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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Some measured and calculated effects of a tip vortex modification device on impulsive noise

The results of a recent wind tunnel test program to evaluate the effectiveness of the Tip Air Mass Injection (TAMI) system in modifying the blade tip vortex occurring during helicopter flight is described with attention to the effect of this modification on the impulsive noise. The measurement program is explained, and the correlation between experimental and predicted results is discussed. Topics considered include the effect of descent rate on noise pressure time histories, the effect of air mass injection on noise, and the analysis based on a dB(A) weighted approach. Impulsive noise generated by the interaction of a helicopter rotor blade and the concentrated tip vortex during forward flight descent is a primary contributor to acoustic annoyance as it draws early attention to the presence of the helicopter.

Pegg, R. J.↗
NASA NTRS1978

High temperature ceramics for automobile gas turbines. Part 2: Development of ceramic components

The development of ceramic components for automobile gas turbine engines is described with attention given to the steady and unsteady thermal conditions the ceramics will experience, and their anti-corrosion and strain-resistant properties. The ceramics considered for use in the automobile turbines include hot-pressed Si3N4, reaction-sintered, isostatically pressed Si3N4, hot-pressed SiC, reaction-bonded SiC, and glass ceramics. Attention is given to the stress analysis of ceramic structures and the state of the art of ceramic structural technology is reviewed, emphasizing the use of ceramics for combustion chambers and ceramic shrouded turbomachinery (a fully ceramic impeller).

Walzer, P.↗
NASA NTRS1977

Interstellar potassium and argon

Isotopic anomalies are calculated in K and Ar that will be expected to be carried in interstellar grains. Special attention is given to the supernova condensates that precipitate during the expansion of the explosive oxygen-burning zone of the interior, because that is where K-39, K-41 and Ar-36, Ar-38 find their natural origins. Expectations are given for K-Ar ages in excess of the solar age in accumulations of presolar grains, and for K anomalies in Ca-rich mineral within Allende inclusions, because experiments searching for such effects are currently underway. Attention is also given to predictions of excess Ar-36 owing to extinct Cl-36 within presolar grains, and to descriptions of new correlations that can confirm its existence.

Clayton, D. D.↗
NASA NTRS1978

Three-dimensional effects on pure tone fan noise due to inflow distortion

A theoretical analysis of pure tone fan noise generated by inflow distortion-rotor interaction is carried out with the aid of the three-dimensional unsteady lifting surface theory developed by Namba (1977, 1974). Particular attention is given to a study of the accuracy of available two-dimensional theory for the prediction of pure tone fan noise due to the interaction of inflow distortion with a subsonic annular blade row. The theoretical model considered consists of a single three-dimensional annular cascade rotating at constant angular velocity in an annular rigid-wall duct of infinite axial extent. Attention is given to the fluctuating pressure induced by a rotor blade row, the fluctuating velocity induced by it, an inflow distortion with only an axial velocity component, the determination of acoustic dipole distribution, the pure tone acoustic power, and two-dimensional theory and quasi-three-dimensional theory.

Kobayashi, H.↗
NASA NTRS1978

The ISEE-C vector helium magnetometer

The ISEE-C magnetometer will make continuous observations of the interplanetary magnetic field near 1 AU. This paper describes the scientific objectives of the magnetometer experiment and gives attention to instrument design (sensor, electronics, and operating principles). A functional block diagram of the system is presented and attention is given to minor modifications required by the ISEE mission (the magnetometer is essentially one that served as the spare unit for the Pioneer 10 and 11 missions to Jupiter).

Frandsen, A. M. A.↗
NASA NTRS1978

Development of flightweight static face seals for 75.84 MPa /11 000 psi/ pressure and cryogenic temperatures

The development of a static seal configuration to meet the lightweight low-leakage requirements of the Space Shuttle Main Engine (pressure carrying capability of up to 75.84 MPa) is discussed. The design features, fabrication methods, lab testing, and performance of seal are examined. Flange and bolt details of the joint assembly are considered with attention to an ultrasonic technique for measuring preload in the bolts. Methods used for leak testing in the laboratory and in the field are described; the practicality of the procedures is considered. Attention is directed to hydrogen-environment embrittlement and its influence on seal and joint design.

Daniels, C. M.↗
NASA NTRS1977

An approach to the multi-axis problem in manual control

The multiaxis control problem is addressed within the context of the optimal pilot model. The problem is developed to provide efficient adaptation of the optimal pilot model to complex aircraft systems and real world, multiaxis tasks. This is accomplished by establishing separability of the longitudinal and lateral control problems subject to the constraints of multiaxis attention and control allocation. Control solution adaptation to the constrained single axis attention allocations is provided by an optimal control frequency response algorithm. An algorithm is developed to solve the multiaxis control problem. The algorithm is then applied to an attitude hold task for a bare airframe fighter aircraft case with interesting multiaxis properties.

