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At least 433 records · Page 24

Examination of returned Surveyor 3 camera visor for alpha radioactivity

The TV camera visor was placed in a vacuum chamber and examined for alpha radioactivity using an alpha-scattering instrument, and plates covered with the same paint and made at the same time as the visor were used as a control. The spectra of visor and plates are very similar, and it is concluded that the gross activity on the visor is due entirely to the activity of the paint. The data were used to obtain the amount of Po-210 activity on the lunar surface. It is felt that the lack of detected alpha radioactivity does not indicate a lack of activity on the moon, since dust layers were knocked off the visor.

Economou, T. E.↗

Heat transfer tests of the McDonnell-Douglas delta wing orbiter mated with -17A booster at Mach number 8

A wind tunnel test program to determine aerodynamic heat transfer distributions on the McDonnell-Douglas configurations is reported. The tests were conducted at the Arnold Engineering Development Center (AEDC) in Tunnel B of the von Karman Gas Dynamics Facility (VKF). Heat-transfer rates were determined by the phase-change paint technique on 0.011-scale Stycast models using Tempilaq as the surface temperature indicator. The nominal test conditions were; Mach 8, freestream unit Reynolds numbers of 0.8 x one million, 2.5 x one million, and 3.7 x one million, and angles of attack of -5 deg, 0 deg, +5deg. Model details, test conditions, phase-change paint photographs and reduced heat-transfer coefficients are presented.

Matthews, R. K.↗

Ascent heat transfer rate distribution on the North American Rockwell delta wing orbiter and the General Dynamics/Convair booster at a Mach number of 8 (mated)

A wind tunnel test program to determine aerodynamic interference heating on the North American Rockwell orbiter mated with the General Dynamics Convair booster is discussed. The tests were conducted at the Arnold Engineering Development Center (AEDC) in Tunnel B of the von Karman Gas Dynamics Facility (VKF). The test period was June 1971. Heat-transfer rates were determined by the phase-change paint technique on 0.013-scale Stycast models using Tempilaq as the surface temperature indicator. The nominal test conditions were: Mach 8, free-stream unit length Reynolds numbers of 1.25 x one million and 2.55 x one million angles of attack of -5, 0, +5 deg. Model details, test conditions, phase-change paint photographs and reduced heat-transfer coefficients are presented.

Matthews, R. K.↗

Heat shields for aircraft - A new concept to save lives in crash fires.

A passenger compartment surrounded by a fire-retardant shell, to protect the occupants long enough for the fire to burn out or for fire-fighting equipment to reach the aircraft and extinguish it, is proposed as a new concept for saving lives in crash fires. This concept is made possible by the recent development of two new fire-retardant materials: a very lightweight foam plastic, called polyisocyanurate foam, and an intumescent paint. Exposed to heat, the intumescent paint expands to many times its original thickness and insulates the surface underneath it. Demonstration tests are illustrated, described and discussed. However, some problems, such as preventing fuselage rupture and protecting windows, must be solved before such a system can be used.

Neel, C. B.↗

Experimental test of plant canopy reflectance models on cotton

Spectroradiometric data on the bidirectional reflectance function was collected for a cotton canopy as a function of observer zenith angle, observer angle, and solar zenith angle. The area under study was about 40 miles from the Gulf of Mexico and the prevailing winds blew inland such that cloud formation increased during the day. The standard reflectance panel was constructed of plywood that had been spray painted with a flat white latex paint. Physical and optical plant parameters were measured. A time lapse mechanism was constructed to operate a 16 mm movie camera such that single frames could be exposed at intervals of one per second up to one per hour. Data were digitized from a strip chart recorder and reflectance panel measurements.

Lemaster, E. W.↗

Fluorescent color coding of power receptacles

Receptacles, color coded according to power ratings, can be easily located. Low-light visibility of fluorescent paint saves considerable time during repair or replacement. Technicians using flashlights have located and identified painted receptacles from as far away as 50 feet (15 meters).

Oleson, C. C.↗

Optical effect of the contamination of infrared windows by the outgassing of materials in outer space

The composition and evaporation rate of the outgassing of a space vehicle thermal control paint as a function of temperature were studied. A contamination chamber was designed, constructed, and tested. Samples of thermal control paint were tested to determine if heating to moderate temperatures causes them to release outgassing products which can be collected on a cooled cesium iodide window for identification by IR analysis. Results showed that outgassing of surfaces other than the sample was a problem. Spectral bands of the deposits collected were compared.

Silberman, E.↗

Status of the NASA-Lewis flat-plate collector tests with a solar simulator

Simulator test results of 15 collector types are presented. Collectors are given performance ratings according to their use for pool heating, hot water, absorption A/C or heating, and solar Rankine machines. Collectors found to be good performers in the above categories, except for pool heating, were a black nickel coated, 2 glass collector, and a black paint 2 glass collector containing a mylar honeycomb. For pool heating, a black paint, one glass collector was found to be the best performer. Collector performance parameters of 5 collector types were determined to aid in explaining the factors that govern performance. The two factors that had the greatest effect on collector performance were the collector heat loss and the coating absorptivity.

Simon, F. F.↗

Development of space stable thermal control coatings for use on large space vehicles

The development of a large scale manufacturing method for the production of a stable zinc orthotitanate pigment is discussed. Major emphasis was placed on the evaluation of the radiation stability of Tektronix, Inc. pigments and of the conditions (time and temperature) leading to high reflection and high optical stability. Paints were formulated in OI-650 and in OI-650G vehicles from pigments which were prepared at various temperatures, some of which were chemically treated to remove ZnO. Ultraviolet irradiation tests of these paints were performed, and observations made regarding optimum pigment preparation parameters.

