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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 991 records · Page 55

All sources NASA NTRS DOE OSTI

NASA NTRS1985

Low-speed stability and control wind-tunnel investigations of effects of spanwise blowing on fighter flight characteristics at high angles of attack

The effects of spanwise blowing on two configurations representative of current fighter airplanes were investigated. The two configurations differed only in wing planform, with one incorporating a trapezoidal wing and the other a 60 delta wing. Emphasis was on determining the lateral-directional characteristics, particularly in the stall/departure angle-of-attack range; however, the effects of spanwise blowing on the longitudinal aerodynamics were also determined. The-tunnel tests included measurement of static force and forced-oscillation aerodynamic data, visualization of the airflow changes created by the spanwise blowing, and free-flight model tests. The effects of blowing rate, chordwise location of the blowing ports, asymmetric blowing, and blowing on the conventional aerodynamic control characteristics were investigated. In the angle-of-attack regions in which the spanwise blowing substantially improved the wing upper-surface flow field (i.e., provided reattachment of the flow aft of the leading-edge vortex), improvements in both static and dynamic lateral-directional stability were observed. Blowing effects on stability could be proverse or adverse depending on blowing rate, blowing port loaction, and wing planform. Free-flight model tests of the trapezoidal wing confirmed the beneficial effects of spanwise blowing measured in the static and dynamic force tests.

Satran, D. R.↗

NASA NTRS1985

Precision antenna reflector structures

The assembly of the Large Precise Reflector Infrared Telescope is detailed. Also given are the specifications for the Aft Cargo Carrier and the Large Precision Reflector structure. Packaging concepts and options, stowage depth and support truss geometry are also considered. An example of a construction scenario is given.

Hedgepeth, J. M.↗

NASA NTRS1985

Langley Research Center Photogrammetric Measurements of Solar Array Dynamics: Preliminary Results

The NASA Langley Research Center participated in the Solar Array Experiment with two primary objectives: (1) to study the structural and control dynamics of a new class of large, lightweight, low-frequency space structures, and (2) to develop technology for remote video measurement of structural motions. The shuttle orbiter's closed circuit television (CCTV) system was used to provide recorded video images of the solar array from four locations in the payload bay, two on the forward bulkhead and two on the aft bulkhead. White reflective targets were placed on the array to provide discrete points at which to track array motion. A dynamic test consisted of a quiescent period in which orbiter operations were inhibited and crew motion restricted, an excitation period, and a free decay period. The orbiter was placed in free drift while in a gravity gradient orientation and dynamics tests were timed to occur at orbital noon so that the Sun would illuminate one side of the array and Earth albedo the other. The CCTV system was turned on during the quiescent period, approximately 3 minutes prior to excitation. Video from all four CCTV cameras was recorded continuously through the excitation and free-decay periods for a total test record of 8 to 10 minutes.

Brumfield, M. L.↗

NASA NTRS1985

Flight investigation of stall, spin and recovery characteristics of a low-wing, single-engine, T-tail light airplane

Flight tests were performed to investigate the stall, spin, and recovery characteristics of a four-place, low-wing, single-engine, T-tail, general aviation research airplane at an aft center-of-gravity position. Most stalls resulted in roll-offs. Spins were oscillatory in roll and pitch at 43 deg angle of attack; the magnitude of the oscillations was determined by aileron position. Power, flap deflection, and landing gear position did not affect the angle of attack to the spin. Antispin rudder followed by forward wheel with ailerons neutral produced the fastest and most consistent recoveries but the initial application of recovery controls did not always stop a spin.

Stough, H. P., III↗

NASA NTRS1985

Experiences with neutral buoyance testing mockups

Contingency operations with neutral bouyancy simulation on a space platform is considered. Some task simulated are aft payload port deployment and retraction, removal and replacement of the control moment cyro, and deployment of the manual hand crank appendage. It is decided that crewmen can perform fine motor activities when simple aids are provided, certain tasks can be accomplished with less efforts when the crewman is afforded additional mobility, manual translation of large mass items is feasible, and that during the installation of replaceable units application of alignment indicators provide significant assistance to crewmen.

