A study was made to determine the feasibility of programing an analog simulation of aircraft stability on a general-purpose analog computer using non-linear differential equations. The simulation was to demonstrate the effects of inertial cross-coupling. An F-4 aircraft was simulated at two different reference flight conditions using the equations derived in the study. (Author).
The study of nonlinear phenomena in aviation and aerospace includes developments in computer technology and the use of nonlinear mathematical models. Nonlinearities are a feature of aircraft dynamics and flight control systems and need to respond to achieve stability and performance. This multiauthor volume comprises selected papers from the conference Nonlinear Problems in Aviation and Aerospace at Embry-Riddle Aeronautical University and additional invited papers from many distinguished scientists. Coverage includes orbit determination of a tethered satellite system using laser and radar tracking, and intelligent control of agile aircraft, flight control with and without control surfaces.
An analog simulation was conducted forthe lo gitudinal axis of the General Electric Self-Adaptive Flight Control (GESAC) System, as proposed for use on the X-15 aerospace vehicle. The gain-changing dynamics of the non-linear loop are considered briefly and the effects of noise on system operation are observed. A method of optimizing the system simulation by first considering the non-linear loop independently is described. It is shown that this system is capable of maintaining aircraft stability throughout the X-15 re-entry flight profile and that noise introuced during system operation do s not seriously degrade system performance. (Author).
An updated and expanded new edition of an authoritative book on flight dynamics and control system design for all types of current and future fixed-wing aircraft Since it was first published, Flight Dynamics has offered a new approach to the science and mathematics of aircraft flight, unifying principles of aeronautics with contemporary systems analysis. Now updated and expanded, this authoritative book by award-winning aeronautics engineer Robert Stengel presents traditional material in the context of modern computational tools and multivariable methods. Special attention is devoted to models and techniques for analysis, simulation, evaluation of flying qualities, and robust control system design. Using common notation and not assuming a strong background in aeronautics, Flight Dynamics will engage a wide variety of readers, including aircraft designers, flight test engineers, researchers, instructors, and students. It introduces principles, derivations, and equations of flight dynamics as well as methods of flight control design with frequent reference to MATLAB functions and examples. Topics include aerodynamics, propulsion, structures, flying qualities, flight control, and the atmospheric and gravitational environment. The second edition of Flight Dynamics features up-to-date examples; a new chapter on control law design for digital fly-by-wire systems; new material on propulsion, aerodynamics of control surfaces, and aeroelastic control; many more illustrations; and text boxes that introduce general mathematical concepts. Features a fluid, progressive presentation that aids informal and self-directed study Provides a clear, consistent notation that supports understanding, from elementary to complicated concepts Offers a comprehensive blend of aerodynamics, dynamics, and control Presents a unified introduction of control system design, from basics to complex methods Includes links to online MATLAB software written by the author that supports the material covered in the book
This project is intended to research and develop new nonlinear methodologies for the control and stability analysis of high-performance, high angle-of-attack aircraft such as HARV (F18). Past research (reported in our Phase 1, 2, and 3 progress reports) is summarized and more details of final Phase 3 research is provided. While research emphasis is on nonlinear control, other tasks such as associated model development, system identification, stability analysis, and simulation are performed in some detail as well. An overview of various models that were investigated for different purposes such as an approximate model reference for control adaptation, as well as another model for accurate rigid-body longitudinal motion is provided. Only a very cursory analysis was made relative to type 8 (flexible body dynamics). Standard nonlinear longitudinal airframe dynamics (type 7) with the available modified F18 stability derivatives, thrust vectoring, actuator dynamics, and control constraints are utilized for simulated flight evaluation of derived controller performance in all cases studied. Mohler, R. R. Unspecified Center ADAPTIVE CONTROL; AIRCRAFT PERFORMANCE; AIRCRAFT STABILITY; FLIGHT SIMULATION; HIGHLY MANEUVERABLE AIRCRAFT; NEURAL NETS; OPTIMAL CONTROL; ANGLE OF ATTACK; CONTROLLERS; F-18 AIRCRAFT; NONLINEAR FEEDBACK...
This research should lead to the development of new nonlinear methodologies for the adaptive control and stability analysis of high angle-of-attack aircraft such as the F18 (HARV). The emphasis has been on nonlinear adaptive control, but associated model development, system identification, stability analysis and simulation is performed in some detail as well. Various models under investigation for different purposes are summarized in tabular form. Models and simulation for the longitudinal dynamics have been developed for all types except the nonlinear ordinary differential equation model. Briefly, studies completed indicate that nonlinear adaptive control can outperform linear adaptive control for rapid maneuvers with large changes in alpha. The transient responses are compared where the desired alpha varies from 5 degrees to 60 degrees to 30 degrees and back to 5 degrees in all about 16 sec. Here, the horizontal stabilator is the only control used with an assumed first-order linear actuator with a 1/30 sec time constant. Mohler, R. R. Unspecified Center...
