Search NASA⌕ Search

SEARCH · Search NASA

Results for “DO-160”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Development of new addition-type composite resins

The most promising of a number of new addition type polyimides and polyaromatic melamine (NCNS) resins for use in high performance composite materials. Three different cure temperature ranges were of interest: 530-560 K (500-550 F), 475-530 K (400-500 F), and 450 K (350 F). Examined were a wide variety of polyimide precursors terminated with 5 norbornene groups and addition polymerized at 560 K similar to PMR-15 and LARC-160 polyimides. In addition, a number of lower curing cinnamal end capped polyimides and a bismaleimide were investigated but were not found promising. A group of NCNS resins were investigated and some were found to be superior to current epoxy resins in moisture resistance, oxidative aging and flame and smoke properties.

Kray, R. J.↗
NASA NTRS1981

Development of silane-hydrolysate binder for UV-resistant thermal control coatings

Detailed characterizaton and formulation studies were performed on a methyltriakoxysilane hydrolysate as a binder for thermal control coatings. The binder was optimized by varying hydrolysis temperature, time, catalyst type, and water concentration. The candidate coating formulations, based on this binder with TiO2 pigment, were optimized via a detailed series of sprayed test panels that included the parameters of binder/pigment ratio, ethanol content, pigment particle size, coating thickness and cure conditions. A typical optimized coating was prepared by acetic acid catalyzed hydrolysis of methyltriethoxysilane with 3.25 mol-equivalents of water over a 24 hour period at room temperature. The resulting hydrolysate was directly mixed with pre-milled TiO2 (12 grams pigment/26 grams binder) to yield a sprayable consistency. Panels were sprayed to result in a nominal cure coating thickness of 2 mils. Cure was affected by air drying for 24 hr at room temperature plus 72 hr at 150 F. These coatings are typically extremely tough and abrasion-resistant, with an absorptance (alpha) of 0.20 and emittance (e) of 0.89. No significant coating damage was observed in the mandrel bend test, even after exposure to thermal cycling from -160 to 160 F. Vacuum exposure of the coatings for 930 hours at 1 equivalent UV sun resulted in no visible degradation and no significant increase in absorptance.

Patterson, W. J.↗
NASA NTRS1980

A magnetic study of spotted UV Ceti flare stars and related late-type dwarfs

A multichannel photoelectric Zeeman analyzer has been used to investigate the magnetic nature of the spotted UV Ceti flare stars. Magnetic observations were obtained on a sample of 19 program objects, of which 5 were currently spotted dKe-dMe stars, 7 were normal dK-dM stars, 7 were UV Ceti flare stars, and 1 was a possible post-T Tauri star. Contrary to most previously published observations and theoretical expectations, no magnetic fields were detected on any of these objects from either the absorption lines or the H-alpha emission line down to an observational uncertainty level of 100-160 gauss (standard deviation).

Vogt, S. S.↗
NASA NTRS1981

An evaluation of nuclear electric propulsion for planetary exploration missions

A set of nuclear electric propulsion (NEP) system parameters for planetary exploration missions is described. Orbiter missions to the planets Saturn, Uranus and Neptune were selected for assessment, and five delivery modes were evaluated. The NEP system envisioned for this application consisted of a nuclear fission reactor with a thermoelectric conversion system and a thrust subsystem comprised of power processors coupled with mercury ion-bombardment thrusters. The results indicate that an NEP system sized at 90-160 kW electrical power rating and operating within a specific impulse range of 4500-5500 sec provides adequate performance for outer planet exploration.

Nagorski, R. P.↗
NASA NTRS1980

AD-1 oblique wing aircraft program

The oblique wing concept for super- and subsonic transport was assessed by analysis and wind tunnel radio control model and remotely piloted vehicle testing. A one-sixth scale wind tunnel model and a low speed manned oblique wing research airplane (AD-1) were developed. Model wind tunnel test data on dynamic structural response characteristics were used in a simulator to develop the control system. The airplane is of simple design with fiber glass skin, weight of approximately 2100 lbs and speeds of up to 175 knots at altitudes up to 15,000 ft. Flight testing will investigate handling and flying qualities, oblique wing flight control characteristics, aeroelastic wing design and will compare actual with predicted aerodynamic characteristics. Nineteen flights were made at 12,000 to 13,000 feet with speeds of 100-160 knots. Flutter clearance as a function of wing sweep angle is now under investigation.

