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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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At least 1,027 records · Page 57

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NASA NTRS1986

Potential directions for a second generation Space Shuttle

This paper reports on trends and potentials for advanced rocket vehicles which may be candidates for eventual phased replacement of the Shuttle. Although such a replacement need is not foreseen until 2002 at the earliest, due to the long time to develop a new vehicle its definition has already begun. The paper discusses the role of such a "Shuttle II' in the architecture of launch vehicles likely to exist in the post-2000 era, leading to its designation as a smaller, primarily passenger-carrying vehicle to complement large, unmanned cargo launch vehicles. While a two-stage glide-back fully reusable configuration is optimum for near-term technology, a single-stage-to-orbit reusable glide-back configuration is optimum for farther-term technology advances. For advanced technology which could be available in the mid-90s, such vehicle could orbit a payload weight equal to their own dry weight - a factor of 10 better than current launch vehicles.

Bekey, I.↗

NASA NTRS1986

How different a modern SST would be

The characteristics of a proposed SST are described. The proposed aircraft is to have two engines and an arrow-wing design, a passenger capacity of 250, and attain speeds of Mach 2.7. The low fineness ratio, low-aspect ratio wing planform, different engine nacelles location, and improved lift-to-drag ratio of the aircraft contribute to attaining an economical supersonic cruise. The proposed structural design and materials for the aircraft are examined; the material and design are to be applicable to high Mach and high temperature. Changes in the SST propulsion system, the nozzle designs, and landing and takeoff procedures to improve the operation of the aircraft are discussed.

Driver, C.↗

NASA NTRS1986

The effect of advanced technology on the second-generation SST

Technological developments that promise to substantially increase the efficiency of next-generation subsonic commercial aircraft, together with additional developments in supersonic aircraft aerodynamics, structures and propulsion systems, are presently evaluated in order to project the extent of performance and economic improvement obtainable for a future SST by comparison to the Concorde SST. It is demonstrated that the second-generation SST projected will double passenger-carrying capacity from 100 for the Concorde to 200, despite reducing takeoff gross weight from 400,000 to 321,000 lbs and extending range by some 2000 nm.

Coen, P. G.↗

NASA NTRS1986

Sleep, sleepiness, and circadian rhythmicity in aircrews operating on transatlantic routes

A two-phase study was performed on B-747 crew members operating on regular passenger flights with 9-h time difference. In phase I, sleep-log surveys were obtained. The results for the layover period indicate congruent sleep patterns with shifts in sleep onset less than 9 h; sleep duration was prolonged. Phase II consisted of polygraphic sleep recordings and multiple sleep latency tests (MSLTs) applied to four cockpit crews in a baseline period, during the layover, and after return to home base. During the layover, mean bed times were shifted by about 4.5 h, and sleep was disturbed by early and prolonged awakenings which led to a reduction of sleep efficiency. The ECG and rectal temperature recordings gave evidence for a desynchronization of the circadian system and an internal dissociation of different body functions.

Wegmann, Hans M.↗

NASA NTRS1987

Structureborne noise control in advanced turboprop aircraft

Structureborne noise is discussed as a contributor to propeller aircraft interior noise levels that are nonresponsive to the application of a generous amount of cabin sidewall acoustic treatment. High structureborne noise levels may jeopardize passenger acceptance of the fuel-efficient high-speed propeller transport aircraft designed for cruise at Mach 0.65 to 0.85. These single-rotation tractor and counter-rotation tractor and pusher propulsion systems will consume 15 to 30 percent less fuel than advanced turbofan systems. Structureborne noise detection methodologies and the importance of development of a structureborne noise sensor are discussed. A structureborne noise generation mechanism is described in which the periodic components or propeller swirl produce periodic torques and forces on downstream wings and airfoils that are propagated to the cabin interior as noise. Three concepts for controlling structureborne noise are presented: (1) a stator row swirl remover, (2) selection of a proper combination of blade numbers in the rotor/stator system of a single-rotation propeller, and the rotor/rotor system of a counter-rotation propeller, and (3) a tuned mechanical absorber.

Loeffler, Irvin J.↗

NASA NTRS1987

Calculated performance, stability, and maneuverability of high speed tilting proprotor aircraft

The feasibility of operating tilting proprotor aircraft at high speeds is examined by calculating the performance, stability, and maneuverability of representative configurations. The rotor performance is examined in high speed cruise and in hover. The whirl flutter stability of the coupled wing and rotor motion is calculated in cruise. Maneuverability is examined in terms of the rotor thrust limit during turns in helicopter configuration. Rotor airfoils, rotor hub configuration, wing airfoil, and airframe structural weights representative of demonstrated advanced technology are considered. Key rotor and airframe parameters are optimized for high speed performance and stability. The basic aircraft design parameters are optimized for minimum gross weight. To provide a focus for the calculations, two high speed tiltrotor aircraft are considered: a 46-passenger civil transport and an air-combat/escort fighter, both with design speeds of about 400 knots. It is concluded that such high speed tiltrotor aircraft are quite practical.

