Graduate engineering practice in mechanical engineering
Separation techniques, bulkhead design, and propellant dump research projects
Source record↗
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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Stress analysis for a Cassinian geometry space station under internal pressure
Stress analysis and design of cylindrical shell bulkhead for spacecraft
Martinez, J. E.↗
Postflight Evaluation of Atlas-Centaur AC-6 (Launched August 11, 1965)
The sixth Atlas Centaur vehicle (AC-6) was successfully launched from the Eastern T e s t Range, Complex 36B, on August 11, 1965, at 0931:04.430 EST. A 2084-pound dynamic model of the Surveyor payload was placed in a simulated lunar transfer trajectory. Vehicle systems operated satisfactorily and all the flight objectives were accomplished. Lift-off within 4 seconds of the window opening demonstrated the launch-on-time capability of the vehicle were accurately compensated for by the Centaur guidance system. the Surveyor model into a near-perfect lunar transfer trajectory would have resulted in an impact of the moon without a midcourse correction. To hit the precise target area on the lunar surface, the required correction would have been 4.25 meters per second, which is well within the spacecraft capability. Normal thrust and impulse levels were obtained with both the A t l a s and Centaur propulsion systems. However, a sizeable thrust overshoot on startup of the Centaur engines has not been resolved. A propellant-utilization system used for the first time on the Centaur, accurately controlled the fuel and oxidant consumption. The turnaround and retrothrust maneuver were performed without incident. Relatively high longitudinal modal excitations and lateral payload excitations were obtained at lift-off; these high perturbations are believed t o be related t o the launcher holddown arms. Nominal temperatures were recorded for both the external vehicle skin and the payload compartment; however, abnormally low temperatures were measured in the forward equipment area, which may have resulted from leakage of cold helium purge gas. All vehicle electrical systems performed satisfactorily; the only difficulty with the RF systems was obtained with the C-band transponder. of the vehicle instrumentation yielded valid data. The AC-6 vehicle was constructed with several new lightweight designs including the forward bulkhead, thrust barrel, interstage adapter and tank skin thickness reduction from 0.016 t o 0.014 inch. No deficiencies were observed in any of these new structural elements.
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An experimental study of axisymmetric modes in various propellant tanks containing liquid
An experimental study of several models used to analyze the longitudinal dynamics of oscillations in launch vehicle propellant tanks, is presented. Several vehicle structural configurations are considered: hemispherical and spherical, cylindrical and spherical, and semiellipsoidal and ellipsoidal. Various bulkheads and flanges are used with each configuration. The results are given in graphs.
Kana, D. D.↗
The influence of radiation shielding on reusable nuclear shuttle design
Alternate reusable nuclear shuttle configurations were synthesized and evaluated. Particular attention was given to design factors which reduced tank exposure to direct and scattered radiation, increased payload-engine separation, and improved self-shielding by the LH2 propellant. The most attractive RNS concept in terms of cost effectiveness consists of a single conical aft bulkhead tank with a high fineness ratio. Launch is accomplished by the INT-21 with the tank positioned in the inverted attitude. The NERVA engine is delivered to orbit separately where final stage assembly and checkout are accomplished. This approach is consistent with NERVA definition criteria and required operating procedures to support an economically viable nuclear shuttle transportation program in the post-1980 period.
Littman, T. M.↗
Saturn S-11 Production Operations Techniques, Production Welding. Volume 3: Circumferential Welding
Special processes and techniques are described for the circumferential welding of Saturn 2 cylinder and bulkhead assemblies to complete the LO2 and LH2 tankage and to maximize efficiency and personnel performance during S-2 follow-on or restart activities. The processes are only applicable to aluminum alloys within the 2000 series.
