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Published: 1978
Total Pages: 1008
ISBN-13:
DOWNLOAD EBOOKLists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Author: Grant Brandford Skelton
Publisher:
Published: 1968
Total Pages: 252
ISBN-13:
DOWNLOAD EBOOKThe concern in the work reported is the development of statistical models for the gust environment in the earth's boundary layer for use in determining the gust response characteristics of V/STOL aircraft. A general gust model based upon published gust data was developed, and analyses of V/STOL responses with that model were conducted to determine the gust descriptors significant to V/STOL performance. An interim gust model embodying the significant descriptors was then developed for use in V/STOL gust analyses. Suggestions for meteorological experiments to measure the significant descriptors are made. The significant gust descriptors determined from the analyses are the diagonal terms of the gust covariance tensor, gust probability distributions, mean wind probability distributions, and the dependencies of these statistics on thermal stability, surface roughness, and altitude. Less critical descriptors include the off-diagonal components in the gust covariance tensor and the space-time interplay in that tensor. The significant gusts seen by the aircraft are head-on and vertical gusts on the wings; head-on and vertical gust shears across the wings; head-on, side, and vertical gusts on the tail; and head-on and side gusts on the fuselage. Mean airspeed and sideslip angle are important parameters in V/STOL gust responses. The wing-to-tail transport delay of the gusts in forward flight also has a significant effect. V/STOL gust responses at low airspeeds are generally small due to the low dynamic pressures, and the responses are decidedly nonlinear except at low gust amplitudes.
Author: Paul M. Reeves
Publisher:
Published: 1969
Total Pages: 80
ISBN-13:
DOWNLOAD EBOOKA comparison of the statistical properties of low altitude atmospheric turbulence and the characteristics of presently used simulation techniques shows that these techniques do not satisfactorily account for the non-Gaussian nature of turbulence. A non-Gaussian turbulence simulation, intended to be used in conjunction with piloted flight simulators, is developed. The simulation produces three simultaneous random processes which represent the three orthogonal gust components. The probability distribution of each component is characterized by a modified Bessel function. The rms intensity and scale length of each component are independent parameters. A general method of introducing cross spectra between components is demonstrated. The multiplication of independent random processes is used to generate each of the gust components. Gaussian white noise generators, analog multipliers, and linear filters are used throughout the simulation. A complete analog circuit diagram is presented. (Author).
Author: R. L. Stapleford
Publisher:
Published: 1965
Total Pages: 174
ISBN-13:
DOWNLOAD EBOOKThe 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.
Author: United States. Naval Air Systems Command
Publisher:
Published: 1975
Total Pages: 148
ISBN-13:
DOWNLOAD EBOOKAuthor: Robert C. Nelson
Publisher:
Published: 1974
Total Pages: 144
ISBN-13:
DOWNLOAD EBOOKThe 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.
Author:
Publisher:
Published: 1990
Total Pages: 560
ISBN-13:
DOWNLOAD EBOOKAuthor: Duane T. McRuer
Publisher: Princeton University Press
Published: 2014-07-14
Total Pages: 809
ISBN-13: 1400855985
DOWNLOAD EBOOKAeronautical 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.
Author:
Publisher:
Published: 1970
Total Pages: 440
ISBN-13:
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