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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 1,135 records · Page 63

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NASA NTRS1975

Manual control displays for a four-dimensional landing approach

Six instrument rated pilots flew a STOL fixed base simulator to study the effectiveness of three displays for a four dimensional approach. The three examined displays were a digital readout of forward position error, a digital speed command, and an analog display showing forward position error and error prediction. A flight director was used in all conditions. All test runs were for a typical four dimensional approach in moderate turbulence that included a change in commanded ground speed, a change in flight path angle, and two standard rate sixty degree turns. Use of the digital forward position error display resulted in large overshoot in the forward position error. Some type of lead (rate or prediction information) was shown to be needed. The best overall performance was obtained using the speed command display. It was demonstrated that curved approaches can be flown with relative ease.

Silverthorn, J. T.↗

NASA NTRS1975

Bosch CO2 Reduction System Development

Refinements in the design of a Bosch CO2 reduction unit for spacecraft O2 production are described. Sealing of the vacuum insulation jacket was simplified so that high vacuum and high insulation performance are easily maintained. The device includes a relatively simple concentric shell recuperative heat exchanger which operates at approximately 95% temperature effectiveness and helps lower power consumption. The influence of reactor temperature, pressure, and recycle gas composition on power consumption was investigated. In general, precise control is not required since power consumption is not very sensitive to moderate variations of these parameters near their optimum values. There are two process rate control modes which match flow rate to process demand. Catalyst conditioning, support, and packing pattern developments assure consistent starts, reduced energy consumption, and extended cartridge life. Operation levels for four or five men were maintained with overall power input values of 50 to 60 watts per man.

Holmes, R. F.↗

NASA NTRS1974

Tropical cyclone rainfall as measured by the Nimbus 5 electrically scanning microwave radiometer

A selected group of 1973 North Pacific Ocean tropical cyclones was studied by using data from the Nimbus 5 Electrically Scanning Microwave Radiometer (ESMR), the Temperature-Humidity Infrared Radiometer (THIR), NOAA-2 and USAF DMSP imageries. From the unique combination of infrared, visible, and microwave data, it was possible during various stages of storm development to differentiate between dense cirrus outflow and rain areas, to identify centers of circulation and areas of low-level moisture, and by the use of a theoretical model to estimate semi-quantitatively areas of light, moderate, and heavy rainfall rates.

Allison, L. J.↗

NASA NTRS1974

Midday Pc 1-2 pulsations observed at a subcleft location

A class of unstructured Pc 1-2 pulsation activity, as identified on Bar I (70.2 N) records taken during 1968-1972, is found to be present in midday hours on about half of the days in summer months. The events have some tendency to occur in the later part of the ring current recovery phase, especially at times of moderate AE when the cleft lines are just poleward of Bar I. The source lines of the Pc 1-2 are found to lie essentially outside the plasmapause. In terms of the proton cyclotron resonance instability the most likely source regions of the Bar I Pc 1-2 are the detached plasma regions convecting sunward on the dayside and the portion of the cleft plasma on the last closed field lines.

Heacock, R. R.↗

NASA NTRS1974

Boron/aluminum for space applications

Several experimental boron/aluminum structures have been built for aircraft and space vehicle applications. The success of these structures has led to the decision to use boron/aluminum tubular struts on the mid-fuselage section of the Space Shuttle Orbiter. The suitability of boron/aluminum for this application has been demonstrated in a program that involved fabricating 100 tubes and performing static, fatigue, corrosion, thermal/mechanical fatigue, and damage tolerance tests on them. Other potential applications for boron/aluminum on the Space Shuttle include the wing carry-through panels and side panels for the mid-fuselage, and the landing gear struts. These applications result in significant weight savings over conventional non-composite designs at moderate costs. Boron/aluminum can now be considered a production material that, in many cases, is competitive on a weight and/or cost basis with an all-metal or resin composite system.

Robertson, A. R.↗

NASA NTRS1974

Coastal wetlands - Prospects for satellite inventory

It is pointed out that coastal wetlands are among the nation's most valuable natural resources. A relatively low cost and moderately accurate method for mapping these areas would, therefore, be very attractive. It appears that such a method could be found by utilizing ERTS-1 data. Two test sites were selected for an intensive study of the feasibility of such an approach. One test area involves a salt marsh complex located at the mouth of the Chincoteague Bay in Virginia. The second area constitutes a near-saline marsh at the mouth of the Nanticoke River, Maryland. The study shows that ERTS-1 digital data provide maximum gray-level resolution for the mapping of wetland species and features.

Anderson, R. R.↗

NASA NTRS1974

20 to 40 micron spectroscopy of the Orion Nebula

Attention is given to a moderate-resolution spectra of the Orion Nebula. Observational data are presented between 20 and 40 microns. Several models are shown that attempt to account for all of the observations from 20 microns to 1 mm. A model in which the dust within the molecular cloud has a clumpy distribution is given. Data show that the individual clumps have effective grain temperatures of 100 deg K and they are optically thick for wavelengths shorter than 400 microns.-

Houck, J. R.↗

NASA NTRS1974

Electron acceleration by parametrically excited Langmuir waves

Simple physical arguments are used to estimate the downward-going energetic electron flux due to parametrically excited Langmuir waves in ionospheric modification experiments. The acceleration mechanism is a single velocity reversal as seen in the frame of the Langmuir wave. The flux is sufficient to produce the observed ionospheric airglow if focusing-type instabilities are invoked to produce moderate local enhancements of the pump field.

