Scale parachute fabrication
Report describes highlights in developing six 12.5-percent scale drogue parachute models. Deployment bags are fabricated for each model.
Bacchus, D.↗
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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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Heat-shrinkable film improves adhesive bonds
Pressure is applied during adhesive bonding by wrapping parts in heat-shrinkable plastic film. Film eliminates need to vacuum bag or heat parts in expensive autoclave. With procedure, operators are trained quickly, and no special skills are required.
Johns, J. M.↗
Investigation of Test Methods, Material Properties, and Processes for Solar Cell Encapsulents
The technical activities were directed toward the assessment of encapsulation processes for use with ethylene/vinyl acetate copolymer as the pottant. Potentially successful formulations were prepared by compounding the raw polymer with ultraviolet absorbers and crosslinking agents to give stabilized and curable compositions. The compounded resin was then converted to a more useful form with an extruder to give pottant in sheets that could be more easily used in lamination. After experimenting with various techniques, the vacuum-bag process was found to be an excellent encapsulation method. Miniature single-celled and multi-celled solar modules of both substrate and superstrate designs were prepared by this technique. The resulting modules were of good appearance, were bubble-free, and successfully passed the thermal cycle test.
Source record↗
Design and fabrication of a super alloy thermal protection system
A lightweight metallic TPS was designed, and two test articles were fabricated, one from Haynes 188 and one from Rene 41. A baseline TPS concept, selected at the beginning of the program, consisted of a Haynes 25 corrugation-stiffened beaded skin surface panel, a specially designed support system, and an insulation system. By optimizing the structure for the design loads and by chem-milling to remove material not needed, the mass of the baseline surface panel was reduced 25%, and the mass of the support structure was reduced 50%. The insulation system mass was reduced 40% by using two types of insulation, each suited to its temperature range, and by eliminating a foul bag which encapsulated the baseline insulation system. These reductions resulted in an overall 35% reduction in mass of the Haynes 188 panel from the baseline Haynes 25 design. Similar reductions were achieved with the Rene 41 system.
Varisco, A.↗
Status of candidate materials for full-scale tests in the 737 fuselage
The test program has the objectives to: (1) increase passenger evacuation time to a minimum of five minutes from commercial aircraft in case of a fire; (2) prevent an external fire from entering closed cabins for five minutes by using fire barrier materials in the exterior wall; (3) demonstrate that a closed cabin will not reach 400 F; and (4) prove that a fire near a cabin opening will not propagate through the cabin for a minimum of five minutes. The materials status is outlined for seat cushions, upholstery and associated seat materials, wall and ceiling panels, floor panels, carpet and carpet underlay, windows, cargo bay liners, insulation bagging, and thermal acoustical insulation.
Supkis, D.↗
Extensive cost reduction studies: Composite empennage component - L-1011 commercial airliner
A series of cover skin laminate studies was conducted. The baseline laminate design is composed of 34 plies with doublers interwoven. This is costly to produce, since the broad goods tape dispersing machine must stop frequently while the doubler plies are inserted by hand during the layup sequence. The use of graphite cloth was investigated for the cover skin. Attention is also given to low resin content prepreg, the selection of optimum tape width, an increase in gap/overlap tolerances, the use of large reusable vacuum bags with mechanical edge seals for production, an integrated laminating center machine, automated hat stiffener processing, a secondary bond assembly process, and a single-stage cure process.
Van Hamersveld, J.↗
Ice nucleation activity of rocket effluent
An investigation was conducted concerning the ice nucleation activity of the exhaust products of solid rockets. The Voyager I and II payloads were launched from Kennedy Space Center on September 5 and August 20, 1977, respectively. A visible stabilized ground cloud (SGC) consisting of rocket effluent and dust formed downwind. An instrumented aircraft was used to make multiple passes in the SGC. A Mylar bag was rapidly filled with SGC aerosol and then immediately sampled with an ice nucleus counter. Analyses of rocket effluent collected are discussed, taking into account the ice nucleus concentration, particle concentration and size distribution, and the elemental composition of individual particles. A description of laboratory experiments is also presented, giving attention to the elemental composition of individual particles and the ice nucleus concentration.
