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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 253 records · Page 14

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NASA NTRS1984

Preliminary concept of a 100-kilowatt miniaturized Cassegrainian concentrator solar array

A miniaturized Cassegrainian concentrator (MCC) solar array system is examined to assess the practicality of assembling the basic MCC element into a total array system capable of producing multi-hundred kilowatts of power for Space Platform/Space Station or other low Earth orbit long lifetime missions. Preliminary mechanical and electrical subsystems are developed in order to determine first order performance characteristics. Results of the study support the feasibility of a 100-kilowatt MCC array system with beginning-of-life (BOL) performance of 160 watts per square meter and 28 W/kg. The performance numbers are based on 20 percent efficient (at operating temperature) solar cells and 0.25-millimeter thick electroformed nickel optics. These performance numbers can be improved upon significantly with the development of higher efficiency solar cells and/or lighter weight optics.

Patterson, R. E.↗

NASA NTRS1983

Development of a miniature scanning electron microscope for in-flight analysis of comet dust

A description is presented of an instrument which was developed with the original goal of being flown on the International Comet Mission, scheduled for a 1985 launch. The Scanning Electron Microscope and Particle Analyzer (SEMPA) electron miniprobe is a miniaturized electrostatically focused electron microscope and energy dispersive X-ray analyzer for in-flight analysis of comet dust particles. It was designed to be flown on board a comet rendezvous spacecraft. Other potential applications are related to asteroid rendezvous and planetary lander missions. According to the development objectives, SEMPA miniprobe is to have the capability for imaging and elemental analysis of particles in the size range of 0.25 microns and larger.

Conley, J. M.↗

NASA NTRS1984

A miniature tactical Rb frequency standard

Work on an innovative design for miniature rubidium frequency standards has reached the pre-production demonstration stage at Litton Guidance and Control Systems. Pre-production units were built and tested under contract to the Rome Air Development Center of the U.S. Air Force Systems Command. The units, which are designed for use in tactical military applications, feature fast warm-up, low power consumption, and vibration insensitivity. The output stability under vibration is maintained without the need for external shock-mounts. The design objectives and test results are discussed.

Kwon, T. M.↗

NASA NTRS1985

An experimental study for a miniature Stirling refrigerator

Experimental results of a miniature two-stage Stirling cryocooler are introduced. The influence of filling gas pressure and refrigeration temperature on the refrigerating capacity along with the relationship between parameters was measured. The valley pressure corresponding to the lowest refrigeration temperature and the cooldown time versus operating pressure are discussed. The coefficient of performance and thermodynamic efficiency of the cryocooler are calculated based on experimental data.

Li, S.↗

NASA NTRS1985

Design, performance investigation and delivery of a miniaturized Cassegrainian concentrator solar array

A miniaturized Cassegrainian concentrator (MCC) solar array concept is being developed with the objective of significantly reducing the recurring cost of multikilowatt solar arrays. The desired cost reduction is obtained as a result of using very small high efficiency solar cells in conjunction with low-cost optics. In the MCC single element concept and panel concept, incident solar radiation is reflected from a primary parabolic reflector to a secondary hyperbolic reflector and finally to a 4-millimetr diameter solar cell. A light catcher cone is used to improve off-axis performance. An element is approximately 13-millimeters thick which permits efficient launch stowage of the concentrator system panels without complex optical component deployments or retractions. The MCC elements are packed in bays within graphite epoxy frames and are electrically connected into appropriate series-parallel circuits. A MCC single element with a 21 sq cm entrance aperture and a 20 percent efficient, 0.25 sq cm gallium arsenide solar cell has the same power output as 30-sq cm of 11-percent efficiency (at 68 C) silicon solar cells. The MCC concept provides the potential for a significant reduction in array cost due to a 99 percent reduction in required cell area and a 30 percent reduction in array area relative to planar array of equivalent power.

Patterson, R. E.↗

NASA NTRS1986

A miniature remote deadweight calibrator

A miniature, computer-controlled, deadweight calibrator was developed to remotely calibrate a force transducer mounted in a cryogenic chamber. This simple mechanism allows automatic loading and unloading of deadweights placed onto a skin friction balance during calibrations. Equipment for the calibrator includes a specially designed set of five interlocking 200-milligram weights, a motorized lifting platform, and a controller box taking commands from a microcomputer on an IEEE interface. The computer is also used to record and reduce the calibration data and control other calibration parameters. The full-scale load for this device is 1,000 milligrams; however, the concept can be extended to accommodate other calibration ranges.

