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  • 1
    Publikationsdatum: 2020-01-23
    Beschreibung: As aircraft move to using composite materials as their primary structure they become lighter and more flexible as well. This presents some significant challenges in association with gust load alleviation. In this paper we develop an aeroservoelastic model for use in developing controllers that utilize distributed control surfaces for active gust load alleviation in a set of wind tunnel experiments. The model is based on an preexisting aeroelastic wing tunnel model and compares the baseline functionality to it. We also provide simple full state feedback simulations for the model.
    Schlagwort(e): Aerodynamics
    Materialart: AIAA 2020-0211 , ARC-E-DAA-TN76375 , AIAA Scitech 2020 Forum; Jan 06, 2020 - Jan 10, 2020; Orlando, FL; United States
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  • 2
    Publikationsdatum: 2020-01-17
    Beschreibung: The key measurement to acquire for understanding unsteady flow is surface pressure. Unsteady Pressure-Sensitive Paint (uPSP) is an emerging optical technique used in wind tunnel testing to measure fluctuating surface pressures. Recently, tests were conducted on NASAs Space Launch System in NASA Ames Research Centers Unitary Plan Wind Tunnel to determine the aeroacoustics environment and assist in developing the buffet forcing functions. Unsteady PSP data was collected during this test campaign. Steady state PSP data, infrared thermography, shadowgraph, accelerometer data, and dynamic pressure transducer data were also collected. In all 50 TB of data were collected during the three days of testing. During these three days of testing, a repeating transonic and supersonic alpha sweep condition was acquired. This paper presents these two wind tunnel conditions and examines how the temperature influences the PSP data. In the first large demonstration of uPSP in 2015 on an NESC-, AETC-sponsored wind tunnel test, lifetime PSP results highlighted the influence the model temperature had on the PSP data. A best practice of heat soaking the model before acquiring calibration images was followed during the test campaign presented in this paper. An infrared thermography camera and thermocouples were installed in the model to collect more details of the model surface temperature. Data processing schemes for uPSP are still in development but will be briefly presented here as well.
    Schlagwort(e): Aerodynamics
    Materialart: ARC-E-DAA-TN76119 , AIAA SciTech Forum; Jan 06, 2020 - Jan 10, 2020; Orlando, FL; United States
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  • 3
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    In:  CASI
    Publikationsdatum: 2006-01-12
    Beschreibung: Practices are outlined for the design, installation, checkout, calibration, and operation of a system to be used for measuring propellant flow in a liquid monopropellant rocket engine. Design guidelines rather than detailed specifications are provided for the critical components of each portion of the system. System elemental uncertainties are presented in an appendix.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: Handbook of Recommended Practices for the Determination of Liquid Monopropellant Rocket Engine Performance; 32 p
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  • 4
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    In:  CASI
    Publikationsdatum: 2006-01-12
    Beschreibung: Practices are outlined for the design, installation, checkout, calibration, and operation of a pressure measuring system to be used during tests of a liquid monopropellant rocket engine. Appendixes include: (1) pressure measurement system elemental uncertainties; (2) short- and long-term pressure measurement system uncertainty; (3) shunt calibration of pressure transducers; (4) special considerations for vacuum measurement; and (5) methods of determining the dynamic characteristics of pressure transducers. Design guidelines are provided for the critical components of each portion of the system to provide a pressure measurement system which meets the performance criteria specified.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: Handbook of Recommended Practices for the Determination of Liquid Monopropellant Rocket Engine Performance; 76 p
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  • 5
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    In:  CASI
    Publikationsdatum: 2006-01-12
    Beschreibung: The design, installation, checkout, calibration, and operation of a temperature measuring system to be used during tests of a liquid monopropellant rocket engine are discussed. Appendixes include: (1) temperature measurement system elemental uncertainties, and (2) tables and equations for use with thermocouples and resistance thermometers. Design guidelines are given for the critical components of each portion of the system to provide an optimum temperature measurement system which meets the performance criteria specified.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: Handbook of Recommended Practices for the Determination of Liquid Monopropellant Rocket Engine Performance; 36 p
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  • 6
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    In:  CASI
    Publikationsdatum: 2006-01-12
    Beschreibung: Practices are outlined for the design, installation, checkout, calibration, and operation of a thrust measurement system to be used during tests of a liquid monopropellant rocket engine. Appendixes include: (1) thrust measurement system elemental uncertainties; (2) short- and long-term thrust measurement system uncertainty; and (3) shunt calibration of force transducers.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: Handbook of Recommended Practices for the Determination of Liquid Monopropellant Rocket Engine Performance; 28 p
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  • 7
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    In:  CASI
    Publikationsdatum: 2006-01-12
    Beschreibung: Definitions, algorithms, and procedures for the reduction of monopropellant thruster measurements to performance parameters are provided. A brief discussion of acquisition and recording systems is also included. Emphasis is placed upon monopropellant hydrazine engines, and some parameters relate specifically to the catalytic decomposition of hydrazine (e.g., percent ammonia dissociation). Performance of other types of monopropellant thrusters may, however, be determined by using procedures similar to those discussed. Two appendixes are included: (1) theoretical performance of monopropellant hydrazine; and (2) calculation of rotational performance.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: Handbook of Recommended Practices for the Determination of Liquid Monopropellant Rocket Engine Performance; 45 p
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  • 8
    Publikationsdatum: 2011-08-17
    Beschreibung: 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.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: Astronautik; 16; 2, 19; 1979
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  • 9
    Publikationsdatum: 2011-08-17
    Beschreibung: To simulate the behavior of a high voltage solar cell array in the ionospheric plasma environment, the large (90 ft x 55 ft diameter) vacuum chamber was used to measure the high-voltage plasma interactions of a 3 ft x 30 ft conductive panel. The chamber was filled with Nitrogen and Argon plasma at electron densities of up to 1,000,000 per cu cm. Measurements of current flow to the plasma were made in three configurations: (a) with one end of the panel grounded, (b) with the whole panel floating while a high bias was applied between the ends of the panel, and (c) with the whole panel at high negative voltage with respect to the chamber walls. The results indicate that a simple model with a constant panel conductivity and plasma resistance can adequately describe the voltage distribution along the panel and the plasma current flow. As expected, when a high potential difference is applied to the panel ends more than 95% of the panel floats negative with respect to the plasma.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
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  • 10
    Publikationsdatum: 2011-08-17
    Beschreibung: Annealing of electron-irradiation damage in GaAs solar cells is important for space applications. This paper describes studies conducted to understand this annealing process. GaAs heteroface solar cells were irradiated with 10 to the 15th 1-MeV electrons/sq cm followed by thermal annealing. An activation energy for annealing of 1.25 + or - 0.14 eV and a frequency factor of (3.7 + or - 1.9) x 10 to the 9th per sec were determined. A small component of the irradiation damage which does not anneal measurably at 200 C was observed.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: Applied Physics Letters; 35; Sept. 15
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  • 11
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    In:  Other Sources
    Publikationsdatum: 2011-08-17
    Beschreibung: The study evaluates the use of electrets as a new contamination-detecting device designed to assess the chemical composition of rocket effluents. Evaluation of electret effectiveness revealed that electrets have multipollutant-measuring capability, simplicity of deployment and rapidity of assessment. Advantages of electrets are small size, light weight and cost-effectiveness. It is shown that electrets compare favorably with other HCl measuring devices. In particular, the summary of the measured data from electrets and HCl detectors is within the limits of computed HCl concentrations from the NASA/MSFC multilayer diffusion model.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: Journal of Applied Meteorology; 18; Jan. 197
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  • 12
    Publikationsdatum: 2011-08-17
    Beschreibung: Dramatic changes in both aircraft and space power systems are being projected. The primary driver is mission cost, although more stringent performance requirements are also being imposed. The order-of-magnitude reductions anticipated in space power, both in cost and specific mass, are partially related to the advent of the Shuttle and the continuing evolution of the STS over the next decade. Automation, microcircuitry, batteries, and structural materials are common aircraft and space technology needs.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: Astronautics and Aeronautics; 17; Feb. 197
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  • 13
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    In:  CASI
    Publikationsdatum: 2017-10-02
    Beschreibung: The design, installation, checkout, and operation of an exhaust gas composition measurement system for collecting and analyzing the exhaust gas from a liquid monopropellant rocket engine are described. Design guidelines are given for the critical components of each portion of the system to provide an exhaust gas composition measurement which meets the performance criteria specified.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: Handbook of Recommended Practices for the Determination of Liquid Monopropellant Rocket Engine Performance; 13 p
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  • 14
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    In:  CASI
    Publikationsdatum: 2019-06-28
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-CR-172838 , NAS 1.26:172838 , PB83-181040
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  • 15
    Publikationsdatum: 2019-06-28
    Beschreibung: The updated study plan for the Space Transportation System orbit transfer vehicle (OTV) engine study is presented. The study program consists of engine system, programmatic, cost, and risk analyses of OTV engine concepts. Detailed task descriptions for the advanced expander cycle engine optimization, alternate low thrust capability, and safety, reliability, and cost comparisons are given.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-CR-161708 , REPT-32999-SP2
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  • 16
    Publikationsdatum: 2019-06-28
