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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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Nickel-cadmium batteries for the Modular Power Subsystem

Nickel-cadmium batteries of 20 and 50 ampere-hour (AH) capacity have been developed and qualified. These batteries provide an energy storage capability of 40 to 150 AH for the Modular Power Subsystem, which is the power source for NASA's Multimission Modular Spacecraft. Battery fabrication is rigidly controlled to assure uniform performance from battery to battery. A unique feature of the battery design is that cells from various manufacturers can be used for battery assembly without modification. Both 20 and 50-AH batteries have been delivered, and an MPS module with three 20-AH batteries is currently operating satisfactorily in low earth orbit. Design characteristics and performance of the batteries are described.

Mueller, V. C.↗
NASA NTRS1930

The Effect of Supercharger Capacity on Engine and Airplane Performance

This report presents the results of an investigation to determine the effect of different supercharger capacities on the performance of an airplane and its engine . The tests were conducted on a DH4-M2 airplane powered with a Liberty 12 engine. In this investigation four supercharger capacities, obtained by driving a roots type supercharger at 1.615, 1.957, 2.4, and 3 time engine speed, were used to maintain sea-level pressure at the carburetor to altitudes of 7,000, 11,500, 17,000, and 22,000 feet, respectively. The performance of the airplane in climb and in level flight was determined for each of the four supercharger drive ratios and for the unsupercharged condition. The engine power was measured during these tests by means of a calibrated propeller. It was found that very little sacrifice in sea-level performance was experienced with the larger supercharger drive ratios as compared with performance obtained when using the smaller drive ratios. The results indicate that further increase in supercharger capacity over that obtained when using 3:1 drive ratio would give a slight increase in ceiling and in high-altitude performance but would considerably impair the performance for an appreciable distance below the critical altitude. As the supercharger capacity was increased, the height at which sea-level high speeds could be equaled or improved became a larger percentage of the maximum height of operation of the airplane.

Schey, O W↗
NASA NTRS1980

Solar thermal plant impact analysis and requirements definition

Progress on a continuing study comprising of ten tasks directed at defining impact and requirements for solar thermal power systems (SPS), 1 to 10 MWe each in capacity, installed during 1985 through year 2000 in a utility or a nonutility load in the United States is summarized. The point focus distributed receiver (PFDR) solar power systems are emphasized. Tasks 1 through 4, completed to date, include the development of a comprehensive data base on SPS configurations, their performance, cost, availability, and potential applications; user loads, regional characteristics, and an analytic methodology that incorporates the generally accepted utility financial planning methods and several unique modifications to treat the significant and specific characteristics of solar power systems deployed in either central or distributed power generation modes, are discussed.

Gupta, Y. P.↗
NASA NTRS1982

Reliability model for planetary gear

A reliability model is presented for planetary gear trains in which the ring gear is fixed, the Sun gear is the input, and the planet arm is the output. The input and output shafts are coaxial and the input and output torques are assumed to be coaxial with these shafts. Thrust and side loading are neglected. This type of gear train is commonly used in main rotor transmissions for helicopters and in other applications which require high reductions in speed. The reliability model is based on the Weibull distribution of the individual reliabilities of the transmission components. The transmission's basic dynamic capacity is defined as the input torque which may be applied for one million input rotations of the Sun gear. Load and life are related by a power law. The load life exponent and basic dynamic capacity are developed as functions of the component capacities.

Savage, M.↗
NASA NTRS1984

A high voltage electrical power system for low Earth orbit applications

The results of testing a high voltage electrical power system (EPS) breadboard using high voltage power processing equipment developed at Marshall Space Flight Center and Ni-Cd batteries are discussed. These test results are used to extrapolate to an efficient, reliable, high capacity EPS for near term low Earth orbit, high power applications. EPS efficiencies, figures of merit, and battery reliability with a battery protection and reconditioning circuit are presented.

Lanier, J. R., Jr.↗
NASA NTRS2004

Multipulse PPM on memoryless channels

memoryless channels. First, we derive the maximum likelihood decision rule and an exact expression for the symbol error rate for n (greater-than or equal) 1, avoiding a numerically unstable aspect of = 1 formula of [GK76] and generalizing the n = 2 result of [SV03]. Next, we compare the capacity of multipulse PPM to that of conventional single-pulse PPM when averaged power, peak, and bandwidth constraints are simultaneously imposed. On the basis, we demonstrate that multipulse PPM does not produce appreciable gains over conventional PPM except at high average power.

optical communications↗
NASA NTRS1977

Electrical power requirements analysis. Single failure tolerant entry

The results of an analysis of the orbiter electrical power system for the case of a single failure tolerant (SFT) entry are presented. The analysis was performed using the shuttle electrical power system analysis computer program. It was performed to permit assessment of the capability of the orbiter systems to support the proposed entry configuration and to provide the data necessary to identify potential constraints and limitations. Three contingency modes have been identified which would require an SFT entry. This analysis addresses an SFT entry resulting from the loss of two fuel cell powerplants, while on orbit. The results of the analysis indicate that, even under near optimum conditions, the fuel cell power demand will exceed the tested operating capacity of 16 kw, and that various electrical components may experience voltages below 24 VDC.