Parungo, F. P.↗
Fire tests for airplane interior materials
Large scale, simulated fire tests of aircraft interior materials were carried out in salvaged airliner fuselage. Two "design" fire sources were selected: Jet A fuel ignited in fuselage midsection and trash bag fire. Comparison with six established laboratory fire tests show that some laboratory tests can rank materials according to heat and smoke production, but existing tests do not characterize toxic gas emissions accurately. Report includes test parameters and test details.
Tustin, E. A.↗
Shaping graphite/epoxy stiffeners
Layers of graphite/epoxy, tape stacked on ridges and in grooves of channel like ribs stiffen curved laminates. Twenty-five to 38 layers of tape on each cap and flange are vacuum-bagged into shape and then interleaved with plies of fabric to form light-weight structural members free of wrinkles and voids. Structure could be parts for cars, trucks, and other vehicles.
Cupp, J. L.↗
Manufacturing methods of a composite cell case for a Ni-Cd battery
Basic manufacturing method refinements for using graphite epoxy material for a nickel cadmium battery cell case were performed to demonstrate production feasibility. The various facets of production scale-up, i.e., process and tooling development, together with material and process control, were integrated into a comprehensive manufacturing process that assures production reproducibility and product uniformity. Test results substantiate that a battery cell case produced from graphite epoxy pre-impregnated material, utilizing the internal pressure bag fabrication method, is feasible.
Bauer, J. L.↗
Roadside tree/pole crash barrier field test
A series of tests was carried out to evaluate the performance of a crash barrier designed to protect the occupants of an automobile from serious injury. The JPL barrier design is a configuration of empty aluminum beverage cans contained in a tear-resistant bag which, in turn, is encased in a collapsible container made of plywood and steel. Tests were conducted with a driven vehicle impacting the barrier. The basic requirements of NCHRP Report 153 were followed except that speeds of 30 mph rather than 60 mph were used. Accelerometer readings on the driver's helmet showed that the driver was never subjected to dangerous decelerations, and never experienced more than temporary discomfort. Also, all of the requirements of the cited report were met. An extrapolation of data indicated that the JPL barrier installed in front of a tree or telephone pole along a roadside would also have met the requirements at a speed of 40 mph.
Wilson, A. H.↗
A spin-recovery parachute system for light general-aviation airplanes
A tail mounted spin recovery parachute system was designed and developed by the NASA Langley Research Center for use on light general aviation airplanes. The system was designed for use on typical airplane configurations, including low wing, single engine, and twin-engine design. A mechanically triggered pyrotechnic slug gun is used to forcibly deploy a pilot parachute which extracts a bag that deploys a ring slot spin recovery parachute. The total system weighs 8.2 kg (18 lb). System design factors included airplane wake effects on parachute deployment, prevention of premature parachute deployment, positive parachute jettison, compact size, low weight, system reliability, and pilot and ground crew safety. Extensive ground tests were conducted to qualify the system. The recovery parachute was used successfully in flight 17 times.
Bradshaw, C.↗
A spin-recovery parachute system for light general-aviation airplanes
A tail mounted spin recovery parachute system was designed and developed for use on light general aviation airplanes. The system was designed for use on typical airplane configurations, including low wing, high wing, single engine and twin engine designs. A mechanically triggered pyrotechnic slug gun is used to forcibly deploy a pilot parachute which extracts a bag that deploys a ring slot spin recovery parachute. The total system weighs 8.2 kg. System design factors included airplane wake effects on parachute deployment, prevention of premature parachute deployment, positive parachute jettison, compact size, low weight, system reliability, and pilot and ground crew safety. Extensive ground tests were conducted to qualify the system. The recovery parachute was used successfully in flight 17 times.
