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  • Other Sources  (120)
  • SPACE VEHICLES  (69)
  • MACHINE ELEMENTS AND PROCESSES  (51)
  • ASTROPHYSICS
  • Chemical Engineering
  • 1970-1974  (120)
  • 1973  (120)
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  • 1970-1974  (120)
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  • 1
    Publication Date: 2019-07-13
    Description: A method of economically evaluating the hydrodynamic forces generated in a gas-lubricated tilting-pad bearing is presented. The numerical method consists of solving the case of the infinite width bearing and then converting this solution to the case of the finite bearing by accounting for end leakage. The approximate method is compared to the finite-difference solution of Reynolds equation and yields acceptable accuracy while running about one-hundred times faster. A mathematical model of a gas-lubricated tilting-pad vertical rotor systems is developed. The model is capable of analyzing a two-bearing-rotor system in which the rotor center of mass is not at midspan by accounting for gyroscopic moments. The numerical results from the model are compared to actual test data as well as analytical results of other investigators.
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: ASLE PREPRINT 73AM-2B-2 , Annual Meeting; Apr 30, 1973 - May 03, 1973; Chicago, IL
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  • 2
    Publication Date: 2019-06-27
    Description: The Small, High-Pressure-Ratio Compressor Program was directed toward the analysis, design, and fabrication of a centrifugal compressor providing a 6:1 pressure ratio and an airflow rate of 2.0 pounds per second. The program consists of preliminary design, detailed areodynamic design, mechanical design, and mechanical acceptance tests. The preliminary design evaluate radial- and backward-curved blades, tandem bladed impellers, impeller-and diffuser-passage boundary-layer control, and vane, pipe, and multiple-stage diffusers. Based on this evaluation, a configuration was selected for detailed aerodynamic and mechanical design. Mechanical acceptance test was performed to demonstrate that mechanical design objectives of the research package were met.
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: NASA-CR-120941 , APS-5404-R-VOL-1
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  • 3
    Publication Date: 2019-06-27
    Description: Four specimens identified as SL-1.3, SL-1.8, SL-1.9 and SL-2.5 were submitted for metallurgical characterization. These specimens had been processed in the M512 Facility as a part of the M553 Sphere Forming Experiment performed during the Skylab 1/2 flight. Three of these specimens, SL-1.3, SL-1.8, and SL-2.5 were designed to be melted completely by the electron beam and detach themselves from their support posts and resolidify while floating free in the near zero gravity and vacuum environment of space. Specimens SL-1.3 and SL-1.8 were completely melted, but it is believed they did not leave their posts before solidifying. Specimen SL-2.5 was only partially melted. Specimen SL-1.9 was to be completely melted and retained on a large sting which was accomplished as planned. The nominal composition of the four specimens was: (1) SL-1.3 - Ni 12% Sn; (2) SL-1.8 - Ni 30% Cu; (3) SL-1.9 - Pure Ni; and (4) SL-2.5 - Pure Ni. These four specimens have been examined according to the Phase B Characterization Plan. The results are discussed and compared with similar characterization analyses run on ground base specimens.
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: NASA-CR-129040
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  • 4
    Publication Date: 2019-06-27
    Description: Both processed nickel-copper alloy specimens apparently completely melted by the electron beam in the Skylab M512 materials processing facility and either floated free in space, but collided with some smooth flat surface before solidifying, or remained attached to its support post during solidification. Both specimens had a smooth flat area on the surface due to this adherence during solidification. The nominal composition of the alloy before processing in space was 70 percent Ni and 30 percent Cu. Tests show that a considerable amount of copper was lost during processing by evaporation. It was further found that less copper was present in the cap areas, particularly at the surface, than was in the remainder of the specimens. The microchemistry of the dendrites and interdendritic regions, however, is in agreement with the phase diagram for this alloy. The measured densities of these specimens were less than the theoretical density of the alloy due to the amount of porosity present, however, no large voids were found by radiographic techniques.
