Engineering topics

Snow, D. B.

Publications and source records attributed to Snow, D. B..

4 records

NASA NTRS1989

Identification of a cast iron alloy containing nonstrategic elements

A program was performed to address the mechanical and environmental needs of Stirling engine heater head and regenerator housing components, while reducing the dependence on strategic materials. An alloy was developed which contained no strategic elemental additions per se. The base is iron with additions of manganese, molybdenum, carbon, silicon, niobium, and ferro-chromium. Such an alloy should be producible on a large scale at very low cost. The resulting alloy, designated as NASAUT 4G-Al, contained 15 Mn, 15 Cr, 2 Mo, 1.5 C, 1.0 Si, 1.0 Nb (in weight percent) with a balance of Fe. This alloy was optimized for chemistry, based upon tensile strength, creep-rupture strength, fracture behavior, and fatigue resistance up to 800 C. Alloys were also tested for environmental compatibility. The microstructure and mechanic properties (including hardness) were assessed in the as-cast condition and following several heat treatments, including one designed to simulate a required braze cycle. The alloy was fabricated and characterized in the form of both equiaxed and columnar-grained castings. The columnar grains were produced by directional solidification, and the properties were characterized in both the longitudinal and transverse orientations. The NASAUT 4G-Al alloy was found to be good in cyclic-oxidation resistance and excellent in both hydrogen and hot-corrosion resistance, especially in comparison to the baseline XF-818 alloy. The mechanical properties of yield strength, stress-rupture life, high-cycle-fatigue resistance, and low-cycle-fatigue resistance were good to excellent in comparison to the current alloy for this application, HS-31 (X-40), with precise results depending in a complex manner on grain orientation and temperature. If required, the ductility could be improved by lowering the carbon content.

Cooper, C. V.↗

NASA NTRS1981

Can advanced technology improve future commuter aircraft

The short-haul service abandoned by the trunk and local airlines is being picked up by the commuter airlines using small turboprop-powered aircraft. Most of the existing small transport aircraft currently available represent a relatively old technology level. However, several manufacturers have initiated the development of new or improved commuter transport aircraft. These aircraft are relatively conservative in terms of technology. An examination is conducted of advanced technology to identify those technologies that, if developed, would provide the largest improvements for future generations of these aircraft. Attention is given to commuter aircraft operating cost, aerodynamics, structures and materials, propulsion, aircraft systems, and technology integration. It is found that advanced technology can improve future commuter aircraft and that the largest of these improvements will come from the synergistic combination of technological advances in all of the aircraft disciplines. The most important goals are related to improved fuel efficiency and increased aircraft productivity.

Williams, L. J.↗

NASA NTRS1975

Hydrogen for the subsonic transport

Relations between air travel and fuel requirements are examined. Alternate fuels considered in connection with problems related to a diminishing supply of petroleum include synthetic jet fuel, methane, and hydrogen. A cruise flight of a subsonic aircraft on a hydrogen-fueled jet engine was demonstrated in 1957. However, more development work is required to provide a sound engineering base for a complete air transportation system using hydrogen as fuel. Aircraft designs for alternate fuels are discussed, giving attention to hydrogen-related technology already available and new developments which are needed.

Korycinski, P. F.↗

NASA NTRS1974

A study of subsonic transport aircraft configurations using hydrogen (H2) and methane (CH4) as fuel

The acceptability of alternate fuels for future commercial transport aircraft are discussed. Using both liquid hydrogen and methane, several aircraft configurations are developed and energy consumption, aircraft weights, range and payload are determined and compared to a conventional Boeing 747-100 aircraft. The results show that liquid hydrogen can be used to reduce aircraft energy consumption and that methane offers no advantage over JP or hydrogen fuel.

Snow, D. B.↗