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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 NTRS1971

The NASA quiet engine

Application of noise reduction technology to design of propulsion system for subsonic civil transport aircraft

Kramer, J. J.↗
NASA NTRS1971

Control considerations in severe turbulence

Jet transport aircraft stability and controllability under atmospheric turbulence conditions, discussing longitudinal and lateral- directional characteristics with particular attention to unstable spiral mode

Gilbert, W. P.↗
NASA NTRS1971

Simulation of flight maneuver-load distributions by utilizing stationary, non-Gaussian random load histories

Random numbers were generated with the aid of a digital computer and transformed such that the probability density function of a discrete random load history composed of these random numbers had one of the following non-Gaussian distributions: Poisson, binomial, log-normal, Weibull, and exponential. The resulting random load histories were analyzed to determine their peak statistics and were compared with cumulative peak maneuver-load distributions for fighter and transport aircraft in flight.

Leybold, H. A.↗
NASA NTRS1972

The NASA quiet engine program

Initial studies on the design and testing of the quiet engine are described. The principal noise sources considered in the engine selection were the fan machinery noise and the fan and core jet noise. Nacelle acoustic linings are also mentioned. Fan and engine tests are discussed briefly and results indicate that it is possible to achieve or exceed noise reduction objectives of 15 to 20 PNdb below the levels of 707/DC-8 long-range transport aircraft.

Kramer, J. J.↗
NASA NTRS1971

Evaluation of active cooling systems for a Mach 6 hypersonic transport airframe, part 2

Transpiration and convective cooling concepts are examined for the fuselage and tail surface of a Mach 6 hypersonic transport aircraft. Hydrogen, helium, and water are considered as coolants. Heat shields and radiation barriers are examined to reduce heat flow to the cooled structures. The weight and insulation requirements for the cryogenic fuel tanks are examined so that realistic totals can be estimated for the complete fuselage and tail. Structural temperatures are varied to allow comparison of aluminum alloy, titanium alloy, and superalloy contruction materials. The results of the study are combined with results obtained on the wing structure, obtained in a previous study, to estimate weights for the complete airframe. The concepts are compared among themselves, and with the uncooled concept on the basis of structural weight, cooling system weight, and coolant weight.

Helenbrook, R. G.↗
NASA NTRS1972

Development of approach control system requirements with applications to a jet transport

The development of requirements for an approach control system and example applications to a jet transport aircraft are presented. The material is divided into a general discussion of approach control requirements, and a specific application resulting in the design of three alternative longitudinal controllers. The point of view taken is that the essential features of the system structure are the feedbacks themselves, their equalization, and their combinations to create control commands. Use is made of the fact that for sucessful systems the possible feedback structures are very limited. They derive primarily from guidance, control, and regulation demands; and secondarily from dynamic response characteristics desired by the pilot. From the systems view it is the satisfaction of these requirements that is important rather than the means automatic, manual, or hygrid manual/automatic approach systems.

Mcruer, D. T.↗
NASA NTRS1972

Transonic transport study: Economics

An economic analysis was performed to evaluate the impact of advanced materials, increased aerodynamic and structural efficiencies, and cruise speed on advanced transport aircraft designed for cruise Mach numbers of .90, .98, and 1.15. A detailed weight statement was generated by an aircraft synthesis computer program called TRANSYN-TST; these weights were used to estimate the cost to develop and manufacture a fleet of aircraft of each configuration. The direct and indirect operating costs were estimated for each aircraft, and an average return on investment was calculated for various operating conditions. There was very little difference between the operating economics of the aircraft designed for Mach numbers .90 and .98. The Mach number 1.15 aircraft was economically marginal in comparison but showed significant improvements with the application of carbon/epoxy structural material. However, the Mach .90 and Mach .98 aircraft are the most economically attractive vehicles in the study.

Smith, C. L.↗
NASA NTRS1972

Night visual approaches: Pilot performance with and without a head-up display

Simulated night visual approaches were flown into two airports with and without a head up display (HUD) in a transport aircraft. The HUD featured pitch stabilized vertical scales which displayed the glide slope angle to the runway aim point and a horizontal bar which aided the pilot in his control of the aircraft flight path angle. One airport was located on flat terrain with numerous foreground lights, the second airport had no foreground lights and the terrain sloped up behind the airport. With the HUD glide slope tracking precision was equally good for either runway. With no HUD glide slope tracking was about three times worse with the flat airport and about eight times worse with the airport with no foreground lights and up-sloping terrain beyond the runway.

Palmer, E. A.↗
NASA NTRS1972

Reduction of wave drag by antisymmetric arrangement of wings and bodies.

The wave interference effects for bodies or wings in a mirror-symmetric arrangement, and in an antisymmetric arrangement are discussed. It is shown that while in the case of a mirror-symmetric arrangement large adverse interference effects can be observed, antisymmetric arrangements provide comparatively much smaller wave drags. The single continuous wing panels also adapt themselves more readily to varying angles of obliquity, and hence, to varying flight speeds. A detailed review is presented of the previous work on the aerodynamic properties and flight stability of oblique elliptic wing combinations. A possible mode of application of these combinations to transport aircraft operating at moderate supersonic speeds is suggested.

Jones, R. T.↗
NASA NTRS1972

Advanced transport structures and materials technology.

A program was undertaken regarding the economic benefits attainable through the application of advanced technologies to the next generation of long-range transport aircraft in the Mach number range from 0.85 to 1.0. In addition to airframe studies, two parallel engine systems studies contracts are also in progress. The manufacturability of composites promises structural concepts which can take forms very similar to those employed in conventional structures or forms very different from conventional approaches. It is pointed out that the findings of the studies discussed justify a considerably expanded effort not only in composite materials but also in other technologies.

Goble, R. L.↗
NASA NTRS1972

An analytical investigation of the impingement jets on curved deflectors

Numerical solutions are obtained for the cases of straight circular jets impinging on axisymmetric curved surfaces and plane jets impinging symmetrically on two-dimensional curved surfaces. These geometries are representative of some types of thrust reversers for transport aircraft. The solutions are based on the assumptions of incompressible and potential flow. The velocity field, pressure distribution at the deflector surface and reverser effectiveness are predicted for deflector turning angles of 15 to 75 deg, deflector width to jet diameter ratios of 1.5 to 2.0, and ratios of deflector clearance to jet diameter of 1.0 to 3.0. Reverser effectiveness is found to be a maximum for a ratio of deflector clearance to jet diameter of about 2.0. The effect of back pressuring due to the presence of the deflector is predicted. Experimental verification of the theoretical predictions is obtained. A compressible solution obtained for a limited number of cases indicates that the incompressible solution is satisfactory for jet exit Mach numbers less than 0.8.

Schnurr, N. M.↗
NASA NTRS1972

Flyover and static tests to investigate external flow effect on jet noise from nonsuppressor and suppressor exhaust nozzles

The effect of external air flowing across exhaust nozzles on the jet noise characteristics of supersonic transport aircraft at high takeoff speeds was investigated. A series of flyover and static tests were conducted using an F-106B aircraft modified with two underwing nacelles each containing a calibrated J85-GE-13 turbojet engine. Comparison of flyover and static data indicated that external flow reduces the noise of an auxiliary inlet ejector nozzle. An unsuppressed plug nozzle was not affected while the plug suppressor configurations were not as effective in flight.

Burley, R. R.↗