Dellacamera, B.↗

NASA NTRS1985

Large format camera photographs: A new tool for understanding arid environments

Large Format Camera (LFC) was developed by NASA to produce high resolution stereo photographs from space with maximum photogrammetric fidelity. The camera has a 30.5 cm focal length lens and an f/6.0 aperture. The optics are corrected to permit operation with black and white (b/w), natural color (col) and color infrared (cir) film. Interchangeable minus-haze and minus-blue filters are located near the aperture stop, and an antivignetting filter is provided on the front element of the lens. The field-of-view of the LFC along track is 73.7 degrees (ratio 1.5 x H) and across track is 41.1 degrees (ratio 0.75 x H). The frame format of the LFC is 23x46 cm with the long dimension in the direction of flight. The camera can be operated to produce 10, 60, 70, or 80 percent forward overlap for stereoscopic coverage. With 80 percent forward overlap, the stereo model base height ratio is 0.3 for successive frames and 1.2 if every fourth frame is used. The LFC magazine has a capacity of 2400 frames. Two horizon-looking stellar cameras, one directed 45 degrees forward and the other 45 degrees aft were used to photograph the star field in synchronism with exposures of the LFC. Post flight mensuration and calculation of the stellar photographs will provide altitude information for the LFC.

Walker, A. S.↗

NASA NTRS1980

Verification of the SRB motor case pin retainer band tips

The pin retainer band is a 1-1/4 in. wide by about 1/32 in. thick steel band that is stretched over the pins circumferentially at the joints of the solid rocket booster (SRB) motor case segments. Its purpose is to hold the retaining pins in place during flight. Since the band is thin and is mounted stretched, or under tension, over the pins which are greased in place, it is necessary to protect it thermally. Three typical areas of the band location on the SRB motor case joints were chosen for verifying the cork thermal prection system (TPS) performance on the band: the joint in front of the attach ring, at the aft skirt joint in front of the kick ring and in an unperturbed area at the forward segments of the SRB motor cases. The kick ring area pin retainer band cork TPS passed the test requirements in the region where there are no phenolic splice caps. In the splice cap areas where the band TPS is closed out around the splice with K5NA, additional amounts of K5NA material is required to adequately protect the steel band. TPS requirements were easily met in the one location where the ends of the steel band are joined together after installation and tensioning. The attack ring area pin retainer band TPS did not quite pass the heat load requirements with the .375 in. thick cork TPS as used for the kick ring area band. It is recommended that the cork thickness here be increased to .50 in. The unperturbed area band TPS presented no problems.

Karu, Z. S.↗

NASA NTRS1979

SRB TPS closeout materials characterization

The recession characteristics of the materials used to closeout the Thermal Protection System (TPS) on the Space Shuttle Solid Rocket Booster (SRB) were assessed. Two candidate closeout materials namely, K5NA and MTA2 is the Marshall Trowelable Ablator. Test panels of each of these two materials were subjected to aerodynamic heat and shear in the NASA Hot Gas Facility. Pretest and Post-test measurements were taken and the rate of recession (R) thus determined was correlated with the heating rate. A least squares curve fit of the data together with another least squares 95% confidence level fit, was performed. The characteristics of the two materials when compared showed that both materials performed equally well at the higher heating rates (10 q 30 Btu/sq ft/sec) but MTA2 was slightly better, not receding as fast, at the lower q values. The comparison of the R versus q curves for K5NA and MTA2 with that of primary TPS P-50 cork on the SRB Aft Skirt was good.