    Beschreibung: The performance optimization of expander cycle engines at vacuum thrust levels of 10K, 15K, and 20K lb is discussed. The optimization is conducted for a maximum engine length with an extendible nozzle in the retracted position of 60 inches and an engine mixture ratio of 6.0:1. The thrust chamber geometry and cycle analyses are documented. In addition, the sensitivity of a recommended baseline expander cycle to component performance variations is determined and chilldown/start propellant consumptions are estimated.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-CR-161710 , REPT-3299-E1-T1
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  • 17
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    In:  Other Sources
    Publikationsdatum: 2019-06-27
    Beschreibung: The computational procedure for signal propagation in the presence of an exhaust plume is presented. Comparisons with well-known analytic diffraction solutions indicate that accuracy suffers when mesh spacing is inadequate to resolve the first unobstructed Fresnel zone at the plume edge. Revisions to the procedure to improve its accuracy without requiring very large arrays are discussed. Comparisons to field measurements during a shuttle solid rocket motor (SRM) test firing suggest that the plume is sharper edged than one would expect on the basis of time averaged electron density calculations. The effects, both of revisions to the computational procedure and of allowing for a sharper plume edge, are to raise the signal level near tail aspect. The attenuation levels then predicted are still high enough to be of concern near SRM burnout for northerly launches of the space shuttle.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: APL JANNAF 11th Plume Technol. Meeting, Vol. 2; p 1-25
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  • 18
    Publikationsdatum: 2019-06-27
    Beschreibung: A model for the boundary layer at the exit plane of a rocket nozzle was developed which, unlike most previous models, includes the subsonic sublayer. The equations for the flow near the nozzle exit plane are presented and the method by which the subsonic sublayer transitions to supersonic flow in the plume is described. The resulting model describes the entire boundary layer and can be used to provide a startline for method-of-characteristics calculations of plume flowfields. The model was incorporated into a method of characteristics computer program and comparisons of computed results to experimental data show good agreement. The data used in the comparisons were obtained in tests in which mass fluxes from a 22.2-N (5 lbf) thrust engine were measured at angles off the nozzle centerline of up to 150 deg. Additional comparisons were made with data obtained during tests of a 0.89-N (0.2 lbr) monopropellant thruster and from the OH-64 space shuttle heating tests. The agreement with the data indicates that the model can be used for calculating plume backflow properties.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: APL JANNAF 11th Plume Technol. Meeting, Vol. 2; p 147-165
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  • 19
    Publikationsdatum: 2019-06-27
    Beschreibung: The paper describes the results of an experimental study of the quantitative determination of the capabilities of the combustion processes associated with coaxial gaseous propellant rocket injectors to drive combustor pressure oscillations. The data, obtained by employing the modified impedance tube technique with compressed air as the oxidizer and acetylene gas as the fuel, describe the frequency dependence of the admittance of the combined injector-combustion process. The measured data are compared with the predictions of the Feiler and Heidmann analytical model utilizing different values for the characteristic combustion time tau sub b. The values of tau sub b which result in a best fit between the measured and predicted data are indicated for different equivalence ratios. It is shown that for the coaxial injector investigated in this study the tau sub b varies between 0.7 and 1.2 msec for equivalence ratios in the range of 0.57 to 1.31. In addition, the experimental data indicate that the tested injector system could drive combustion instabilities over a frequency range that is in qualitative agreement with the predictions of the Feiler and Heidmann model.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: Combustion Science and Technology; 20; 5-6,; 1979
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  • 20
    Publikationsdatum: 2019-06-27
    Beschreibung: A computer code is presented for predicting incident thermal radiation from defined plume gas properties in either axisymmetric or cylindrical coordinate systems. The radiation model is a statistical band model for exponential line strength distribution with Lorentz/Doppler line shapes for 5 gaseous species (H2O, CO2, CO, HCl and HF) and an appoximate (non-scattering) treatment of carbon particles. The Curtis-Godson approximation is used for inhomogeneous gases, but a subroutine is available for using Young's intuitive derivative method for H2O with Lorentz line shape and exponentially-tailed-inverse line strength distribution. The geometry model provides integration over a hemisphere with up to 6 individually oriented identical axisymmetric plumes, a single 3-D plume, Shading surfaces may be used in any of 7 shapes, and a conical limit may be defined for the plume to set individual line-of-signt limits. Intermediate coordinate systems may specified to simplify input of plumes and shading surfaces.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-CR-161496 , RTR-014-9
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  • 21
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    In:  CASI
    Publikationsdatum: 2019-06-27
    Beschreibung: A propulsion concept was developed based on a proposed resonance between coherent, pulsed electromagnetic wave forms, and gravitational wave forms (or space-time metrics). Using this concept a spacecraft propulsion system potentially capable of galactic and intergalactic travel without prohibitive travel times was designed. The propulsion system utilizes recent research associated with magnetic field line merging, hydromagnetic wave effects, free-electron lasers, laser generation of megagauss fields, and special structural and containment metals. The research required to determine potential, field resonance characteristics and to evaluate various aspects of the spacecraft propulsion design is described.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-TM-80961 , JSC-16073
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  • 22
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    In:  CASI
    Publikationsdatum: 2019-06-27
    Beschreibung: The design, procurement, testing, and application of aerospace quality, hermetically sealed nickel-cadmium cells and batteries are presented. Cell technology, cell and battery development, and spacecraft applications are emphasized. Long term performance is discussed in terms of the effect of initial design, process, and application variables. Design guidelines and practices are given.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-RP-1052
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  • 23
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    In:  CASI
    Publikationsdatum: 2019-06-27
    Beschreibung: Inert gas thrusters considered for space propulsion systems were investigated. Electron diffusion across a magnetic field was examined utilizing a basic model. The production of doubly charged ions was correlated using only overall performance parameters. The use of this correlation is therefore possible in the design stage of large gas thrusters, where detailed plasma properties are not available. Argon hollow cathode performance was investigated over a range of emission currents, with the positions of the inert, keeper, and anode varied. A general trend observed was that the maximum ratio of emission to flow rate increased at higher propellant flow rates. It was also found that an enclosed keeper enhances maximum cathode emission at high flow rates. The maximum cathode emission at a given flow rate was associated with a noisy high voltage mode. Although this mode has some similarities to the plume mode found at low flows and emissions, it is encountered by being initially in the spot mode and increasing emission. A detailed analysis of large, inert-gas thruster performance was carried out. For maximum thruster efficiency, the optimum beam diameter increases from less than a meter at under 2000 sec specific impulse to several meters at 10,000 sec. The corresponding range in input power ranges from several kilowatts to megawatts.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-CR-159813
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  • 24
    Publikationsdatum: 2019-06-27
    Beschreibung: The results of the verification testing sequence V-2 performed on the space shuttle solid rocket booster thrust vector control subsystem are presented. A detailed history of the hot firings plus additional discussion of the auxiliary power unit and the hydraulic component performance is presented. The test objectives, data, and conclusions are included.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-TM-78258
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  • 25
    Publikationsdatum: 2019-06-27
    Beschreibung: A rocket propellant feed system utilizing a bleed turbopump to supercharge a topping turbopump is presented. The bleed turbopump is of a low pressure type to meet the cavitation requirements imposed by the propellant storage tanks. The topping turbopump is of a high pressure type and develops 60 to 70 percent of the pressure rise in the propellant.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
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  • 26
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    In:  CASI
    Publikationsdatum: 2019-06-27
    Beschreibung: The analysis, design, fabrication, and testing of a liquid rocket engine thrust chamber which is gas transpiration cooled in the high heat flux convergent portion of the chamber and water jacket cooled (simulated regenerative) in the barrel and divergent sections of the chamber are described. The engine burns LOX-hydrogen propellants at a chamber pressure of 600 psia. Various transpiration coolant flow rates were tested with resultant local hot gas wall temperatures in the 800 F to 1400 F range. The feasibility of transpiration cooling with hydrogen and helium, and the use of photo-etched copper platelets for heat transfer and coolant metering was successfully demonstrated.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-CR-159742
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  • 27
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    In:  CASI
    Publikationsdatum: 2019-06-27
    Beschreibung: An injector for 3000 psia chamber pressure using liquid oxygen and gaseous methane propellants is presented. The injector is intended to be evaluated during a series of pressure-fed test firings using a water-cooled calorimeter chamber and a milled-slot regenerative chamber. Combustion efficiency, combustion stability, ignition and injector face heat transfer assessments were made for candidate injector body and pattern design approaches. This evaluation resulted in baselining an oxidizer post type manifold with a 60 element platelet coaxial swirler injector pattern. An axial acoustic resonator cavity was created at the injector/chamber interface.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-CR-161343 , REPT-33205F
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  • 28
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    In:  CASI
    Publikationsdatum: 2019-06-27
    Beschreibung: An orbital transfer vehicle OTV engine study program was undertaken to provide additional expander and staged combustion cycle data in the design definition of the OTV engine. The proposed program effort optimizes the expander cycle engine concept (consistent with identified OTV engine requirements), investigates the feasibility of kitting the staged combustion cycle engine to provide extended low thrust operation, and conducts in-depth analysis of development risk, crew safety, and reliability for both cycles. Additional tasks to establish the cost of a 10K thrust expander cycle engine and to render support of OTV systems study contractors are reported.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-CR-161338 , ASR79-116 , MPR-2
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  • 29
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    In:  CASI
    Publikationsdatum: 2019-06-28