Gilligan, J. E.↗

Radiative property investigation

Measurements of the bidirectional reflections of NASA paints Z-93 and S-13G were made for 0.5, 1.78, and 2.5 microns, source incidence angles of 0, 30, 60, and 75 deg, and four detector azimuth positions. The bidirectional reflectance distribution was found to be near Lambert for azimuth positions not to close to 180 deg from the source incident azimuth. The reflectance distribution at an azimuth of 180 deg from the source is close to Lambert for near normal source incidents angles, and becomes much larger than Lambert as the source incident angle approach grazing. The reflectance deviates from Lambert as the wavelength increases. Comparison of data for the paints shows Z-93 reflectance is much closer to Lambert than S-13G. When there is a peak in the reflectance distribution it occurred at the specular angle or an angle larger than the specular angle.

Scott, R. L., Jr.↗

Optical effect of the contamination of infrared windows by the outgassing of materials in outer space

The products and kinetics of outgassing from S13G paint were studied by using infrared absorption measurements of the material outgassed (using an evaporation cell and vacuum chamber). Two separate long-term experimental depositions from heated samples of the S13G paint were made. Before each experiment, the vacuum chamber and sample holder were carefully cleaned and outgassed to ensure that subsequent deposits on the colled-window were due only to the products evaporated from the sample. Results of experiments are listed and discussed.

Silberman, E.↗

Status of the NASA-Lewis flat-plate collector tests with a solar simulator

Simulator test results of 15 collector types are reported. Collectors are given performance ratings according to their use for pool heating, hot water, absorption A/C or heating and solar Rankine machines. Collectors found to be good performers in the above categories, except for pool heating, were a black nickel coated, 2 glass collector, and a black paint 2 glass collector containing a mylar honeycomb. For pool heating, a black paint, one glass collector was found to be the best performer. Collector performance parameters of 5 collector types were determined to aid in explaining the factors that govern performance. The two factors that had the greatest effect on collector performance were the collector heat loss and the coating absorptivity.

Simon, F. F.↗

A study of molecular contamination

Contamination kinetics of typical space materials were studied using several techniques, including ellipsometry. Data were obtained on contaminant deposition rates, sticking coefficients, and reevaporation of the contamination. Materials studied included silicone sealants, a thermal control paint, and a graphite laminate as contaminant sources, and gold coated surfaces, a thermal control paint and a second surface mirror material as the contaminees. Both deposition and reevaporation rates were found to be nonlinear with time, and followed an exponential decay. A hypothesis is presented that the nonlinear behavior was a result of disproportionation of the molecular weight fractions of the polymers. The measured sticking coefficients were found to vary substantially with temperature over narrow ranges. Simulated space radiation was found to reduce the evaporation rates of contaminants by several orders of magnitude.

Allen, T. H.↗

Testing of typical spacecraft materials in a simulated substorm environment

An investigation to determine spacecraft materials characteristics under charging conditions was conducted at the Lewis Research Center substorm simulation facility. The test specimens were spacecraft paints, silvered Teflon, thermal blankets and solar array segments. The samples, ranging in size from 300 to 1,000 sq cm were exposed to monoenergetic electron energies from 2 to 20 keV at a current density of 1 nA sq cm. The samples generally behaved as capacitors with strong voltage gradients at their edges. The charging characteristics of the silvered Teflon, Kapton, and solar cell covers were controlled by the secondary emission characteristics. Insulators that did not discharge were the spacecraft paints and the quartz fiber cloth thermal blanket sample. All other samples did experience discharges when the surface voltage reached -8 to -16 kV. The discharges were photographed. The breakdown voltage for each sample was determined and the average energy lost in the discharge was computed.

Stephens, N. J.↗

Space stable thermal control coatings

Efforts to develop an engineering paint were concentrated on inorganic silicate-bonded systems as opposed to the silicone coatings. The UV-vacuum stability of potassium silicate-Zn2TiO4 paints were shown to be quite good. Reflectance optimization of these systems is being studied by maximizing thickness and pigment to binder ratio.

Harada, Y.↗

Space stable thermal control coatings

Both pigment and paint studies were conducted to determine the effect of calcination conditions on optical properties of Zn2TiO4. Paint studies were concerned with the effects of spraying technique, of pigment to binder ratio, and of thickness on the properties of finished coatings. The results are reviewed in detail. Pigments prepared by calcination at 600 deg. to 800 deg. were evaluated. Low temperature syntheses were conducted to determine; (1) extent of ZnO + TiO2 reaction; and (2) the potential of higher peak reflectance with finer particle size powder obtained at lower temperatures.

Harada, Y.↗

Thermal-leak analyzer for vacuum-jacketed lines

Technique involves coating suspected area with water-soluble black paint that gives even, infrared emission. Painted area is warmed with heat gun; an infrared scanner is used to detect cooled spot on jacket exterior. Introduction of atmospheric pressure into jacket intensifies leak jet and improves test sensitivity.

Heisman, R. M.↗

Coating for hot sliding seals

Heat resistant paint is effective surface coating for sliding seals that must operate at elevated temperatures. Economical paint is easy to apply, offers minimal friction, and improves reliability of seals.

Stock, J.↗