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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 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

A program for calculating turbofan-driven lift-fan propulsion system performance

The performance of a turbofan-powered lift fan propulsion system for vertical takeoff and landing (VTOL) aircraft is calculated. The program formulation consists of taking bleed air from a turbofan engine, heating the bleed air in an interburner, and passing it through a tip turbine to drive a lift fan. Two options are available: bleed air from the engine exhaust, or bleed air that has passed through the engine fan only. This computer program will benefit persons unfamiliar with the thermodynamics of engine cycle analysis.

Tauber, M. E.↗
NASA NTRS1976

Mathematical model for lift/cruise fan V/STOL aircraft simulator programming data

Simulation data are reported for the purpose of programming the flight simulator for advanced aircraft for tests of the lift/cruise fan V/STOL Research Technology Aircraft. These simulation tests are to provide insight into problem areas which are encountered in operational use of the aircraft. A mathematical model is defined in sufficient detail to represent all the necessary pertinent aircraft and system characteristics. The model includes the capability to simulate two basic versions of an aircraft propulsion system: (1) the gas coupled configuration which uses insulated air ducts to transmit power between gas generators and fans in the form of high energy engine exhaust and (2) the mechanically coupled power system which uses shafts, clutches, and gearboxes for power transmittal. Both configurations are modeled such that the simulation can include vertical as well as rolling takeoff and landing, hover, powered lift flight, aerodynamic flight, and the transition between powered lift and aerodynamic flight.

Bland, M. P.↗
NASA NTRS1977

Study on steady state wind and turbulence environments

The structure of wakes and how this structure is related to the size and shape of buildings and other obstacles, and to ambient winds, was investigated. Mean values of natural atmospheric flow were obtained and used in conjunction with theoretical relationships developed by dimensional analysis to establish a model of the flow in the wake. Results indicate that conventional and V/STOL aircraft passing through the wake during takeoff and landing would experience not only a change in turbulence level, but also a change in mean wind speed of a magnitude roughly equivalent to that of the eddy components.

Brundidge, K. C.↗
NASA NTRS1975

Low-speed wind-tunnel tests of a one-tenth-scale model of a blended-arrow advanced supersonic transport

Tests were conducted in the Langley full scale tunnel to determine the low-speed aerodynamic characteristics of a 1/10 scale model of a blended-arrow advanced supersonic transport. Tests were made for the clean configuration and a high-lift configuration with several combinations of leading- and trailing-edge flaps deflected for providing improved lift and longitudinal stability in the landing and takeoff modes. The tests were conducted for a range of angles of attack from about -6 deg to 30 deg, sideslip angles from -5 deg to 10 deg, and for Reynolds numbers from 6.78 x 1,000,000 to 13.85 x 1,000,000 corresponding to test velocities of 41 knots to 85 knots, respectively.

Lemore, H. C.↗
NASA NTRS1977

Recommended procedures for measuring aircraft noise and associated parameters

Procedures are recommended for obtaining experimental values of aircraft flyover noise levels (and associated parameters). Specific recommendations are made for test criteria, instrumentation performance requirements, data-acquisition procedures, and test operations. The recommendations are based on state-of-the-art measurement capabilities available in 1976 and are consistent with the measurement objectives of the NASA Aircraft Noise Prediction Program. The recommendations are applicable to measurements of the noise produced by an airplane flying subsonically over (or past) microphones located near the surface of the ground. Aircraft types covered by the recommendations are fixed-wing airplanes powered by turbojet or turbofan engines and using conventional aerodynamic means for takeoff and landing. Various assumptions with respect to subsequent data processing and analysis were made (and are described) and the recommended measurement procedures are compatible with the assumptions. Some areas where additional research is needed relative to aircraft flyover noise measurement techniques are also discussed.

