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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

The insertion of human dynamics models in the flight control loops of V/STOL research aircraft. Appendix 2: The optimal control model of a pilot in V/STOL aircraft control loops

An overview is presented of research work focussed on the design and insertion of classical models of human pilot dynamics within the flight control loops of V/STOL aircraft. The pilots were designed and configured for use in integrated control system research and design. The models of human behavior that were considered are: McRuer-Krendel (a single variable transfer function model); and Optimal Control Model (a multi-variable approach based on optimal control and stochastic estimation theory). These models attempt to predict human control response characteristics when confronted with compensatory tracking and state regulation tasks. An overview, mathematical description, and discussion of predictive limitations of the pilot models is presented. Design strategies and closed loop insertion configurations are introduced and considered for various flight control scenarios. Models of aircraft dynamics (both transfer function and state space based) are developed and discussed for their use in pilot design and application. Pilot design and insertion are illustrated for various flight control objectives. Results of pilot insertion within the control loops of two V/STOL research aricraft (Sikorski Black Hawk UH-60A, McDonnell Douglas Harrier II AV-8B) are presented and compared against actual pilot flight data. Conclusions are reached on the ability of the pilot models to adequately predict human behavior when confronted with similar control objectives.

Zipf, Mark E.↗
NASA NTRS1973

Conceptual design studies of candidate V/STOL lift fan commercial short haul transport for 1980 - 1985 V/STOL lift fan study

Conceptual designs of V/STOL lift fan commercial short haul transport aircraft for the 1980-85 time period were studied to determine their technical and economic feasibility. The engine concepts included both integral and remote fans. The scope of the study included definition of the hover control concept for each propulsion system, aircraft design, aircraft mass properties, cruise performance, noise and ride qualities evaluation. Economic evaluating was also studied on a basis of direct operating costs and route structure.

Eldridge, W. M.↗
NASA NTRS1988

An adaptive human response mechanism controlling the V/STOL aircraft. Appendix 3: The adaptive control model of a pilot in V/STOL aircraft control loops

Importance of the role of human operator in control systems has led to the particular area of manual control theory. Human describing functions were developed to model human behavior for manual control studies to take advantage of the successful and safe human operations. A single variable approach is presented that can be extended for multi-variable tasks where a low order human response model is used together with its rules, to adapt the model on-line, being capable of responding to the changes in the controlled element dynamics. Basic control theory concepts are used to combine the model, constrained with the physical observations, particularly, for the case of aircraft control. Pilot experience is represented as the initial model parameters. An adaptive root-locus method is presented as the adaptation law of the model where the closed loop bandwidth of the system is to be preserved in a stable manner with the adjustments of the pilot handling qualities which relate the latter to the closed loop bandwidth and damping of the closed loop pilot aircraft combination. A Kalman filter parameter estimator is presented as the controlled element identifier of the adaptive model where any discrepancies of the open loop dynamics from the presented one, are sensed to be compensated.

Kucuk, Senol↗
NASA NTRS2015

Introduction to Autogyros, Helicopters, and Other V/STOL Aircraft Volume III: Other V/STOL Aircraft

The period from Ciervas demonstration of his C.6A Autogiro in Farnborough, England, in October 1925, up to when Pan American World Airways ushered in jet age service to Europe with a Boeing 707-120 on October 26, 1958, was one of enormous progress in the aviation world. This progress was made primarily in the fixed-wing world. This 33-year period saw the conventional takeoff and landing (CTOL) machine achieve increases in cruise speed, range, cruise altitude, and number of passengers carried. These improvements were not, however, accompanied by reductions in takeoff and landing space required. In fact, just the opposite occurred. And with the arrival of the autogyro, and then the helicopter, fixed-wing advocates were presented with a clear challenge to fix the airplanes major shortcomings stalling and loss of control at low speed. I do not think airplane advocates felt particularly threatened by autogyros in the late 1920s because it quickly became apparent that the cruise performance of these short takeoff and landing (STOL) aircraft would never become competitive. Even the vertical takeoff and landing (VTOL) capability offered by the helicopter was relegated to a niche market. Fixed-wing advocates felt (and still feel, in my opinion) that helicopters would never take much of the traveling publics business away from their major civil airlines or trains, buses, cars, or ships for that matter. Understanding the fundamental performance problem of the CTOL is a prerequisite to learning about VTOLs and STOLs. Therefore, let me use this introduction to set the stage for an in-depth discussion of vertical and short takeoff and landing (VSTOL) aircraft.

