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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 955 records · Page 53
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Safety considerations in the design and operation of large wind turbines

The engineering and safety techniques used to assure the reliable and safe operation of large wind turbine generators utilizing the Mod 2 Wind Turbine System Program as an example is described. The techniques involve a careful definition of the wind turbine's natural and operating environments, use of proven structural design criteria and analysis techniques, an evaluation of potential failure modes and hazards, and use of a fail safe and redundant component engineering philosophy. The role of an effective quality assurance program, tailored to specific hardware criticality, and the checkout and validation program developed to assure system integrity are described.

Reilly, D. H.↗
NASA NTRS1979

Postseismic viscoelastic surface deformation and stress. Part 1: Theoretical considerations, displacement and strain calculations

A model of viscoelastic deformations associated with earthquakes is presented. A strike-slip fault is represented by a rectangular dislocation in a viscoelastic layer (lithosphere) lying over a viscoelastic half-space (asthenosphere). Deformations occur on three time scales. The initial response is governed by the instantaneous elastic properties of the earth. A slower response is associated with viscoelastic relaxation of the lithosphere and a yet slower response is due to viscoelastic relaxation of the asthenosphere. The major conceptual contribution is the inclusion of lithospheric viscoelastic properties into a dislocation model of earthquake related deformations and stresses. Numerical calculations using typical fault parameters reveal that the postseismic displacements and strains are small compared to the coseismic ones near the fault, but become significant further away. Moreover, the directional sense of the deformations attributable to the elastic response, the lithospheric viscoelastic softening, and the asthenospheric viscoelastic flow may differ and depend on location and model details. The results and theoretical arguments suggest that the stress changes accompanying lithospheric relaxation may also be in a different sense than and be larger than the strain changes.

Cohen, S. C.↗
NASA NTRS1979

Design considerations for compression panels at elevated temperature

The potential of graphite/polyimide is assessed on a graphite/polyimide honeycomb sandwich panels and stiffened panel concepts to develop lightweight panels for use at elevated temperatures. The capability is attained to correctly predict panel buckling behavior and panel strength at elevated temperatures.

Mcwithey, R. R.↗
NASA NTRS1979

Lunar building materials: Some considerations on the use of inorganic polymers

The use of inorganic polymer systems synthesized from the available lunar chemical elements, viz., silicon, aluminum, and oxygen to make adhesives, binders, and sealants needed in the fabrication of lunar building materials and the assembly of structures is considered. Inorganic polymer systems, their background, status, and shortcomings, and the use of network polymers as a possible approach to synthesis are examined as well as glassy metals for unusual structural strength, and the use of cold-mold materials as well as foam-sintered lunar silicates for lightweight shielding and structural building materials.

Lee, S. M.↗
NASA NTRS1979

Design considerations for the Tandem Junction Solar Cell

Structure and operation of the tandem junction cell (TJC) are described. The impact of using only back contacts is discussed. A model is presented which explains operation of the TJC in terms of transistor action. The model is applied to predict TJC performance as a function of physical parameters.

Matzen, W. T.↗
NASA NTRS1978

Environmental considerations for the microwave beam from a solar power satellite

Solar power satellite (SPS) systems in geosynchronous orbit are possible future energy sources. The SPS concept uses a highly focused microwave beam to transmit the energy to the earth. The microwave power transmission system parameters are summarized, emphasizing those parameters which may affect the earth's environment. Environmental impacts of the microwave beam are discussed. The power levels for the main beam, sidelobes, grating lobes, and ground receiving antenna reradiation patterns are presented. Ionospheric/microwave beam interaction studies, experimental and theoretical, are reviewed. Possible radio frequency interference sources and the magnitude of expected interference levels are discussed.

Arndt, G. D.↗
NASA NTRS1978

Support system considerations for STS biological investigations

Equipment required for Space Transportation System biological experiments is considered, and environmental factors and operational constraints affecting the performance of experiments are examined. Specimen housing is discussed, problems associated with telemetry procedures are characterized, and attention is directed to the problems of handling hazardous fixatives, radioisotopes, and chemicals.

Bowman, G. H.↗
NASA NTRS1977

Shuttle Ku-band bent-pipe implementation considerations

This paper describes an approach for relay of data-modulated subcarriers from Shuttle payloads through the Shuttle Ku-band communications subsystem (and subsequently through a tracking and data relay satellite system to a ground terminal). The novelty is that a channel originally provided for baseband digital data is shown to be suitable for this purpose; the resulting transmission scheme is referred to as a narrowband bent-pipe scheme. Test results demonstrating the validity of the narrowband bent-pipe mode are presented, and limitations on system performance are described.

Batson, B. H.↗
NASA NTRS1978

Design considerations for solar power satellites

This report summarizes the performance characteristics of a conceptual solar power satellite (SPS) system with emphasis on the microwave power transmission system. The latest tradeoff studies on photovoltaic and thermal systems for converting solar energy into electricity at the satellite are reviewed. The microwave system, consisting of dc-RF amplifiers, a 1-km phased array, and a ground antenna/rectifier scheme is capable of delivering 5 GW of power to the commercial grid. The transmission efficiencies of smaller system sizes (down to 1 GW) are compared with that of the nominal 5 GW system. At present the frequency region of interest is the IMS (industrial, medical, and scientific) band at 2450 plus or minus 50 MHz. Economic and technical tradeoffs as a function of the microwave operating frequency are considered. Candidate dc-RF power converter tubes, including medium-power amplitrons, high-power klystrons, and low-power solid state amplifiers, are examined.