Supplee, Frank H., Jr.↗

NASA NTRS1988

Miniature Remote Deadweight Calibrator

Miniature, computer-controlled deadweight calibrator developed to calibrate remotely force transducer located in cryogenic chamber. Used with microcomputer, calibration system automatically applies deadweight loads to skin-friction balance, records and reduces data, and prints out results. Actuator controller and interlocking-weight system key elements in precise, automatic transducer calibrator. Designed for full-scale load of 1,000 mg. Concept extended to accommodate other full-scale load ranges.

Supplee, Frank H., Jr.↗

NASA NTRS1987

Design, fabrication and delivery of a miniature Cassegrainian concentrator solar array system

The optical design of the miniature Cassegrainian concentrator (MCC) element was improved for both offpoint and onpoint power capability. The cell stack design has shown no losses under the high short term thermal stresses imposed by component level test and is projected to be capable of greater than five years thermal cycle life in low Earth orbit. The structural design met all requirements for stiffness and flatness and requires adjustable inserts for fine tuning of the GFRP structure to meet flatness goals. The completed, fully populated small and large MCC panels deliverable under this contract perform electrically as expected. A solid acceptance inspection program to guarantee quality of all purchased parts, and continued manufacturing process improvements will make the MCC design a viable low cost alternative to standard flat panel technology. Minor improvements to the cell stack design of the MCC element can make significant improvements in both the performance and manufacturability of the MCC system.

Kruer, Mark A.↗

NASA NTRS1989

Miniature Centrifugal Compressor

Miniature turbocompressor designed for reliability and long life. Cryogenic system includes compressor, turboexpander, and heat exchanger provides 5 W of refrigeration at 70 K from 150 W input power. Design speed of machine 510,000 rpm. Compressor has gas-lubricated journal bearings and magnetic thrust bearing. When compressor runs no bearing contact and no wear.

Sixsmith, Herbert↗

NASA NTRS1988

Miniaturized compact water-cooled pitot-pressure probe for flow-field surveys in hypersonic wind tunnels

An experimental investigation of the design of pitot probes for flowfield surveys in hypersonic wind tunnels is reported. The results show that a pitot-pressure probe can be miniaturized for minimum interference effects by locating the transducer in the probe support body and water-cooling it so that the pressure-settling time and transducer temperature are compatible with hypersonic tunnel operation and flow conditions. Flowfield surveys around a two-to-one elliptical cone model in a 20-inch Mach 6 wind tunnel using such a probe show that probe interference effects are essentially eliminated.

Ashby, George C.↗

NASA NTRS1989

Miniature multiple-function probe for OTV turbopump health monitoring

A miniature multifunction rotating machinery shaft displacement sensor designed for a turbopump health monitoring system is described. The sensor probe tip has three independent sensing electrodes running in a groove made in the shaft of the machine. One of these electrodes, situated at the tip of the sensor, measures the radial displacement of the shaft, while the two side electrodes measure the axial displacements of the sides of the groove. The displacement sensor is also used to measure speed, by providing a notch in the side of the groove facing one sensor electrode. Results obtained with experimental sensors demonstrated that multifunction capacitive sensing is practical and reduces instrumentation penetration into rotating machinery housings.

Bickford, R. L.↗

NASA NTRS1990

On the design and development of a miniature ceramic gimbal bearing

A review is made of a program to develop ceramic gimbal bearings for a miniaturized missile guidance system requiring nonmagnetic properties and higher load capacity than possible with conventional AISI 440C stainless steel bearings. A new gimbal design concept is described which utilizes the compressive strength and nonmagnetic properties of silicon nitride (Si3N4) ceramics for the gimbal bearing. Considerable manufacturing development has occurred in the last 5 years making ceramic bearings a viable option in the gimbal design phase. A preliminary study into the feasibility of the proposed design is summarized. Finite element analysis of the brittle ceramic bearing components under thermal stress and high acceleration loading were conducted to ensure the components will not fail catastrophically in service. Finite element analysis was also used to optimize the adhesive joint design. Bearing torque tests run at various axial loads indicate that the average running torque of ceramic bearings varies with load similarly to that of conventional steel bearings.