Harris, Franklin Dewitt↗
NASA NTRS1973

Evaluation of V/STOL research aircraft design

The evaluation and evolution of direct jet lift V/STOL transport aircraft designs are discussed. The V/STOL transport design selected as an example is a lift-fan design that was evaluated as a candidate configuration for a possible future V/STOL research transport. The paper includes discussion of potential advanced V/STOL landing approach profiles as key design requirements for V/STOL aircraft, description and experimental results of an integrated propulsion/control system designed to achieve desired advanced V/STOL near-terminal operating capabilities, and results from evaluating V/STOL designs on piloted moving-base simulators. This paper discusses use of the piloted moving-base simulator as a design tool for evolving satisfactory V/STOL stabilization and propulsion/control systems. Included are problems and solutions identified during simulation of simultaneous decelerating/descent steep curved landing approaches under instrument flight conditions. Simulation results are also compared to flight results obtained with the DO-31 V/STOL research transport.

Deckert, W. H.↗
NASA NTRS1977

Moving V/STOL from technology to system

The design of future V/STOL aircraft is seen to revolve around tradeoffs of V/STOL capability with classical figures of merit. The Navy may soon drive V/STOL technology to the threshold of a major advancement. It has decided to proceed with a significant V/STOL effort and, based on results, decide whether or not to procure significant numbers and types of V/STOL aircraft. The author envisages a line of development beginning with Navy Type A multipurpose subsonic V/STOL aircraft, followed by derivatives for civil utility applications, followed ultimately by V/STOL commercial transports.

Deckert, W. H.↗
NASA NTRS1979

V/STOL flight simulation

The requirements for a new research aircraft to provide in-flight V/STOL simulation were reviewed. The required capabilities were based on known limitations of ground based simulation and past/current experience with V/STOL inflight simulation. Results indicate that V/STOL inflight simulation capability is needed to aid in the design and development of high performance V/STOL aircraft. Although a new research V/STOL aircraft is preferred, an interim solution can be provided by use of the X-22A, the CH-47B, or the 4AV-8B aircraft modified for control/display flight research.

Source record↗
NASA NTRS1988

Flight testing a V/STOL aircraft to identify a full-envelope aerodynamic model

Flight-test techniques are being used to generate a data base for identification of a full-envelope aerodynamic model of a V/STOL fighter aircraft, the YAV-8B Harrier. The flight envelope to be modeled includes hover, transition to conventionally flight and back to hover, STOL operation, and normal cruise. Standard V/STOL operation, and normal cruise. Standard V/STOL procedures such as vertical takeoff and landings, and short takeoff and landings are used to gather data in the powered-lift flight regime. Long (3-5-min) maneuvers which include a variety of input types are used to obtain large-amplitude control and response excitations. The aircraft is under continuous radar tracking; a laser tracker is used for V/STOL operations near the ground. Tracking data are used with state-estimation techniques to check data consistency and to derive unmeasured variables, for example, angular accelerations. A propulsion model of the YAV-8B's engine and reaction control system is used to isolate aerodynamic forces and moments for model identification. Representative V/STOL flight data are presented. The processing of a typical short-takeoff and slow-landing maneuver is illustrated.

