Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “flight computer”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,765 records · Page 98
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Analytical comparison of hypersonic flight and wind tunnel viscous/inviscid flow fields

Flow fields were computed about blunted, 0.524 and 0.698 radians, cone configurations to assess the effects of nonequilibrium chemistry on the flow field geometry, boundary layer edge conditions, boundary layer profiles, and heat transfer and skin friction. Analyses were conducted at typical space shuttle entry conditions for both laminar and turbulent boundary layer flow. In these calculations, a wall temperature of 1365 K (2000 F) was assumed. The viscous computer program used in this investigation was a modification of the Blottner non-similar viscous code which incorporated a turbulent eddy viscosity model after Cebeci. The results were compared with equivalent calculations for similar (scaled) configurations at typical wind tunnel conditions. Wind tunnel test gases included air, nitrogen, CF4 and helium. The viscous computer program used for wind tunnel conditions was the Cebeci turbulent non-similar computer code.

Fivel, H. J.↗
NASA NTRS1976

Effect of color on pilot performance and transfer functions using a full-spectrum, calligraphic, color display system

The use of blue and red color in out-of-window cockpit displays, in full-spectrum calligraphic computer-generated display systems, is studied with attention given to pilot stereographic depth perception and response to visual cues. Displays for vertical approach, with dynamic and frozen-range landing approach and perspective arrays, are analyzed. Pilot transfer function and the transfer function associated with the contrasted approach and perspective arrays are discussed. Out-of-window blue lights are perceived by pilots as indicating greater distance depth, red lights as indicating proximity. The computer-generated chromatic display was adapted to flight simulators for the tests.

Chase, W. D.↗
NASA NTRS1982

Initial analysis of OSTA-1 ocean color experiment imagery

NASA's Ocean Color Experiment (OCE) was designed to map ocean features with an eight-channel scanning radiometer installed on the second flight of the Space Shuttle Columbia. Digital computer enhancement and band-ratio techniques were applied to radiometrically corrected spectral data in order to emphasize chlorophyll distribution patterns. Such a pattern was evident in the Yellow Sea between Korea and China, and the effects of discharge from the Yangtze and other rivers were also observed. Two scenes, from orbits 30 and 32, revealed the movement of plankton patches in the Gulf of Cadiz. Geometric correction of the images permitted ocean current velocities to be deduced, and water depth variability over the Grand Bahama Bank was estimated by means of OCE's blue-green channel. Bottom-reflected sunlight produced a sensor signal that was inversely related to water depth.

Kim, H. H.↗
NASA NTRS1982

Flight testing the Rotor Systems Research Aircraft (RSRA)

The Rotor Systems Research Aircraft (RSRA) is a dedicated rotor test vehicle whose function is to fill the gap between theory, wind tunnel tests and flight verification data. Its flight test envelope has been designed to encompass the expected envelopes of future rotor systems under all flight conditions. The test configurations of the RSRA include pure helicopter and compound (winged helicopter) modes. In addition, should it become necessary to jettison an unstable rotor system in flight, the RSRA may be flown as a fixed wing aircraft. The heart of the RSRA's electronic flight control system is the TDY-43 computer, which can be programmed in numerous ways to change stability and control or force feel system gains. Computer programming changes allow the RSRA to be used as a five-degree-of-freedom inflight simulator for studying the handling qualities of research rotors.

Merrill, R. K.↗
NASA NTRS1985

Fundamental Algorithms of the Goddard Battery Model

The Goddard Space Flight Center (GSFC) is currently producing a computer model to predict Nickel Cadmium (NiCd) performance in a Low Earth Orbit (LEO) cycling regime. The model proper is currently still in development, but the inherent, fundamental algorithms (or methodologies) of the model are defined. At present, the model is closely dependent on empirical data and the data base currently used is of questionable accuracy. Even so, very good correlations have been determined between model predictions and actual cycling data. A more accurate and encompassing data base has been generated to serve dual functions: show the limitations of the current data base, and be inbred in the model properly for more accurate predictions. The fundamental algorithms of the model, and the present data base and its limitations, are described and a brief preliminary analysis of the new data base and its verification of the model's methodology are presented.

Jagielski, J. M.↗
NASA NTRS1985

NASA's hypersonic fluid and thermal physics program (Aerothermodynamics)

This survey paper gives an overview of NASA's hypersonic fluid and thermal physics program (recently renamed aerothermodynamics). The purpose is to present the elements of, example results from, and rationale and projection for this program. The program is based on improving the fundamental understanding of aerodynamic and aerothermodynamic flow phenomena over hypersonic vehicles in the continuum, transitional, and rarefied flow regimes. Vehicle design capabilities, computational fluid dynamics, computational chemistry, turbulence modeling, aerothermal loads, orbiter flight data analysis, orbiter experiments, laser photodiagnostics, and facilities are discussed.

Graves, R. A.↗
NASA NTRS1985

Energy management of three-dimensional minimum-time intercept

A real-time computer algorithm to control and optimize aircraft flight profiles is described and applied to a three-dimensional minimum-time intercept mission. The proposed scheme has roots in two well known techniques: singular perturbations and neighboring-optimal guidance. Use of singular-perturbation ideas is made in terms of the assumed trajectory-family structure. A heading/energy family of prestored point-mass-model state-Euler solutions is used as the baseline in this scheme. The next step is to generate a near-optimal guidance law that will transfer the aircraft to the vicinity of this reference family. The control commands fed to the autopilot (bank angle and load factor) consist of the reference controls plus correction terms which are linear combinations of the altitude and path-angle deviations from reference values, weighted by a set of precalculated gains. In this respect the proposed scheme resembles neighboring-optimal guidance. However, in contrast to the neighboring-optimal guidance scheme, the reference control and state variables as well as the feedback gains are stored as functions of energy and heading in the present approach. Some numerical results comparing open-loop optimal and approximate feedback solutions are presented.

