Approximate Airframe Transfer Functions And Application To Single Sensor Control Systems

pt.3: The dynamic coupling of rigid and elastic degrees of freedom of an airplane are described by two methods. In the first, coupling is described by the changes in airframe characteristic equation roots caused by the introduction of coupling terms to the equations of motion. The second method employs modal response coefficients to compare the relative amplitudes of rigid and elastic degrees of freedom at each coupled mode frequency. Simple literal expressions are obtained for each of these descriptors and physical interpretations given. Time vector diagrams are also used to show the major parameters affecting coupling. (Author).

Aeronautical engineers concerned with the analysis of aircraft dynamics and the synthesis of aircraft flight control systems will find an indispensable tool in this analytical treatment of the subject. Approaching these two fields with the conviction that an understanding of either one can illuminate the other, the authors have summarized selected, interconnected techniques that facilitate a high level of insight into the essence of complex systems problems. These techniques are suitable for establishing nominal system designs, for forecasting off-nominal problems, and for diagnosing the root causes of problems that almost inevitably occur in the design process. A complete and self-contained work, the text discusses the early history of aircraft dynamics and control, mathematical models of linear system elements, feedback system analysis, vehicle equations of motion, longitudinal and lateral dynamics, and elementary longitudinal and lateral feedback control. The discussion concludes with such topics as the system design process, inputs and system performance assessment, and multi-loop flight control systems. Originally published in 1974. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.

pt.3: The dynamic coupling of rigid and elastic degrees of freedom of an airplane are described by two methods. In the first, coupling is described by the changes in airframe characteristic equation roots caused by the introduction of coupling terms to the equations of motion. The second method employs modal response coefficients to compare the relative amplitudes of rigid and elastic degrees of freedom at each coupled mode frequency. Simple literal expressions are obtained for each of these descriptors and physical interpretations given. Time vector diagrams are also used to show the major parameters affecting coupling. (Author).

Stability and Control of Airplanes and Helicopters deals with aircraft flying qualities that determine the stability and control of airplanes and helicopters. It includes problems based on real aircraft, selected to represent the gamut from simple to complicated, and from conventional utility designs to futuristic research types. Many of these problems involve comparison of theory and experiment to demonstrate their mutual relationship. Comprised of 25 chapters, this book begins with a discussion on the aerodynamics of the component parts related to the lift and moment characteristics of an airplane, including wings and associated accessories; bodies such as fuselages, nacelles, and tip tanks; and control surfaces. The reader is then introduced to some mathematical techniques for linear differential equations; steady flight at different speeds; and stick force and control-free stability. Subsequent chapters focus on flaps and high-lift devices; power and compressibility effects; and the manner in which the aircraft responds to the application of control. Aeroelasticity and longitudinal equations of motion are also examined. This monograph is intended for undergraduate and graduate students taking modern engineering courses.

This report presents the results of analytical studies of a variety of handling quality topics related to advanced manned aircraft.

The hover analysis considers pilot attitude and position control tasks in the presence of horizontal gusts. The effects of each of the stability derivatives on the difficulty of the control tasks and on the closed-loop gust responses are determined. It is clearly shown that the handling qualities studies of control sensitivity and angular damping must consider the influences of M sub u (or L sub v) and should include gust inputs. These conclusions are substantiated by previous variable-stability-helicopter experiments. The effects of vehicle size and geometry are investigated by several approaches. The key result of increasing size is found to be a reduction in M sub u and L sub v which can, in turn, lower the requirements for control power and damping. The handling qualities during transition of two vehicles, a tilt duct and a tilt wing, which were previously tested on a simulator are analyzed. It is shown that both trim control and perturbations about the trim conditions must be considered. In fact, part of the increased difficulty in landing transitions, in comparison with takeoff transitions, is due to more difficult trim control; the much more stringent position control requirements in landing are also a contributing factor.

The investigation deals with the dynamic behavior of an airplane encountering aircraft wake turbulence. A digital computer simulation was developed to study the response of an aircraft flying into a trailing vortex wake. The simulation includes the complete six degree of freedom equations of motion, a description of the vortex velocity field, unsteady aerodynamics, and pilot control input. The parameters included the penetration angle, separation distance, aircraft size, and pilot control input. Predicted vortex induced motions are presented for general aviation, business, and light jet transport type aircraft.