Mcnally, B. David↗
NASA NTRS1991

The power induced effects module: A FORTRAN code which estimates lift increments due to power induced effects for V/STOL flight

A user friendly FORTRAN code that can be used for preliminary design of V/STOL aircraft is described. The program estimates lift increments, due to power induced effects, encountered by aircraft in V/STOL flight. These lift increments are calculated using empirical relations developed from wind tunnel tests and are due to suckdown, fountain, ground vortex, jet wake, and the reaction control system. The code can be used as a preliminary design tool along with NASA Ames' Aircraft Synthesis design code or as a stand-alone program for V/STOL aircraft designers. The Power Induced Effects (PIE) module was validated using experimental data and data computed from lift increment routines. Results are presented for many flat plate models along with the McDonnell Aircraft Company's MFVT (mixed flow vectored thrust) V/STOL preliminary design and a 15 percent scale model of the YAV-8B Harrier V/STOL aircraft. Trends and magnitudes of lift increments versus aircraft height above the ground were predicted well by the PIE module. The code also provided good predictions of the magnitudes of lift increments versus aircraft forward velocity. More experimental results are needed to determine how well the code predicts lift increments as they vary with jet deflection angle and angle of attack. The FORTRAN code is provided in the appendix.

Sandlin, Doral R.↗
NASA NTRS1976

Prediction methods for jet V/STOL propulsion aerodynamics

The current status of prediction methods for propulsive flows and propulsion-induced effects which occur on jet V/STOL aircraft is reviewed. Among the major topics studied are flows in propulsive ducts, propulsion-induced ground and thermal effects, aerodynamic loads induced during V/STOL and transition flight, flow vectoring devices, and thrust augmented ejector and lift-fan studies. The current predictive capability in jet V/STOL propulsion aerodynamics is assessed. Future research needs are identified, with particular reference to activities that can improve the usefulness of prediction methods for jet V/STOL aircraft.

Platzer, M. F.↗
NASA NTRS1980

Future challenges in V/STOL flight propulsion control integration

A survey of propulsion control requirements forming part of an advanced V/STOL control requirements study has to date determined, among other findings: (1) that the dependence of V/STOL flying qualities on propulsive lift makes it necessary to identify propulsion control requirements early in a development program; (2) that V/STOL controls of the future should relieve the pilot of control functions and elevate him to the position of a flight operations manager, with substantial gains in capability and/or safety; and (3) that research is required to define the V/STOL control system reliability requirements and specific component reliability allocations. An interactive, integrated design process for the realization of these objectives is also described.

Roth, S. P.↗
NASA NTRS1985

Future of V/STOL aircraft systems: A survey of opinions

The recent success of the British Harriers in the Falkland Islands conflict vividly underscored the potential of V/STOL aircraft in military operations in a difficult environment. Despite this apparent success of the Harrier, there has been a major decline of V/STOL funding in the research and development budgets of the U.S. government and industry. The recent funding history of V/STOL systems is examined. Responses to a questionnaire which asked the question, Should there be an operational V/STOL aircraft other than the AV-8A and AV-8B in the military aircraft fleet of the U.S.A.? are presented and discussed.

White, K. C.↗
NASA NTRS1988

Flight testing a V/STOL aircraft to identify a full-envelope aerodynamic model

Flight-test techniques are being used to generate a data base for identification of a full-envelope aerodynamic model of a V/STOL fighter aircraft, the YAV-8B Harrier. The flight envelope to be modeled includes hover, transition to conventional flight and back to hover, STOL operation, and normal cruise. Standard V/STOL procedures such as vertical takeoff and landings, and short takeoff and landings are used to gather data in the powered-lift flight regime. Long (3 to 5 min) maneuvers which include a variety of input types are used to obtain large-amplitude control and response excitations. The aircraft is under continuous radar tracking; a laser tracker is used for V/STOL operations near the ground. Tracking data are used with state-estimation techniques to check data consistency and to derive unmeasured variables, for example, angular accelerations. A propulsion model of the YAV-8B's engine and reaction control system is used to isolate aerodynamic forces and moments for model identification. Representative V/STOL flight data are presented. The processing of a typical short takeoff and slow landing maneuver is illustrated.

