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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Flying qualities - A costly lapse in flight-control design

Generic problems in advanced aircraft with advanced control systems which suffer from control sensitivity, sluggish response, and pilot-induced oscillation tendencies are examined, with a view to improving techniques for eliminating the problems in the design phase. Results of two NASA and NASA/AIAA workshops reached a consensus that flying qualities criteria do not match control system development, control system designers are not relying on past experience in their field, ground-based simulation is relied on too heavily, and communications between flying qualities and control systems engineers need improvement. A summation is offered in that hardware and software have outstripped the pilot's capacity to use the capabilities which new aircraft offer. The flying qualities data base is stressed to be dynamic, and continually redefining the man/machine relationships.

Berry, D. T.↗
NASA NTRS1983

Longitudinal flying qualities criteria for single-pilot instrument flight operations

Modern estimation and control theory, flight testing, and statistical analysis were used to deduce flying qualities criteria for General Aviation Single Pilot Instrument Flight Rule (SPIFR) operations. The principal concern is that unsatisfactory aircraft dynamic response combined with high navigation/communication workload can produce problems of safety and efficiency. To alleviate these problems. The relative importance of these factors must be determined. This objective was achieved by flying SPIFR tasks with different aircraft dynamic configurations and assessing the effects of such variations under these conditions. The experimental results yielded quantitative indicators of pilot's performance and workload, and for each of them, multivariate regression was applied to evaluate several candidate flying qualities criteria.

Stengel, R. F.↗
NASA NTRS1983

Space Shuttle flying qualities and flight control system assessment study, phase 2

A program of flying qualities experiments as part of the Orbiter Experiments Program (OEX) is defined. Phase 1, published as CR-170391, reviewed flying qualities criteria and shuttle data. The review of applicable experimental and shuttle data to further define the OEX plan is continued. An unconventional feature of this approach is the use of pilot strategy model identification to relate flight and simulator results. Instrumentation, software, and data analysis techniques for pilot model measurements are examined. The relationship between shuttle characteristics and superaugmented aircraft is established. STS flights 1 through 4 are reviewed from the point of view of flying qualities. A preliminary plan for a coordinated program of inflight and simulator research is presented.

Myers, T. T.↗
NASA NTRS1985

The interpretation of flying qualities requirements for flight control system design

An experimental flight test program was designed for the Total In Flight Simulator (TIFS) directed toward the interface between flying qualities requirements and flight control system design criteria. The eventual goal is to provide an interpretation or translation of flying qualities requirements for use by the flight control system designer. Specifically, an angle of attack and pitch rate command system matrix involving both short term and long term dynamics are specified for evaluation. Flying qualities criteria and flight control system configuration or architecture can be independent was demonstrated. Finally, additional configurations are proposed to evaluate the efficacy of dynamic decoupling.

Rynaski, E. G.↗
NASA NTRS1986

Effect of time delay on flying qualities: An update

Flying qualities problems of modern, full-authority electronic flight control systems are most often related to the introduction of additional time delay in aircraft response to a pilot input. These delays can have a significant effect on the flying qualities of the aircraft. Time delay effects are reexamined in light of recent flight test experience with aircraft incorporating new technology. Data from the X-29A forward-swept-wing demonstrator, a related preliminary in-flight experiment, and other flight observations are presented. These data suggest that the present MIL-F-8785C allowable-control system time delay specifications are inadequate or, at least, incomplete. Allowable time delay appears to be a function of the shape of the aircraft response following the initial delay. The cockpit feel system is discussed as a dynamic element in the flight control system. Data presented indicate that the time delay associated with a significant low-frequency feel system does not result in the predicted degradation in aircraft flying qualities. The impact of the feel system is discussed from two viewpoints: as a filter in the control system which can alter the initial response shape and, therefore, the allowable time delay, and as a unique dynamic element whose delay contribution can potentially be discounted by special pilot loop closures.

Smith, R. E.↗
NASA NTRS1986

Longitudinal flying qualitites criteria for single-pilot instrument flight operations

Modern estimation and control theory, flight testing, and statistical analysis were used to deduce flying qualities criteria for General Aviation Single Pilot Instrument Flight Rule (SPIFR) operations. The principal concern is that unsatisfactory aircraft dynamic response combined with high navigation/communication workload can produce problems of safety and efficiency. To alleviate these problems, the relative importance of these factors must be determined. This objective was achieved by flying SPIFR tasks with different aircraft dynamic configurations and assessing the effects of such variations under these conditions. The experimental results yielded quantitative indicators of pilot's performance and workload, and for each of them, multivariate regression was applied to evaluate several candidate flying qualities criteria.

