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At least 307 records · Page 17

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NASA NTRS1977

Flight simulation testing of advanced composites for supersonic cruise aircraft applications

The goal of this program is to characterize advanced composite systems before and after exposures to simulated supersonic cruise environments for real times of up to 50,000 hours. Fatigue data for specimens tested at various temperatures and stress ratios are presented. The changes in properties and the degradation mechanisms during high temperature aging are discussed and illustrated using metallographic and fractographic techniques. Initial results of long term flight simulation tests are presented and compared with wearout model predictions based on accelerated flight simulation exposures.

Haskins, J. F.↗

NASA NTRS1977

Design and performance of energy efficient propellers for Mach 0.8 cruise

It is believed that a fuel saving of 14 to 40 percent may be realized by the use of an advanced high-speed turboprop. This turboprop must be capable of high efficiency at Mach 0.8 cruise above 9.144 km altitude if it is to compete with turbofan powered commercial aircraft. Several advanced aerodynamic concepts were investigated in recent wind tunnel tests under NASA sponsorship on two propeller models. These concepts included aerodynamically integrated propeller/nacelles, area-ruling, blade sweep, reduced blade thickness and power (disk) loadings several times higher than conventional designs. The aerodynamic design methodology for these models is discussed in this paper. In addition, some of the preliminary test results are presented which indicate that propeller net efficiencies near 80 percent were obtained for high disk loading propellers operating at Mach 0.8.

Mikkelson, D. C.↗

NASA NTRS1977

Atmospheric effects on inlets for supersonic cruise aircraft

Time response effects of atmospheric-type disturbances on inlets and some implications regarding inlet controls are considered. A study involving the simulation of a mixed-compression inlet is described. The study employs a linear dynamic analysis, modified for a significant nonlinearity. Transient disturbances in ambient temperature and pressure and wind gusts are considered independently at the inlet cruise Mach number of 2.5. The presented results show the maximum amplitude of a triangular-wave disturbance, that does not cause inlet unstart, as a function of disturbance pulse width.

Cole, G. L.↗

NASA NTRS1977

Recent ground-based and in-flight simulator studies of low-speed handling characteristics of supersonic cruise transport aircraft

Several advanced arrow-wing concepts have evolved from NASA's Supersonic Cruise Aircraft Research (SCAR) Program. Evaluations of the low-speed handling characteristics of these configurations have been conducted at Langley Research Center using a fixed-base ground simulator with a visual landing scene. A brief in-flight simulation program was also conducted using Calspan's Total In-Flight Simulator (TIFS) in order to provide: (1) points of reference for interpretation of the ground-simulator results, (2) data for control-system design tradeoffs, and (3) data on effects of real-world visual height cues and cockpit-motion cues not available in the fixed-base simulation. The more significant results of these studies are presented.

Grantham, W. D.↗

NASA NTRS1977

Effect of an integrated scramjet installation on the subsonic performance of an aircraft designed to Mach 6 cruise

Various factors contributing to the high drag caused by the installation of a six-module scramjet engine were determined from wind tunnel tests at Mach numbers from 0.2 to 0.7. Methods for alleviating this drag were also explored. The external exhaust nozzle, required for good cruise performance, was a major contributor. Of the drag produced by the engine modules, a significant fraction was attributable to wall divergence in the combustor. Good drag simulation could be achieved by using a single fuel injection strut having approximately the same cross-sectional area as the three used on the full-scale engine. External exhaust nozzle fences had a small but beneficial effect on maximum L/D and a flap which diverted the flow away from the inlet was effective in decreasing drag but only at low angles of attack.

Johnston, P. J.↗

NASA NTRS1977

Stratospheric cruise emission reduction program

A recently implemented NASA effort specifically aimed at reducing cruise oxides of nitrogen from high-altitude aircraft is discussed. The desired emission levels and the combustor technology required to achieve them are discussed. A brief overview of the SCERP operating plan is given. Lean premixed-prevaporized combustion and some of the potential difficulties that are associated with applying this technique to gas turbine combustors are examined. Base technology was developed in several key areas. These fundamental studies are viewed as a requirement for successful implementation of the lean premixed combustion technique.