Johnson, Wayne↗

NASA NTRS1986

Calculated performance, stability, and maneuverability of high-speed tilting-prop-rotor aircraft

The feasability of operating tilting-prop-rotor aircraft at high speeds is examined by calculating the performance, stability, and maneuverability of representative configurations. The rotor performance is examined in high-speed cruise and in hover. The whirl-flutter stability of the coupled-wing and rotor motion is calculated in the cruise mode. Maneuverability is examined in terms of the rotor-thrust limit during turns in helicopter configuration. Rotor airfoils, rotor-hub configuration, wing airfoil, and airframe structural weights representing demonstrated advanced technology are discussed. Key rotor and airframe parameters are optimized for high-speed performance and stability. The basic aircraft-design parameters are optimized for minimum gross weight. To provide a focus for the calculations, two high-speed tilt-rotor aircraft are considered: a 46-passenger, civil transport and an air-combat/escort fighter, both with design speeds of about 400 knots. It is concluded that such high-speed tilt-rotor aircraft are quite practical.

Johnson, Wayne↗

NASA NTRS1986

The use of flight test techniques in aircraft accident investigations

Wind shear is a serious safety hazard to commercial aviation. Low level wind shear (downburst) was the cause of the takeoff accident in New Orleans, July 9, 1982, and the landing accident in Dallas, Aug. 2, 1985. Shear layer instability is a common cause of clear air turbulence (CAT) at cruising altitudes. A number of encounters with severe CAT, in which passengers were injured, have recently occurred (Hannibal, MO, April 1981; Morton, WY, July 1982; etc.). Improved accident investigation techniques can lead to a better understanding of the nature of the wind environment associated with downbursts and CAT and to better detection and avoidance procedures. For the past several years, NASA-Ames has worked closely with the National Transportation Safety Board in the investigation of wind related accidents.

Parks, E. K.↗

NASA NTRS1987

Static tests of the propulsion system

Advanced, highly-loaded, high-speed propellers, called propfans, are promising to revolutionize the transport aircraft industry by offering a 15- to 30-percent fuel savings over the most advanced turbofans without sacrificing passenger comfort or violating community noise standards. NASA Lewis Research Center and industry have been working jointly to develop the needed propfan technology. The NASA-funded Propfan Test Assessment (PTA) Program represents a key element of this joint program. In PTA, Lockheed-Georgia, working in concert with Hamilton Standard, Rohr Industries, Gulfstream Aerospace, and Allison, is developing a propfan propulsion system which will be mounted on the left wing of a modified Gulfstream GII aircraft and flight tested to verify the in-flight characteristics of a 9-foot diameter, single-rotation propfan. The propfan, called SR-7L, was designed and fabricated by Hamilton Standard under a separate NASA contract. Prior to flight testing, the PTA propulsion system was static tested at the Rohr Brown Field facility. In this test, propulsion system operational capability was verified and data was obtained on propfan structural response, system acoustic characteristics, and system performance. This paper reports on the results of the static tests.

Withers, C. C.↗

NASA NTRS1987

Pool fires in a simulated aircraft cabin interior with ventilation

Results of experiments conducted at the JPL to evaluate aircraft postcrash fire hazards are presented. The experiments were carried out in a one-third scale simulated aircraft cabin geometry to study pool fire and ventilation flow interactions. It is shown that wind-induced ventilation may significantly affect fire plume orientation, smoke transport, and heat fluxes and thus will affect subsequent fire spread and the immediate survivability of the passengers.

Bankston, C. P.↗

NASA NTRS1986

Development of rotorcraft interior noise control concepts. Phase 3: Development of noise control concepts

The goal of this research is the understanding of helicopter internal noise mechanisms and the development, design, and testing of noise control concepts which will produce significant reductions in the acoustic environment to which passengers are exposed. The Phase 3 effort involved the identification and evaluation of current and advanced treatment concepts, including isolation of structure-borne paths. In addition, a plan was devised for the full-scale evaluation of an isolation concept. Specific objectives were as follows: (1) identification and characterization of various noise control concepts; (2) implementation of noise control concepts within the S-76 SEA (statistical energy analysis) model; (3) definition and evaluation of a preliminary acoustic isolation design to reduce structure-borne transmission of acoustic frequency main gearbox gear clash vibrations into the airframe; (4) formulation of a plan for the full-scale validation of the isolation concept; and (5) prediction of the cabin noise environment with various noise control concepts installed.

Yoerkie, Charles A.↗

NASA NTRS1986

Presentation of Class 1 designs for a family of commuter airplanes

The Class 1 configuration designs of a family of commuter aircraft are presented. The proposed aircraft will have a capacity of from 25 to 100 passengers. They are to have the following common features: (1) 2 aft fuselage mounted engines; (2) a low wing; (3) a T-tail type empennage; and (4) a tricycle type landing gear. A family concept is introduced to achieve structural, systems and handling quality commonality throughout. Implementing commonality can substantially reduce manufacturing and production costs. By achieving common system designs, maintenance costs can be reduced by permitting airlines to stock a smaller inventory of spares. Therefore, the higher degree of commonality, the lower the direct operating and life cycle costs. The attempt to implement some of the commonality requirements has caused configuration design problems, i.e., the twin-body concept was introduced. Design data are compared to existing aircraft, and the extent of structural, systems and handling qualities achieved are reviewed.