Abel, D. G.↗
Airlock
An airlock for use in transferring waste objects from a positively pressurized enclosure aboard an operative space vehicle, to a waste receiver attached to the vehicle and maintained at the negative pressure of a celestial space environment. The airlock is characterized by a shell having an internal chamber and hermetically sealed within an opening formed in a bulkhead of the enclosure. The shell is provided with an insertion hatch adjacent to the enclosure, and an ejection hatch adjacent the waste receiver, each of the hatches being hermetically sealed by a hatch cover supported for deployment to a hatch-opening disposition through a manipulation of a hatch-deploying mechanism. A three-way selector valve is coupled with the deploying mechanism and ported to an internal chamber of the shell, the enclosure, and the environment and is provided for alternately coupling the chamber with the enclosure and the receiver, in direct communication, in response to a manipulation of the mechanism whereby a sequence is imposed on the operation of the airlock.
Linderfelt, H. R.↗
Room temperature stretch forming of scale space shuttle external tank dome gores. Volume 1: Technical
An account of activities and data gathered in the Room Temperature Stretch Forming of One-third Scale External Tank Bulkhead Gores for space shuttle study, and a tooling design and production cost study are reported. The following study phases are described: (1) the stretch forming of three approximately one-third scale external tank dome gores from single sheets of 2219-T37 aluminum alloy; (2) the designing of a full scale production die, including a determination of tooling requirements; and (3) the determination of cost per gore at the required production rates, including manufacturing, packaging, and shipping.
Blunck, R. D.↗
Design criteria monograph for metal tanks and tank components
Significant elements in detail tank design are wall and end structures, weld joints at bulkhead and attachment junctures, and ports and access openings. Additional design considerations are influence and effect of fabrication processes on tank component design, and finally, testing and inspection that are required to establish confidence in tank design.
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SBASI: Actuated pyrotechnic time delay initiator
A precision pyrotechnic time delay initiator for missile staging was developed and tested. Incorporated in the assembly is a single bridgewire Apollo standard initiator (SBASI) for initiation, a through-bulkhead-initiator to provide isolation of the SBASI output from the delay, the pyrotechnic delay, and an output charge. An attempt was made to control both primary and secondary variables affecting functional performance of the delay initiator. Design and functional limit exploration was performed to establish tolerance levels on manufacturing and assembling operations. The test results demonstrate a 2% coefficient of variation at any one temperature and an overall 2.7% coefficient of variation throughout the temperature range of 30 to 120 F. Tests were conducted at simulated operational altitude from sea level to 200,000 feet.
Salter, S. J.↗
Shuttle Kit Freezer Refrigeration Unit Conceptual Design
The refrigerated food/medical sample storage compartment as a kit to the space shuttle orbiter is examined. To maintain the -10 F in the freezer kit, an active refrigeration unit is required, and an air cooled Stirling Cycle refrigerator was selected. The freezer kit contains two subsystems, the refrigeration unit, and the storage volume. The freezer must provide two basic capabilities in one unit. One requirement is to store 215 lbs of food which is consumed in a 30-day period by 7 people. The other requirement is to store 128.3 lbs of medical samples consisting of both urine and feces. The unit can be mounted on the lower deck of the shuttle cabin, and will occupy four standard payload module compartments on the forward bulkhead. The freezer contains four storage compartments.
Copeland, R. J.↗
Vibroacoustic testing of Space Shuttle thermal protection system panels
The modes and acoustic responses of two panels representing Space Shuttle thermal protection panels were investigated. The panels consisted of flat aluminum sheet stiffened longitudinally with hat-section stringers and corrugated supporting panels representing Shuttle ring frame bulkheads. In addition, one panel had 24 tiles of LI900 silica thermal insulation material and a strain isolator pad bonded to the face sheet. Both panels were found to have approximately eight modal frequencies in the 60 to 500 Hz range, where Shuttle acoustic loads are expected to be high. The strain response to a progressive acoustic wave representing a Shuttle spectrum was characterized by the occurrence of larger strains in the direction normal to the stringers than in the direction parallel to the stringers; three modes in the 100 to 400 Hz range contributed significantly to the strain response.
