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Results for “simulator study”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,117 records · Page 62

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NASA NTRS1976

Sounder design considerations in the selection of temperature sensing channels

Simulation studies on the performance of IR sounders under varying conditions of cloud cover and cloud heights are carried out for Nimbus 6. An analytic function is derived for calculating the relative response to cloud height errors for arbitrary cloud-sensing channels. Based on the values of the response function, the best choice of channels for determining cloud amounts are obtained. An algorithm is described for determining cloud heights, and the sensitivity of cloud-height sensing channels is tested. It is found that for the HIRS instrument, the most transparent channel in the 4.3-micron band is optimal for adjusting cloud heights, while the channel in the 15-micron band peaking closest to the surface is best for determining cloud amounts

Halem, M.↗

NASA NTRS1976

Effects of modifications to the space shuttle entry guidance and control systems

A nonlinear six degree of freedom entry simulation study was conducted to identify space shuttle guidance and control system software modifications which reduce the control system sensitivity to the guidance system sampling frequency. Several modifications which eliminated the control system sensitivity and associated control limit cycling were examined. The result of the modifications was a reduction in required reaction control system fuel.

Powell, R. W.↗

NASA NTRS1976

Development of longitudinal handling qualities criteria for large advanced supersonic aircraft

A piloted simulation study was conducted with the aim of advancing the development of longitudinal handling qualities criteria for large supersonic cruise aircraft. The areas of study investigated included high-speed cruise maneuvering, and stall-recovery control power. Comparisons were made with existing criteria and, for the cruise condition, a time response criterion was developed which correlated well with pilot ratings and comments. For low-speed stall recovery a new criterion was developed in terms of nose-down angular acceleration capability.

Sudderth, R. W.↗

NASA NTRS1977

Application of NASA-ARC delayed flap approach procedures to Boeing 727 airplane

The results of an engineering and piloted simulator study to adapt a NASA developed-approach energy management system (AEMS) concept to the B727 are presented. The AEMS concept was developed and flight tested on a CV-990. The purpose of the AEMS is to reduce approach time, fuel, and noise by providing computer-driven cockpit displays to assist the pilot in flying optimized delayed flap approach (DFA) procedures. Development of the DFA flight profiles, the AEMS airborne digital computer algorithm, and associated cockpit displays were studied. Study ground rules and pertinent aerodynamic and noise trend data used in developing the flight profiles are presented. Approach time, fuel, and noise for the DFA are compared to several other types of procedures.

Allison, R. L.↗

NASA NTRS1977

Effects of simulated turbulence on aircraft handling qualities

The influence of simulated turbulence on aircraft handling qualities is presented. Pilot opinions of the handling qualities of a light general aviation aircraft were evaluated in a motion-base simulator using a simulated turbulence environment. A realistic representation of turbulence disturbances is described in terms of rms intensity and scale length and their random variations with time. The time histories generated by the proposed turbulence models showed characteristics which are more similar to real turbulence than the frequently-used Gaussian turbulence model. The proposed turbulence models flexibly accommodate changes in atmospheric conditions and are easily implemented in flight simulator studies.

Jacobson, I. D.↗

NASA NTRS1977

Lubricant rheology applied to elastohydrodynamic lubrication

Viscosity measurements in a high pressure rheometer, elastohydrodynamic simulator studies (including the development of a temperature measuring technique), and analytical fluid modeling for elastohydrodynamic contacts are described. The more recent research which is described concerns infrared temperature measurements in elastohydrodynamic contacts and the exploration of the glassy state of lubricants. A correlation, of engineering significance, was made between transient surface temperature measurements and surface roughness profiles. Measurements of glass transitions of lubricants and the study of the effect of rate processes on materials lead to the conclusion that typical lubricants go into the glassy state as they pass through the contact region of typical elastohydrodynamic contacts.

Winer, W. O.↗

NASA NTRS1976

A moving-window parameter adaptive control system for the F8-DFBW aircraft

This paper describes the moving-window parameter adaptive control system developed for the NASA F8-DFBW aircraft. The control system employs a parameter identification process that, iteratively, adjusts parameters of a model of the aircraft motions in a batch processing manner so that responses generated from the model fit the outputs of sensors stored in a finite record referred to as the moving window. Tests are made on the validity of the parameter estimates before using the parameters in an on-line design process. The on-line design process is an algebraic mapping of the parameters of the model into primary control system feedback and feedforward gains. The mapping was selected to satisfy specific flying quality characteristics over the range of parameter variations expected. Results are presented from simulation studies on the identification algorithm, tests for parameter validity, and the on-line design process.

Montgomery, R. C.↗

NASA NTRS1976

The formulation of simulation models of aeronautical systems

Recent developments in formula-manipulation compilers have led to a significant reduction in the time spent in formulating models of complex multi-degrees-of-freedom dynamical systems. MACSYMA, a computer system that can be used to perform symbolic manipulations in an interactive mode, is applied to the problem of formulating models of aeronautical systems for simulation studies. An example demonstrates that once the procedure is established, the formulation and modification of the models can be reduced to a series of routine computer operations.

