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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 919 records · Page 51
All sourcesNASA NTRSDOE OSTI
NASA NTRS1970

Twin-spool turbopumps for ''low'' net positive suction pressure operations

Modified single-shaft turbopump incorporates inducer and main pump, each separately driven at different speeds through coaxial-shaft arrangement. Inducer operates at low speed for low net positive suction pressure, main pump operates at high speed to generate high pressure. This arrangement requires no external control for the inducer.

Bair, E. K.↗
NASA NTRS1972

Space shuttle: Static aerodynamic characteristics of the MSC-040A the Msc-040A space shuttle orbiter with wedge centerline vertical and twin vertical tails at Mach numbers from 0.6 to 4.96

The results are presented from experimental aerodynamic investigations conducted on a 0.6-percent scale model of the MSC-040 space shuttle orbiter in a 14 inch trisonic wind tunnel. The purpose of the test program was to define the stability, control, and performance characteristics of the baseline MSC-040A orbiter configuration with proposed alternate wing pods, with several vertical tail configurations with and without flared rudders, and with upper wing surface flap deflections. Force and moment data and model base and balance cavity pressure data were obtained for a Mach range of 0.60 through 4.96 and dynamic pressure range of 465 through 1580 psf. Model attitude was varied from 0 to +34 degrees angle of attack at zero sideslip and -4 to +10 degrees angle of sideslip at 0, 10, 20, and 24 degrees angle of attack.

Glass, K. J.↗
NASA NTRS1972

Supersonic aerodynamic damping and oscillatory stability in pitch and yaw fro a model of a variable-sweep fighter airplane with twin vertical tails

Wind-tunnel measurements of the aerodynamic damping and oscillatory in pitch and yaw for a 1/22-scale model of a proposed carrier-based variable-sweep fighter airplane have been made by using a small-amplitude forced-oscillation technique. Tests were made with a wing leading-edge sweep angle of 68 deg at angles of attack from about -1.5 deg to 15.6 deg at a Mach number of 1.60 and at angles of attack from about -3 deg to 21 deg at Mach numbers of 2.02 and 2.36. The results of the investigation indicate that the basic configuration has positive damping and positive oscillatory stability in pitch for all test conditions. In yaw, the damping is generally positive except near an angle of attack of 0 deg at a Mach number of 1.60. The oscillatory stability in yaw is positive except at angles of attack above 16 deg at Mach numbers of 2.02 and 2.36. The addition of external stores generally causes increases in both pitch and yaw damping. The oscillatory stability in pitch is reduced throughout the angle-of-attack range by the addition of the external stores. The effect of adding stores on the oscillatory stability in yaw is a function of angle of attack and Mach number. The effect of changing horizontal-tail incidence on the pitch parameters is also very dependent on angle of attack and Mach number.

Kilgore, R. A.↗
NASA NTRS1973

Twin payload observations of incident and backscattered auroral electrons.

Energy spectra and pitch angle distributions of auroral electrons have been measured in a premidnight multiple arc auroral display by a Javelin rocket containing two identical payloads that separated in flight. The rocket was launched from Fort Churchill, Canada, at 0459 UT on March 2, 1968, and covered an altitude range up to 800 km. The electron energy spectra between 40 eV and 20 keV show a 'continuum' spectrum with a superimposed energetic peak. The center energy of the peak was observed to shift from 10-12 keV over the arcs to 2-3 keV between the arcs. This spectral structure is shown to be similar to the inverted 'V' structure reported by other investigators. The in flight separation of the two payloads allowed investigation of spatial versus temporal effects in the auroral precipitation.

Reasoner, D. L.↗
NASA NTRS1974

Pressure distribution of a twin-engine upper-surface blown jet-flap model

An investigation has been made to determine the chordwise and spanwise pressure distributions of a small-scale upper-surface blown jet-augmented flap STOL model. The model was powered by two simulated high-bypass-ratio turbofan engines mounted ahead of and above an unswept-untapered wing in a nacelle having a rectangular nozzle. The results of the investigation are presented as tabulated and plotted chordwise pressure distribution coefficients for nine spanwise stations.

Smith, C. C., Jr.↗
NASA NTRS1976

Preliminary flight-test results of an advanced technology light twin-engine airplane /ATLIT/

The present status and flight-test results are presented for the ATLIT airplane. The ATLIT is a Piper PA-34 Seneca I modified by the installation of new wings incorporating the GA(W)-1 (Whitcomb) airfoil, reduced wing area, roll-control spoilers, and full-span Fowler flaps. Flight-test results on stall and spoiler roll characteristics show good agreement with wind-tunnel data. Maximum power-off lift coefficients are greater than 3.0 with flaps deflected 37 deg. With flaps down, spoiler deflections can produce roll helix angles in excess of 0.11 rad. Flight testing is planned to document climb and cruise performance, and supercritical propeller performance and noise characteristics. The airplane is scheduled for testing in the NASA-Langley Research Center Full-Scale Tunnel.