Karu, Z. S.↗

NASA NTRS1982

Study of NSI and related cable performance during tests performed in the NASA Hot Gas Facility

Some seven different configurations of the NSI and other cables were tested in the NASA-MSFC Hot Gas Facility (HGF). The tests were conducted to study what happens to the cables when they are exposed to hot flow as was the case in the first two Shuttle flights, the STS-1 and STS-2. Protection of these components is vital for various functions especially to attain proper nozzle separation. The tests in the HGF demonstrated the severity of the aerodynamic forces combined with aero heating environment on the test cables and helped, in general, to evaluate the cable wrap materials and cable mounting hardware and technique. Blastape 2 cable wrap which is adequate for thermal protection of the cables must be properly clamped at its ends. The nylon clamps (or ties) used to secure cables to metal components inside the skirt could not withstand the heating. K5NA closeout material used on the outboard surface of the aft skirt when troweled over the cables performed excellently in protecting the cables and mounting hardware.

Karu, Z. S.↗

NASA NTRS1984

Demonstration of relaxed static stability on a commercial transport

Increasing jet aircraft fuel costs from 25 percent to nearly 60 percent of the aircraft direct operating costs have led to a heavy emphasis on the development of transport aircraft with significantly improved aerodynamic performance. The application of the concept of relaxed static stability (RSS) and the utilization of an active control stability augmentation system make it possible to design an aircraft with reduced aerodynamic trim drag due to a farther-aft cg balance. Reduced aerodynamic parasite drag and lower structural weight due to a smaller horizontal tail surface can also be obtained. The application of RSS has been studied under a NASA-sponsored program to determine ways of improving the energy efficiency in current and future transport aircraft. Attention is given to a near-term pitch active control system, an advanced pitch active control system, and an operational overview.

Rising, J. J.↗

NASA NTRS1984

The revolutionary impact of evolving aeronautical technologies

Recent advances in aeronautical technologies which could produce revolutionary changes in transport aircraft if fully implemented are delineated. Laminar flow control offers a L/D improvement from the current 18 to 22 if used with a 767 configuration. Higher aspect and thickness/chord ratios could yield more efficient structural designs and further drag reduction. High-strength, fiber-reinforced composite structures can reduce structural weight by 10-30 percent. Improved engine cooling methods, higher stage loadings and exhaust temperatures can lower the SFC by 15 percent, engine weight by 15 percent, and the parts count by 50 percent. Aft-mounted counterrotating propellers can potentially decrease the SFC an additional 15-20 percent. Supersonic transport aircraft with L/D ratios of 18 and 70 seat miles/gal fuel efficiency can now be built that weigh half as much as the Concorde and carry the same load. The new SST would have superplastic-molded Al alloy structures.

Kayten, G. G.↗

NASA NTRS1985

Three dimensional aerodynamics of an annular cascade in a non-uniform inlet flow

Three-dimensional viscous and inviscid numerical analyses are currently being developed to predict the complex flow through turbomachine blade passages. To be of value to the designer, these numerical solutions must be evaluated and subsequent refinements directed by correlating predicted flow fields with data obtained from experiments which model the fundamental three-dimensional flow phenomena inherent in blade rows. This paper describes a series of experiments to provide such data. In particular, the effect of a potential and a rotational inlet flow field on the detailed three-dimensional aerodynamic performance of an extensively instrumented cambered airfoil cascade has been determined at two levels of aerodynamic loading. Data presented quantify the pressure and suction surface static pressure chordwise distributions on the hub, mean, and tip streamlines; the velocity distribution in the cascade aft-passage region; and the cascade exit region flow field. Appropriate data are correlated with predictions.

Manwaring, S. R.↗

NASA NTRS1984

Heat-transfer distributions for biconics at incidence in hypersonic-hypervelocity real-gas flows

Laminar heat-transfer distributions were measured on spherically blunted, 13/7 deg straight and bent biconics at freestream velocities from 4.5 to 6.9 km/s and Mach numbers from 6 to 9. The flows were generated in the NASA's Langley Expansion Tube using helium, nitrogen, air, and carbon dioxide; angle of attack, referenced to the axis of the aft cone, was varied from zero to 20 deg. The penalty in windward heating to the fore cone due to the 7-deg nose bend diminished rapidly with increasing angle of attack and was only 10 to 20 percent at the design trim angle of attack of 20 deg. Leeward heating initially decreased, then increased, with increasing angle of attack. Windward heating rates predicted with a computer code that solves the parabolized Navier-Stokes equations were in good agreement with measurements for helium and air. The study used a 1.9-percent scale model of the proposed generic planetary vehicle and is directly applicable to the orbital transfer vehicle, which incorporates a spherically blunted biconic.

