The investigation of dynamics throws up avenues for problem-specific intuitive control law development, which fits well in this unified framework. Direct control strategies to avoid aircraft departures resulting from the onset of instability and control law prototyping based on nonlinear control techniques for different flight control problems adequately supplement the integrated treatment of the subject. These features are intended to add pedagogical value and distinguish the text from other works on this topic.
The expected reader group for this book would ideally be senior undergraduate and graduate students, practicing aerospace/flight simulation engineers/scientists from industry as well as researchers in various organizations. It is expected that readers would have had exposure in some form to basic aerodynamics, numerical simulation tools, and knowledge of calculus, linear algebra, etc. The computing environments used are MATLAB® for time simulations and the numerical continuation algorithms AUTO and MATCONT available in the public domain for steady-state analysis and control schedules. The chapters are distributed fairly uniformly, touch�ing on different aspects of the subject.