Kelley, H. J.↗
NASA NTRS1986

Modeling Ni-Cd performance. Planned alterations to the Goddard battery model

The Goddard Space Flight Center (GSFC) currently has a preliminary computer model to simulate a Nickel Cadmium (Ni-Cd) performance. The basic methodology of the model was described in the paper entitled Fundamental Algorithms of the Goddard Battery Model. At present, the model is undergoing alterations to increase its efficiency, accuracy, and generality. A review of the present battery model is given, and the planned charges of the model are described.

Jagielski, J. M.↗
NASA NTRS1985

Preliminary evaluation of the airborne imaging spectrometer for vegetation analysis in the Klamath National Forest of northeastern California

The experiences and results associated with a project entitled Preliminary Evaluation of the Airborne Imaging Spectrometer for Vegetation Analysis is documented. The primary goal of the project was to provide ground truth, manual interpretation, and computer processing of data from an experimental flight of the Airborne Infrared Spectrometer (AIS) to determine the extent to which high spectral resolution remote sensing could differentiate among plant species, and especially species of conifers, for a naturally vegetated test site. Through the course of the research, JPL acquired AIS imagery of the test areas in the Klamath National Forest, northeastern California, on two overflights of both the Dock Well and Grass Lake transects. Over the next year or so, three generations of data was also received: first overflight, second overflight, and reprocessed second overflight. Two field visits were made: one trip immediately following the first overflight to note snow conditions and temporally-related vegetation states at the time of the sensor overpass; and a second trip about six weeks later, following acquisition of prints of the images from the first AIS overpass.

Strahler, A. H.↗
NASA NTRS1987

A Vibroacoustic Database Management Center for Shuttle and expendable launch vehicle payloads

A Vibroacoustic Database Management Center has recently been established at the Jet Propulsion Laboratory (JPL). The center uses the Vibroacoustic Payload Environment Prediction System (VAPEPS) computer program to maintain a database of flight and ground-test data and structural parameters for both Shuttle and expendable launch-vehicle payloads. Given the launch-vehicle environment, the VAPEPS prediction software, which employs Statistical Energy Analysis (SEA) methods, can be used with or without the database to establish the vibroacoustic environment for new payload components. This paper summarizes the VAPEPS program and describes the functions of the Database Management Center at JPL.

Thomas, Valerie C.↗
NASA NTRS1988

Numerical simulation of helicopter multi-bladed rotor flow

A numerical method for solving the Euler equations for multiblade rotors has been developed. The computed results, including one nonlifting forward-flight and several lifting hovering cases, are compared with experimental data. For forward-flight case, the unsteady growth and decay of the shock agree well with experimental results. For hovering case, at low and moderate transonic tip speed, the results show good agreement with experimental data in the tip region. The near-wake effects can be captured without wake modeling.

Chen, C. L.↗
NASA NTRS1987

Atmospheric effect on spectral signature - Measurements

In order to study the spectral atmospheric effect on remote sensing, measurements of the spectral signature of surface cover were conducted during hazy conditions. Simultaneous measurements of the aerosol optical thickness and its vertical distribution were carried out. The upward radiance in high flight were also simulated by radiative transfer computations, and the results were compared with the measurements. It is suggested that the radiances over dark areas can be used to derive the aerosol optical thickness. Combined with climatological information, the derived optical thickness can be used to perform corrections of the atmospheric effect.

Kaufman, Yoram J.↗
NASA NTRS1988

Radiation dose and shielding for the space station

Significant differences in dose prediction for Space Station arise depending on whether or not the magnetic field model is extrapolated into the future. The basis for these calculations is examined in detail, and the importance of the residual atmospheric layer at altitudes below 1000 km, with respect to radiation attenuation, is emphasized. Dosimetry results from Shuttle flights are presented and compared with the computed results. It is recommended that, at this stage, no extrapolation of the magnetic field into the future be included in the calculations. A model adjustment, to replace this arbitrary procedure, is presented. Dose predictions indicate that, at altitudes below 500 km and at low inclination, and with nominal module wall thickness (0.125 in. aluminum), orbit stay times of 90 days in Space Station would result in quarterly radiation doses to the crew, which are well within present limits for both males and females. Countermeasures would be required for stay times of a year or more and the measure of increasing shielding is examined.

Mccormack, Percival D.↗
NASA NTRS1989

Numerical simulation of high-incidence flow over the F-18 fuselage forebody

As part of the NASA High Alpha Technology Program, fine-grid Navier-Stokes solutions have been obtained for flow over the fuselage forebody and wing leading-edge extension of the F/A-18 High Alpha Research Vehicle at large incidence. The resulting flows are complex and exhibit cross-flow separation from the sides of the forebody and from the leading-edge extension. A well-defined vortex pattern is observed in the leeward-side flow. Results obtained for laminar flow show good agreement with flow visualizations obtained in ground-based experiments. Further, turbulent flows computed at high-Reynolds-number flight-test conditions show good agreement with surface and off-surface visualizations obtained in flight.

Schiff, Lewis B.↗
NASA NTRS1989

Development of AFE aerobrake aerothermodynamic data book

The computation method developed for the NASA Aeroassist Flight Experiment (AFE) data book generates a design reference for the AFE's aerothermodynamic environment using an optimized technology for a 4100-lb vehicle. This environment is defined by convective, radiative, and total heating rates, radiation equilibrium temperatures, and local surface pressures along the AFE pitch-plane and associated off-pitch planes. The Boundary Layer Integral Matrix Procedure is the major program code used in this analysis; a partially catalytic wall was assumed on the basis of measured recombination rates.

Ting, Paul C.↗