Harrington, W. W.↗
NASA NTRS1979

Geophysics of Mars

A physical model of Mars is presented on the basis of light-scattering observations of the Martian atmosphere and surface and interior data obtained from observations of the geopotential field. A general description of the atmosphere is presented, with attention given to the circulation and the various cloud types, and data and questions on the blue haze-clearing effect and the seasonal darkening wave are summarized and the Mie scattering model developed to explain these observations is presented. The appearance of the planet from earth and spacecraft through Mariner 9 is considered, and attention is given to the preparation of topographical contour maps, the canal problem and large-scale lineaments observed from Mariner 9, the gravity field and shape of the planet and the application of Runcorn's geoid/convection theory to Mars. Finally, a summary of Viking results is presented and their application to the understanding of Martian geophysics is discussed.

Wells, R. A.↗
NASA NTRS1980

An experimental evaluation of head-up display formats

Three types of head-up display format are investigated. Type 1 is an unreferenced (conventional) flight director, type 2 is a ground referenced flight path display, and type 3 is a ground referenced director. Formats are generated by computer and presented by reflecting collimation against a simulated forward view in flight. Pilots, holding commercial licenses, fly approaches in the instrument flight mode and in a combined instrument and visual flight mode. The approaches are in wind shear with varied conditions of visibility, offset, and turbulence. The displays are equivalent in pure tracking but there is a slight advantage for the unreferenced director in poor conditions. Flight path displays are better for tracking in the combined flight mode, possibly because of poor director control laws and the division of attention between superimposed fields. Workloads is better for the type 2 displays. The flight path and referenced director displays are criticized for effects of symbol motion and field limiting. In the subjective judgment of pilots familiar with the director displays, they are rated clearly better than path displays, with a preference for the unreferenced director. There is a fair division of attention between superimposed fields.

Naish, J. M.↗
NASA NTRS1979

Quality assurance and control in the production and static tests of the solid rocket boosters for the Space Shuttle

The paper surveys the various aspects of design and overhaul of the solid rocket boosters. It is noted that quality control is an integral part of the design specifications. Attention is given to the production process which is optimized towards highest quality. Also discussed is the role of the DCA (Defense Contract Administration) in inspecting the products of subcontractors, noting that the USAF performs this role for prime contractors. Fabrication and construction of the booster is detailed with attention given to the lining of the booster cylinder and the mixing of the propellant and the subsequent X-ray inspection.

Cerny, O. F.↗
NASA NTRS1980

Solar cell array design handbook - The principles and technology of photovoltaic energy conversion

Photovoltaic solar cell array design and technology for ground-based and space applications are discussed from the user's point of view. Solar array systems are described, with attention given to array concepts, historical development, applications and performance, and the analysis of array characteristics, circuits, components, performance and reliability is examined. Aspects of solar cell array design considered include the design process, photovoltaic system and detailed array design, and the design of array thermal, radiation shielding and electromagnetic components. Attention is then given to the characteristics and design of the separate components of solar arrays, including the solar cells, optical elements and mechanical elements, and the fabrication, testing, environmental conditions and effects and material properties of arrays and their components are discussed.

Rauschenbach, H. S.↗
NASA NTRS1981

Design concepts for large antenna reflectors

A type of antenna reflector was studied in which a stiff structure is constructed to hold a membrane like reflector mesh in the correct position. An important basic restriction is that the mesh be controlled only by the structure and that no additional local shaping be employed. Furthermore, attention is confined to structures in which no adjustments would be made on assembly. Primary attention is given to the tetrahedral truss configuration because of its outstanding stiffness and dimensional stability.

Hedgepeth, J. M.↗
NASA NTRS1980

Formate esters of 1,2-ethanediol - Major decomposition products of p-dioxane during storage

Research done on detecting the contaminants of p-dioxane that cause a positive response for highly reactive acyl groups is discussed. Attention is given to the fact that the positive hydroxamate response might indicate an unsuspected hazard. It is found that all acyl groups transferred are formyl groups, and the mono- and diformates of 1,2-ethanediol are identified as major sources of this activity. It is also found that the formate esters are formed by way of peroxide intermediates. Concentrations of the formate ester group as high as 1.8 M are found in partially consumed bottles of dioxane but not in other common ethers stored under similar conditions. Attention is called to the possibility that the exposure to the glycol formates is probably much wider than expected. It is noted that by purging containers of dioxane with nitrogen each time they are opened and storing them in the cold away from light can prevent both the economic loss and possible health hazard caused by contamination with peroxide and formate ester.