Arndt, G. D.↗
NASA NTRS1978

Considerations in STS payload environmental verification

The current philosophy of the GSFS regarding environmental verification of Shuttle payloads is reviewed. In the structures area, increased emphasis will be placed on the use of analysis for design verification, with selective testing performed as necessary. Furthermore, as a result of recent cost optimization analysis, the multitier test program will presumably give way to a comprehensive test program at the major payload subassembly level after adequate workmanship at the component level has been verified. In the thermal vacuum area, thought is being given to modifying the approaches used for conventional spacecraft.

Keegan, W. B.↗
NASA NTRS1979

Critical considerations for wind-tunnel testing V/STOL aircraft models

Low-speed wind-tunnel testing of V/STOL aircraft concepts to determine the aerodynamic-propulsion interaction effects during the transition between hover and wingborne flight is a necessary step in the development cycle of this type of aircraft. The paper examines factors which must be dealt with to assure that the information obtained in experiments is accurate and representative of the full-scale aircraft modeled. Areas of discussion include: (1) Proper engine simulation selection and model size constraints as a result of the selection; (2) selection of reference power-off condition for determining propulsion interaction effects; (3) modeling of realistic flight conditions to obtain a comprehensive evaluation of the entire transition performance; and (4) wind-tunnel boundary interferences and how these are highly configuration dependent.

Margason, R. J.↗
NASA NTRS1978

Aperture and detector cavity considerations for wide and medium field-of-view radiometers

Design constraints regarding the ERBSS nonscanning radiometers are related to the necessity to exclude, as much as possible, unwanted radiation from the detectors. The usual approach to accomplish this is to provide an aperture which is both blackened and serrated on its interior surfaces. However, such an approach is not entirely satisfactory for a number of reasons. A somewhat different method to aperture design is, therefore, considered. This method minimizes the three sources of unwanted radiation and alleviates also the problem of aperture temperature variations. To achieve the potential accuracy of the considered type of radiometer, it is essential to design the cavity in such a way that any entering photon will experience at least five reflections before it is allowed to exit the radiometer. A number of feasible cavity configurations are considered.

Babcock, R. A.↗
NASA NTRS1978

System considerations for an earth radiation budget scanning radiometer

Error sources that might affect the earth radiation budget (ERBSI) scanner radiometer are discussed. Effects of sensor time response, spatial averaging by the field of view, onboard processing, and level III averaging are examined, coverage of grid regions is considered, and an analysis procedure for a scanning radiometer is derived. ERBSI consists of a scanning radiometer, sensors, and a solar radiometer, and it is suggested that ERBSI be included in the instrument complement of NOAA operational spacecraft.

Smith, G. L.↗
NASA NTRS1979

Configuration considerations in the design of earth-to-orbit transports

The various configuration options for earth-to-orbit transports are discussed with specific attention given to: ballistic vs. winged vehicles; horizontal takeoff vs. vertical takeoff; two stage vs. single stage; rocket propulsion system options; structure and thermal protection systems options; and weight growth vs. size. It is suggested that the single-stage system has many attractive features such as the elimination of booster-to-orbiter mating problems and the elimination of the need for the development of a cruise system. From the standpoint of weight reduction, it appears desirable to combine as many functions as possible in the outer shell of the transport system.

Macconochie, I. O.↗
NASA NTRS1979

Technology and operational considerations for low-heat-rate trajectories

A broad parametric study which examines several critical aspects of low-heat-rate entry trajectories is performed. Low planform loadings associated with future winged earth-entry vehicles coupled with the potential application of metallic thermal protection systems (TPS) suggest that such trajectories are of particular interest. Studied are three heating conditions - reference, stagnation, and windward centerline, for both laminar and turbulent flow; configuration-related factors including planform loading and hypersonic angle of attack; and mission-related factors such as cross-range and orbit inclination. Results indicate benefits in the design of TPS to be gained by utilizing moderate angles of attack as opposed to high-lift coefficient, high angles of attack, during entry. An assessment of design and technology implications is made.

Wurster, K. E.↗
NASA NTRS1979

Planetary mission requirements, technology and design considerations for a solar electric propulsion stage

High energy planetary missions such as comet rendezvous, Saturn orbiter and asteroid rendezvous require development of a Solar Electric Propulsion Stage (SEPS) for augmentation of the Shuttle-IUS. Performance and functional requirements placed on the SEPS are presented. These requirements will be used in evolution of the SEPS design, which must be highly interactive with both the spacecraft and the mission design. Previous design studies have identified critical SEPS technology areas and some specific design solutions which are also presented in the paper.

Cork, M. J.↗
NASA NTRS1979

Control considerations for CCV fighters at high angles of attack

Wind tunnel and piloted simulation studies show that the use of the CCV concept of relaxed static pitch stability on fighter aircraft at high angles of attack can result in pitch departures caused by inertia and/or kinematic coupling and in deep stall trim. These problems can be avoided by sufficient nose-down pitch control at high attack angles, and effectiveness of several pitch control configurations such as aft-mounted stabilators, canard mounted flaps, and all-movable canards was investigated. A variable incidence canard with a large travel range was the most effective means of obtaining the required pitch control, although very large deflections may be required on highly unstable configurations. Control laws were developed for cases where the high angle of pitch control requirement is not met, but they can limit aircraft roll capability and thus compromise maneuverability.

Nguyen, L. T.↗