Diehl, L. A.↗

NASA NTRS1977

Bibliography of Supersonic Cruise Aircraft Research (SCAR) Program from 1972 to Mid-1977

This bibliography documents publications of the supersonic cruise aircraft research (SCAR) program that were generated during the first 5 years of effort. The reports are arranged according to systems studies and five SCAR disciplines: propulsion, stratospheric emissions impact, structures and materials, aerodynamic performance, and stability and control. The specific objectives of each discipline are summarized. Annotation is included for all NASA inhouse and low-number contractor reports. There are 444 papers and articles included.

Hoffman, S.↗

NASA NTRS1977

Effect of fuel properties on performance of single aircraft turbojet combustor at simulated idle, cruise, and takeoff conditions

The performance of a single-can JT8D combustor was investigated with a number of fuels exhibiting wide variations in chemical composition and volatility. Performance parameters investigated were combustion efficiency, emissions of CO, unburned hydrocarbons and nitrogen oxides, as well as liner temperatures and smoke. The most pronounced effects of changes in fuel composition were observed at simulated cruise and takeoff conditions where smoke and liner temperatures increased significantly as the hydrogen content of the fuel decreased. At the simulated idle condition, emissions of CO and unburned hydrocarbons increased slightly and, accordingly, combustion efficiencies decreased slightly as the hydrogen content of the fuels decreased.

Butze, H. F.↗

NASA NTRS1977

Study of metallic structural design concepts for an arrow wing supersonic cruise configuration

A structural design study was made, to assess the relative merits of various metallic structural concepts and materials for an advanced supersonic aircraft cruising at Mach 2.7. Preliminary studies were made to ensure compliance of the configuration with general design criteria, integrate the propulsion system with the airframe, select structural concepts and materials, and define an efficient structural arrangement. An advanced computerized structural design system was used, in conjunction with a relatively large, complex finite element model, for detailed analysis and sizing of structural members to satisfy strength and flutter criteria. A baseline aircraft design was developed for assessment of current technology. Criteria, analysis methods, and results are presented. The effect on design methods of using the computerized structural design system was appraised, and recommendations are presented concerning further development of design tools, development of materials and structural concepts, and research on basic technology.

Turner, M. J.↗

NASA NTRS1978

A procedure for the determination of the effect of fuselage nose bluntness on the wave drag of supersonic cruise aircraft

The incremental wave drag penalty due to nose blunting of a fuselage was investigated using a three dimensional finite difference scheme. An aircraft typical of current supersonic cruise concepts was considered. Computational problems with the finite difference scheme as the fuselage afterbody closes were addressed. A linear theory method was employed to compute the afterbody aerodynamics and effectively extends the finite difference scheme to closing afterbodies. Acceptable drag increments for various levels of nose bluntness were demonstrated using this approach.

Walkley, K. B.↗

NASA NTRS1977

Rationale for selection of a flight control system for lift cruise fan V/STOL aircraft

Various features of the lift cruise fan V/STOL concept are briefly reviewed. The ability to operate from small ships in adverse weather, low visibility, and rough sea conditions is emphasized as is the need for a highly capable, flexible, and reliabile flight control system. A three channel control by wire, digital flight control system is suggested. The requirement for automatic flight control, the advantage of control by wire implementation, the preference for a digital computer, and the need for three channel redundancy are among the factors discussed.

Konsewicz, R. K.↗

NASA NTRS1978

Study of advanced composite structural design concepts for an arrow wing supersonic cruise configuration, task 3

A structural design study was conducted to assess the relative merits of structural concepts using advanced composite materials for an advanced supersonic aircraft cruising at Mach 2.7. The configuration and structural arrangement developed during Task I and II of the study, was used as the baseline configuration. Allowable stresses and strains were established for boron and advanced graphite fibers based on projected fiber properties available in the next decade. Structural concepts were designed and analyzed using graphite polyimide and boron polyimide, applied to stiffened panels and conventional sandwich panels. The conventional sandwich panels were selected as the structural concept to be used on the wing structure. The upper and lower surface panels of the Task I arrow wing were redesigned using high-strength graphite polyimide sandwich panels over the titanium spars and ribs. The ATLAS computer system was used as the basis for stress analysis and resizing the surface panels using the loads from the Task II study, without adjustment for change in aeroelastic deformation. The flutter analysis indicated a decrease in the flutter speed compared to the baseline titanium wing design. The flutter analysis indicated a decrease in the flutter speed compared to the baseline titanium wing design. The flutter speed was increased to that of the titanium wing, with a weight penalty less than that of the metallic airplane.