    Beschreibung: The feasibility of using Brayton power systems for nuclear electric spacecraft was investigated. The primary performance parameters of systems mass and radiator area were determined for systems from 100 to 1000 kW sub e. Mathematical models of all system components were used to determine masses and volumes. Two completely independent systems provide propulsion power so that no single-point failure can jeopardize a mission. The waste heat radiators utilize armored heat pipes to limit meteorite puncture. The armor thickness was statistically determined to achieve the required probability of survival. A 400 kW sub e reference system received primary attention as required by the contract. The components of this system were defined and a conceptual layout was developed with encouraging results. An arrangement with redundant Brayton power systems having a 1500 K (2240 F) turbine inlet temperature was shown to be compatible with the dimensions of the space shuttle orbiter payload bay.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-CR-168942 , NAS 1.26:168942 , AIRESEARCH-31-3321
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  • 30
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    In:  CASI
    Publikationsdatum: 2019-06-28
    Beschreibung: The recession characteristics of the materials used to closeout the Thermal Protection System (TPS) on the Space Shuttle Solid Rocket Booster (SRB) were assessed. Two candidate closeout materials namely, K5NA and MTA2 is the Marshall Trowelable Ablator. Test panels of each of these two materials were subjected to aerodynamic heat and shear in the NASA Hot Gas Facility. Pretest and Post-test measurements were taken and the rate of recession (R) thus determined was correlated with the heating rate. A least squares curve fit of the data together with another least squares 95% confidence level fit, was performed. The characteristics of the two materials when compared showed that both materials performed equally well at the higher heating rates (10 q 30 Btu/sq ft/sec) but MTA2 was slightly better, not receding as fast, at the lower q values. The comparison of the R versus q curves for K5NA and MTA2 with that of primary TPS P-50 cork on the SRB Aft Skirt was good.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-CR-170885 , NAS 1.26:170885 , LMSC-HREC-TN-D697757
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  • 31
    Publikationsdatum: 2019-07-27
    Beschreibung: An experimental program to determine the feasibility of using a heavy hydrocarbon fuel as a rocket propellant is reported herein. A method of predicting performance of a heavy hydrocarbon in terms of vaporization effectiveness is described and compared to other fuels and to experimental test results. The work was done at a chamber pressure of 4137 KN/sq M (600 psia) with RP-1, JP-10, and liquefied natural gas as fuels, and liquid oxygen as the oxidizer. Combustion length effects were explored over a range of 21.6 cm (8 1/2 in.) to 55.9 cm (22 in.). Four injector types were tested, each over a range of mixture ratios. Further configuration modifications were obtained by 'reaming' each injector several times to provide test data over a range of injector pressure drop.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: Combustion Conference; Sept. 10-14, 1979; Monterey, CA
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  • 32
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    In:  Other Sources
    Publikationsdatum: 2019-06-27
    Beschreibung: Age related cracks in the graphite phenolic linear and/or ATJ insert in several nine year old Altair IIA solid rocket nozzles were investigated and determined to be limited to a single lot of nozzles. Test results and photomicrographs of fracture surfaces are presented which establish that in the discrepant nozzles the bond between the graphite fibers and the phenolic resin was tenacious, resulting in a nearly homogenous behavior. These materials are shown to have a relatively weak resin - fiber bond and behave more like a released fiber composite. Lot qualification fiber directional tensile strength and the chemical composition of the two materials were comparable, indicating that standard acceptance testing could not have differentiated between the desirable and undesirable material. Review of processing records failed to reveal any cause for the difference in the aging characteristics.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: APL The 1979 JANNAF Propulsion Meeting, Vol. 1; p 461-472
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  • 33
    Publikationsdatum: 2019-06-27
    Beschreibung: The design, installation, and operation of systems to be used for directly measuring quantities of fundamental importance to the determination of monopropellant thruster performance is described. Areas covered include: (1) force and impulse measurement; (2) propellant mass usage and flow measurement; (3) pressure measurement; (4) temperature measurement; (5) exhaust gas composition measurement; and (6) data reduction and performance determination.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-CR-162111 , JPL-PUB-79-32
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  • 34
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    In:  CASI
    Publikationsdatum: 2019-06-27
    Beschreibung: The development of an analytical technique used in the solution of nonlinear velocity-sensitive combustion instability problems is presented. The Galerkin method was used and proved successful. The pressure wave forms exhibit a strong second harmonic distortion and a variety of behaviors are possible depending on the nature of the combustion process and the parametric values involved. A one dimensional model provides insight into the problem by allowing a comparison of Galerkin solutions with more exact finite difference computations.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-CR-158884
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  • 35
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    In:  CASI
    Publikationsdatum: 2019-06-27
    Beschreibung: The problems of combustion instability in an annular combustion chamber are investigated. A modified Galerkin method was used to produce a set of modal amplitude equations from the general nonlinear partial differential acoustic wave equation. From these modal amplitude equations, the two variable perturbation method was used to develop a set of approximate equations of a given order of magnitude. These equations were modeled to show the effects of velocity sensitive combustion instabilities by evaluating the effects of certain parameters in the given set of equations. By evaluating these effects, parameters which cause instabilities to occur in the combustion chamber can be ascertained. It is assumed that in the annular combustion chamber, the liquid propellants are injected uniformly across the injector face, the combustion processes are distributed throughout the combustion chamber, and that no time delay occurs in the combustion processes.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-CR-158885
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  • 36
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    In:  CASI
    Publikationsdatum: 2019-06-27
    Beschreibung: Plug cluster engine design, performance, weight, envelope, operational characteristics, development cost, and payload capability, were evaluated and comparisons were made with other space tug engine candidates using oxygen/hydrogen propellants. Parametric performance data were generated for existing developed or high technology thrust chambers clustered around a plug nozzle of very large diameter. The uncertainties in the performance prediction of plug cluster engines with large gaps between the modules (thrust chambers) were evaluated. The major uncertainty involves, the aerodynamics of the flow from discrete nozzles, and the lack of this flow to achieve the pressure ratio corresponding to the defined area ratio for a plug cluster. This uncertainty was reduced through a cluster design that consists of a plug contour that is formed from the cluster of high area ratio bell nozzles that have been scarfed. Light-weight, high area ratio, bell nozzles were achieved through the use of AGCarb (carbon-carbon cloth) nozzle extensions.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-CR-159520
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  • 37
    Publikationsdatum: 2019-06-27
    Beschreibung: A program for predicting the linear stability of liquid propellant rocket engines is presented. The underlying model assumptions and analytical steps necessary for understanding the program and its input and output are also given. The rocket engine is modeled as a right circular cylinder with an injector with a concentrated combustion zone, a nozzle, finite mean flow, and an acoustic admittance, or the sensitive time lag theory. The resulting partial differential equations are combined into two governing integral equations by the use of the Green's function method. These equations are solved using a successive approximation technique for the small amplitude (linear) case. The computational method used as well as the various user options available are discussed. Finally, a flow diagram, sample input and output for a typical application and a complete program listing for program MODULE are presented.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-CR-3169
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  • 38
    Publikationsdatum: 2019-06-27
    Beschreibung: Three rocket thrust chambers with copper liners and a thrust level of 20.9 kN were cyclically test fired to failure. Two of the liners were made from oxygen free, high conductivity (OFHC) copper and from annealed Amzirc. The milled coolant channels were closed out with a thin copper closeout over which a fiberglass composite was wrapped to provide hoop strength only. Experimental data are presented, along with the results of a preliminary analysis that was performed before fabrication to evaluate the life extending potential of a thin copper closeout with a fiberglass overwrap.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-TP-1456 , E-9870
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  • 39
    Publikationsdatum: 2019-07-13
    Beschreibung: An investigation of parameters that affect the erosion rates of 30-cm-diameter mercury-ion-thruster components is described. A sputter-erosion model is formulated in terms of the design, operational, and material characteristics of the thruster. The erosion model is applied to the screen electrode, which is assumed to be the life-limiting component of the 30-cm thruster, resulting in a model of wearout lifetime. Results of short-term erosion-rate tests are presented that illustrate the dependence of component wear rates on variables such as discharge voltage, accelerator-grid open-area fraction, ion energy, electrode material, and the partial pressure of facility residual gases such as nitrogen. Test results are compared with wearout rates predicted by the sputter-erosion model.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-2079 , International Electric Propulsion Conference; Oct 30, 1979 - Nov 01, 1979; Princeton, NJ
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  • 40
    facet.materialart.
    Unbekannt
    In:  Other Sources
    Publikationsdatum: 2019-07-13
    Beschreibung: Cathodes, isolators, and vaporizers are critical components in determining the performance and lifetime of mercury ion thrusters. The results of life tests of several of these components are reported. A 30-cm thruster CIV test in a bell jar has successfully accumulated over 26,000 hours. The cathode has undergone 65 restarts during the life test without requiring any appreciable increases in starting power. Recently, all restarts have been achieved with only the 44 volt keeper supply with no change required in the starting power. Another ongoing 30-cm Hg thruster cathode test has successfully passed the 10,000 hour mark. A solid-insert, 8-cm thruster cathode has accumulated over 4,000 hours of thruster operation. All starts have been achieved without the use of a high voltage ignitor. The results of this test indicate that the solid impregnated insert is a viable neutralizer cathode for the 8-cm thruster.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-2116 , International Electric Propulsion Conference; Oct 30, 1979 - Nov 01, 1979; Princton, NJ
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  • 41
    facet.materialart.