Pipher, M. D.↗
NASA NTRS1984

STS II - Beyond Shuttle

Advanced launch vehicle systems, which could replace the Space Shuttle to meet the expanded space transportation demands of commercial, governmental, and military space users in the post 2000 time frame, are examined. Vehicle scenarios, mission requirements, vehicle concepts, economics, and technology requirements are assessed. Vehicle requirements are to achieve significant reductions in operations and life-cycle costs while increasing the overall launch capacity. Vehicle designs emphasize conventional rocket-powered configurations derived from Space Shuttle concepts and based on evolutionary technologies. Technologies focus on high performance, cost-effective design and manufacturing and on high operational productivity.

Eldred, C. H.↗
NASA NTRS1986

Error control techniques for satellite and space communications

The performance of NASA Telecommand System was analyzed. A random coding approach was taken to determine the optimum code rate to use in forward error correcting (FEC) system with a fixed signal energy to noise power density ration, but no bandwidth constraint. Capacity and cutoff rates of concatened coding systems were determined. A lower bound on the minium distance growth rate between unmerged codewords was obtained for time invarient convolutional codes.

Costello, D. J., Jr.↗
NASA NTRS1993

Momentum accumulation due to solar radiation torque, and reaction wheel sizing, with configuration optimization

This paper has a two-fold objective: determination of yearly momentum accumulation due to solar radiation pressure, and optimum reaction wheel sizing. The first objective is confronted while determining propellant consumption by the attitude control system over a spacecraft's lifetime. This, however, cannot be obtained from the daily momentum accumulation and treating that constant throughout the year, because the orientation of the solar arrays relative to the spacecraft changes over a wide range in a year, particularly if the spacecraft has two arrays, one normal and the other off-normal to different extent at different times to the sun rays. The paper first develops commands for the arrays for tracking the sun, the arrays articulated to earth-pointing spacecraft with two rotational degrees of freedom, and spacecraft in an arbitrary circular orbit. After developing expressions for solar radiation torque due to one or both arrays, arranged symmetrically or asymmetrically relative to the spacecraft bus, momentum accumulation over an orbit and then over a year are determined. The remainder of the paper is concerned with designing reaction wheel configurations. Four-, six-, and three-wheel configurations are considered, and for given torque and momentum requirements, their cant angles with the roll/yaw plane are optimized for minimum power consumption. Finally, their momentum and torque capacities are determined for one-wheel failure scenario, and six configurations are compared and contrasted.

Hablani, Hari B.↗
NASA NTRS1994

Optical storage media data integrity studies

Optical disk-based information systems are being used in private industry and many Federal Government agencies for on-line and long-term storage of large quantities of data. The storage devices that are part of these systems are designed with powerful, but not unlimited, media error correction capacities. The integrity of data stored on optical disks does not only depend on the life expectancy specifications for the medium. Different factors, including handling and storage conditions, may result in an increase of medium errors in size and frequency. Monitoring the potential data degradation is crucial, especially for long term applications. Efforts are being made by the Association for Information and Image Management Technical Committee C21, Storage Devices and Applications, to specify methods for monitoring and reporting to the user medium errors detected by the storage device while writing, reading or verifying the data stored in that medium. The Computer Systems Laboratory (CSL) of the National Institute of Standard and Technology (NIST) has a leadership role in the development of these standard techniques. In addition, CSL is researching other data integrity issues, including the investigation of error-resilient compression algorithms. NIST has conducted care and handling experiments on optical disk media with the objective of identifying possible causes of degradation. NIST work in data integrity and related standards activities is described.

Podio, Fernando L.↗
NASA NTRS2008

NASA Global Hawk Project Overview

This viewgraph presentation reviews the Global Hawk project planning. Global Hawk is the only available system capable of simultaneously meeting the requirements for high altitude (65K ft), long endurance (>31 hours), power (10 KVA), and a large payload capacity (2000 lbs). There are important science data gathering and satellite validation requirements that can only be met with the combination of capabilities provided by the Global Hawk system. Global Hawk will give a unique range, shown in maps, at a high altitude. An overview of the design of the aircraft, and the ground station is given. The flights are scheduled to begin in 2009, and will carry instruments that will be used to validate the Aura satellite data and also be used in hurricane and severe storm research.

