Engineering Papers⌕ Search

Engineering topics

Williams, L. J.

Publications and source records attributed to Williams, L. J..

30 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Air transportation energy consumption - Yesterday, today, and tomorrow

The energy consumption by aviation is reviewed and projections of its growth are discussed. Forecasts of domestic passenger demand are presented, and the effect of restricted fuel supply and increased fuel prices is considered. The most promising sources for aircraft fuels, their availability and cost, and possible alternative fuels are reviewed. The energy consumption by various air and surface transportation modes is identified and compared on typical portal-to-portal trips. A measure of the indirect energy consumed by ground and air modes is defined. Historical trends in aircraft energy intensities are presented and the potential fuel savings with new technologies are discussed.

Mascy, A. C.↗
NASA NTRS1975

Advanced subsonic aircraft concepts for passenger transportation

This paper discusses the potential for new subsonic transport aircraft designs that may evolve in the relatively near future, taking into account the added requirements for improved environmental compatibility and the potential constraints due to system congestion, substantial financial risk, and higher fuel costs or limited availability. Reflecting these additional requirements, potential aircraft developments are presented for new CTOL transports with significantly improved fuel economy, new STOL transports with improved short field capability, and new VTOL transports that could provide direct city-center service.

Waters, M. H.↗
NASA NTRS1974

Prospects for reduced energy transports: A preliminary analysis

The recent energy crisis and subsequent substantial increase in fuel prices have provided increased incentive to reduce the fuel consumption of civil transport aircraft. At the present time many changes in operational procedures have been introduced to decrease fuel consumption of the existing fleet. In the future, however, it may become desirable or even necessary to introduce new fuel-conservative aircraft designs. This paper reports the results of a preliminary study of new near-term fuel conservative aircraft. A parametric study was made to determine the effects of cruise Mach number and fuel cost on the optimum configuration characteristics and on economic performance. For each design, the wing geometry was optimized to give maximum return on investment at a particular fuel cost. Based on the results of the parametric study, a nominal reduced energy configuration was selected. Compared with existing transport designs, the reduced energy design has a higher aspect ratio wing with lower sweep, and cruises at a lower Mach number. It has about 30% less fuel consumption on a seat-mile basis.

Ardema, M. D.↗
NASA NTRS1972

Study of buoyancy systems for flight vehicles

The performance potential of buoyant systems and flexible structures used in air vehicles for short-haul passenger transportation is discussed. The study was intended only to determine if sufficient performance potential existed, and to provide a focus for a more extensive design study, if such a study appeared desirable. A relatively conventional helium system was examined along with a more unusual configuration employing hot-air as the buoyant fluid. Both configurations were examined in the VTOL and STOL modes of operation. The helium system appears to have some superiority in the VTOL mode, while the hot-air system has a superiority in the STOL mode. Both configurations exhibit sufficient performance potential to suggest that a much more extensive design study might well be undertaken.

Havill, C. D.↗
NASA NTRS1972

Automated synthesis of transonic transports.

The development of a vehicle synthesis program, called TRANSYN, designed to perform automated preliminary design of long-haul transport aircraft is briefly described. The TRANSYN-TST program was used in a study of commercial transonic transports designed for introduction in the early 1980s. The optimum engine cycles of all the study aircraft are within the current state-of-the-art, but fan noise suppression will be required to meet the noise requirements of FAR Part 36. It was found that full use of advanced composite materials in the wing and fuselage structure is neutrally cost effective when compared with aluminum for aircraft designed to cruise in the low transonic regime (Mach 0.90 to 1.0), but that such materials are very cost effective for aircraft designed to cruise in the high transonic regime (Mach 1.0 to 1.15). Finally, increasing speed results in reduced trip times with at most very slight increases in cost in the low transonic regime, but cruise speeds in the high transonic regime result in a significant economic penalty for the conventional configurations considered in this study.

Ardema, M. D.↗
NASA NTRS1972

Transonic transport study: Structures and aerodynamics

The structural and aerodynamic aspects of a general study of advanced transonic transports are presented. Aircraft designed to cruise at Mach numbers of 0.90, 0.98, and 1.15 were comparatively analyzed. The wings of all three aircraft employ supercritical sections, and the two aircraft with the highest cruise Mach numbers also employ fuselage area ruling. Structural/aerodynamic characteristics and interactions are investigated both parametrically and with the aid of an automated configuration optimization program. The effects of replacing conventional aluminum airframe structure by advanced filamentary composite (carbon/epoxy) structure receive particular attention. The methods employed in the structural/aerodynamic analysis are discussed.

Ardema, M. D.↗
NASA NTRS1972

Transonic transport study, summary

The effects of possible increases in cruise speed over present-day transport aircraft were investigated. Increased cruise speed is desirable not only because of a possible competitive market advantage, but also because of the resulting increase in aircraft productivity. Aircraft designed to cruise at Mach numbers greater than those of present-day transports but less than those which produce a sonic boom on the ground were studied. The purpose of the study was three-fold: (1) to compare, on an equal basis, the performance and economics of advanced commercial transport aircraft designed to cruise at Mach numbers 0.90, 0.98, and 1.15; (2) to determine the sensitive technical areas affecting the performance and economics of the aircraft; and (3) to assess the impact of advanced technology, particularly the supercritical wing and advanced composite materials on the performance and economics of the aircraft.

Williams, L. J.↗
NASA NTRS1972

Some applications of buoyancy systems and parawings to replace conventional and proposed transportation systems.

An exploratory study has been conducted to assess the performance potential of buoyant airships and parawings in short-haul passenger transportation. Results show that such systems can be used effectively, from a performance standpoint, in a VTOL or STOL mode of operation. A supplementary assessment of potential applications of such vehicles is examined, with a brief look at economic factors and an examination of missions for which they might be effectively used.

Havill, C. D.↗