Bradshaw, C.↗
A spin-recovery parachute system for light general aviation airplanes
A tail-mounted spin-recovery parachute system has been designed and developed by the NASA Langley Research Center for use on light general aviation airplanes. The system was designed for use on typical airplane configurations, including low-wing, high-wing, single- and twin-engine designs. A mechanically triggered pyrotechnic slug gun is used to forcibly deploy a pilot parachute which extracts a bag that deploys a ring-slot spin-recovery parachute. The total system weighs 8.2 kg (18 lb). System design factors included airplane wake effects on parachute deployment, prevention of premature parachute deployment, positive parachute jettison, compact size, low weight, system reliability, and pilot and ground crew safety. Extensive ground tests were conducted to qualify the system. The recovery parachute has been used successfully in flight 17 times.
Bradshaw, C. F.↗
Manufacturing methods of a composite cell case for a Ni-Cd battery
Graphite epoxy material for a nickel cadmium battery cell case has been evaluated and determined to perform in the simulated environment of the battery. The basic manufacturing method requires refinement to demonstrate production feasibility. The various facets of production scale-up, i.e., process and tooling development together with material and process control, have been integrated into a comprehensive manufacturing process that assures production reproducibility and product uniformity. Test results substantiate that a battery cell case produced from graphite epoxy pre-impregnated material utilizing internal pressure bag fabrication method is feasible.
Bauer, J. L.↗
Development of orthotropic birefringent materials for photoelastic stress analysis
Materials were selected and fabrication procedures developed for orthotropic birefringent materials. An epoxy resin (Maraset 658/558 system) was selected as the matrix material. Fibers obtained from style 3733 glass cloth and type 1062 glass roving were used as reinforcement. Two different fabrication procedures were used. In the first one, layers of unidirectional fibers removed from the glass cloth were stacked, impregnated with resin, bagged and cured in the autoclave at an elevated temperature. In the second procedure, the glass roving was drywound over metal frames, impregnated with resin and cured at room temperature under pressure and vacuum in an autoclave. Unidirectional, angle-ply and quasi-isotropic laminates of two thicknesses and with embedded flaws were fabricated. The matrix and the unidirectional glass/epoxy material were fully characterized. The density, fiber volume ratio, mechanical, and optical properties were determined. The fiber volume ratio was over 0.50. Birefringent properties were in good agreement with predictions based on a stress proportioning concept and also, with one exception, with properties predicted by a finite element analysis.
Daniel, I. M.↗
Flaw criticality of circular disbond defects in compressive laminates
The compressive behavior of T300/5208 graphite-epoxy laminates containing circular delaminations was studied to determine the flaw criticality of two types of implanted defect, Kapton bag and Teflon film, on several laminate configurations. Defect size was varied. Results, presented in the form of residual strength curves, indicate that the Teflon film defect reduced strength more than the Kapton bad defect in 12-ply samples, but that two laminates (+ or - 45) sub 2s and (90/+ or - 45) sub s were insensitive to any implanted defect. A clear thickness effect was shown to exist for the (o/+ pr 45) sub ns laminate and was attributed to failure mode transition. The analytically predicted buckling loads show excellent agreement with experimental results and are useful in predicting failure mode transition.
Webster, J. D.↗
An improved lamination technique for solar arrays
Encapsulating solar cells by lamination has been plagued with problems such as bubbles, cell shifting, ripples, and cracked cells. A low-cost laminating procedure has been developed using a double vacuum bagging technique and recently improved formulations of ethylene vinyl acetate, successfully minimizing these problems. The lamination fixturing used is described. The causes and cures of various problems are discussed and solutions to these problems presented. The apparent modulus of the face sheet seen by the module being laminated is believed to be the primary variable which must be optimized. Conditions at the module edge are also considered to be important for producing an acceptable product.
Garcia, A., III↗