Rucker, C. E.↗
Resonance testing of space shuttle thermoacoustic structural specimen
The resonance testing of a structural specimen related to the space shuttle vehicle is described. The specimen consisted of a thin aluminum skin reinforced by hat-section stringers and supported by two ribs or bulkheads of corrugated web. A representative section of the space shuttle thermal protection system was bonded to the outer surface of the skin. The tests were completed by using miniature accelerometers to collect vibration data from locations forming a predetermined mesh over the tiles and base structure. The signals were recorded on FM magnetic tape and subsequently analyzed on a modal analysis system.
Abrahamson, A. L.↗
The Shuttle Orbiter Airlock Support Subsystem /ALSS/
The Orbiter Airlock Support Subsystem (ALSS) is designed to provide shirtsleeve intervehicular transfer (IVA) between the orbiter and payload spacelab. Also, the airlock provides for extravehicular transfer (EVA) of two crewman to space and/or unpressurized payload from a pressurized cabin environment. The orbiter airlock design permits three planned EVA's for periods up to 6 hr. The airlock is designed to be interchangeable in three different locations, in the crew cabin, attached to the cabin aft bulkhead or attached to transfer tunnel adapter both which are located in the cargo bay. The Orbiter Airlock Support Subsystem described herein provides ventilation, pressurization, depressurization, prebreathing, personnel oxygen system supply (POS), and Extravehicular Mobility Unit support (EMU). This paper defines the system configuration for each airlock location and the commonality between them. Emphasis is also placed on the design data used to define repressurization and depressurization requirements, ventilation, water cooling, wastewater discharge, flow rates, and valve sizing.
Brown, J. T.↗
Heat sink structural design concepts for a hypersonic research airplane
Hypersonic research aircraft design requires careful consideration of thermal stresses. This paper relates some of the problems in a heat sink structural design that can be avoided by appropriate selection of design options including material selection, design concepts, and load paths. Data on several thermal loading conditions are presented on various conventional designs including bulkheads, longerons, fittings, and frames. Results indicate that conventional designs are inadequate and that acceptable designs are possible by incorporating innovative design practices. These include nonintegral pressure compartments, ball-jointed links to distribute applied loads without restraining the thermal expansion, and material selections based on thermal compatibility.
Taylor, A. H.↗
Safe venting for electronic components
Vented enclosure is made from lightweight metal. Printed-circuit boards are attached to bottom and end bulkheads and to top cover. Airflow cools components indirectly through walls of inner compartment. Flammability and smoke tests demonstrate safety of enclosure.
Currin, R., Jr.↗
Passive propellant system
The system utilizes a spherical tank structure A separated into two equal volume compartments by a flat bulkhead B. Each compartment has four similar gallery channel legs located in the principal vehicle axes, ensuring that bulk propellant will contact at least one gallery leg during vehicle maneuvers. The forward compartment gallery channel legs collect propellant and feed it into the aft compartment through communication screens which protrude into the aft compartment. The propellant is then collected by the screened gallery channels in the aft compartment and supplied to the propellant outlet. The invention resides in the independent gallery assembly and screen structure by means of which propellant flow from forward to aft compartments is maintained. Liquid surface tension of the liquid on the screens is used to control liquid flow. The system provides gas-free propellants in low or zero-g environments regardless of axial accelerations and propellant orientation in bulk regions of the vessel.
Hess, D. A.↗
Material characteristics of Space Shuttle reinforced carbon-carbon
Reinforced carbon-carbon with an oxidation-resistant coating is used as the thermal protection system for the Space Shuttle Orbiter high-temperature wing leading edge and nose cap surfaces. The reinforced carbon-carbon system is capable of multimission reuse, and, in addition, provides a smooth external moldline while transmitting aerodynamic loads to the fuselage forward bulkhead and wing spar through mechanical attachments. This paper describes the material and processes developed, strength and thermal/physical properties which characterize performance.
Curry, D. M.↗