Engineering topics

Sawko, P. M.

Publications and source records attributed to Sawko, P. M..

At least 19 records

NASA NTRS1994

Insulating Blankets Withstand Higher Temperatures

Thermal-insulation blankets withstand repeated exposure to temperatures up to 2,000 degrees C. Thin, light in weight, and flexible. Developed to protect proposed aerospacecraft like Aeroassisted Space Transfer Vehicle and National Aerospace Plane, exposed to temperatures higher than those on surface of Space Shuttle during reentry into atmosphere of Earth. Also useful as furnace insulation and in firefighters' clothing. Sewing threads made of silicon carbide yarn essential components of blankets.

Kourtides, D. A.↗

NASA NTRS1990

Optical Properties Of Ceramic Fabrics

Report discusses optical properties of ceramic fabrics woven from silica, aluminoborosilicate, and silicon carbide yarns. Directional hemispheric reflectance and transmittance data given for several different weave patterns, yarn constructions, and fabric weights.

Covington, M. A.↗

NASA NTRS1986

Optical properties of woven ceramic fabrics for flexible heat shields

Optical-properties data for ceramic fabrics woven from silica, aluminoborosilicate, or silicon carbide yarns are presented. The normal hemispheric reflectances and transmittances measured at room temperature and over the spectral range of 250 to 2500 nm show a large dependence on fabric weight and a lesser dependence on fabric weave pattern. Reflectances of silicon carbide fabrics are lower by a factor of about 10 than those of silica and aluminoborosilicate. The reflectance and transmittance of silica and aluminoborosilicate fabrics decrease at wavelengths below 500 nm because of material absorption. A two-flux analytical model is used to derive spectral absorption and scattering coefficients for the silica and aluminoborosilicate fabrics from the measured reflectance and transmittance data, and comparisons are made with available data for other ceramics.

Covington, M. A.↗

NASA NTRS1986

Insulation Blankets for High-Temperature Use

Insulating blanket resists temperatures up to 1,500 degrees F (815 degrees C). Useful where high-temperature resistance, flexibility, and ease of installation are important - for example, insulation for odd-shaped furnaces and high-temperature ducts, curtains for furnace openings and fire control, and conveyor belts in hot processes. Blanket is quilted composite consisting of two face sheets: outer one of silica, inner one of silica or other glass cloth with center filling of pure silica glass felt sewn together with silica glass threads.

Goldstein, H.↗

NASA NTRS1985

Strength and flexibility properties of advanced ceramic fabrics

The mechanical properties of four advanced ceramic fabrics were measured at a temperature range of 23C to 1200C. The fabrics evaluated were silica, high and low-boria content aluminoborosilicate, and silicon carbide. Properties studied included fabric break strengths from room temperature to 1200C, and bending durability after temperature conditioning at 1200C and 1400C. The interaction of the fabric and ceramic insulation was also studied for shrinkage, appearance, bend resistance, and fabric-to-insulation bonding. Based on these tests, the low-boria content aluminoborosilicate fabric retained more strength and fabric durability than the other fabrics studied at high temperature.

Sawko, P. M.↗

NASA NTRS1985

Strength and flexibility properties of advanced ceramic fabrics

The mechanical properties of four advanced ceramic fabrics are measured at a temperature range of 23 C to 1200 C. The fabrics evaluated are silica, high-and low-boria content aluminoborosilicate, and silicon carbide. Properties studied include fabric break strengths from room temperature to 1200 C, and bending durability after temperature conditioning at 1200 C and 1400 C. The interaction of the fabric and ceramic insulation is also studied for shrinkage, appearance, bend resistance, and fabric-to-insulation bonding. Based on these tests, the low-boria content aluminoborosilicate fabric retains more strength and fabric durability than the other fabrics studied at high temperature.

Sawko, P. M.↗

NASA NTRS1985

Effect of processing treatments on strength of silica thread for quilted ceramic insulation on Space Shuttle

The effects of chemical, mechanical, and thermal processing treatments on the preflight strength properties of a silica sewing thread used to fabricate an external flexible Thermal Protection System (TPS) for the Space Shuttle vehicle are discussed. Below 540 C, loss of strength was observed for all treatments studied, but above conditioning temperatures of 540 C little change in strength properties was measured, indicating no appreciable mechanical damage to the yarn as a consequence of these processing treatments.

Sawko, P. M.↗

NASA NTRS1983

In-flight load testing of advanced shuttle thermal protection systems

NASA Ames Research Center has conducted in-flight airload testing of some advanced thermal protection systems (TPS) at the Dryden Flight Research Center. The two flexible TPS materials tested, felt reusable surface insulation (FRSI) and advanced flexible reusable surface insulation (AFRSI), are currently certified for use on the Shuttle orbiter. The objectives of the flight tests were to evaluate the performance of FRSI and AFRSI at simulated launch airloads and to provide a data base for future advanced TPS flight tests. Five TPS configurations were evaluated in a flow field which was representative of relatively flat areas without secondary flows. The TPS materials were placed on a fin, the Flight Test fixture (FTF), that is attached to the underside of the fuselage of an F-104 aircraft. This paper describes the test approach and techniques used and presents the results of the advanced TPS flight test. There were no failures noted during post-flight inspections of the TPS materials which were exposed to airloads 40 percent higher than the design launch airloads.