Marsh, A. H.↗
NASA NTRS1977

Low speed wind tunnel tests of 1/10-scale model of a blended-arrow supersonic cruise aircraft

Low speed static force tests have been conducted in a full scale tunnel to determine the low speed aerodynamic characteristics of a 1/10-scale model of a blended-arrow supersonic cruise aircraft. A clean configuration and a high lift configuration with several combinations of leading- and trailing-edge flaps to provide improved lift and longitudinal stability in the landing and takeoff modes were used. The tests were made at angles of attack from about -6 deg to 30 deg, sideslip angles from -5 deg to 10 deg, and Reynolds numbers from 6.78 x 1 million to 13.85 x 1 million corresponding to test velocities of 41 to 85 knots.

Mclemore, H. C.↗
NASA NTRS1977

Sources of low-level wind shear around airports

Some potential sources of low-level wind shear in and around airports and their likely effects are probed and analyzed. Wind shear over flat terrain with near-homogeneous surface properties (roughness, specific heat), the turning layer, shear flows over inhomogeneous terrain (airport + urban areas), thunderstorms, turbulent flowfields over bluff bodies (individual buildings), and recirculating wake flow downstream of three-dimensional block bodies are among the topics covered. Overshoot or undershoot of runways, and induced moments (pitch, roll, yaw) in takeoff and landing, and other potential hazards traceable to wind shear patterns at low heights are discussed, with emphasis on mean flow or steady-state wind shear (time-averaged, say 2-min averaged, wind fields). Wind tunnel studies and V/STOL operations are included in the study.

Fichtl, G. H.↗
NASA NTRS1977

V/STOL Conference, Palo Alto, Calif., June 6-8, 1977, Technical Papers

Papers are presented on practical aspects of commercial STOL operations, a Vertical Attitude Takeoff and Landing (VATOL) program, powered-lift STOL ground effects, conceptual design studies of Navy Type A V/STOL aircraft, and a V/STOL shaft propulsion system analytical performance model. Also considered are the management of swirling flows with application to wind tunnel design and V/STOL testing, flight control testing of the VAK-191B, and surface fluctuating pressure measurements on a 1/4-scale YC-14 boilerplate model.

Source record↗
NASA NTRS1977

Status of the NASA/General Electric experimental clean combustor program, phase 3

The technology required to design and develop advanced commercial, conventional-takeoff-and-landing aircraft engines with significantly lower pollutant exhaust emissions levels than those of current-technology engines was generated and demonstrated. The target pollutant emissions reductions in tests of an advanced commercial aircraft turbofan engine were attained by developing advanced combustor designs. This technology is intended to be applicable to advanced military aircraft engines. The primary focus was on reducing the levels of the gaseous pollutant emissions.

Bahr, D. W.↗
NASA NTRS1977

Cost benefit study of advanced materials technology for aircraft turbine engines

The cost/benefits of eight advanced materials technologies were evaluated for two aircraft missions. The overall study was based on a time frame of commercial engine use of the advanced material technologies by 1985. The material technologies evaluated were eutectic turbine blades, titanium aluminide components, ceramic vanes, shrouds and combustor liners, tungsten composite FeCrAly blades, gamma prime oxide dispersion strengthened (ODS) alloy blades, and no coat ODS alloy combustor liners. They were evaluated in two conventional takeoff and landing missions, one transcontinental and one intercontinental.

Hillery, R. V.↗
NASA NTRS1974

Analysis of spread multi-jet VTOL aircraft in hover

An investigation of vertical takeoff and landing aircraft lift losses in hover was conducted to evaluate a method for a simplified test technique. Three flat plate models were tested to determine their usefulness in predicting hover characteristics by comparing results between plate and three-dimensional models. Data obtained for the plate models were correlated to three-dimensional results by the application of a geometrical equivalent height correction factor. The correlation of plate and tunnel models indicated that lift losses in ground effect were essentially independent of the efflux characteristics for the engine simulators.

Albang, L. F.↗
NASA NTRS1978

Evaluation of the tilt rotor concept: The XV-15's role

The need for an aircraft combining the efficient vertical takeoff and landing capability of a helicopter with the efficient high speed characteristics of a fixed wing turboprop is examined. The ability of the tilt rotor concept to fill this requirement and examples as to its potential usefulness in both military and civil missions is discussed.

