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Composite-Material Pipes for Liquid Hydrogen

Weight is saved by eliminating metal components. Pipes made of graphite-fiber/epoxymatrix composites have been shown to be suitable as conduits for liquid hydrogen. Conceived for as replacements for heavier metallic liquid-hydrogen feedlines in spacecraft, pipes like these could also be advantageous in terrestrial applications in which there are requirements to minimize weights.

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Refractory, Oxidation-Resistant Ceramic/Carbon Insulation

These materials can withstand temp- eratures up 1,700 °C. Lightweight, refractory ceramic/carbon thermal-insulation materials have been invented. These materials, consist of carbon, silicon, and oxygen in suitable pro- portions combined into molecular structures that are stable at high temperatures. Insulating tiles and other com- ponents made of these materials can retain their shapes and strengths at temperatures as high as 1,700 °C.

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Analysis of Multilayer Thermal Insulation for Reentry

A paper presents a study of multilayer thermal insulations for protecting spacecraft against aerodynamic heating during reentry into a planetary atmosphere. A multilayer insulation considered in the study comprised (1) thin ceramic/composite foils coated with gold for high reflectance interspersed with (2) fibrous polycrystalline alumina spacers, all wrapped in (3) a bag made of ceramic fabric. The radiation heat transfer in the fibrous insulation spacers was modeled using the two-flux method assuming isotropic scattering. Combined radiative and conductive heat transfer in such blankets were computed by use of a finite-volume numerical model. The model was validated in steady-state and transient thermal tests of sample insulations.

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Ablative Coat Protects Against Brief, Intense Heating

A substrate can be protected against a rocket blast for a short time. An ablative composite coating has been developed to protect a steel substrate against a short-duration exposure to supersonic stream of hot gases and molten ceramic particles. In the original application, the short-duration hot, abrasive flow is resultant from the shuttle solid-fuel rocket motor exhaust during launch. The steel substrate to be protected is a holddown-post blast shield on a space-shuttle mobile launcher platform. The maximum temperature in the rocket blast exceeds 5,500 °F (≈3,000 °C), and the heat load on the blast shield can exceed 8,000 Btu/ft2s (≈91 MW/m2s). Other components and launch accessories exposed to similar intense, short-duration, heat loads could also be protected by use of similar composite coatings.

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Insertion of Reactive Material for Treating Groundwater

There is no need to remove most of the overlying soil. An improved method of inserting reactive material in the ground for treating groundwater contaminated with chlorinated solvents has been devised. An older method involves the removal of a significant portion of soil overlying the treatment volume, and consequently the expensive off-site disposal of the large amount of removed soil (some or all of which is contaminated). In the improved method, only a relatively small amount of soil need be removed.

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Lightweight Solar Sail for a Spacecraft Flying Near the Sun

A report proposes a high-temperature- resistant solar sail with an areal mass density less than 1 g/m2, for a spacecraft that would approach the Sun to within a distance of 0.2 astronomical unit (≈3 × 107 km). The sail would be made in multiple segments of a carbon microtruss fabric held in a network of tensioned lines. The segments and network would be designed to minimize tension in the fabric. The porosity of the fabric would be tailored so that to photons, the fabric would behave as though it were solid. Reflective metal surface films could be attached to the fabric. In advanced versions, the fabric could be directly coated with metal, or, alternatively, the fabric surface would be the sail surface and there would be no metal layer. The sail fabric would be wrapped around a sail cylinder and deployed by use of centrifugal force. A separate structure next to the sail cylinder would contain most of the deployment hardware and would be ejected after deployment of the sail to reduce the mass staying with the sail.

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Fabricating Better PSSA-PVDF-Based MEAs for Fuel Cells

Changes in the fabrication process enhance electrochemical performance. Some changes have been made in the fabrication of PSSA/ PVDF-based membrane/electrode assemblies for direct methanol fuel cells. The effect of the changes is to improve the electrochemical performances of the cells.

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