Miller, C. G.↗

NASA NTRS1983

Airborne Doppler-lidar and ground-based Doppler radar observations of a thunderstorm in Oklahoma

The results of airborne Doppler-lidar and ground-based Doppler radar observations of multicellular storms, marked by heavy rainfall, strong surface outflow, and a gust-front tornado, on June 30, 1981 are analyzed. The airborne lidar comprised a CO2-laser operating in the IR region, which was discharged once each second at 20 deg fore and aft, alternatively, of the normal to the aircraft's heading, and a quarter-wave plate for registering the returning frequency-shifted beams. Wind fields are plotted taking into account the advection effects. The lidar data set is noted for its self-consistency, though limited to a range of 5 km by the high moisture levels. Fair agreement was found between the lidar-derived and radar-derived average ground-based radial wind fields, with discrepancies on the order of 1.5 m/s.

Bluestein, H. B.↗

NASA NTRS1985

Numerical simulation of flow through scramjet inlets using a three-dimensional Navier-Stokes code

A three-dimensional Reynolds-averaged Navier-Stokes code has been used to numerically analyze flow through a two-strut, supersonic combustion ramjet (scramjet) inlet configuration. It solves the governing equations in full conservation form using either the fully explicit or explicit-implicit method due to MacCormack. An algebraic two-layer eddy viscosity model is used for turbulent flow calculations. The analysis allows inclusion of end effects which are caused by the aft placement of the cowl on the underside of the inlet. A special grid has been developed to accommodate the struts embedded in the inlet flow field. Detailed numerical results are presented here for the two-strut configuration, and a comparison is made with the available experimental results.

Kumar, A.↗

NASA NTRS1985

Laser velocimeter measurements of the flow fields around single- and counter-rotation propeller models

A two-component LV system was used to make detailed measurements of the flow field around both a single-rotation and a counter-rotation propeller/nacelle. The conditions measured for the single-rotation tractor configuration include two different blade angles and two propeller advance ratios, and for the counter-rotation propeller configuration include both pusher and tractor mounts. The measurements show the increasing slipstream velocities and contraction with increasing blade angle and with decreasing advance ratios. Data for the counter-rotation system show that the aft propeller turns the flow in the opposite direction from the front propeller. Additionally, the LV system was used as a diagnostic tool to provide data to explain the large side force measured on the propeller/nacelle at angle-of-attack.

Dunham, D. M.↗

NASA NTRS1986

Composite Lightning Rods for Aircraft

Composite, lightweight sacrificial tip with graphite designed reduces lightning-strike damage to composite parts of aircraft and dissipates harmful electrical energy. Device consists of slender composite rod fabricated from highly-conductive unidirectional reinforcing fibers in matrix material. Rods strategically installed in trailing edges of aircraft wings, tails, winglets, control surfaces, and rearward-most portion of aft fuselage.

Bryan, Charles F., Jr.↗

NASA NTRS1985

Numerical procedure for three-dimensional hypersonic viscous flow over aerobrake configuration

A numerical method, which is simpler and more efficient than others currently in use, is proposed for the computation of the full viscous flow over an aerobrake body in hypersonic stream at high altitude. It treats the shock layer surrounding the blunt forebody and the near wake behind the base simultaneously by formulating the Navier-Stokes equations in conformal and azimuthal-angle coordinates. The computational domain is confined by the body wall, outflow surface and the shock, which is adjusted along the coordinate normal to the wall in the course of iterations. Because of the optimal grid and a well developed alternating direction implicit factorization technique for the governing equations, reasonably accurate results can be obtained with a 28 x 36 x 7 grid and 400 time-marching iterations. Excellent agreement of shock location is found between the present result and the schlieren photograph. Details of the base flow and shear layer impingement on the cylindrical aft body are presented for an adiabatic wall case.

Li, C. P.↗