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    In:  Other Sources
    Publikationsdatum: 2019-07-13
    Beschreibung: Ground-based tests of Hg ion thrusters have identified sputter erosion of thruster components as one of the main life limiting phenomena. Subsequent measurements have revealed that sputtering rates can be affected by background gases at pressures as low as 10 to the -10th torr. With the recent interest in thin film technology, sputtering in the presence of reactive gases has been studied in great detail. This paper presents the results of many of those studies and applies them to the sputtering of electric thrusters. A model, which assumes that chemisorption is the dominant mechanism, is applied to the sputtering rate measurements of the screen grid of a 30-cm thruster in the presence of nitrogen. The model utilizes inputs from a variety of experimental and analytical sources. The model of environmental effects on sputtering was applied to thruster conditions of low discharge voltage and a discussion of the comparison of theory and experiment is presented.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-2061 , International Electric Propulsion Conference; Oct 30, 1979 - Nov 01, 1979; Princeton, NJ
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  • 42
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    In:  Other Sources
    Publikationsdatum: 2019-07-13
    Beschreibung: Inert gas thrusters, particularly with large diameters, have continued to be of interest for space propulsion applications. Two plasma processes are treated in this study: electron diffusion across magnetic fields and double ion production in inert-gas thrusters. A model is developed to describe electron diffusion across a magnetic field that is driven by both density and potential gradients, with Bohm diffusion used to predict the diffusion rate. This model has applications to conduction across magnetic fields inside a discharge chamber, as well as through a magnetic baffle region used to isolate a hollow cathode from the main chamber. A theory for double ion production is presented, which is not as complete as the electron diffusion theory described, but it should be a useful tool for predicting double ion sputter erosion. Correlations are developed that may be used, without experimental data, to predict double ion densities for the design of new and especially larger ion thrusters.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-2055 , International Electric Propulsion Conference; Oct 30, 1979 - Nov 01, 1979; Princeton, NJ
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  • 43
    Publikationsdatum: 2019-07-13
    Beschreibung: Measurements of the pulsed plasma thruster (PPT) plume upstream mass flux were made in the Molecular Sink (MOLSINK) vacuum facility in order to minimize the plume-tank wall reflected mass flux. Using specially designed collimators on 4 rows of Quartz Crystal Microbalanced (QCMs) mounted on a support extending radially away from the plume axis, measurements were made of the mass flux originating in a thin slice of the PPT primary plume at an arbitrary dip angle with respect to the thruster axis. The measured and analytically corrected mass flux from particles reflected from the MOLSINK walls was substracted from the collimated QCM measurements to improve their accuracy. These data were then analytically summed over dip angle to estimate the total plume backflow upstream of the thruster nozzle. The results indicate that the PPT backflow is of order 10 to the minus 10th power g/square cm/pulse in the region from 38 to 86 cm from the PPT axis in the nozzle exit plane. This flux drops with the square of the radial distance from the PPT axis and is comparable to the backflow of an 8 cm ion thruster, which has performance characteristics similar to those of the PPT.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-CR-162786 , JPL-PUB-79-105 , AFRPL-TR-79-60
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  • 44
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    In:  CASI
    Publikationsdatum: 2019-07-13
    Beschreibung: The regenerative cooling limits (maximum chamber pressure) for 02/hydrocarbon gas generator and staged combustion cycle rocket engines over a thrust range of 89,000 N (20,000lbf) to 2,669,000 N (600,000 lbf) for a reusable life of 250 missions were defined. Maximum chamber pressure limits were first determined for the three propellant combinations (O2/CH4, O2/C3H8, and O2/RP-1 without a carbon layer (unenhanced designs). Chamber pressure cooling enhancement limits were then established for seven thermal barriers. The thermal barriers evaluated for these designs were: carbon layer, ceramic coating, graphite liner, film cooling, transpiration cooling, zoned combustion, and a combination of two of the above. All fluid barriers were assessed a 3 percent performance loss. Sensitivity studies were then conducted to determine the influence of cycle life and RP-1 decomposition temperature on chamber pressure limits. Chamber and nozzle design parameters are presented for the unenahanced and enhanced designs. The maximum regenerative cooled chamber pressure limits were attained with the O2/CH4 propellant combination. The O2/RP-1 designs relied on a carbon layer and liquid gas injection chamber contours, short chamber, to be competitive with the other two propellant combinations. This was attributed to the low decomposition temperature of RP-1.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-CR-159790 , RI/RD79-310
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  • 45
    facet.materialart.
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    In:  CASI
    Publikationsdatum: 2019-07-13
    Beschreibung: Experimental tests results demonstrating that reductions in screen grid thickness enhance the performance of ion thruster grids are presented. Shaping of the screen hole cross section is shown on the other hand not to affect performance substantially. The effect of the magnetic field in the vicinity of the hollow cathode on cathode performance is studied and test results are presented that show reductions in keeper voltages of a few volts can be realized by judicious applications of fields on the order of 100 gauss. The plasma downstream of a SERT 2 thruster operating without high voltage is studied. A model describing electron escape from the thruster under these conditions is discussed. A model defining the performance of the baffle aperture of an ion thruster is refined and experimental verification of the model is undertaken.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-CR-159784
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  • 46
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    In:  CASI
    Publikationsdatum: 2019-07-13
    Beschreibung: A consistent engine system data base was generated for defining advantages and disadvantages, system performance and operating limits, engine parametric data, and technology requirements for candidate high pressure LO2/HC engine systems. Optimum LO2/HC engine power cycles were synthetized and representative conceptual engine design generated for a specified advanced surface to orbit transportation system.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-CR-161350 , MPR-33452M-1
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  • 47
    Publikationsdatum: 2019-07-13
    Beschreibung: The design, fabrication, and demonstration of a 111 newton (25 lb) thrust, integrated auxiliary propulsion system (IAPS) thruster for use with LH2/LO2 propellants is described. Hydrogen was supplied at a temperature range of 22 to 33 K (40 to 60 R), and oxygen from 89 to 122 K (160 to 220 R). The thruster was designed to operate in both pulse mode and steady-state modes for vehicle attitude control, space maneuvering, and as an abort backup in the event of failure of the main propulsion system. A dual-sleeve, tri-axial injection system was designed that utilizes a primary injector/combustor where 100 percent of the oxygen and 8 percent of the hydrogen is introduced; a secondary injector/combustor where 45 percent of the hydrogen is introduced to mix with the primary combustor gases; and a boundary layer injector that uses the remaining 45 percent of the hydrogen to cool the thrust throat/nozzle design. Hot-fire evaluation of this thruster with a BLC injection distance of 2.79 cm (1.10 in.) indicated that a specific impulse value of 390 sec can be attained using a coated molybdenum thrust chamber. Pulse mode tests indicated that a chamber pressure buildup to 90 percent thrust can be achieved in a time on the order of 48 msec. Some problems were encountered in achieving ignition of each pulse during pulse trains. This was interpreted to indicate that a higher delivered spark energy level ( 100 mJ) would be required to maintain ignition reliability of the plasma torch ignition system under the extra 'cold' conditions resulting during pulsing.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-CR-159674 , RI/RD79-217
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  • 48
    facet.materialart.