Andrews, W. H.↗
NASA NTRS1980

Screening of high temperature adhesives for large area bonding

High temperature-resistant adhesive systems were screened for processability, mechanical and physical properties, operational capability at 589 K (600 F), and the ability to produce large area bonds of high quality in fabricating Space Shuttle components. The adhesives consisted primarily of polyimide systems, including FM34B-18, NR-150B2 (DuPont), PMR-15, LARC-13, LARC-160, Thermid 600, and AI-1130L (AMOCA). The processing studies included preparation of polyimide resins, fabrication of film adhesives, development of lay-up and cure procedures, fabrication of honeycomb sandwich panels, and fabrication of mid-plane bonded panels in joints up to 30.5 cm (12 in.) wide. The screening program included tests for tack and drape properties, reticulation and filleting characteristics, ability to produce void-free or low porosity bonds in mid-plane bonded panels, out-time stability, lap shear strength, climbing drum peel strength, and glass transition temperature (Tg). This paper describes the processing methods developed and the test results.

Stenersen, A. A.↗
NASA NTRS1982

Development of critical molecular weight-property specifications for high performance polymers used as adhesives and composites

The polyimide resin, LARC-160, was prepared from diethyl-3, 3', 4,4'-benzophenone tetracarboxylate, ethyl-5-norbornene-2,3-dicarboxylate and Jeffamine AP-22. The imidization reactions of NE and BTDE were studied by HPLC, C-13-NMR and IR. NE imidizes slowly at 12 C; BTDE imidizes when the resin is heated above 100 C. Both imidization reactions proceed directly to the imide. Neither amic acid is present in significant quantities at any stage of the imidization reactions. The monomer mixture was stored at 12 C for periods up to 14 months. The effects of resin aging at this temperature on the chemical composition of the resin monomer mixture and the imidized polymer formed on curing were investigated. Aging the resin monomer mixture has the effect of partially advancing the imidization reaction. The average size of the cured polymer increases slightly with resin age.

Kranbuehl, D. E.↗
NASA NTRS1982

Contaminant characterization of five satellite materials

An extensive laboratory test program was performed to characterize outgassing of five satellite materials. The materials were Chemglaze Z-306 over 9922 primer, M-773 adhesive, multilayer insulation, polyurethane foam, and silverized Teflon. The souces were prepared to the specifications of a typical satellite program. Dynamic thermogravimetric mass loss characteristics of these five materials were obtained in vacuum with a beam microbalance. The temperature of the material was linearly raised from 25 C to over 650 C while monitoring the mass loss, rate of mass loss, temperature, and the composition of the outgassed material by residual gas analysis. Isothermal source emission/capture coefficients/reemission parameters were obtained with an array of quartz crystal microbalances (QCM). A detailed test matrix in which the temperatures of the QCMs (-160 C, - 100 C, -40 C, and +10 C) and the source material (125 C, and 90 C, and 50 C) were varied was performed. The array of QCMs was also used to measure the spatial distribution of the source emission. The effects of vacuum ultraviolet radiation on the deposition and reemission parameters was determined.

Muscari, J. A.↗
NASA NTRS1982

The vacuum ultraviolet spectra of HCN, C2N2, and CH3CN

Quantitative vacuum ultraviolet absorption spectra for HCN, C2N2, and CH3CN have been obtained over the wavelength range 60-160 nm. Where comparison is possible, the measurements of the absorption coefficients for HCN and C2N2 are consistent with previous studies. Because of the superior resolution of this work (0.05 nm), vibrational assignments in the valence and Rydberg transitions of HCN have been extended while higher members of the Rydberg series in CH3CN have been identified.

Nuth, J. A.↗
NASA NTRS1981

Development and demonstration of manufacturing processes for fabricating graphite/Larc-160 polyimide structural elements, part 4, paragraph B

Progress in the development of processes for production of Celion/LARC-160 graphite-polyimide materials, quality control, and the fabrication of Space Shuttle composite structure components is reported. Liquid chromatographic analyses of three repeatibility batches were performed and are compared to previous Hexcel standard production and to variables study LARC-160 intermediate resins. Development of processes for chopped fiber molding are described and flexural strength, elastic modulus, and other physical and mechanical properties of the molding are presented.