Source record↗

NASA NTRS1978

Low-speed aerodynamic characteristics from wind-tunnel tests of a large-scale advanced arrow-wing supersonic-cruise transport concept

Tests have been conducted to extend the existing low speed aerodynamic data base of advanced supersonic-cruise arrow wing configurations. Principle configuration variables included wing leading-edge flap deflection, wing trailing-edge flap deflection, horizontal tail effectiveness, and fuselage forebody strakes. A limited investigation was also conducted to determine the low speed aerodynamic effects due to slotted training-edge flaps. Results of this investigation demonstrate that deflecting the wing leading-edge flaps downward to suppress the wing apex vortices provides improved static longitudinal stability; however, it also results in significantly reduced static directional stability. The use of a selected fuselage forebody strakes is found to be effective in increasing the level of positive static directional stability. Drooping the fuselage nose, which is required for low-speed pilot vision, significantly improves the later-directional trim characteristics.

Smith, P. M.↗

NASA NTRS1978

Progress in supersonic cruise aircraft technology

The Supersonic Cruise Aircraft Resarch (SCAR) program identified significant improvements in the technology areas of propulsion, aerodynamics, structures, take-off and landing procedures, and advanced configuration concepts. A brief overview of the highlights of the NASA supersonic technology program is presented.

Driver, C.↗

NASA NTRS1978

Supersonic through-flow fan engines for supersonic cruise aircraft

Engine performance, weight and mission studies were carried out for supersonic through flow fan engine concepts. The mission used was a Mach 2.32 cruise mission. The advantages of supersonic through flow fan engines were evaluated in terms of mission range comparisons between the supersonic through flow fan engines and a more conventional turbofan engine. The specific fuel consumption of the supersonic through flow fan engines was 12 percent lower than the more conventional turbofan. The aircraft mission range was increased by 20 percent with the supersonic fan engines compared to the conventional turbofan.

Franciscus, L. C.↗

NASA NTRS1976

Cruise aerodynamics of USB nacelle/wing geometric variations

Experimental results are presented on aerodynamic effects of geometric variations in upper surface blown nacelle configurations at high speed cruise conditions. Test data include both force and pressure measurements on two and three dimensional models powered by upper surface blowing nacelles of varying geometries. Experimental results are provided on variations in nozzle aspect ratio, nozzle boattail angle, and multiple nacelle installations. The nacelles are ranked according to aerodynamic drag penalties as well as overall installed drag penalties. Sample effects and correlations are shown for data obtained with the pressure model.

Braden, J. A.↗

NASA NTRS1978

Progress in supersonic cruise aircraft technology

The supersonic cruise aircraft research program identified significant improvements in the technology areas of propulsion, aerodynamics, structures, takeoff and landing procedures, and advanced configuration concepts. Application of these technology areas to a commercial aircraft is discussed. An advanced SST family of aircraft which may be environmentally acceptable, have flexible range-payload capability, and be economically viable is projected.

Driver, C.↗

NASA NTRS1978

Aerodynamic characteristics of a fixed arrow-wing supersonic cruise aircraft at Mach numbers of 2.30, 2.70, and 2.95

Tests were conducted in the Langley Unitary Plan wind tunnel at Mach numbers of 2.30. 2.70, and 2.95 to determine the performance, static stability, and control characteristics of a model of a fixed-wing supersonic cruise aircraft with a design Mach Number of 2.70 (SCAT 15-F-9898). The configuration had a 74 deg swept warped wing with a reflexed trailing edge and four engine nacelles mounted below the reflexed portion of the wing. A number of variations in the basic configuration were investigated; they included the effect of wing leading edge radius, the effect of various model components, and the effect of model control deflections.

Morris, O. A.↗