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    In:  Other Sources
    Publikationsdatum: 2019-07-13
    Beschreibung: The theoretical and experimental study described was carried out to gain insight into the physical-chemical mechanism which controls hypergolic propellant reactive stream separation (RSS), with a view toward establishing design criteria. The approach employed was to observe photographically single element injector combustion of N2O4/MMH, N2O4/A-50, and N2O4/N2H4 propellants. Single element injectors were used to provide an unobstructed view of the impingement zone. Hot firings were conducted in a special photographic chamber. High-speed color motion pictures were used to identify the occurrence of RSS. Four conventional unlike doublet injectors, two conventional triplet injectors, and three platelet injectors were used in the tests. A simulation of the Space Shuttle platelet injector was included. The most important design criterion derived from the study states that the element should be designed to avoid transitions between mixed and separated modes within the engine operational envelope.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-0154 , American Institute of Aeronautics and Astronautics, Aerospace Sciences Meeting; Jan 15, 1979 - Jan 17, 1979; New Orleans, LA
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  • 49
    Publikationsdatum: 2019-07-13
    Beschreibung: This paper discusses the design of a Nuclear Electric Propulsion (NEP) system, selection of thrusters and propellant. Outer planet exploration requirements are compared to earth orbital power requirements and a nuclear electric power system with a power level of 200 to 250 kWe is recommended. Current technology appears capable of accomplishing the early missions and growth potential exists for accomplishing more difficult later missions without significant changes in the basic system.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-1337 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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  • 50
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    In:  Other Sources
    Publikationsdatum: 2019-07-13
    Beschreibung: The successful static test of the fourth Development Space Shuttle Solid Rocket Motor (SRM) in February 1979 concluded the development testing phase of the SRM Project. Qualification and flight motors are currently being fabricated, with the first qualification motor to be static tested. Delivered thrust-time traces on all development motors were very close to predicted values, and both specific and total impulse exceeded specification requirements. 'All-up' static tests conducted with a solid rocket booster equipment on development motors achieved all test objectives. Transportation and support equipment concepts have been proven, baselining is complete, and component reusability has been demonstrated. Evolution of the SRM transportation support equipment, and special test equipment designs are reviewed, and development activities discussed. Handling and processing aspects of large, heavy components are described.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-1136 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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  • 51
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    In:  Other Sources
    Publikationsdatum: 2019-07-13
    Beschreibung: The propellant management device that was successfully used in the Viking Orbiter spacecraft was selected for the main propulsion system of the Teleoperator Retrieval System (TRS). Due to differences in the missions and different propellants, the operation of this sheet metal vane device required reverification for the TRS application. An analytical investigation was performed considering the adverse acceleration environment and the high contract angle of the hydrazine propellant. Drop tower tests demonstrated that the device would provide propellant acquisition while the TRS was docked with Skylab, but its operation would have to be supplemented through propellant settling when free-flying.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-1259 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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  • 52
    Publikationsdatum: 2019-07-13
    Beschreibung: The results of an investigation are presented on the applicability of a microwave Doppler shift technique for directly determining propellant response functions over the desired frequency range. The investigation consisted of three phases. In Phase 1 the validity of the technique was established by comparing measured pressure-coupled response function data to existing data from T-burners and rotating valve tests. In Phase 2 a new microwave burner-pressure modulation system capable of achieving frequencies and mean chamber pressures of at least 1500 Hz and 10.5 MPa (1500 psia), respectively, was developed. During Phase 3 test firings are being carried out to define the frequency limit, response function resolution, and precision of the new design.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-1211 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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  • 53
    Publikationsdatum: 2019-07-13
    Beschreibung: The Solid Rocket Booster, Thrust Vector Control (TVC) system was designed in accordance with the following requirements: self-contained power supply, fail-safe operation, 20 flight uses after exposure to seawater landings, optimized cost, and component interchangeability. Trade studies were performed which led to the selection of a recirculating hydraulic system powered by Auxiliary Power Units (APU) which drive the hydraulic actuators and gimbal the solid rocket motor nozzle. Other approaches for the system design were studied in arriving at the recirculating hydraulic system powered by an APU. These systems must withstand the imposed environment and be usable for a minimum of 20 Space Transportation System flights with a minimum of refurbishment. The TVC system has completed the major portion of qualification and verification tests and is prepared to be cleared for the first Shuttle flight (STS-1). Substantiation data will include analytical and test data.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-1139 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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  • 54
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2019-07-13
    Beschreibung: Life predictions of regeneratively cooled rocket thrust chambers are normally derived from classical material fatigue principles. The failures observed in experimental thrust chambers do not appear to be due entirely to material fatigue. The chamber coolant walls in the failed areas exhibit progressive bulging and thinning during cyclic firings until the wall stress finally exceeds the material rupture stress and failure occurs. A preliminary analysis of an oxygen free high conductivity (OFHC) copper cylindrical thrust chamber demonstrated that the inclusion of cumulative cyclic plastic effects enables the observed coolant wall thinout to be predicted. The thinout curve constructed from the referent analysis of 10 firing cycles was extrapolated from the tenth cycle to the 200th cycle. The preliminary OFHC copper chamber 10-cycle analysis was extended so that the extrapolated thinout curve could be established by performing cyclic analysis of deformed configurations at 100 and 200 cycles. Thus the original range of extrapolation was reduced and the thinout curve was adjusted by using calculated thinout rates at 100 and 100 cycles. An analysis of the same underformed chamber model constructed of half-hard Amzirc to study the effect of material properties on the thinout curve is included.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-CR-159522 , LMSC-HREC-TR-D568827-VOL-1
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  • 55
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2019-07-13
    Beschreibung: A model, which assumes that chemisorption is the dominant mechanism, is applied to the sputtering rate measurements of the screen grid of a 30 cm thruster in the presence of nitrogen. The model utilizes inputs from a variety of experimental and analytical sources. The model of environmental effects on sputtering was applied to thruster conditions of low discharge voltage and a discussion of the comparison of theory and experiment is presented.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-TM-79266 , E-181 , Intern. Conf. on Electric Propulsion; Oct 31, 1979 - Nov 02, 1979; Princeton, NJ; United States
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  • 56
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    In:  CASI
    Publikationsdatum: 2019-07-13
    Beschreibung: A history of the fuel cell technology is presented and compared with NASA's increasing space power requirements. The role of fuel cells is discussed in perspective with other energy storage systems applicable for space using such criteria as type of mission, weight, reliability, costs, etc. Potential applications of space fuel cells with projected technology advances were examined.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-TM-79182 , E-042 , Energy Conversion Eng. Conf.; Aug 05, 1979 - Aug 10, 1979; Boston, MA; United States
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  • 57
    facet.materialart.
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    In:  Other Sources
    Publikationsdatum: 2019-07-13
    Beschreibung: The paper analyzes the consequences of heat pipe failures, that resulted in modifications to the basic design of a heat-pipe cooled, fast spectrum nuclear reactor and led to consideration of an entirely different core design. The new design features an integral laminated core configuration consisting of alternating layers of UO2 and molybdenum sheets that span the diameter of the core. Design characteristics are presented and compared for two reactors. A conceptual design for a heat exchanger between the core and the thermionic converter assembly is described. This heat exchanger would provide design and fabrication decoupling of these two assemblies.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: LA-UR-79-1243 , Intersociety Energy Conversion Engineering Conference; Aug 05, 1979 - Aug 10, 1979; Boston, MA
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  • 58
    facet.materialart.
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    In:  Other Sources
    Publikationsdatum: 2019-07-13
    Beschreibung: The system breadboard for the demonstration of Automated Power Systems Management (APSM) functions has been designed, fabricated, and is in the final stages of verification and testing. APSM functions fall into categories of fault detection and correction, commanding system and subsystem test and diagnoses, relay position monitoring, data acquisition and processing, and power management. All these functions are accomplished through software residing in 8-bit microprocessors dedicated to each group of Viking Orbiter power breadboard subassemblies and a 16-bit microprocessor serving as the central processor for the power system. This paper describes key monitoring, diagnostic, and control algorithms used in the APSM breadboard.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: Intersociety Energy Conversion Engineering Conference; Aug 05, 1979 - Aug 10, 1979; Boston, MA
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  • 59
    facet.materialart.
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    In:  Other Sources
    Publikationsdatum: 2019-07-13
    Beschreibung: The Standard Power Regulator Unit (SPRU) which forms the central building block of the Modular Power Subsystem (MPS) for the Multi-mission Modular Spacecraft (MMS) is described. A functional description of the SPRU is presented, detailing key design features, operational characteristics, and internal redundancy as well as giving block and schematic diagrams for all major subassemblies. The description of a qualification test program consisting of ten sequences ranging from a physical examination of the unit to calculating vibration and sine sweep of power on shock tests is presented. The results showed that some significant anomalies were encountered but no catastrophic failures were indicated, although several power module failures were found due to overvoltage malfunctions of the solar array stimulator.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: Intersociety Energy Conversion Engineering Conference; Aug 05, 1979 - Aug 10, 1979; Boston, MA
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  • 60
    facet.materialart.
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    In:  Other Sources
    Publikationsdatum: 2019-07-13
    Beschreibung: A large scale test of 6.0 Ah Nickel-Cadmium Cells conducted at the Naval Weapons Support Center, Crane, Indiana has demonstrated a methodology for predicting battery life based on failure data from cells cycled in an accelerated mode. After examining eight variables used to accelerate failure, it was determined that temperature and depth of discharge were the most reliable and efficient parameters for use in accelerating failure and for predicting life.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: Intersociety Energy Conversion Engineering Conference; Aug 05, 1979 - Aug 10, 1979; Boston, MA
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  • 61
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    Publikationsdatum: 2019-07-13