Source record↗
NASA NTRS1982

Observed composition of the ionosphere of Venus - Implications for the ionization peak and the maintenance of the nightside ionosphere

Across the nightside of Venus, daily measurements from the PV Orbiter Ion Mass Spectrometer often indicate an ionosphere of relatively abundant concentration, with a composition characteristic of the dayside ionosphere. Such conditions are interspersed by other days on which the ionosphere appears to largely 'disappear' down to about 200 km, with ion concentrations at lower heights also much reduced. These characteristics, coupled with observations of strong day to night flows of O(+) in the upper ionosphere, support arguments that ion transport from the dayside is important for the maintenance of the nightside ionosphere. In the range 140-160 km, strong concentrations of O2(+) and NO(+) indicate that the ionization peak is at times composed of at least two prominent ion species. Nightside concentrations of O2(+) and NO(+) as large as 100,000 and 10,000/cu cm, respectively, appear to require sources in addition to that provided by transport. The most probable sources are considered briefly, and no satisfactory explanation is yet found for the observed NO(+) concentrations.

Taylor, H. A., Jr.↗
NASA NTRS1983

Lorentz forces on the dust in Jupiter's ring

The paths of dust particles in the Jovian ring are investigated using a numerical integration program, including the acceleration due to gravity and the Lorentz and drag accelerations arising from the motions of the charged dust through the Jovian plasma. It is determined that the orbit of a 2.5 micron radius spherical dust particle with a density of 2 g/cu cm -10V will become significantly perturbed. The ring will tend to warp northwards near 130-160 deg longitude, with the maximum excursion of the Jupiter ring grains equalling about 0.1 deg (consistent with a distance of 220 km above the equatorial plane). It is found that either the particles are larger or the voltages on them less than what has been determined by previous investigators, while the plasma near the ring may be considerably cooler than was estimated. Calculations show that particles of 0.3 micron with -10 V potentials are spread from 1.68-1.98 of the radius of Jupiter and inclined up to 7 deg out of the equatorial plane. The paths of these particles do not follow Keplerian orbits, and the particle positions are not symmetric about the equatorial plane. Particles of 0.4 micron radius have less asymmetric orbits than 0.3 micron particles, while particles less than 0.2 micron are perturbed into Jupiter cloudtops within a few tens of hours.

Consolmagno, G. J.↗
NASA NTRS1983

Surface analysis of graphite fiber reinforced polyimide composites

Several techniques have been used to establish the effect of different surface pretreatments on graphite-polyimide composites. Composites were prepared from Celion 6000 graphite fibers and the polyimide LARC-160. Pretreatments included mechanical abrasion, chemical etching and light irradiation. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used in the analysis. Contact angle of five different liquids of varying surface tensions were measured on the composites. SEM results showed polymer-rich peaks and polymer-poor valleys conforming to the pattern of the release cloth used durng fabrication. Mechanically treated and light irradiated samples showed varying degrees of polymer peak removal, with some degradation down to the graphite fibers. Minimal changes in surface topography were observed on concentrations of surface fluorine even after pretreatment. The light irradiation pretreatment was most effective at reducing surface fluorine concentrations whereas chemical pretreatment was the least effective. Critical surface tensions correlated directly with the surface fluorine to carbon ratios as calculated from XPS.

Messick, D. L.↗
NASA NTRS1984

Edge crack growth of thermally aged graphite/polyimide composites

Laminates of Celion 6000/LARC-160 and Celion 6000/PMR-15 graphite/polyimide composite materials were aged in air at temperatures of 202, 232, 260 and 288 C for various times up to 15,000 hours. Three unidirectional specimen types were studied: short beam shear (SBS), flexure, and 153 mm square panels. The interior region of the square panels exhibited little or no property degradation, whereas both laminate materials degraded and cracked preferentially at the specimen edge perpendicular to the fibers. Using a dye penetrant, the specimens were X-rayed and the crack depth measured as a function of time and temperature. A time temperature superposition of the crack data was successfully performed using an Arrhenius form for the shift factor. A direct correlation was found for edge crack depth and SBS strength for the LARC-160 laminates but the correlation for PMR-15 laminates was more complex.