Bar-Gill, A.↗
NASA NTRS1986

Effect of time delay on flying qualities - An update

Flying qualities problems of modern, full-authority electronic flight control systems are most often related to the introduction of additional time delay in aircraft response to a pilot input. These delays can have a significant effect on the flying qualities of the aircraft. This paper reexamines time delay effects in light of recent flight test experience with aircraft incorporating new technology. Data from the X-29A forward-swept-wing demonstrator, a related preliminary in-flight experiment, and other flight observations are presented. These data suggest that the present MIL-F-8785C allowable-control system time delay specifications are inadequate or, at least, incomplete. Allowable time delay appears to be a function of the shape of the aircraft response following the initial delay. The cockpit feel system is discussed as a dynamic element in the flight control system. Data presented indicate that the time delay associated with a significant low-frequency feel system does not result in the predicted degradation in aircraft flying qualities. The impact of the feel system is discussed from two viewpoints: as a filter in the control system which can alter the initial response shape and, therefore, the allowable time delay, and as a unique dynamic element whose delay contribution can potentially be discounted by special pilot loop closures.

Smith, R. E.↗
NASA NTRS1986

Archive data base and handling system for the Orbiter flying qualities experiment program

The OFQ archives data base and handling system assembled as part of the Orbiter Flying Qualities (OFQ) research of the Orbiter Experiments Program (EOX) are described. The purpose of the OFQ archives is to preserve and document shuttle flight data relevant to vehicle dynamics, flight control, and flying qualities in a form that permits maximum use for qualified users. In their complete form, the OFQ archives contain descriptive text (general information about the flight, signal descriptions and units) as well as numerical time history data. Since the shuttle program is so complex, the official data base contains thousands of signals and very complex entries are required to obtain data. The OFQ archives are intended to provide flight phase oriented data subsets with relevant signals which are easily identified for flying qualities research.

Myers, T. T.↗
NASA NTRS1977

Control of free-flying space robot manipulator systems

To accelerate the development of multi-armed, free-flying satellite manipulators, a fixed-base cooperative manipulation facility is being developed. The work performed on multiple arm cooperation on a free-flying robot is summarized. Research is also summarized on global navigation and control of free-flying space robots. The Locomotion Enhancement via Arm Pushoff (LEAP) approach is described and progress to date is presented.

Cannon, Robert H., Jr.↗
NASA NTRS1988

Interaction of feel system and flight control system dynamics on lateral flying qualities

An investigation of feel system and flight control system dynamics on lateral flying qualities was conducted using the variable stability USAF NT-33 aircraft. Experimental variations in feel system natural frequency, force-deflection gradient, control system command architecture type, flight control system filter frequency, and control system delay were made. The experiment data include pilot ratings using the Cooper-Harper (1969) rating scale, pilot comments, and tracking performance statistic. Three test pilots served as evaluators. The data indicate that as the feel system natural frequency is reduced lateral flying qualities degrade. At the slowest feel system frequency, the closed-loop response becomes nonlinear with a 'bobweight' effect apparent in the feel system. Feel system influences were essentially independent of the control system architecture. The flying qualities influence due to the feel system was different than when the identical dynamic systenm was used as a flight control system element.

Bailey, Randall E.↗
NASA NTRS1989

The conceptual design of a Mach 2 Oblique Flying Wing supersonic transport

This paper is based on a performance and economics study of a Mach two oblique flying wing transport aircraft that is to replace the B747B. In order to fairly compare our configuration with the B747B an equal structural technology level is assumed. It will be shown that the oblique flying wing configuration will equal or outperform the B747 in speed, economy and comfort while a modern stability and control system will balance the aircraft and smooth out gusts. The aircraft is designed to comply with the FAR25 airworthiness requirements and FAR36 stage 3 noise regulations. Geometry, aerodynamics, stability and control parameters of the oblique flying wing transport are discussed.

Vandervelden, Alexander J. M.↗
NASA NTRS1987

Use of control umbilicals as a deployment mode for free flying telerobotic work systems

Work to date on telerobotic work systems for use in space generally consider two deployment modes, free flying, or fixed within a limited work envelope. Control tethers may be employed to obtain a number of operational advantages and added flexibility in the basing and deployment of telerobotic work systems. Use of a tether allows the work system to be separated into two major modules, the remote work package and the control module. The Remote Work Package (RWP) comprises the free flying portion of the work system while the Control Module (CM) remains at the work system base. The chief advantage of this configuration is that only the components required for completion of the work task must be located at the work site. Reaction mass used in free flight is stored at the Control module and supplied to the RWP through the tether, eliminating the need for the RWP to carry it. The RWP can be made less massive than a self contained free flying work system. As a result, reaction mass required for free flight is lower than for a self contained free flyer.