    Beschreibung: The paper presents a mechanism which offers an explanation of the observed behavior of nickel-cadmium cells during voltage reversal. Constant current reversals using aerospace Ni-Cd cells showed that at rates of C/100 and temperatures of 20 C, a steady condition of constant pressure is achieved with continuous overdischarge. Results of a test employing a battery pack of thirteen 24 Ah cells at 10 C showed that: (1) no net evolution of H occurs in Ni-Cd cells during overdischarge, (2) as H pressure increases the rate of pressure rise decreases, and (3) after attaining pressure equilibrium at a given overdischarge rate, a pressure decrease is noted when the discharge is lowered. Other tests using varying overdischarge rates were examined and have resulted in the development of a laboratory cell with a safe overdischarge capability of C/20 which is three times as great as state-of-the-art Ni-Cd cells.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: Intersociety Energy Conversion Engineering Conference; Aug 05, 1979 - Aug 10, 1979; Boston, MA
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  • 62
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    Publikationsdatum: 2019-07-13
    Beschreibung: A concept for solar array augmentation of the power normally provided by the Shuttle Orbiter fuel cells in support of payloads is discussed. Justification for the use of solar arrays rather than additional cryogenic fuel kits for extension of on-orbit stay time is presented. This is followed by a description of the array power system and an examination of its interfaces with the existing Orbiter fuel cell system. The system produces 29 kW total with 14 kW allocated to the Orbiter and 15 kW to payloads and permits an increase in on-orbit mission duration from 6 to approximately 20 days at 21 kW with four cryo kits. It is capable of producing full output in diverse vehicle orientations since the array is deployed and oriented by the Orbiter remote manipulator system (RMS). Power produced by the arrays is reduced to 32.25 to 32.5 volts by pulse-width-modulated buck voltage regulators to force the Orbiter fuel cells into an idle mode during the sunlighted portions of the orbit.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: Intersociety Energy Conversion Engineering Conference; Aug 05, 1979 - Aug 10, 1979; Boston, MA
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  • 63
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    Publikationsdatum: 2019-07-13
    Beschreibung: This paper presents a study of evolutionary growth concepts for the 25 kW power module to augment STS mission support future capabilities. The study aimed to establish user payload requirements, define evolution methods for system initial operational capability, and formulate a development program and conceptual designs. The payload requirements analysis focused on material processing in space, public services, and solar terrestrial observations; evolutionary system concepts were evaluated to derive the power module and system support requirements, and four reference orbits were used to construct the nominal program scenario. The mission accomodations analysis evaluated the capability of the nominal program scenario and associated power module concepts to meet user needs. Finally, the recommended modular design consisting of electric power, attitude control, thermal control, and command and data handling is described, and it is concluded that the 25 kW power module is a logical first step to support the near term NASA sortie and free-flyer mission requirements.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: Intersociety Energy Conversion Engineering Conference; Aug 05, 1979 - Aug 10, 1979; Boston, MA
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  • 64
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    Publikationsdatum: 2019-07-13
    Beschreibung: The Pioneer Venus Orbiter and the Multiprobe spacecraft propulsion subsystems and their performance are presented. Monopropellant hydrazine subsystems on each spacecraft provided the capability to spin up the spacecraft after separation and perform all spin rate, velocity, and attitude changes required by the control subsystem to satisfy mission objectives. The propulsion subsystem provides thrust on demand by supplying anhydrous hydrazine from the propellant tanks through manifolds, filters and valves to the thrust chamber assemblies where the hydrazine is catalytically decomposed and expanded in a conical nozzle. The subsystems consist of seven 1 lbf thrusters for the Orbiter and six 1 lbf thrusters for the multiprobe which are isolated by two latch valves from the two propellant tanks so that two redundant thruster clusters are provided to ensure mission completion in the event of a single point failure. The propellant feed system is of all-welded construction to minimize weight and leakage and titanium is used as the primary material of construction. The multiprobe burned up on entering the Venus atmosphere with enough propellant left for the mission and the Orbiter was inserted into Venus orbit with enough propellant remaining for more than 2 earth years of orbital operations.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-1329 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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  • 65
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    Publikationsdatum: 2019-07-13
    Beschreibung: During the last year, significant progress was made toward the development of the Space Shuttle Main Engine, which will provide propulsion for the Space Shuttle Orbiter vehicle. Engine system testing continued at the National Space Technology Laboratories on both single engines and a three-engine cluster. A third single engine test position was activated at the Rocketdyne Santa Susana Field Laboratory to provide additional capability for demonstrating increasing engine maturity and for solving problems. The results of engine system testing is discussed as well as the major problems identified and the design changes incorporated to solve those problems. A review of the program efforts toward the delivery of the first set of flight engines and the certification of the SSME for manned flight is included.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-1141 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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  • 66
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    Publikationsdatum: 2019-07-13
    Beschreibung: The need for large structures in high orbit is discussed in terms of the many mission opportunities which require such structures. Mission and transportation options for large structures are presented, and it is shown that low-thrust propulsion is an enabling requirement for some missions and greatly enhancing to many others. A general comparison of electric and low-thrust chemical propulsion is made and the need for and requirements of low-thrust chemical propulsion are discussed in terms of the interactions that are perceived to exist between the propulsion system and the large structure.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-1182 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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  • 67
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    Publikationsdatum: 2019-07-13
    Beschreibung: A 30-cm-diam mercury ion thruster, using two or three grid ion accelerating systems, is operated at increased values of beam current. Comparisons with the SEP (Solar Electric Propulsion) and EPSEP (Extended Performance SEP) baseline thrusters are made with respect to performance and lifetime. It is found that when a third, or decelerator, grid is added to the conventional two-grid optics of a SEP-like thruster, the ion beam focusing properties are improved, as expected from theoretical considerations. The total thruster efficiency as a function of specific impulse, is increased for values of specific impulse in the range 1200-2800 sec. Lifetime test results predict a thruster lifetime, under space conditions, not less than that of the baseline SEP thruster.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-0910 , Conference on Advanced Technology for Future Space Systems; May 08, 1979 - May 10, 1979; Hampton, VA
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  • 68
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    Publikationsdatum: 2019-06-27
    Beschreibung: A methodology for the reliability analysis of a reusable solid rocket motor case is discussed in this paper. The analysis is based on probabilistic fracture mechanics and probability distribution for initial flaw sizes. The developed reliability analysis can be used to select the structural design variables of the solid rocket motor case on the basis of minimum expected cost and specified reliability bounds during the projected design life of the case. Effects on failure prevention plans such as nondestructive inspection and the material erosion between missions can also be considered in the developed procedure for selection of design variables. The reliability-based procedure that has been discussed in this paper can easily be modified to consider other similar structures of reusable space vehicle systems with different fracture control plans.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 77-384
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  • 69
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    In:  CASI
    Publikationsdatum: 2019-06-27
    Beschreibung: An approximate technique for analyzing nonlinear waves in solid propellant rocket motors is presented which inexpensively provides accurate results up to amplitudes of ten percent. The connection with linear stability analysis is shown. The method is extended to third order in the amplitude of wave motion in order to study nonlinear stability, or triggering. Application of the approximate method to the behavior of pulses is described.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AGARD Solid Rocket Motor Technol.; 15 p
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  • 70
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    In:  CASI
    Publikationsdatum: 2019-06-27
    Beschreibung: A passive propellant acquisition and feed system is disclosed which acquires and feeds gas-free propellant in low or zero-g environments during orbital maneuvers and retains this propellant under high axially directed acceleration such as may be experienced during launch of a space vehicle and orbit-to-orbit transfer is described. The propellant system includes a dual compartment propellant tank with independent surface tension acquisition channels in each compartment to provide gas-free flow of pressurized liquid propellant from one compartment to the other in one direction only.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
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  • 71
    Publikationsdatum: 2019-06-27
    Beschreibung: The charge exchange plasma environment around a spacecraft that uses mercury ion thrusters for propulsion is described. The interactions between the plasma environment and the spacecraft are determined and a model which describes the propagation of the mercury charge exchange plasma is discussed. The model is extended to describe the flow of the molybdenum component of the charge exchange plasma. The uncertainties in the models for various conditions are discussed and current drain to the solar array, charge exchange plasma material deposition, and the effects of space plasma on the charge exchange plasma propagation are addressed.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-CR-162358 , JPL-PUB-79-90
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  • 72
    Publikationsdatum: 2019-06-27
    Beschreibung: A detailed computer model of the expander cycle engine system steady-state operation was developed. Payload performance data for the expander cycle engine for 100K pounds and 65K pounds Space Shuttle missions were examined to establish peak payload thrusts. It was found that peak payload for the 100K pound gross weight single engine case occurred at nearly 15,000 pounds thrust for both engine mixture ratios of 6:1 and 7:1. Peak payload at engine mixture ratio of 6:1 was 4 percent greater than at 7:1 mixture ratio. The two engine configuration peak paYloads occurred at engine thrust below 7,500 pounds (extrapolated) and were lower than single engine payloads. For the 65K pound gross weight mission, peak payloads for the single engine configuration occurred at nearly 10,000 pounds for both mixture ratios. Mixture ratio of 7:1 payloads were 5 percent lower than 6:1 payloads. Two engine configuration payloads occurred at engine thrusts considerably below 10K pounds.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-CR-161318 , ASR79-109 , BMPR-1
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  • 73
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    In:  CASI
    Publikationsdatum: 2019-06-27
    Beschreibung: A propulsion system analysis of the dual fuel, dual throat engine for launch vehicle applications was conducted. Basic dual throat engine characterization data were obtained to allow vehicle optimization studies to be conducted. A preliminary baseline engine system was defined.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-CR-161304 , REPT-32967F
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  • 74
    Publikationsdatum: 2019-06-27
    Beschreibung: A rotating, positive displacement vane pump with an integral boost stage was designed to pump saturated liquid oxygen and liquid hydrogen for auxiliary propulsion system of orbit transfer vehicle. This unit is designed to ingest 10% vapor by volume, contamination free liquid oxygen and liquid hydrogen. The final pump configuration and the predicted performance are included.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-CR-159648
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  • 75
