Longitudinal Handling Qualities for Hovering
Longitudinal Handling Qualities for Hovering

Author: E. Seckel

Publisher:

Published: 1961

Total Pages: 74

ISBN-13:

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Flight tests with a variable stability helicopter were conducted to determine the effect of certain stability parameters on precision hovering in atmospheric turbulence. A course was devised to emphasize the precision control required to pick up sling loads, deliver litter patients, dunk Sonar buoys, Etc., under gusty conditions. The effect of velocity stability was determined to be of particular importance. The most important effect is that the pitching disturbances felt by the pilot due to turbulence are essentially proportional to this parameter. Secondary effects are the control gradient for trim at low speed, and the dynamic stability. The range of velocity stability variation was from practically zero, which was considered very favorable, to values that were unacceptable or even disastrous. Certain pilot ratings did not correspond to previously published handling qualities criteria. Investigation disclosed that higher angular damping and greater control effectiveness are desired by pilots for precision hovering than had been determined. (Author).

Criteria for Low-Speed Longitudinal Handling Qualities
Criteria for Low-Speed Longitudinal Handling Qualities

Author: H.A. Mooij

Publisher: Springer Science & Business Media

Published: 2013-04-18

Total Pages: 151

ISBN-13: 9401711933

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In-fl ight simulation experiments performed in 1967 with a variable-stabil ity aircraft during the author's stay at Princeton University, motivated the study of handl ing characteristics of future transport aircraft with closed-loop fl ight control systems. In 1972, the first experiment took place at the National Aerospace Laboratory NLR, using one of its research aircraft. In anticipation of expected developments in (digital) fl ight control technology, the research programme following the first experiments was aimed at the establ ishment of quantitative handl ing qual ities criteria. An appreciable part of that programme has been sponsored by the Netherlands Agency for Aerospace Programs (Nederlands Instituut voor VI iegtuigontwikkel ing en Ruimtevaart) and the Department of Civil Aviation of the Netherlands (Rijksluchtvaartdienst). In 1981, a thorough review of the extensive and valuable data gathered was started. The result, presented in this book, was also included in the author's thesis for a Ph.D. degree of the Delft University of Technology. To introduce the reader to the multi-discipl inary field of handl ing qual ities research, introductory chapters are presented on longitudinal aircraft dynamics, closed-loop fl ight control systems using non-mechanical signal transmission, human pilot dynamics, hand I ing qual ities assessment techniques, and the present status of handl ing qual ity criteria.

An Analytical Study of V/STOL Handling Qualities in Hover and Transition
An Analytical Study of V/STOL Handling Qualities in Hover and Transition

Author: R. L. Stapleford

Publisher:

Published: 1965

Total Pages: 174

ISBN-13:

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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.

An Examination of Handling Qualities Criteria for V/STOL Aircraft
An Examination of Handling Qualities Criteria for V/STOL Aircraft

Author: Seth B. Anderson

Publisher:

Published: 1960

Total Pages: 58

ISBN-13:

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A study has been undertaken to define hand-ling qualities criteria for V/STOL aircraft. With the current military requirements for helicopters and airplanes as a framework, modifications and additions were made for conversion to a preliminary set of V/STOL requirements using a broad background of flight experience and pilots' comments from VTOL and STOL aircraft, BLC (boundary-layer-control) equipped aircraft, variable stability aircraft, flight simulators and landing approach studies. The report contains a discussion of the reasoning behind and the sources of information leading to suggested requirements. The results of the study indicate that the majority of V/STOL requirements can be defined by modifications to the helicopter and/or airplane requirements by appropriate definition of reference speeds. Areas where a requirement is included but where the information is felt to be inadequate to establish a firm quantitative requirement include the following: Control power and damping relationships about all axes for various sizes and types of aircraft; control power, sensitivity, d-amping and response for height control; dynamic longitudinal and dynamic lateral- directional stability in the transition region, including emergency operation; hovering steadiness; acceleration and deceleration in transition; descent rates and flight-path angles in steep approaches, and thrust margin for approach.

Fixed-base Simulator Investigation of the Effects of L [alpha] and True Speed on Pilot Opinion of Longitudinal Flying Qualities
Fixed-base Simulator Investigation of the Effects of L [alpha] and True Speed on Pilot Opinion of Longitudinal Flying Qualities

Author: Charles R. Chalk

Publisher:

Published: 1963

Total Pages: 174

ISBN-13:

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The study is directed toward investigating the effects on pilots rating of large variations (L alpha) in the relative amplitude and phase of the basic airplane responses to elevator control. The effects of L alpha and true speed on longitudinal flying qualities, optimum control gain, and normal acceleration response to turbulence were investigated in a ground simulator. The steady state ratio of normal acceleration to angle of attack was found to be of significance both to the flying qualities of an airplane and to the optimum longitudinal control gain. Normal acceleration response to rough air was demonstrated to be primarily a function of L alpha and the short period frequency and damping ratio.