Mcnally, B. David↗
NASA NTRS1989

A zonal approach to V/STOL vehicle aerodynamics

A zonal method based on an iterative coupling between an inviscid panel method and two viscous finite difference methods is applied to solve for the region of jets issued from generic V/STOL models in order to assess the influence of the jet upon V/STOL configurations. The low-order panel method, VSAERO, is used to solve for the entire flow region, which includes the V/STOL model and jet boundary. ARC3D, a well known compressible, thin layer Navier-Stokes (NS) code developed at NASA-Ames, and APPL, a parabolized NS code, are used to solve for the jet region subject to the boundary condition provided by the VSAERO calculation. Overlapping boundaries are used for the purpose of coupling. Results are presented with the available experimental data for the jet and V/STOL configurations.

Yoo, Sungyul↗
NASA NTRS1972

A look at V/STOL for business aircraft.

Attempt to ascertain the economic viability of the V/STOL capability for business aircraft and the manner in which this viability depends on the aircraft concept. A cost-benefit analysis is presented which indicates that a VTOL business aircraft would be more viable economically than a contemporary turbine-powered business aircraft. The combination of traveler's time value and trip distance for which each aircraft dominates is shown. The significance of disk loading in V/STOL concept application is discussed, and preliminary design configuration studies for three different business-aircraft-sized V/STOLs, using three concepts covering a range of disk loading, are presented as examples. Finally, a discussion of operational aspects of interest to future users of V/STOL business aircraft is presented which centers around the requirements for routine IFR terminal-area operations.

Feistel, T. W.↗
NASA NTRS1972

Noise radiation from V/STOL aircraft.

This paper presents a detailed evaluation of design factors affecting noise annoyance by V/STOL aircraft. Community noise annoyance is quantified on the basis of recent analyses of survey data, and the implications on V/STOL design discussed. The effect of fundamental design choices on noise levels is analysed. The principal noise sources, and therefore the optimum noise control measures, are a function of disc loading. It is found that increase in rotor scale gives a substantial benefit in subjective levels at the lower disc loadings. Rotor noise source mechanisms are discussed in detail and the dominant effect of the unsteady aerodynamic input to the rotor demonstrated. Data on the effects of recirculation on noise is presented. Two approaches for low noise V/STOL seem to be feasible. These are the low disc loading open rotor, and a ducted fan with substantial duct attenuation treatment. The principal noise control methods for each approach are given.

Lowson, M. V.↗
NASA NTRS1973

Some comments on V/STOL wind tunnel testing in the transition flight region

Flow breakdown and flow distortion are discussed as the two limitations to wind tunnel testing of V/STOL models at speeds within or near the transition region. It is shown that a very large wind tunnel would be most useful for research into basic aerodynamic phenomena associated with V/STOL aircraft. The large tunnel will not be able to meet the requirements of all the desired testing of V/STOL models, and smaller existing tunnels will continue to be used. There is need for more work, both experimental and theoretical, to bring about a more correct use of the smaller wind tunnels. The large tunnel would be a most useful tool in this work.

Rae, W. H., Jr.↗
NASA NTRS1975

Design of a V/STOL technology airplane

A two-engine three-fan V/STOL airplane was designed to demonstrate and develop the technology for operational V/STOL and STO-VL aircraft having safe engine-out characteristics. Engine-out requirements, integration of propulsion and aerodynamic controls, and propulsion installation are the major factors affecting the configuration. Use of variable pitch fans enhances the control system providing a responsive and versatile airplane. The ability to operate over the entire flight spectrum from zero speed to M = 0.8 is required to demonstrate operational capability with a V/STOL system.

Zabinsky, J. M.↗