Howard, J. C.↗

NASA NTRS1977

Inertial attitude control of Voyager spacecraft using dry tuned rotor gyro

The inertial attitude control system designed for the Voyager spacecraft, which will carry out flybys of Jupiter and Saturn in 1979 and 1981, respectively, is described. The attitude of the spacecraft in three-dimensional space will be measured by a Dry Inertial Reference Unit (DIRU) based on three identical two-degree-of-freedom dry gyros. A software estimation process has been developed to use DIRU data and other information to obtain optimum estimates of spacecraft position, velocity, and acceleration. The attitude of the spacecraft is corrected using these estimates by activating hydrazine thrusters. The operation of dry gyros is discussed, together with the network compensation techniques used in their associated capture loop to obtain a capture capability of 8 deg/sec and a frequency response of 10 Hz (3-dB point). The control law and estimation process are examined. Results of computer simulation studies of the performance of the attitude control system are presented.

Bahrami, K.↗

NASA NTRS1976

Reference orbits from range and Doppler observations

The paper is concerned with the height accuracy of reference orbits obtained by a system composed of one laser and three Doppler stations. It is thought that reference orbits obtained by this system could be used for altimeter evaluation, although height errors increased up to 50% over those from the orbits with four lasers. Simulation studies and real data results are analyzed, and the implications for the GEOS-3 project are considered.

Berbert, J.↗

NASA NTRS1977

The 5th Meeting of the Ad Hoc Panel on Terminal Configured Vehicles

A report of the fifth meeting of the NASA Research and Technology Advisory Council, Ad Hoc panel on Terminal Configured Vehicles is presented. Some of the following topics were discussed; (1) microwave landing systems; (2) whole word computer system status; (3) flight path angle control: (4) VTOL approaches and landing technology; and (5) simulation study in wind shear.

Source record↗

NASA NTRS1977

V/STOL hover stability impact on hover control task

Longitudinal static stability requirements for V/STOL aircraft are discussed in terms of vertical landing on a small ship at night, response of the aircraft to air turbulence, and hovering flight. The increased pilot workload encountered under these flight conditions is considered. Results of a flight simulation study performed to evaluate a specific hover control task, two control systems - attitude rate command and translational velocity command, and the pilots' performance with and without turbulence are reported. It is concluded that the translational velocity command system provides the control requirements for good spot hovering capability and reduced pilot workload.

Whitaker, A. B.↗

NASA NTRS1977

Summary report of the Simulation Committee

Topics discussed by the simulation committee included: (1) simulators and their uses; (2) atmospheric disturbance modeling requirements; (3) Status of simulators' capabilities for modeling disturbances; and (4) status of atmospheric disturbance models. Also discussed were specific problem areas; simulation studies criteria, aircraft/atmospheric disturbance response modeling and pilot learning effects.

Kurkowski, R. L.↗

NASA NTRS1978

An approach to the determination of aircraft handling qualities using pilot transfer functions

It was shown that a correlation exists between pilot-aircraft system closed-loop characteristics, determined by using analytical expressions for pilot response along with the analytical expression for the aircraft response, and pilot ratings obtained in many previous flight and simulation studies. Two different levels of preferred pilot response were used. These levels were: (1) a static gain and a second-order lag function with a lag time constant of 0.2 second; and (2) a static gain, a lead time constant of 1 second, and a 0.2-second lag time constant. If a system response with a pitch-angle time constant of 2.6 seconds and a stable oscillatory mode of motion with a period of 2.5 seconds could be achieved with the first-level pilot model, it was shown that the pilot rating will be satisfactory for that vehicle.

Adams, J. J.↗

NASA NTRS1978

Thematic mapper design parameter investigation

This study simulated the multispectral data sets to be expected from three different Thematic Mapper configurations, and the ground processing of these data sets by three different resampling techniques. The simulated data sets were then evaluated by processing them for multispectral classification, and the Thematic Mapper configuration, and resampling technique which provided the best classification accuracy were identified.

Colby, C. P., Jr.↗

NASA NTRS1978

Wind shear modeling for aircraft hazard definition

Mathematical models of wind profiles were developed for use in fast time and manned flight simulation studies aimed at defining and eliminating these wind shear hazards. A set of wind profiles and associated wind shear characteristics for stable and neutral boundary layers, thunderstorms, and frontal winds potentially encounterable by aircraft in the terminal area are given. Engineering models of wind shear for direct hazard analysis are presented in mathematical formulae, graphs, tables, and computer lookup routines. The wind profile data utilized to establish the models are described as to location, how obtained, time of observation and number of data points up to 500 m. Recommendations, engineering interpretations and guidelines for use of the data are given and the range of applicability of the wind shear models is described.

Frost, W.↗

NASA NTRS1978

Analysis and in-simulator evaluation of display and control concepts for a terminal configured vehicle in final approach in a windshear environment

Display Control configurations for the Terminal configured Vehicle in approach to landing situations were analyzed. A pilot/vehicle model was used to compare with a real time simulation study. Model results are presented and extended for the approach task during wind shear and random turbulence environments. In general, model results of performance trends matched those obtained experimentally.

Levison, W. H.↗

NASA NTRS1978

Description and performance of the Langley visual landing display system

A television/model board system is described which provides a means of generating a six-degree-of-freedom visual out-the-window scene for the pilot of a simulated aircraft. The hardware and its performance of capability for meeting the visual requirements for a wide range of simulation studies are detailed. Also included is a description of the computer software required for the system. An example of software implementation in a real-time computer program is provided.

Rollins, J. D.↗