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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 1,081 records · Page 60
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Development of the propulsion simulator - A test tool applicable to V/STOL configurations

A turbine engine multi-mission propulsion simulator, capable of representing inlet/airframe/nozzle flowfield interactions for supersonic V/STOL aircraft wind tunnel models, is described. The propulsion simulator replaces conventional aero flow-through and jet effects models with a single model; flow field interactions modeled by the simulator may include close-coupled inlets and nozzles, non-axisymmetric vectoring exhaust nozzles, and forward canards mounted near the inlets and wings. Wind tunnel tests of the simulation system at Mach numbers up to 1.2 are reported for a model typical of a F-15 aircraft installation. The possibility of applying the simulator to advanced V/STOL design programs is also discussed.

Eigenmann, M. F.↗
NASA NTRS1978

Modeling and parameter uncertainties for aircraft flight control system design

As aircraft designs trend toward further applications of control-configured vehicle concepts, aircraft control systems increasingly rely on stability augmentation to obtain normal flying qualities and reasonable structural margins. Although the control system designer would choose to have a perfect dynamic description of the vehicle, he knows that a level of uncertainty of plant dynamics will exist. This paper gives typical values of plant uncertainties for some recent aircraft design and development programs. Histories of pertinent aerodynamic, inertial, and structural parameters from program initiation to aircraft certification are given. These data can be used as typical of future vehicles so that control system design concepts can be evaluated with due consideration to their sensitivity to uncertainties in plant dynamics.

Rickard, W. W.↗
NASA NTRS1980

Atmospheric turbulence simulation techniques with application to flight analysis

Statistical modeling of atmospheric turbulence is discussed. The statistical properties of atmospheric turbulence, in particular the probability distribution, the spectra, and the coherence are reviewed. Different atmospheric turbulence simulation models are investigated, and appropriate statistical analyses are carried out to verify their validity. The models for simulation are incorporated into a computer model of aircraft flight dynamics. Statistical results of computer simulated landings for an aircraft having characteristics of a DC-8 are reported for the different turbulence simulation techniques. The significance of various degrees of sophistication in the turbulence simulation techniques on the landing performance of the aircraft is discussed.

Wang, S. T.↗
NASA NTRS1980

Carbon/graphite fiber risk analysis and assessment study: Assessment of risk to the Lockheed Model L-1011 commercial transport aircraft

The risk associated with the accidental release of carbon/graphite fibers (CF) from fires on commercial transport aircraft incorporating composite materials was assessed. Data are developed to evaluate the potential for CF damage to electrical and electronic equipment, assess the cost risk, and evaluate the hazard to continued operation. The subjects covered include identification of susceptible equipments, determination of infiltration transfer functions, analysis of airport operations, calculation of probabilities of equipment failures, assessment of the cost risk, and evaluation of the hazard to continued operation. The results show the risks associated with CF contamination are negligible through 1993.

Daniledes, J.↗
NASA NTRS1979

Assessment of airframe noise

A component method of airframe noise prediction is used to predict levels of operational and proposed aircraft airframe noise to assess the contribution of airframe noise to community noise levels. This is done after first evaluating the prediction method using newly acquired detailed measurements from full-scale aircraft and models. In the course of the evaluation, modeling techniques of airframe noise sources are examined with attention to scaling. Finally, when used to predict approach airframe EPNLs, the levels fell about 10 EPNdB below current noise regulations and about 5 EPNdB below proposed noise regulations.

Block, P. J. W.↗
NASA NTRS1980

Analysis of wind tunnel test results for a 9.39-per cent scale model of a VSTOL fighter/attack aircraft. Volume 2: Evaluation of prediction methodologies

An evaluation of current prediction methodologies to estimate the aerodynamic uncertainties identified for the E205 configuration is presented. This evaluation was accomplished by comparing predicted and wind tunnel test data in three major categories: untrimmed longitudinal aerodynamics; trimmed longitudinal aerodynamics; and lateral-directional aerodynamic characteristics.

