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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,603 records · Page 89
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Apollo/Saturn C00.00.19.3 operations and maintenance. Cathodic protection of communication cables

Operating and maintenance instructions for cathodic protection of communication cables at the Cape Kennedy Launch Complex are presented. The system is designed to prevent or arrest corrosion of communication cables buried in soil or submerged in water by impressing sufficient direct current from the rectifier through the anodes to the cable. This process neutralizes or counteracts current flowing from the cable into the soil or water, thus preventing or arresting corrosion of the cable sheath material.

Source record↗
NASA NTRS1972

Refurbishment cost study of the thermal protection system of a space shuttle vehicle. Phase 2: Supplement

The labor costs and techniques associated with the maintenance of a bonded-on ablator thermal protection system (TPS) concept, suitable for Space Shuttle application are examined. The baseline approach to TPS attachment involves bonding reusable surface insulation (RSI) and/or ablators to the structural skin of the vehicle. The RSI and/or ablators in the form of either flat or contoured panels can be bonded to the skin of the primary structure directly or by way of an intermediate silicone foam rubber pad. The use of foam rubber pads permits the use of buckling skins and protruding heat rivets on the primary structure, minimizing structural weight and fabrication costs. In the case of the RSI, the foam rubber pad serves as a required strain isolator. For purpose of comparison, test data were obtained for an installation with and without the use of a strain isolator. The refurbishment aspects of a bonded-on RSI concept (without a strain isolator) were examined experimentally along with several externally removable panel concepts employing both ablator and RSI TPS. The various concepts are compared.

Haas, D. W.↗
NASA NTRS1971

Advanced Extravehicular Protective Systems (AEPS) study

A description is given of life support subsystem concepts for advanced extravehicular protective systems (AEPS) intended for use on future orbital, lunar surface, and Mars surface missions in the late 1970's and 1980's. Primary interest was centered around the thermal control and carbon dioxide control subsystems because they offer the greatest potential for total weight savings. Emphasis was placed on the generation of regenerable subsystem concepts; however, partially regenerable and expendable concepts were also considered. Previously conceived and developed subsystem concepts were included in the study. Concepts were evaluated on the basis of subsystem weight and volume, and subsystem contribution to parent vehicle weight and volume, which included spares, regeneration equipment, expendables, expandables storage penalty, power penalty, and process heating or cooling penalty. Results are presented showing total weight and volume penalty as a function of total mission extravehicular activity (EVA) hours, and showing EVA weight and volume as a function of EVA duration. Subsystem concepts are recommended for each life support function, and secondary concepts which should be developed are also identified.

Williams, J. L.↗
NASA NTRS1972

Oxidation protected carbon-carbon

Pyrolized carbon-carbon has one unique advantage over other materials that makes its application to the space shuttle thermal protection system very attractive. This unique characteristic is the increase in material strength and modulus with increase in temperature up to about 2500 K (4040 F). Offsetting this unique advantage are disadvantages which include brittleness, high cost, and the tendency of the material to react with oxygen, particularly at high temperatures. The development of an oxidation inhibitor for the material and the definition of fabrication processes for selected full-scale components are considered.

Pavlosky, J. E.↗
NASA NTRS1972

Beryllium heat shield technology in the area of thermal protection devices

For future space applications, it is important that thermal protection systems be reusable for space shuttle flights. Beryllium offers a unique combination of properties for use as a heat shield material (stiffness, lightweight, ability to absorb heat). In order to adequately test these properties, it was necessary to fabricate heat shields. The concept used was a two-section test panel 99.1 x 99.1 cm (39 x 39 inch) with each section made of two 0.051 cm (0.020 inch) thick beryllium corrugations brazed together as a mirror image, with titanium (Ti-6Al-4V) used as standoffs to support the panel structure. The work prior to fabrication included brazability of both beryllium and titanium, forming of beryllium and titanium, machining processes involving beryllium and chem-milling beryllium. Sub-scale samples were made of all details before actual fabrication of the large panel. The full scale test panel was hot-formed at 950 K, chem-milled to 0.041 + or - 0.005 cm (0.016 + or - 0.002 inches), trimmed, vacuum brazed, drilled and assembled.

Muhl, A. E.↗
NASA NTRS1972

Evaluation of coated columbian alloy heat shields for space shuttle thermal protection system application. Volume 1: Phase 1 - Environmental criteria and material characterization, October 1970 - March 1972

The studies presented are directed toward establishing criteria for a niobium alloy thermal protection system for the space shuttle. Evaluation of three niobium alloys and two silicon coatings for heat shield configurations culminated in the selection of two coating/substrate combinations for environmental criteria and material characterization tests. Specimens were exposed to boost and reentry temperatures, pressure, and loads simulating a space shuttle orbiter flight profile.

Black, W. E.↗
NASA NTRS1971

Oxidation screening at 1204 C /2200 F/ of candidate alloys for the space shuttle thermal protection system.

Evaluation of the oxidation resistance of 15 alloys under some of the environmental conditions that might be encountered by the shuttle thermal protection system. The alloys included nickel-, iron-, and cobalt-base wrought alloys. Specimens were self-resistively heated to 1204 C (2200 F) in a 10-torr still-air environment for 100 thirty-minute cycles. Specimen weight, thickness, and microstructural changes were noted, and surface scales were identified by room-temperature X-ray diffraction. Based on these observations, the behavior of the alloys was evaluated in terms of overall amount of metal consumption due to oxide formation and relative tendency toward oxide spalling and scale vaporization.