Brown, J. H., Jr.↗
NASA NTRS1978

Viscous flow simulations in VTOL aerodynamics

The critical issues in viscous flow simulations, such as boundary-layer separation, entrainment, turbulence modeling, and compressibility, are discussed with regard to the ground effects problem for vertical-takeoff-and-landing (VTOL) aircraft. A simulation of the two-dimensional incompressible lift jet in ground proximity is based on solution of the Reynolds-averaged Navier-Stokes equations and a turbulence-model equation which are written in stream function-vorticity form and are solved using Hoffman's augmented-central-difference algorithm. The resulting equations and their shortcomings are discussed when the technique is extended to two-dimensional compressible and three-dimensional incompressible flows.

Bower, W. W.↗
NASA NTRS1978

Expansion of flight simulator capability for study and solution of aircraft directional control problems on runways

The development, evaluation, and evaluation results of a DC-9-10 runway directional control simulator are described. An existing wide bodied flight simulator was modified to this aircraft configuration. The simulator was structured to use either two of antiskid simulations; (1) an analog mechanization that used aircraft hardware; or (2) a digital software simulation. After the simulation was developed it was evaluated by 14 pilots who made 818 simulated flights. These evaluations involved landings, rejected takeoffs, and various ground maneuvers. Qualitatively most pilots evaluated the simulator as realistic with good potential especially for pilot training for adverse runway conditions.

Kibbee, G. W.↗
NASA NTRS1977

Research Study to Identify Technology Requirements for Advanced Earth-Orbital Transportation Systems, Dual-Mode Propulsion

The results of a study of dual mode propulsion concepts applied to advanced earth orbital transportation systems using reuseable single stage to orbit vehicle concepts were summarized. Both series burn and parallel burn modes of propulsion were analyzed for vertical takeoff, horizontal landing vehicles based on accelerated technology goals. A major study objective was to assess the merits of dual mode main propulsion concepts compared to single mode concepts for carrying payloads of Space Shuttle type to orbit.

Source record↗
NASA NTRS1978

Pilot evaluation of sailplane handling qualities

The evaluation sailplanes were found generally deficient in the area of cockpit layout. The pilots indicated general dissatisfaction with high pitch sensitivity especially when coupled with inertially induced stick forces. While all sailplanes were judged satisfactory for centering thermals and in the ease of speed control in circling flight, pilot opinions diverged on the maneuvering response, pull-out characteristics from a dive, and on phugoid damping. Lateral-directional control problems were noted mainly during takeoff and landing for most sailplanes with the landing wheel ahead of center of gravity. Pilot opinion of in-flight lateral-directional stability and control was generally satisfactory. Five of the evaluation sailplanes exhibited a very narrow airspeed band in which perceptible stall warning buffet occurred. However, this characteristic was considered not objectionable when stall recovery was easy. The pilots objected to the characteristics of a wide airspeed band of stall warning followed by a stall with yawing and rolling tendency and substantial loss of altitude during the stall. Glide path control for the evaluation sailplanes was found to be generally objectionable.

Bennett, A. G., Jr.↗
NASA NTRS1976

Analytical developments for definition and prediction of USB noise

A systematic acoustic data base and associated flow data are used in identifying the noise generating mechanisms of upper surface blown flap configurations of short takeoff and landing aircraft. Theory is developed for the radiated sound field of the highly sheared flow of the trailing edge wake. An empirical method is also developed using extensive experimental data and physical reasonings to predict the noise levels.

Reddy, N. N.↗
NASA NTRS1978

Effect of twist and camber on the low-speed aerodynamic characteristics of a powered close-coupled wing-canard configuration

A series of wind-tunnel tests were conducted in a V/STOL tunnel to determine the low-speed longitudinal aerodynamic characteristics of a powered close-coupled wing/canard fighter configuration. The data was obtained for a high angle-of-attack maneuvering configuration and a takeoff and landing configuration. The data presented in tabulated form are intended for reference purposes.

Paulson, J. W., Jr.↗