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: NASA-CR-129039
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  • 5
    Publication Date: 2019-06-27
    Description: An optimal atmospheric flight branched trajectory-shaping capability is presented based on the Davidon-Fletcher-Powell variable metric parameter optimization technique. Gradient information is generated using finite difference methods. A typical atmospheric flight branched optimization problem is analyzed which requires the determination of 31 parameters. This parameter set includes the three-dimensional description of vehicle attitude control angles for three branches of flight: first-stage ascent, second-stage ascent, and first-stage flyback. The important inflight inequality contraints required to maintain the integrity of the vehicles are considered. Some of the numerical methods employed are discussed, along with several new auxiliary techniques developed to improve the compatibility of the numerical gradient and iterator.
    Keywords: SPACE VEHICLES
    Type: Automatica; 9; Nov. 197
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  • 6
    Publication Date: 2019-07-13
    Description: Small, high-performance LO2 and LH2 turbopump assembly configurations were selected, detail designs were prepared and two of each unit were fabricated with each unit consisting of pump, turbine gas generator, and appropriate controls. Following fabrication, development testing was conducted on each type to demonstrate performance, durability, transient characteristics, and heat transfer under simulated altitude conditions. Following successful completion of development effort, the two LO2 turbopump units and one LH2 turbopump unit were acceptance tested as specified. Inspection of the units following development testing revealed no deleterious effects of testing. The test results of LO2 turbopump assembly testing correlated well with predicted performance while the LH2 turbopump test results, though generally consistent with predicted values, did show lower than anticipated developed head at the design point and in the high flow range of operation.
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: NASA-CR-120193
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  • 7
    Publication Date: 2019-07-13
    Keywords: SPACE VEHICLES
    Type: ASME PAPER 73-ENAS-5 , Intersociety Conference on Environmental Systems; Jul 16, 1973 - Jul 19, 1973; San Diego, CA; US
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  • 8
    Publication Date: 2019-07-13
    Description: Trade-off studies and a preliminary design were accomplished to investigate the Versatile Upper Stage (VUS) concept. This concept entails the development by one contractor of a family of stages with a great deal of commonality to perform a spectrum of potential unmanned automated missions planned through 1990. The trade studies and analyses revealed areas where the penalty for commonality between stages was excessive in weight and performance loss. This occurred in the selection of the vehicle structural shell. In many of the expensive subsystems, especially astrionics, it was found that establishing the requirements for all family members and the application of commonality in subsystem selection could result in significant savings.
    Keywords: SPACE VEHICLES
    Type: AIAA PAPER 73-589 , Joint Space Mission Planning and Execution Meeting; Jul 10, 1973 - Jul 12, 1973; Denver, CO
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  • 9
    Publication Date: 2019-06-27
    Description: An energy-balance analysis is presented for adhesive failure in end loaded cantilever beams. The analysis includes the effects of input work, stored strain energy, dissipated plastic energy, and specific adhesive surface energy. Experimental results obtained with 6061-T6 aluminum are presented as evidence for the validity of the approach.-
    Keywords: MACHINE ELEMENTS AND PROCESSES
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  • 10
    Publication Date: 2019-06-27
    Description: Techniques were studied to reinforce or strengthen electroformed nickel to allow a fuller utilization of electroforming as a reliable and low cost fabrication technique for regenerately cooled thrust chambers. Techniques for wire wrapping while electrodepositing were developed that can result in a structurally strong wall with less weight than a conventional electroformed wall. Also a technique of codepositing submicron sized THO2 particles with the nickel to form a dispersion strengthened structure was evaluated. The standard nickel cylinders exhibited an average hoop strength of 80,000 psi with a yield strength of 65,000 psi and a modulus of 25.6 x 10 to the 6th power psi. The as produced dispersion strengthened nickel showed a hoop strength of 97,000 psi with a yield strength of 67,000 psi. This is an increase of 17,000 psi or 21% over the standard nickel hoop strength. The wire wrapping cylinders showed an increased strength over the standard nickel test samples of 26,000 to 66,800 psi which is in the range of 26 to 104% increase in strength over the base standard nickel. These latter test results are indicative of a volume percent wire reinforcement from 15 to 31. The measured hoop strengths agree with calculated composite strengths based upon rule of mixtures.
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: NASA-CR-134480 , GTC-297
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