Sanders, W. A.↗
NASA NTRS1972

Comparison of thermal protection systems for a space shuttle booster and orbiter.

Selection of the most appropriate thermal protection system design approaches requires evaluation of alternate concepts. Such an evaluation was conducted for a representative booster and orbiter configurations. TPS concept examined for the booster included heat sink, metallic reradiative, reusable surface insulation, and surface cooled types. For the orbiter, emphasis was placed on metallic reradiative and reusable surface insulation concepts with uncooled, phase change material cooled, and water-cooled substructures. Three insulation materials of different densities were examined for the orbiter reradiative TPS to identify the weight sensitivity of various substructural design approaches to this variable.

Anthony, F. M.↗
NASA NTRS1972

Structural design aspects of reusable surface insulation thermal protection systems.

Low density fiber ceramic materials coated with refractory ceramics meet the requirements of reusable low weight thermal protection systems. The structural characteristics of this class of material impose unique design and analysis requirements on the application to spacecraft structural elements. Finite element type stress analysis techniques are required to adequately predict the structural response of the system. Parametric analyses have been performed to determine the response of the system to variations in geometry, and to thermal and structural load conditions. Sensitivity of coating, insulation and attachment stresses are presented and critical failure modes are identified.

Michalak, R. J.↗
NASA NTRS1973

Glass encapsulation provides extra protection for IC semiconductor devices

Oxide-passivated semiconductor chip is given protective glass coating by means of vapor deposition over metallic substrate of integrated circuit (IC). Method provides more reliable oxide-passivation and hermetic sealing in current use. Chips and scratches incurred during dicing, testing, and assembly are markedly reduced.

Doelp, W. L., Jr.↗
NASA NTRS1973

Electroshock protection circuit

Circuit was developed to prevent accidental shock through electrodes used to test subjects as part of Skylab program. This circuit is placed between electrical apparatus and electrode that is attached to patient's body. Thus, patient is effectively protected from dangerous electrical shock that might be caused by failure in electrical apparatus.

Heskett, H.↗
NASA NTRS1972

Evaluation of nondestructive testing techniques for the space shuttle nonmetallic thermal protection system

A program was conducted to evaluate nondestructive analysis techniques for the detection of defects in rigidized surface insulation (a candidate material for the Space Shuttle thermal protection system). Uncoated, coated, and coated and bonded samples with internal defects (voids, cracks, delaminations, density variations, and moisture content), coating defects (holes, cracks, thickness variations, and loss of adhesion), and bondline defects (voids and unbonds) were inspected by X-ray radiography, acoustic, microwave, high-frequency ultrasonic, beta backscatter, thermal, holographic, and visual techniques. The detectability of each type of defect was determined for each technique (when applicable). A possible relationship between microwave reflection measurements (or X-ray-radiography density measurements) and the tensile strength was established. A possible approach for in-process inspection using a combination of X-ray radiography, acoustic, microwave, and holographic techniques was recommended.

Tiede, D. A.↗
NASA NTRS1972

A numerical investigation of film cooling as an alternate thermal protection system for spacecraft during atmospheric reentry

Research was undertaken to determine the mass required to protect a surface during atmospheric reentry by injecting a cold gas tangentially along the surface. A consideration of this problem revealed that the boundary layer equations could be employed to approximate the most important flow configurations which occur in film cooling. However, even with this simplification, the equations to be solved are complex, nonlinear, coupled partial differential equations. Due to the relative weakness of classical methods of boundary layer analysis, finite difference methods were chosen as the best approach to the formidable problem under consideration. Instead of blindly adopting a proposed technique and trying to force it to the problem, a more systematic study was deemed to be not only desirable but necessary. A relatively basic study of the application of finite difference methods was undertaken with the objective of developing an algorithm capable of obtaining accurate solutions to film cooling problems.

Clausing, A. M.↗
NASA NTRS1972

Optimization of thermal protection systems for the space shuttle vehicle. Volume 1: Final report

A study performed to continue development of computational techniques for the Space Shuttle Thermal Protection System is reported. The resulting computer code was used to perform some additional optimization studies on several TPS configurations. The program was developed in Fortran 4 for the CDC 6400, and it was converted to Fortran 5 to be used for the Univac 1108. The computational methodology is developed in modular fashion to facilitate changes and updating of the techniques and to allow overlaying the computer code to fit into approximately 131,000 octal words of core storage. The program logic involves subroutines which handle input and output of information between computer and user, thermodynamic stress, dynamic, and weight/estimate analyses of a variety of panel configurations. These include metallic, ablative, RSI (with and without an underlying phase change material), and a thermodynamic analysis only of carbon-carbon systems applied to the leading edge and flat cover panels. Two different thermodynamic analyses are used. The first is a two-dimensional, explicit precedure with variable time steps which is used to describe the behavior of metallic and carbon-carbon leading edges. The second is a one-dimensional implicity technique used to predict temperature in the charring ablator and the noncharring RSI. The latter analysis is performed simply by suppressing the chemical reactions and pyrolysis of the TPS material.

Source record↗
NASA NTRS1973

Apollo experience report: Protection against radiation

Radiation protection problems on earth and in space are discussed. Flight through the Van Allen belts and into space beyond the geomagnetic shielding was recognized as hazardous before the advent of manned space flight. Specialized dosimetry systems were developed for use on the Apollo spacecraft, and systems for solar-particle-event warning and dose projection were devised. Radiation sources of manmade origin on board the Apollo spacecraft present additional problems. Methods applied to evaluate and control or avoid the various Apollo radiation hazards are discussed.

English, R. A.↗