Lummus, J. R.↗
NASA NTRS1981

Effect of sweep and aspect ratio on the longitudinal aerodynamics of a spanloader wing in and out of ground effect

A wind tunnel investigation was conducted in the Langley 4 by 7 meter tunnel to determine the effects of leading edge sweep, aspect ratio, flap deflection, and elevon deflection on the longitudinal aerodynamic characteristics of a span distributed load advanced cargo aircraft (spanloader). Model configurations consisted of leading edge sweeps of 0, 15, 30 and 45 deg and aspect ratios of approximately 2, 4, 6, and 8. Data were obtained for angles of attack of -8 to 18 deg out of ground effect and at angles of attack of -2, 0, and 2 deg in ground effect at Mach number equal 0.14. Flap and elevon deflections ranged from -20 to 20 deg. The data are represented in tabulated form.

Kjelgaard, S. O.↗
NASA NTRS1980

Analytical study of twin-jet shielding

The development of an analytical model, an aircraft noise prediction computer program, to estimate the shielding of one jet by an adjacent jet in a twin jet configuration, is discussed. Noise estimations included consideration not only of noise sources on the aircraft, but also of the propagation path between source and receiver. A three-dimensional case is considered in which noise source is a discrete frequency point source at rest with respect to the jet axis. The shielding jet is assumed to be a cylinder of heated flow in which the temperature and flow velocity profiles are constant across the jet. The effect on shielding of the orientation of the emitting jet with respect to the shielding jet was investigated. Forward and backward scattering phenomena as well as the influence of jet flow speed were also investigated.

Gerhold, C. H.↗
NASA NTRS1982

Aerodynamics on a transport aircraft type wing-body model

The DFLR-F4 wing-body combination is studied. The 1/38 model is formed by a 9.5 aspect ratio transonic wing and an Airbus A 310 fuselage. The F4 wing geometrical characteristics are described and the main experimental results obtained in the S2MA wind tunnel are discussed. Both wing-fuselage interferences and viscous effects, which are important on the wing due to a high rear loading, are investigated by performing 3D calculations. An attempt is made to find their limitations.

Schmitt, V.↗
NASA NTRS1980

Curved flow wind tunnnel test of F-18 aircraft

The curved flow capability of a stability wind tunnel was used to investigate the lateral directional characteristics of an F-18 aircraft. The model is described and the procedures used to obtain and correct the data and a graphical presentation of the results are presented. The results include graphs of lateral directional derivatives versus sideslip or static plots, the lateral directional static stability derivatives versus angle of attack, and finally the lateral directional derivatives versus nondimensional yaw rate for different angles of attack and sideslip. Results are presented for several configurations including complete, complete without vertical tails, complete without horizontal tails, fuselage wing and fuselage alone. Each of these were tested with and without wing leading edge extensions.

Lutze, F. H.↗
NASA NTRS1982

Interior noise considerations for advanced high-speed turboprop aircraft

This paper describes recent research on noise generated by high-speed propellers, on noise transmission through acoustically treated aircraft sidewalls and on subjective response to simulated turboprop noise. Propeller noise discussion focuses on theoretical prediction methods for complex blade shapes designed for low noise at Mach = 0.8 flight and on comparisons with experimental test results. Noise transmission experiments using a 168 cm. diameter aircraft fuselage model and scaled heavy-double-wall treatments indicate that the treatments perform well and that the predictions are usually conservative. Studies of subjective comfort response in an anechoic environment are described for noise signatures having combinations of broadband and propeller-type tone components.

Mixson, J. S.↗
NASA NTRS1983

An investigation of motion base cueing and G-seat cueing on pilot performance in a simulator

The effect of G-seat cueing (GSC) and motion-base cueing (MBC) on performance of a pursuit-tracking task is studied using the visual motion simulator (VMS) at Langley Research Center. The G-seat, the six-degree-of-freedom synergistic platform motion system, the visual display, the cockpit hardware, and the F-16 aircraft mathematical model are characterized. Each of 8 active F-15 pilots performed the 2-min-43-sec task 10 times for each experimental mode: no cue, GSC, MBC, and GSC + MBC; the results were analyzed statistically in terms of the RMS values of vertical and lateral tracking error. It is shown that lateral error is significantly reduced by either GSC or MBC, and that the combination of cues produces a further, significant decrease. Vertical error is significantly decreased by GSC with or without MBC, whereas MBC effects vary for different pilots. The pattern of these findings is roughly duplicated in measurements of stick force applied for roll and pitch correction.