Hanson, Robert A.↗

NASA NTRS1989

Lunar Get-Away-Special - Exploring the moon with a miniature electrically propelled spacecraft

A spacecraft and mission concept designed to carry out a search for water at the lunar poles is described. The main elements of the concept are solar-electric propulsion, a miniature spacecraft, and a highly focused scientific mission. The major challenges to the spacecraft design were the mass and volume limits of the GAS canister, the incorporation of solar electric propulsion, and the high radiation exposure in the Van Allen belt. The capability of ion drive in carrying out high-performance missions is demonstrated.

Salazar, R. P.↗

NASA NTRS1991

Planetary instrument definition and development program: 'Miniature Monochromatic Imager'

The miniature monochromatic imager (MMI) development work became the basis for the preparation of several instruments which were built and flown on the shuttle STS-39 as well as being used in ground based experiments. The following subject areas are covered: (1) applications of the ICCD to airglow and auroral measurements and (2) a panchromatic spectrograph with supporting monochromatic imagers.

Broadfoot, A. L.↗

NASA NTRS1990

Miniaturized, 9-12 micron heterodyne spectrometer with space qualifiable design features

A demonstration-prototype CO2-laser heterodyne spectrometer operating at 9-12 microns and suitable for long-term space missions is described and illustrated with extensive diagrams, drawings, photographs, and graphs of test performance data. The spectrometer has total volume 0.63 cu m, mass 30 kg, and power requirement 60-70 W, compatible with miniature-class Space Shuttle experiment payload specifications. It comprises three modules: (1) an optical front end with reflecting optics, a 2-GHz BW HgCdTe photomixer, and a 0-2-GHz 40-dB RF preamplifier; (2) a local oscillator with an RF-excited waveguide CO2 laser, a 75-percent-efficiency RF amplifier, a stepper-driven grating mode selector, and an etalon stabilized for over 30,000 h of use; and (3) an RF-filter-bank spectral-line receiver with a 25-MHz RF channel, 1.6-GHz IF spectral coverage, onboard instrument control, a serial link to the host computer, and highly integrated design.

Glenar, D. A.↗

NASA NTRS1991

Development of a miniaturized, light-weight magnetic sector for a field-portable mass spectrograph

A miniaturized, lightweight magnetic sector for a focal plane mass spectrograph (Mattauch-Herzog design) has been designed and fabricated by using a new high-energy-product magnet material (Nd-B-Fe alloy) and a high permeability magnet yoke material (V-Co-Fe alloy). The magnetic sector weighs less than 10 kg, has a focal plane of 5.1 cm in length, and covers a nominal mass range of 40-240 amu. Such a magnetic sector, in conjunction with an array detector and a short microbore capillary column, is well suited for the development of a field-portable gas chromatograph-mass spectrometer instrument of high performance.

Sinha, M. P.↗

NASA NTRS1991

Miniaturized fiber-optic Michelson-type interferometric sensors

A novel, miniaturized Michelson-type fiber-optic interferometric sensor that is relatively insensitive to temperature drifts is presented. A fused-biconical tapered coupler is cleaved immediately after the coupled length and polished down to the region of the fused cladding, but short of the interaction region. The end of one core is selectively coated with a reflective surface and is used as the reference arm; the other core serves as the sensing arm. The detection of surface acoustic waves, microdisplacements, and magnetic fields is reported. The sensor is shown to be highly stable in comparison to a classic homodyne, uncompensated Michelson interferometer, and signal-to-noise ratios of 65 dB have been obtained.

Murphy, Kent A.↗

NASA NTRS1992

Forebody vortex control with miniature, rotatable nose-boom strakes

Experiments have been conducted in water and wind tunnel facilities to investigate the effectiveness of using rotatable miniaturized forebody nose-boom strakes to manipulate and control fighter aircraft forebody vortices at moderate to high angles of attack to provide potential aerodynamic control power in yaw. Water tunnel tests including flow visualization and yaw moment measurements were conducted on several different models of the F-16 fighter. Wind tunnel force and moment tests investigated the effects of several nose-boom strake configurations on an isolated 1/8th-scale X-29A forebody model. The primary variables of interest were strake size, configuration and roll angle orientation on the nose-boom. Both experiments showed clearly that small nose-boom strakes can be very effective in controlling the forebody vortex flowfield. Different degrees of flow asymmetry can be obtained by rotating a single or a pair of small strakes located on the nose-boom. With large fixed forebody strakes, such as those on the X-29A configuration, the effectiveness of the nose-boom strakes is significantly reduced.

Suarez, Carlos J.↗