Creighton, Tom↗

NASA NTRS1986

Integrated Application of Active Controls (IAAC) technology to an advanced subsonic transport project: Program review

This report summarizes the Integrated Application of Active Controls (IAAC) Technology to an Advanced Subsonic Transport Project, established as one element of the NASA/Boeing Energy Efficient Transport Technology Program. The performance assessment showed that incorporating ACT into an airplane designed to fly approximately 200 passengers approximately 2,000 nmi could yield block fuel savings from 6 to 10 percent at the design range. The principal risks associated with incorporating these active control functions into a commercial airplane are those involved with the ACT system implementation. The Test and Evaluation phase of the IAAC Project focused on the design, fabrication, and test of a system that implemented pitch axis fly-by-wire, pitch axis augmentation, and wing load alleviation. The system was built to be flight worthy, and was planned to be experimentally flown on the 757. The system was installed in the Boeing Digital Avionics Flight Controls Laboratory (DAFCL), where open loop hardware and software tests, and a brief examination of a direct drive valve (DDV) actuation concept were accomplished. The IAAC Project has shown that ACT can be beneficially incorporated into a commercial transport airplane. Based on the results achieved during the testing phase, there appears to be no fundamental reason(s) that would preclude the commercial application of ACT, assuming an appropriate development effort is included.

Source record↗

NASA NTRS1988

Analytical modeling of the structureborne noise path on a small twin-engine aircraft

The structureborne noise path of a six passenger twin-engine aircraft is analyzed. Models of the wing and fuselage structures as well as the interior acoustic space of the cabin are developed and used to evaluate sensitivity to structural and acoustic parameters. Different modeling approaches are used to examine aspects of the structureborne path. These approaches are guided by a number of considerations including the geometry of the structures, the frequency range of interest, and the tractability of the computations. Results of these approaches are compared with experimental data.

Cole, J. E., III↗

NASA NTRS1988

The role of aviation technology in the Caribbean Basin

Aviation technology can play a significant role in the development of the countries of the Caribbean Basin. A variety of applications of rotorcraft in the region, the benefits, both economic and political which can result from utilization of rotorcraft in both a public service and commercial role are presented. A computer simulation of rotorcraft used as emergency medical vehicles is applied to compare and evaluate the advantages of using rotorcraft technology such as civil derivatives of the new tiltrotor. It is concluded that by using a civil derivative of the tiltrotor, significant improvements can be obtained in the level of health service in the region. The potential for cargo and passenger transport applications are currently being investigated and a second computer simulation is being developed to be used to evaluate the potential benefits to be derived from such applications.

Smith, Robert W.↗

NASA NTRS1988

Concept development of a Mach 3.0 high-speed civil transport

A baseline concept for a Mach 3.0 high-speed civil transport concept was developed as part of a national program with the goal that concepts and technologies be developed which will enable an effective long-range high-speed civil transport system. The Mach 3.0 concept reported represents an aggressive application of advanced technology to achieve the design goals. The level of technology is generally considered to be that which could have a demonstrated availability date of 1995 to 2000. The results indicate that aircraft are technically feasible that could carry 250 passengers at Mach 3.0 cruise for a 6500 nautical mile range at a size, weight and performance level that allows it to fit into the existing world airport structure. The details of the configuration development, aerodynamic design, propulsion system design and integration, mass properties, mission performance, and sizing are presented.

Robins, A. Warner↗

NASA NTRS1988

The influence of subsonic mission segments on the use of variable-sweep wings for high speed civil transport configurations

A Mach-3.0, 250-passenger, 6500-n. mi. range SST configuration's alternative use of fixed-planform or variable-sweep wings is presently evaluated, with a view to effects on aerodynamics, mission performance, and sizing. After preliminary design, the fixed and variable-wing configurations were resized to perform missions incorporating subsonic cruise segments of as much as 4000 n. mi.; the effect of subsonic segment length on design gross weight and block time was then ascertained. Due to the reduced supersonic efficiency of the variable-sweep aircraft, over one-half of the 6500-n. mi. mission would have to be flown subsonically for its sizing to reach a lower ramp weight than that of its fixed-geometry counterpart.

Martin, Glenn L.↗

NASA NTRS1985

Damage tolerant composite wing panels for transport aircraft

Commercial aircraft advanced composite wing surface panels were tested for durability and damage tolerance. The wing of a fuel-efficient, 200-passenger airplane for 1990 delivery was sized using grahite-epoxy materials. The damage tolerance program was structured to allow a systematic progression from material evaluations to the optimized large panel verification tests. The program included coupon testing to evaluate toughened material systems, static and fatigue tests of compression coupons with varying amounts of impact damage, element tests of three-stiffener panels to evaluate upper wing panel design concepts, and the wing structure damage environment was studied. A series of technology demonstration tests of large compression panels is performed. A repair investigation is included in the final large panel test.

Smith, Peter J.↗