Mckissick, B. T.↗
NASA NTRS1985

Dynamic Calibration of Pressure Transducers

Sinusoidal calibration signal produced in 4- to 100-Hz range. Portable oscillating-pressure device measures dynamic characteristics of pressure transducers installed in models or aircraft at frequency and oscillating-pressure ranges encountered during unsteady-pressure-measurement tests. Calibration is over range of frequencies and amplitudes not available with commercial acoustic calibration devices.

Hess, R. W.↗
NASA NTRS1984

Flight service evaluation of two aluminum-brazed titanium spoilers

The long-term service evaluation of two aluminum-brazed titanium (ABTi) honeycomb flight spoilers was concluded. The two spoilers had about 7.5 years of commercial flight experience on All Nippon Airways Model 737 aircraft. All Nippon Airways was selected because Japan has one of the most severe marine-industrial environments in the world. The results indicated that both flight spoilers still had the same load-carrying capability as when they were originally installed. No direct evidence of any corrosion was observed on either spoiler. Another significant accomplishment of this effort was the development of a braze design for efficiently distributing point loads from the fittings and skin into the honeycomb core.

Boyer, R. R.↗
NASA NTRS1984

PAN AIR prediction of NASA Ames 12-foot pressure wind-tunnel interference on a fighter configuration

Models tested in the NASA Ames 12-Foot Pressure Wind Tunnel over an angle of attack range from 0 deg to 90 deg are mounted on a floor strut that protrudes from a fairly large support bump. In high-angle-of-attack tests (angle of attack = 40 deg to 90 deg), for which the floor support was originally designed, the effects of the flow angularities produced by the bump are often negligible. This is not so for low-angle-of-attack tests (0 deg to 40 deg). Since there are no standard means for correcting test data for this bump effect, low-angle-of-attack testing with the bump is not recommended by the Ames wind-tunnel staff. This paper presents an exploratory study of a technique for correcting balance forces and experimental pressures for combined wall and bump effects. This is done by modeling the aircraft, wind-tunngl walls, and bump, with PAN AIR. The wall-and-bump-induced increments in the lift coefficient and pitching-moment coefficient predicted by PAN AIR are compared with increments obtained from the Ames 12-foot tunnel with the bump and an 8 x 12 low speed wind tunnel which has no bump.

Snyder, L. D.↗
NASA NTRS1984

PAN AIR modeling studies. II - Sideslip option, network gaps, three-dimensional forebody flow, and thick-trailing-edge representation

PAN AIR is a computer program that calculates linear potential flow about arbitrary configurations at both subsonic and supersonic Mach numbers. This paper is a follow-on of another paper entitled 'PAN AIR Modeling Studies', in which several studies were presented that exhibited PAN AIR's versatility for modeling diverse configurations. Results from four modeling studies of interest in modeling realistic aircraft shapes are presented. The topics addressed are (1) half-geometry option in sideslip, (2) network gaps, (3) three-dimensional forebody flows, and (4) trailing-edge representation.

Strande, S.↗
NASA NTRS1983

Analytical redundancy management mechanization and flight data analysis for the F-8 digital fly-by-wire aircraft flight control sensors

The details are presented of an onboard digital computer algorithm designed to reliably detect and isolate the first failure in a duplex set of flight control sensors aboard the NASA F-8 digital fly-by-wire aircraft. The algorithm's successful flight test program is summarized, and specific examples are presented of algorithm behavior in response to software-induced signal faults, both with and without aircraft parameter modeling errors.

Deckert, J. C.↗