Nelson, J. B.↗
NASA NTRS1984

Contamination Measurements During Ius Thermal Vacuum Tests in A Large Space Chamber

The levels of contamination that originate from inside the IUS equipment support section (ESS) due to outgassing from electronics components and wiring operating at elevated temperatures (80-160 F) were investigated. Pressure was measured inside and outside the ESS. Mass deposition measurements were made with quartz crystal microbalances (QCM) facing into and away from ESS vents. The OCM's were operated at -50 C and -180 C using thermoelectrically and cryogenically cooled QCM's. Gaseous nitrogen flow inside the ESS was used to obtain the effective molecular flow vent area of the ESS, which was evaluated to be 359 sq cm (56 sq in) compared to the 978 sq cm (150 sq in) estimated by an earlier atmosphere pressure billowing test. The total outgassing rate of the ESS materials at a temperature of 60 C (140 F) decays with a time constant of 11.5 hours based on pressure measurements during the hot cycle. A time constant of 22 hours was estimated for the fraction of the outgassing which will condense on a -50 C surface. In contrast, the time constant is only 10.1 hours for the outgassing material which condenses on a surface at -180 C. A surface at -180 C collects approximately one half of the material vented from the ESS which impinges on it. Pressure measurements show very good correlation with the mass deposition measurements.

C R Mullen↗
NASA NTRS1983

Thermal aging of graphite/polyimide composites

Celion 6000/PMR-15, Celion 6000/LARC-160, and Celion 6000/RK-99 graphite/polyimides were aged in circulating air ovens at temperatures of 202, 232, 260, and 288 C for various times, up to 15,000 h. Three unidirectional specimens were studied: short-beam-shear (SBS), flexure, and 153-mm square panels. The interior region of the square panels exhibited little or no property degradation. Based on the individually aged SBS specimen results, the relative thermal-oxidative stability from highest to lowest is as follows: PMR-15, LARC-160, RK-99, Celion 6000/PMR-15 and Celion 6000/LARC-160 laminates retained at least 80 percent of their initial flexural strengths for the duration of aging at each temperature. Celion 6000/RK-99 laminates exhibited a 20 to 50 percent loss of flexural strength at all aging temperatures. All three graphite/polyimide laminate materials degraded preferentially at the specimen edge perpendicular to the fibers.

Nelson, J. B.↗
NASA NTRS1984

Far-infrared studies of Herbig-Haro objects and their exciting stars

Far-infrared (40-160 micron) observations of Herbig-Haro objects and their probable exciting stars are presented. The importance of these far-infrared observations is epitomized by the fact that, on average, 70 percent of the bolometric luminosity of a typical candidate star is radiated beyond the longest detected ground-based wavelength, even for those objects observed out to 20 micron from the ground. Extended far-infrared emission characterizes some of these regions. Some Herbig-Haro nebulae are themselves conspicuous 100 micron peaks (e.g., HH 1 and HH 25). A bipolar structure is found at 100 micron in the vicinity of the Cohen-Schwartz star. All the exciting stars must be low-mass objects (approximately less than 3 solar mass). It is argued that they might be approximately 1 solar mass protostars still in their accretion phase.

Cohen, M.↗
NASA NTRS1984

Long-term thermal aging of 2 graphite-polyimide composite materials

Two graphite/polyimide composite materials were aged in circulating air ovens at temperatures 204 C, 232 C, 260 C, and 288 C for various times up to 25000 hours. The composites were: (1) Celanese Celion 6000 graphite fiber and PMR-15 polyimide resin (Celion/PMR-15) and (2) Celion 6000 graphite fiber and LARC-160 polyimide resin (Celion/LARC-160). Three unidirectional specimen geometries were studied: short beam shear (SBS) specimens, flexure specimens, and 153 mm square panels. The interior regions of the square panels exhibited only minor property degradation. The individually aged SBS and flexure specimens exhibited large reductions in strengths after aging. Both laminate materials cracked and degraded preferentially at the specimen edge perpendicular to the fibers.

Nelson, J. B.↗