Jewett, D.↗
NASA NTRS1980

Physical characteristics of cometary dust from dynamical studies - A review

Progress made in the determination of the physical characteristics of cometary dust particles from studies of dust tail dynamics is reviewed. Applications of the combined dynamical photometric approach of Finson and Probstein (1968) to studies of cometary tails exhibiting continuous light intensity variations are discussed, with attention given to determinations of the particle-size-related distribution function of the solar radiation pressure exerted on the particles, the contribution of comets to the interplanetary dust, calculations of dust ejection rates and a Monte Carlo approach to the analysis of dust tails. Investigations of dust streamers and striae, which are believed to be related to comet outbursts entailing brief but sharp enhancements of dust production, are then reviewed, with particular attention given to observations of Comet West 1976 VI. Finally, the question of cometary particle type is addressed, and it is pointed out that the presence of submicron absorbing particles in the striae of Comet West is not incompatible with the presence of micron-size dielectric particles in the inner coma.

Sekanina, Z.↗
NASA NTRS1981

Rotorcraft researchers and operators - Is there is common ground

An investigation is conducted concerning the extent to which a program for rotorcraft research presented by NASA meets the user needs. Problems of civil operators are examined, taking into account powerplants, reliability and maintainability, environment, noise and vibration, and lack of space for passengers' baggage. A description of applicable technology is provided, giving attention to aerodynamics and structures, propulsion, power transfer methodology, flight control, avionic systems, human factors, and vehicle configurations. One of the most difficult challenges in trying to bring research to bear on operator problems is that in general researchers are working on long-term solutions while operators are seeking short-term answers. Attention is also given to potential technological bright spots, higher risk technologies, highest technological risks, and advanced vehicle configurations.

Talbot, P. D.↗
NASA NTRS1981

Annual survey of spaceflight safety systems: 11th supplement. Survey period - July 1980-June 1981

Reports in the field of space flight safety applicable to current and future operational space activities which appeared between July 1980 and June 1981 are surveyed. Subjects in the area of flight rescue and safety during launch, on-orbit, reentry and landing phases include the major activities and findings of the first Shuttle test flight, a slidewire system for emergency egress from the Space Shuttle on the launch pad, and the testing of the Spacelab engineering model. In the area of human capabilities and crew roles, attention is given to reports of repairs to the Salyut 6 space station made by a Soyuz crew, and an assessment of weightlessness effects on space worker health and safety. Safety requirements for STS payloads including pressure vessels, and the Orbiter window system and for spacecraft testing are also presented, along with those for a television system to aid in monitoring astronaut extravehicular activities. For the operation of large space structures, reports include EVA equipment for satellite servicing and the safety aspects of connectors used in construction. Finally, attention is given to safety-related criteria in a study of Shuttle interactions with the proposed Space Operations Center.

Brown, N. E.↗
NASA NTRS1981

The industrial processing of unidirectional fiber prepregs

Progress made in the industrial processing of preimpregnated composites with unidirectional fibers is discussed, with particular emphasis on applications within the aerospace industry. Selection of industrial materials is considered. Attention is given to the conditions justifying the use of composites and the properties required of industrial prepregs. The hardening cycle is examined for the cases of nonmodified and polymer modified resins, with attention given to the stabilization of flow, the necessary changes of state, viscosity control, and the elimination of porosity. The tooling necessary for the fabrication of a laminated plate is illustrated, and the influence of fabrication and prepreg properties on the mechanical characteristics of a laminate are indicated. Finally, the types of prepregs available and the processing procedures necessary for them are summarized.

Laird, B.↗
NASA NTRS1981

Early development of ceramic fiber insulation for the Space Shuttle

The evolution of reusable surface insulation is described, with attention to the mullite and other aluminosilicates, zirconia, and silicon carbide-coated carbon compositions experimented with in the late 1960s and early 1970s. Evaluation and development concentrated in this period on such aspects of design and material properties as cold soak performance, attachment, shock impingement, surface coating cracks, and tile gap design and heating. In addressing the central problem of heat-shield thermal conductivity, it was found that for a given density, silica fibers had a lower conductivity than those of mullite. This was due to the one-micron, as opposed to 4.7-micron, diameter of the silica fibers, which resulted in smaller pores and therefore less convective and radiative heat transfer. Attention is also given to tile coating materials and the high-temperature processes by which they were applied.

Buckley, J. D.↗