DelFrate, John↗
NASA NTRS2009

The Concept and Experimental Investigation of CO2 and Steam Co-electrolysis for Resource Utilization in Space Exploration

CO2 acquisition and utilization technologies will have a vital role in determining sustained and affordable life support and in-situ fuel production architectures for human and robotic exploration of Moon and Mars. For long-term human exploration to be practical, reliable technologies have to be implemented to capture and chemically reduce the metabolic CO2 from the cabin air to restitute oxygen consumption. Technologies that facilitate the in-situ capture and conversion of atmospheric CO2 to fuel are essential for a viable human mission to Mars and their demonstration on the moon is critical as well. This paper describes the concept and experimental investigation of a CO2 capture and reduction system that comprises an adsorption compressor and a CO2 and steam co-electrolysis unit. The process products include oxygen for life support and Syngas (CO and H2) for synthetic fuel production. Electrochemical performance in terms of CO2 conversion, oxygen production, and power consumption of a system with a capacity to process 1kg CO2 per day (1-person equivalent) will be discussed.

Stoots, Carl↗
NASA NTRS2010

Instrument for Analysis of Greenland's Glacier Mills

A new instrument is used to study the inner workings of Greenland s glacier mills by riding the currents inside a glacier s moulin. The West Greenland Moulin Explorer instrument was deployed into a tubular shaft to autonomously record temperature, pressure, 3D acceleration, and location. It is built with a slightly positive buoyancy in order to assist in recovery. The unit is made up of several components. A 3-axis MEMS (microelectromechanical systems) accelerometer with 0.001-g resolution forms the base of the unit. A pressure transducer is added that is capable of withstanding 500 psi (=3.4 MPa), and surviving down to -40 C. An Iridium modem sends out data every 10 minutes. The location is traced by a GPS (Global Positioning System) unit. This GPS unit is also used for recovery after the mission. Power is provided by a high-capacity lithium thionyl chloride D-sized battery. The accelerometer is housed inside a cylindrical, foot-long (=30 cm) polyvinyl chloride (PVC) shell sealed at each end with acrylic. The pressure transducer is attached to one of these lids and a MEMS accelerometer to the other, recording 100 samples per second per axis.

Behar, Alberto E.↗
NASA NTRS2010

The Extravehicular Maneuvering Unit's New Long Life Battery and Lithium Ion Battery Charger

The Long Life (Lithium Ion) Battery is designed to replace the current Extravehicular Mobility Unit Silver/Zinc Increased Capacity Battery, which is used to provide power to the Primary Life Support Subsystem during Extravehicular Activities. The Charger is designed to charge, discharge, and condition the battery either in a charger-strapped configuration or in a suit-mounted configuration. This paper will provide an overview of the capabilities and systems engineering development approach for both the battery and the charger

Russell, Samuel P.↗
NASA NTRS2022

International Standard Measures During the AGBRESA Bed Rest Study

The Artificial Gravity Bed Rest with European Space Agency (AGBRESA) study involved 2 campaigns of 60-day bed rest at 6° head down tilt in the:envihab facility in Cologne, Germany, in 2019. The objective was to determine whether centrifugation of supine subjects mitigates physiological changes that occur due to the exposure to the spaceflight analog of 6° head down tilt. A set of international standard measures was used to evaluate bone, muscle, nutritional status, ocular changes, and psychological state and to assess cardiovascular, sensorimotor, and immune systems functions. After 60 days of bed rest, the subjects who were not exposed to centrifugation had significant decreases in mineral density at the hip and lumbar spine, decreased muscle strength of the knee and ankle, reduced maximal aerobic capacity, orthostatic intolerance, and impaired balance and locomotion, as well as significant biochemical, immunological, and psychological alterations. A daily 30-min exposure to 1 Gz supine centrifugation at the center of mass (0.3 Gz at the head, 2 Gz at the feet) mitigated mineral density loss in the femur neck and lumbar spine; and lessened the effects of bed rest on aerobic capacity, biochemistry, and immunology. However, low statistical power could contribute to the non-significant effects that are reported.

Bed rest↗
NASA NTRS2015

Zero Boil-Off System Testing

Cryogenic propellants such as liquid hydrogen (LH2) and liquid oxygen (LO2) are a part of NASA's future space exploration due to their high specific impulse for rocket motors of upper stages suitable for transporting 10s to 100s of metric tons of payload mass to destinations outside of low earth orbit and for their return. However, the low storage temperatures of LH2 and LO2 cause substantial boil-off losses for missions with durations greater than several months. These losses can be eliminated by incorporating high performance cryocooler technology to intercept heat load to the propellant tanks and modulating the cryocooler to control tank pressure. The active thermal control technology being developed by NASA is the reverse turbo-Brayton cycle cryocooler and its integration to the propellant tank through a distributed cooling tubing network coupled to the tank wall. This configuration was recently tested at NASA Glenn Research Center, in a vacuum chamber and cryoshroud that simulated the essential thermal aspects of low Earth orbit, its vacuum and temperature. Testing consisted of three passive tests with the active cryocooler system off, and 7 active tests, with the cryocooler powered up. The test matrix included zero boil-off tests performed at 90 full and 25 full, and several demonstrations at excess cooling capacity and reduced cooling capacity. From this, the tank pressure response with varied cryocooler power inputs was determined. This test series established that the active cooling system integrated with the propellant tank eliminated boil-off and robustly controlled tank pressure.

Plachta, David W.↗