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    In:  CASI
    Publikationsdatum: 2019-06-27
    Beschreibung: The principal characteristics of the 30-centimeter ion propulsion thrust subsystem technology that was developed to satisfy the propulsion needs of future planetary and early orbital missions are described. Functional requirements and descriptions, interface and performance requirements, and physical characteristics of the hardware are described at the thrust subsystem, BIMOD engine system, and component level.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-TM-79191 , E-060
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  • 76
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    In:  CASI
    Publikationsdatum: 2019-06-27
    Beschreibung: A power control circuit connected between a solar array and an ion thruster receives voltage and current signals from the solar array. The control circuit multiplies the voltage and current signals together to produce a power signal which is differentiated with respect to time. The differentiator output is detected by a zero crossing detector and, after suitable shaping, the detector output is phase compared with a clock in a phase demodulator. An integrator receives no output from the phase demodulator when the operating point is at the maximum power but is driven toward the maximum power point for non-optimum operation. A ramp generator provides minor variations in the beam current reference signal produced by the integrator in order to obtain the first derivative of power.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
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  • 77
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    Publikationsdatum: 2019-07-27
    Beschreibung: The 25-kW power module design and operational characteristics and the benefits for payloads are presented. The module will allow the Shuttle Orbiter to be utilized on-orbit to its optimum capability of power and duration for sortie/Spacelab missions, and will provide central power-rich base for free-flyer payloads requiring increased electrical power and on-orbit stay-times of up to 5 years. Concepts of the module in the sortie and free-flyer modes are depicted with resource capabilities for experimentation in astronomy, solar physics, solar terrestrial observations, and materials processing which require long duration and/or high power missions. In the sortie mode operation the Orbiter fuel cell will be in an idle mode, with the 25-kW module providing payload power needs, and in the free-flyer mode the module will provide power needs to multiple payloads. Design considerations, the thermal control subsystem, the attitude control subsystem, command and data handling, and the electrical power subsystem are described.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: IAF PAPER 79-164 , International Astronautical Federation, International Astronautical Congress; Sept. 17-22, 1979; Munich
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  • 78
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    Publikationsdatum: 2019-07-27
    Beschreibung: High-acceleration mass drivers are discussed including the MD2 model of axial geometry, with individually powered drive coils of 13.1 cm diameter. Timing is derived through the interruption of light beams by the moving armature (bucket). Electric power is provided by the resonant discharge of sector capacitor banks through silicon-controlled rectifiers in a two-phase, quadrature circuit. The bucket flies in vacuum, guided by passive dynamic eddy-current magnetic forces, those currents flowing in strip conductors lining the inside of a nonconducting vacuum pipe. Quantitative measurements are obtained with a solid bucket carrying two superconducting coils with a current density of 25 kA/sq cm. A cryogenic station for cooling the bucket to liquid helium temperature is connected to the vacuum pipe.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: IAF PAPER 79-118 , International Astronautical Federation, International Astronautical Congress; Sept. 17-22, 1979; Munich
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  • 79
    Publikationsdatum: 2019-08-14
    Beschreibung: The development of a technique to be used in the solution of nonlinear velocity-sensitive combustion instability problems is described. The orthogonal collocation method was investigated. It found that the results are heavily dependent on the location of the collocation points and characteristics of the equations, so the method was rejected as unreliabile. The Galerkin method, which has proved to be very successful in analysis of the pressure sensitive combustion instability was found to work very well. It was found that the pressure wave forms exhibit a strong second harmonic distortion and a variety of behaviors are possible depending on the nature of the combustion process and the parametric values involved. A one-dimensional model provides further insight into the problem by allowing a comparison of Galerkin solutions with more exact finite-difference computations.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-CR-159733
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  • 80
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    In:  CASI
    Publikationsdatum: 2019-07-13
    Beschreibung: The paper describes the development of a thick (t/c = 0.18) transonic, multifoil, blown augmentor-wing section and discusses the results of a series of wind-tunnel tests on the configuration. The results show that the blown multifoil section enjoys two advantages over a conventional unblown single-foil supercritical section or the same overall thickness-chord ratio: 1) "effective" drag reduced by blowing, and 2) increased drag rise Mach number (M(sub D) = 0.75); they also demonstrate that augmentor blowing improves the buffet boundaries of the section. Thus, overall, it has been shown that the augmentor flap configuration is capable of extending the speed range of a jet transport aircraft to the very low approach speeds required by STOL aircraft [as demonstrated by the NASA/DITC (Canadian Department of Industry Trade and Commerce) augmentor-wing STOL research aircraft] and also to the high subsonic speed required for cruise, where it is shown to be competitive with the plain supercritical airfoil.
    Schlagwort(e): Aerodynamics
    Materialart: AIAA Paper 77-606 , Journal of Aircraft; 15; 755-761|V/STOL Conference; Jun 06, 1977 - Jun 08, 1977; Palo Alto, CA; United States
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  • 81
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    Publikationsdatum: 2019-08-28
    Beschreibung: The NASA Electric Propulsion technology program is focused at three major specific objectives - to develop the Baseline Solar Electric Propulsion (SEP) technology for interplanetary transportation applications; to develop ion thruster technology for auxiliary propulsion applications; and to research fundamental processes and advanced concepts. This paper will discuss accomplishments since the last Electric Propulsion Conference, the current status of the program, and future directions.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-2118 , International Electric Propulsion Conference; Oct 30, 1979 - Nov 01, 1979; Princeton, NJ
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  • 82
    Publikationsdatum: 2019-08-28
    Beschreibung: The glossary presented is based entirely on terms used in the monographs on Chemical Propulsion. Significant terms relating to material properties and to material fabrication are presented. The terms are arranged in alphabetical order, with multiple word terms appearing in the normal sequence of usage; for example, ablative cooling appears as such, not as cooling, ablative, and lip seal appears as such, not as seal, lip. Conversion Factors for converting U.S. customary units to the International System of Units are presented in alphabetical order of the physical quantity (e.g., density, heat flux, specific impulse) involved.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: NASA-SP-8126
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  • 83
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    Publikationsdatum: 2019-07-13
    Beschreibung: A low specific weight (20 to 40 Kg/Kwe), long life (6 to 10 year), 100 to 400 KWe nuclear electric propulsion (NEP) system can deliver 2,000 to 10,000 Kg payloads for intensive study of our solar system. The nuclear power source is about 80% of the NEP system mass, thus the NASA program is focused on developing the power source technology. Because of the long life requirements, direct thermal to electric energy conversion technology (thermionic and thermoelectric) is being pursued. In order to meet the low specific weight it is necessary to develop a 10 to 15% conversion module with a 875 K minimum heat rejection temperature and a 1675 K maximum input temperature. The thermoionic converter is about 9% efficient at these temperatures. The thermoelectric converter is limited to a 1300 K input temperature. So, the thermionic program is focused on improving the efficiency while the thermoelectric program is focused on increasing the temperature.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-2088 , International Electric Propulsion Conference; Oct 30, 1979 - Nov 01, 1979; Princeton, NJ
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  • 84
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    Publikationsdatum: 2019-07-13
    Beschreibung: The characteristics of power processors strongly impact the overall performance and cost of electric propulsion systems. A program was initiated to evaluate simplifications of the thruster-power processor interface requirements. The power processor requirements are mission dependent with major differences arising for those missions which require a nearly constant thruster operating point (typical of geocentric and some inbound planetary missions) and those requiring operation over a large range of input power (such as outbound planetary missions). This paper describes the results of tests which have indicated that as many as seven of the twelve power supplies may be eliminated from the present Functional Model Power Processor used with 30-cm diameter Hg ion thrusters.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-2081 , International Electric Propulsion Conference; Oct 30, 1979 - Nov 01, 1979; Princeton, NJ
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  • 85
    Publikationsdatum: 2019-07-13
    Beschreibung: The paper deals with some preliminary results of the Mission Profile Life Test planned to conduct a program of long-term test segments of 30-cm diameter thrusters and power processing units under computer control. Thruster performance data and other operational characteristics taken at various times during a test segment are compared and the results are evaluated in light of the life-timing mechanisms. Thruster control algorithms are also presented. The first test segment completed 2700 hr of a planned 4000 hr test with a J-series 30-cm thruster. The last 1600 hr used a functional model power processing unit (PPU) operated in vacuum. The thruster-PPU was controlled by a computer with software developed to control start-ups, throttling, and variety of off-normal conditions.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-2078 , International Electric Propulsion Conference; Oct 30, 1979 - Nov 01, 1979; Princeton, NJ
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  • 86
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    Publikationsdatum: 2019-07-13
    Beschreibung: A theoretical model describing the formation of nitrogen species subject to chemisorption on ion thruster discharge chamber surfaces is presented. Molecules, atoms, atomic ions and molecular ions are identified as the important species in the analysis. Current densities of the atomic and molecular ions predicted by the model are compared to current densities measured in the beam of a SERT II thruster. The predicted and measured values of these two current densities are shown to agree within about + or - 100%. The mechanisms involved in the erosion of a surface subjected to simultaneous nitrogen chemisorption and sputter erosion by high energy ions are also discussed.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-2062 , International Electric Propulsion Conference; Oct 30, 1979 - Nov 01, 1979; Princeton, NJ
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  • 87
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    Publikationsdatum: 2019-07-13
    Beschreibung: The use of advanced electric propulsion systems will provide cost and performance benefits for future energetic space missions. A methodology to predict the characteristics of advanced electric propulsion systems was developed and programmed for computer calculations to allow evaluation of a broad set of technology and mission assumptions. The impact on overall thrust system characteristics was assessed for variations of propellant type, total accelerating voltage, thruster area, specific impulse, and power system approach. The data may be used both to provide direction to technology emphasis and allow for preliminary estimates of electric propulsion system properties for a wide variety of application.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-2041 , International Electric Propulsion Conference; Oct 30, 1979 - Nov 01, 1979; Princeton, NJ
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  • 88
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    Publikationsdatum: 2019-07-13