Holmes, B. J.↗
NASA NTRS1977

Twin-capacitive shaft angle encoder with analog output signal

A precision capacitive shaft encoder providing a dc signal corresponding to the angular position of a shaft is described. Two variable capacitances are coupled in tandem by a rotatable shaft. Each capacitor has a capacitance that varies linearly with a change in the angular position of the shaft. The sum of the two capacitances is always constant for any angular position of the shaft. Each capacitance is alternately coupled to a reference dc voltage and a discharge circuit. The capacitances are electrically coupled in series and the charge periodically acquired at the junction of the capacitance is a function of the position of the shaft. An error-compensating voltage is imposed on the junction when the capacitances are coupled to the reference voltages. The junction is coupled to sample-and-hold apparatus provided with a error-correcting circuit.

Hruby, R. J.↗
NASA NTRS1976

Wind-tunnel investigation of aerodynamic performance, steady amd vibratory loads, surface temperatures, and acoustic characteristics of a large-scale twin-engine upper-surface blown jet-flap configuration

Static and wind-on tests were conducted to determine the aerodynamic characteristics of and the effects of jet impingement on the wing of a large scale upper surface blown configuration powered with an actual turbine engine. The wing and flaps were instrumented with experimental dual-sensing transducer units consisting of a fluctuating pressure gage, a vibratory accelerometer, and a surface mounted alumel thermocouple. Noise directivity and spectral content measurements were obtained for various flap configurations and various engine thrust settings to provide baseline noise data for other upper surface blown configurations.

Source record↗
NASA NTRS1978

Aerodynamic characteristics induced on a supercritical wing due to vectoring twin nozzles at Mach numbers from 0.40 to 0.95

The induced lift characteristics are studied for a vectored-thrust concept in which jet-exhaust nozzles were located in the fuselage at the wing trailing edge. The wing had a supercritical airfoil section. The investigation was conducted at Mach numbers from 0.4 to 0.95, angles of attack up to 14 deg, and thrust coefficients up to 0.35, and nozzle deflection angles of 0 deg and 30 deg. Separate force balances were used to determine both total aerodynamic and thrust forces alone which allowed for a direct measurement of jet turning angle at forward speeds. The Reynolds number per meter varied from 8.20 x 1 million to 12.80 x 1 million. The results show that the configuration with the supercritical wing generally had a better performance with respect to both lift augmentation and drag reduction than the same configuration with a 64 series airfoil.

Capone, F. J.↗
NASA NTRS1979

Twin jet shielding

For an over-the-wing/under-the-wing engine configuration on an airplane, the noise produced by the upper jet flow is partially reflected by the lower jet. An analysis has been performed which can be used to predict the distribution of perceived noise levels along the ground plane at take-off for an airplane which is designed to take advantage of the over/under shielding concept. Typical contours of PNL, the shielding benefit in the shadow zone, and the EPNL values at 3.5 nautical miles from brake release as well as EPNL values at sideline at 0.35 nautical miles have been calculated. This has been done for a range of flow parameters characteristic of engines producing inverted velocity profile jets suitable for use in a supersonic cruise vehicle. Reductions up to 6.0 EPNdB in community noise levels can be realized when the over engines are operated at higher thrust and the lower engines simultaneously operated with reduced thrust keeping the total thrust constant.

Parthasarathy, S. P.↗
NASA NTRS1979

Twin jet noise shielding for a supersonic cruise vehicle

An engine arrangement for a supersonic cruise vehicle (SCV) has been developed that shows promise for jet noise reduction without the performance penalties associated with mechanical suppressors and engine oversizing. This arrangement, wherein two engines are placed on top of the wing directly above two similarly-mounted engines below the wing, can produce 3 to 5 dB less noise below the aircraft flight path than when four engines are installed under the wing. This noise reduction is due to acoustic shielding of the upper jets by the lower jets. Test data are reviewed to verify this acoustical shielding phenomenon, and detailed takeoff trajectories are calculated to show the effects of sideline and flyover noise levels on constraining maximum range SCV configurations. Engine placement variation and differential throttling, wherein thrust is unloaded from the lower engine and added to the upper engine, are to be explored as means for maximizing the shielding effect.

Clauss, J. S., Jr.↗
NASA NTRS1979

Effects of fuselage forebody geometry on low-speed lateral-directional characteristics of twin-tail fighter model at high angles of attack

Low-speed, static wind-tunnel tests were conducted to explore the effects of fighter fuselage forebody geometry on lateral-directional characteristics at high angles of attack and to provide data for general design procedures. Effects of eight different forebody configurations and several add-on devices (e.g., nose strakes, boundary-layer trip wires, and nose booms) were investigated. Tests showed that forebody design features such as fineness ratio, cross-sectional shape, and add-on devices can have a significant influence on both lateral-directional and longitudinal aerodynamic stability. Several of the forebodies produced both lateral-directional symmetry and strong favorable changes in lateral-directional stability. However, the same results also indicated that such forebody designs can produce significant reductions in longitudinal stability near maximum lift and can significantly change the influence of other configuration variables. The addition of devices to highly tailored forebody designs also can significantly degrade the stability improvements provided by the clean forebody.

Carr, P. C.↗