Trujillo, B. M.↗

NASA NTRS1983

In-flight load testing of advanced thermal protection systems

NASA Ames Research Center has conducted in-flight airload testing of some advanced thermal protection systems (TPS) at the Dryden Flight Research Center. The two flexible TPS materials tested, felt reusable surface insulation (FRSI) and advanced flexible reusable surface insulation (AFRSI), are currently certified for use on the Shuttle orbiter. The objectives of the flight tests were to evaluate the performance of FRSI and AFRSI at simulated launch airloads and to provide a data base for future advanced TPS flight tests. Five TPS configurations were evaluated in a flow field which was representative of relatively flat areas without secondary flows. The TPS materials were placed on a fin, the Flight Test Fixture (FTF), that is attached to the underside of the fuselage of an F-104 aircraft. This paper describes the test approach and techniques used and presents the results of the advanced TPS flight test. There were no failures noted during post-flight inspections of the TPS materials which were exposed to airloads 40 percent higher than the design launch airloads.

Trujillo, B. M.↗

NASA NTRS1980

Structural wood panels with improved fire resistance

Structural wood paneling or other molded wood compositions consisting of finely divided wood chips, flour, or strands are bound together and hot pressed with a modified novolac resin which is the cured product of a prepolymer made from an aralkyl ether or halide with a phenol and a hardening agent such as hexamethylene tetramine. The fire resistance of these articles is further improved by incorporating in the binder certain inorganic fillers, especially a mixture of ammonium oxalate and ammonium phosphate.

Sawko, P. M.↗

NASA NTRS1980

Self-curing polyimide foam

Chemical formulation produces foamed polyimide plastic without externalheat. Foam is less dense and more flame and acid resistant than conventional polyimide foams. Self curing foam can be formed "onsite" in limitedaccess locations where application of heat is difficult or impossible.

Riccitiello, S. R.↗

NASA NTRS1979

Catalysts for polyimide foams from aromatic isocyanates and aromatic dianhydrides

Polyimide foam products having greatly improved burn-through and flame-spread resistance are prepared by the reaction of aromatic polyisocyanates with aromatic dianhydrides in the presence of metallic salts of octoic acid. The salts, for example stannous octoate, ferric octoate and aluminum octoate, favor the formation of imide linkages at the expense of other possible reactions.

Riccitiello, S. R.↗

NASA NTRS1979

Fire protection covering for small diameter missiles

Flexible intumescent protection sheeting of unusually uniform thickness were prepared from epoxy-polysulfide compositions, containing microfibers and the ammonium salt of 1,4-nitroaniline-2-sulfonic acid, as disclosed in U.S. Pat. No. 3,663,464, except that an ammonium salt particle size in the order of 5 to 8 microns and a fiber size of about 1/128th inch in length and 3 to 5 microns in diameter were found critical to obtain the required density of 1.46 to 1.50 g/cc. The insulation sheeting was prepared by a continuous process involving vacuum mixing, calendering, and curing under very strict conditions which depend to some extent upon the thickness of the sheet produced.

Riccitiello, S. R.↗

NASA NTRS1979

Fire-resistant wood composites

Hot pressed wood panels made with modified novolak resins have burnthrough time of 450 s as compared to 280 s for products using conventional novolak resins. Incorporation of inorganic filler reduces flame spread index of panels from more than 200 to 60 or 70.

Sawko, P. M.↗

NASA NTRS1979

Improved imide polymerization catalyst

Catalyzation of imide polymers with metallic salts of 2-ethyl hexanoic acid allows reaction in production of flame resistant foams to proceed in one step without formation of undesirable heat-sensitive byproducts.

Estrella, C. A.↗

NASA NTRS1979

Fire-retardant covering for small containers

Flexible intumescent sheets of exceptionally uniform thickness may be used to protect containers and other small objects less than 25.4 cm in diameter from fire hazards.

Riccitiello, S. R.↗

NASA NTRS1979

Ambient curing fire resistant foams

The feasibility of development of an ambient curing foam is described. The thermal stability and flame spread index of the foams were found to be comparable to those of the high-temperature cured polyimide foams by Monsanto two-foot tunnel test and NASA T-3 Fire test. Adaptation of the material to spray in place applications is described

Hamermesh, C. L.↗

NASA NTRS1978

Ambient cure polyimide foams

Flame and temperature resistant polyimide foams are prepared by the reaction of an aromatic dianhydride, (pyromellitic dianhydride) with an aromatic polyisocyanate, (polymethylene polyphenylisocyanate), in the presence of an inorganic acid and furfuryl alcohol. Usable acids include dilute sulfuric acid, dilute nitric acid, hydrochloric acid, polyphosphoric acid, and phosphoric acid, with the latter being preferred. The dianhydride and the isocyanate in about equimolar proportions constitute about 50% of the reaction mixture, the rest being made up with the acid and the alcohol in a ratio of about 1:10. An exothermic reaction between the acid and the alcohol provides the heat necessary for the other components to polymerize without recourse to external heat sources. The mixture can be sprayed on any surface to form polymeric foam in locations where the application of heat is not practical or possible, for instance, between walls or on mine tunnel surfaces.

Sawko, P. M.↗