Kuehn, J. S.↗
NASA NTRS1988

Ongonite and topazite dikes in the Flying W ranch area, Tonto basin, Arizona

The petrogenesis of the topaz-rich ongonite and topazite dikes in the Flying W ranch area (Tonto basin, Arizona) was investigated, and the possible origin of the topaz in the Flying W rhyolite is discussed. The field, textural geochemical, and mineralogical characteristics of the topaz-bearing dikes in the Flying W ranch area all were found to support the genesis of the topaz-bearing bodies from a magma. The evidence obtained contradicts an origin for these rock types by greisenization or veining.

Kortemeier, Winifred T.↗
NASA NTRS1989

Initial flight test of a ground deployed system for flying qualities assessment

NASA-Ames has developed a safe, repeatable, high-precision flying-qualities study system whose Adaptable Target Lighting Array System (ATLAS) furnishes a flying-qualities task that emulates a ground-attack mission with ground-deployed targets lighted in an unpredictable sequence; the pilot must aim the aircraft at whatever target is lighted. Two flight-test programs have been instituted to test the suitability of ATLAS. While the first of these uses a variable-stability aircraft to ascertain whether ATLAS has provided a suitable task for general flying qualities research, using an HUD-tracking task for comparison, the second employed the X-29A FSW research aircraft to demonstrate that ATLAS is appropriate for such research in the case of a specific aircraft.

Shafer, Mary F.↗
NASA NTRS1990

Fly-by-light flight control system technology development plan

The results of a four-month, phased effort to develop a Fly-by-Light Technology Development Plan are documented. The technical shortfalls for each phase were identified and a development plan to bridge the technical gap was developed. The production configuration was defined for a 757-type airplane, but it is suggested that the demonstration flight be conducted on the NASA Transport Systems Research Vehicle. The modifications required and verification and validation issues are delineated in this report. A detailed schedule for the phased introduction of fly-by-light system components has been generated. It is concluded that a fiber-optics program would contribute significantly toward developing the required state of readiness that will make a fly-by-light control system not only cost effective but reliable without mitigating the weight and high-energy radio frequency related benefits.

Chakravarty, A.↗
NASA NTRS1989

Simulation evaluation of transition and hover flying qualities of a mixed-flow, remote-lift STOVL aircraft

Using a generalized simulation model developed for piloted evaluations of STOVL aircraft, an initial fixed-base simulation of a mixed-flow, remote-lift configuration has been completed. Objectives were to evaluate the integration of the aircraft's flight and propulsion controls to achieve good flying qualities throughout the low-speed flight envelope; to determine control power used during transition, hover, and vertical landing; and to evaluate the transition flight envelope considering the influence of thrust deflection of the remote-lift component. Pilots' evaluations indicated that Level 1 flying qualities could be achieved for deceleration to hover in instrument conditions, for airfield landings, and for recovery to a small ship when attitude and velocity stabilization and command augmentation control modes were provided. Level 2 flying qualities were obtained for these same tasks when only the attitude command mode was used, leaving the pilot to perform the task of thrust management required to control the flight-path and speed in transition and the horizontal and vertical translational velocities in hover. Thrust margins were defined for vertical landing as a function of ground effect and hot-gas ingestion.

Franklin, James A.↗
NASA NTRS1990

Control of free-flying space robot manipulator systems

New control techniques for self contained, autonomous free flying space robots were developed and tested experimentally. Free flying robots are envisioned as a key element of any successful long term presence in space. These robots must be capable of performing the assembly, maintenance, and inspection, and repair tasks that currently require human extravehicular activity (EVA). A set of research projects were developed and carried out using lab models of satellite robots and a flexible manipulator. The second generation space robot models use air cushion vehicle (ACV) technology to simulate in 2-D the drag free, zero g conditions of space. The current work is divided into 5 major projects: Global Navigation and Control of a Free Floating Robot, Cooperative Manipulation from a Free Flying Robot, Multiple Robot Cooperation, Thrusterless Robotic Locomotion, and Dynamic Payload Manipulation. These projects are examined in detail.

Cannon, Robert H., Jr.↗
NASA NTRS1934

Complete tank tests of two flying-boat hulls with pointed steps - N.A.C.A. Models 22-A and 35

This note presents the results of complete tank test of N.A.C.A. Models 22-A and 35, two flying-boat hulls of the deep pointed-step type with low dead rise. Model 22-A is a form derived by modification of Model 22, the test results of which are given in N.A.C.A. Technical Note No. 488. Model 35 is a form of the same type but has a higher length-beam ratio than either Model 22 or 22-A. Take-off examples are worked out using data from these tests and a previous test of a conventional model applied to an arbitrary set of design specifications for a 15,000-pound flying boat. The comparison of these examples shows both pointed-step models to be superior to the conventional form, and Model 35 to be the better of the two. Model 35 is applied to a hypothetical 100,000-pound flying boat of the twin-hull type and performance calculations are made both for take-off and range. The results indicate that the high performance of this type of hull will enable the designer to use higher wing and power loadings than are found in current practice, with a resulting increase in range and pay load.

Shoemaker, James M↗