    Beschreibung: Experiments in which a high-power, quasi-steady MPD thruster is scaled down by a factor of two indicate that the key features of MPD thruster operation are replicated in the smaller version. Voltage-current data over a 24:1 mass flow range show that the ablation onset parameter is constant for each thruster, although the constant is not the same. Time-integrated photographs of the discharge radiance reveal strikingly similar features at scaled values of current and mass flow. The measured terminal properties of the half-scale thruster are similar to the full-scale thruster, but the regime of operation is smaller and generally less efficient, except within a restricted range of arc current and mass flow.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-2075 , International Electric Propulsion Conference; Oct 30, 1979 - Nov 01, 1979; Princeton, NJ
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  • 89
    Publikationsdatum: 2019-07-13
    Beschreibung: Magnetoplasmadynamic (MPD) thrusters with 10-cm and 2.5-cm long thoriated tungsten cathodes have been operated with both inductive and capacitive energy sources at currents up to 8 kA. Voltage-current characteristics and magnetic field measurements show that over most of the operating range, the inductively driven thruster acts as a continuously varying quasi-steady accelerator at the same current. However, at values of a specified parameter near the onset condition for voltage fluctuations and electrode and insulator erosion, the voltage for the inductively driven thruster is higher than its quasi-steady counterpart. This higher voltage occurs because the equilibration time constant of the MPD discharge, is too large to allow the terminal voltage to attain a quasi-steady value as the inductively driven current decreases.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-2073 , International Electric Propulsion Conference; Oct 30, 1979 - Nov 01, 1979; Princeton, NJ
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  • 90
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    In:  Other Sources
    Publikationsdatum: 2019-07-13
    Beschreibung: The exhaust plume of the one millipound pulsed plasma thruster has a measurable backflow upstream of the nozzle exit plane which may deposit on and degrade the performance of exposed spacecraft surfaces. High speed photographs and Faraday cup measurements suggest that this backflow is predominantly an electrically neutral, relatively low energy vapor. Articulated collimator quartz crystal microbalance measurements of this backflow were made for a thruster with a radically modified nozzle and a flat plate backflow shield, to determine the backflow sensitivity to nozzle design changes. The results are compared with the original nozzle backflow and show a measurable reduction in the backflow directly upstream of the shield.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-2106 , International Electric Propulsion Conference; Oct 30, 1979 - Nov 01, 1979; Princeton, NJ
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  • 91
    Publikationsdatum: 2019-07-13
    Beschreibung: The design, fabrication, and test of foldout and rollout multikilowatt solar array models are discussed. Consideration is given to the development of (1) thin 50-micron solar cells; (2) laminated Kapton plus substrates; (3) thin 50 to 100-micron coverglass; (4) low-mass structure designs; (5) low-mass blanket designs; and (6) solar insolation concentrators to enhance solar array performance. It is noted that the recent achievements in solar cell technology have shown that blanket specific power of 120 W/kg and higher is realizable for solar arrays, thus meeting propulsion stage requirements.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-2087 , International Electric Propulsion Conference; Oct 30, 1979 - Nov 01, 1979; Princeton, NJ
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  • 92
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    In:  Other Sources
    Publikationsdatum: 2019-07-13
    Beschreibung: Orbit precession returned the SERT II spacecraft to continuous sunlight in January 1979 for the first time since early 1972, and new experiments were planned and conducted. Neutralization of an ion beam was accomplished by a second neutralizer cathode located 1 meter away. Plasma potential measurements were made of the plasma surrounding the ion beam and connecting the beam to the second neutralizer. When the density of the connecting plasma was increased by turning on the main discharge of a neighboring ion thruster, the neutralization of the ion beam occurred with improved (lower) coupling voltage. These and other tests reported should aid in the future design of spacecraft using electric thruster systems. Data taken indicate that cross neutralization of ion thrusters in a multiple thruster array should occur readily.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-2064 , International Electric Propulsion Conference; Oct 30, 1979 - Nov 01, 1979; Princeton, NJ
    Format: text
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  • 93
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    In:  Other Sources
    Publikationsdatum: 2019-07-13
    Beschreibung: Recent research results have inferred that the self-field magnetoplasmadynamic (MPD) thruster can attain efficiency and specific impulse levels which are competitive with ion thrusters. Based on these results, a program was initiated at JPL to develop this thruster for application on future spacecraft. Preliminary mission analyses have shown that the high thrust density MPD arcjet is advantageous for high power missions, such as a short trip time earth orbit transfer vehicle or a nuclear powered outer planet explorer. Direct thrust stand verification of the inferred performance levels used in these analyses is planned for a facility being assembled at Princeton University. A parallel effort at JPL is considering various thruster system configurations, energy storage concepts and propellant control techniques. In addition, a one pulse per second thruster test facility is planned at JPL to be used for thruster optimization studies including erosion and lifetime measurements.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-2050 , International Electric Propulsion Conference; Oct 30, 1979 - Nov 01, 1979; Princeton, NJ
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 94
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    In:  Other Sources
    Publikationsdatum: 2019-07-13
    Beschreibung: Results of the first probing of the screen hole sheath of an ion accelerator system are presented. The screen hole sheath, represented as a set of equipotential contours, extends over a large distance within the discharge plasma. Under no conditions examined does the sheath enter the screen hole. Edge hole defocusing of multiaperture accelerator systems is due primarily to local plasma density variations rather than adjacent screen hole sheath interactions. The sheath boundary is independent of screen-to-accelerator grid spacing when the grid set is operated at the minimum ion beam divergence condition. Significant ion focusing effects occur in the sheath adjacent to the screen grid webbing leading to increased ion source beam current efficiency with decreasing screen-to-accelerator grid separation and/or screen grid thickness.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-2114 , International Electric Propulsion Conference; Oct 30, 1979 - Nov 01, 1979; Princeton, NJ
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 95
    facet.materialart.
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    In:  Other Sources
    Publikationsdatum: 2019-07-13
    Beschreibung: Presented are the designs used in the construction of the 2.5 m mass driver and the results of the initial testing program. The mass driver consists of equal length sections of acceleration and deceleration each containing 59 drive coils of 13.1 cm caliber. Intermediate energy storage is provided by sector capacitors which are recharged every half cycle by an external power source. The drive coils are individually energized through SCR's with timing supplied by position sensing optical detectors. The drive consists of two phases which operate in quadrature. The initial bucket to be propelled through the mass driver contains two coils of aluminum wire chilled to liquid nitrogen temperatures to momentarily sustain superconducting field intensities. Magnetic flight is generated by eddy current repulsion from six copper guide strips lining the mass driver. Nominal acceleration is 5000 m/sec per sec giving a maximum bucket velocity of 112 m/s.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-2095 , International Electric Propulsion Conference; Oct 30, 1979 - Nov 01, 1979; Princeton, NJ
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 96
    facet.materialart.
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    In:  Other Sources
    Publikationsdatum: 2019-07-13
    Beschreibung: Development of 66 W/kg and 200 W/kg solar arrays for solar electric propulsion is discussed along with two basic concentrator solar array design concepts. Considerable testing was performed to demonstrate the availability and capability of the technology used for these arrays. To provide complete demonstration of 66 W/kg technology, a full-scale wing was built and tested and NASA decided to fly it as an experiment on one of the early Shuttle flights. Performance of the concentrator array system was demonstrated by model testing in a thermal-vacuum chamber.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-2086 , International Electric Propulsion Conference; Oct 30, 1979 - Nov 01, 1979; Princeton, NJ
    Format: text
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  • 97
    facet.materialart.
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    In:  Other Sources
    Publikationsdatum: 2019-07-13
    Beschreibung: The propellant gas for a pulsed self-field MPD thruster must be supplied by a valve which will necessarily be separated from the thruster injectors by some ullage volume. A model and experimental data are presented showing the effect of the ullage volume on the propellant pulse shape, along with a discussion of the proper location for the propellant flow choke point(s). Prospective MPD pulse valves are surveyed and the performance of two solenoid valves, one with a pulse length less than 2 milliseconds, is included. Pulse shape data is presented for a thruster specially modified to reduce the ullage volume.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-2074 , International Electric Propulsion Conference; Oct 30, 1979 - Nov 01, 1979; Princeton, NJ
    Format: text
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  • 98
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    Unbekannt
    In:  Other Sources
    Publikationsdatum: 2019-07-13
    Beschreibung: The SERT II spacecraft, launched in 1970, has been maintained in an operational, but intermittently active status since 1971. Periodic thruster status has been reported while waiting for normal orbit precession to return the spacecraft to continuous sunlight in 1979. Now, the thruster has been operated for 600 hours in the first quarter of 1979. Thruster startup and operation in 1979 is unchanged after 9 years in space. The ion thruster was gimbaled and used to maintain spin stabilization of the spacecraft. Minor components of the spacecraft have failed, but have not interfered with the functional status of the spacecraft.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-2063 , International Electric Propulsion Conference; Oct 30, 1979 - Nov 01, 1979; Princeton, NJ
    Format: text
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  • 99
    Publikationsdatum: 2019-07-13
    Beschreibung: The use of a hollow cathode in place of an oxide cathode to increase thruster operating lifetimes requires, among other things, the addition of a baffle to restrict the flow of electrons from the hollow cathode. A theoretical model is developed which relates the baffle aperture area of a hollow-cathode thruster to the magnetic flux density and plasma properties in the aperture region, with the result that this model could be used as an aid in thruster design. Extensive Langmuir probing is undertaken to verify the validity of the model and demonstrate its capability. It is shown that the model can be used to calculate the aperture area required to effect discharge operation at a specified discharge voltage and arc current.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-2060 , International Electric Propulsion Conference; Oct 30, 1979 - Nov 01, 1979; Princeton, NJ
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
    facet.materialart.
    Unbekannt
    In:  Other Sources
    Publikationsdatum: 2019-07-13
    Beschreibung: The discharge chambers of mercury ion thrusters are modelled so the principal effects and processes which govern discharge plasma properties and thruster performance are described. The conservation relations for mass, charge and energy when applied to the Maxwellian electron population in the ion production region yield equations which may be made one-dimensional by the proper choice of coordinates. Solutions to these equations with the appropriate boundary conditions give electron density and temperature profiles which agree reasonably well with measurements. It is then possible to estimate plasma properties from thruster design data and those operating parameters which are directly controllable. By varying the operating parameter inputs to the computer code written to solve these equations, perfromance curves are obtained which agree quite well with measurements.
    Schlagwort(e): SPACECRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 79-2054 , International Electric Propulsion Conference; Oct 30, 1979 - Nov 01, 1979; Princeton, NJ
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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