Fejer, J. A.↗

NASA NTRS1974

Temperature and density structure of thermal proton flows

Thermal proton flows along magnetic field lines are an important feature of magnetosphere-ionosphere coupling. In this paper we report the results of a theoretical study of the thermal structure of such flows. The adopted steady state model is based upon O+, H+, and electrons with self-consistent solutions for the separate O+, H+, and electron temperatures, the O+ and H+ densities and the H+ drift velocity. Through investigation of a number of parameters affecting the model, it is shown that Joule heating arising from the flow of H+ through O+ preferentially heats H+, so that the H+ temperature is substantially greater than the O+ temperature. Low O+ densities characteristic of the trough region appear to give high H+/O+ temperature ratios. Typical O+ densities characteristic of polar wind flow regions give moderate H+/O3 temperature ratios. The Mach number of H+ outflow is substantially reduced in the present models in comparison with the older fixed temperature calculations.

Banks, P. M.↗

NASA NTRS1975

Effect of compressibility on the nonlinear prediction of the aerodynamic loads on lifting surfaces

The vortex-lattice technique for incompressible flow which accounts for separation at sharp edges is modified to account for compressibility. This is accomplished by extending the Prandtl-Glauert transformation to moderate angles of attack. Thus, the aerodynamic characteristics for the compressible case are obtained from the solution of an equivalent incompressible problem. Numerical results are presented for parallelogram and delta wings to assess the effects of compressibility. The results are in good agreement with available experimental data.

Kandil, O. A.↗

NASA NTRS1975

An experimental study of the effect of treated length on fan inlet noise suppressors

An experimental study of the effect of length of acoustic treatment was performed on a full scale fan using two different inlets. Analysis of the data revealed that measured suppression varied linearly with the length of the ringed linear segments as anticipated. Further analysis indicated that the wall only portion of the treatment was substantially more effective than anticipated suggesting that, if only moderate suppression is needed, wall only treatment may suffice. Contrary to expectation the two inlets behaved similarly. Introduction of a hard exhaust splitter into the configuration resulted in a noise increase at certain frequencies.

Dittmar, J. H.↗

NASA NTRS1975

Airloads near the open port of a one-meter airborne telescope

An infrared telescope is mounted in a cavity in the fuselage of a C-141 airplane. The cavity is sealed off from the rest of the fuselage and can be opened to the outside for viewing. A retractable porous spoiler is installed ahead of the opening to inhibit cavity resonance. The paper presents the mean pressures, pressure fluctuations, spectra, phase, and coherence of the pressures in the cavity and on the fuselage near the cavity, along with pertinent acceleration and torque information for the aircraft structure and telescope. It is shown that a moderate spoiler extension controls resonance in normal flight attitudes and produces a cavity environment with approximately the same turbulence intensity as an attached turbulent boundary layer.

Buell, D. A.↗

NASA NTRS1975

Dynamic stall experiments on oscillating airfoils

Dynamic stall and unsteady boundary layer separation have been studied in incompressible flow at moderately large Reynolds numbers. By varying the leading-edge geometry of an NACA 0012 airfoil, three different types of stall were produced. For most of the configurations studied, including the basic NACA 0012 profile, dynamic stall was found not to originate with the bursting of a leading-edge laminar separation bubble, as is commonly believed. Instead, the vortex shedding phenomenon, which is the predominant feature of dynamic stall, appears to be fed its vorticity by the breakdown of the turbulent boundary layer.

Mccroskey, W. J.↗

NASA NTRS1974

Fine structural changes in the lateral vestibular nucleus of aging rats

The fine structure of the lateral vestibular nucleus was investigated in Sprague-Dawley rats, that were sacrified at 4 weeks, 6-8 weeks, 6-8 months, and 18-20 months of age. In the neuronal perikaria, the following age-associated changes were seen with increasing frequency with advancing age: rodlike nuclear inclusions and nuclear membrane invaginations; cytoplasmic dense bodies with the characteristics of lipofuscin; and moderate disorganization of the granular endoplasmic reticulum. Dense bodies were also seen in glial cells. Rats 18 to 20 months old showed dendritic swellings, axonal degeneration, and an apparent increase in the number of axosomatic synaptic terminals containing flattened vesicles (presumed to be inhibitory in function).

Johnson, J. E., Jr.↗

NASA NTRS1975

Minimization of jet and core noise of a turbojet engine by swirling the exhaust flow

A noise abating improvement for jet engines has been investigated and demonstrated using a full scale turbojet engine which provided the means for significant reductions in jet and core noise with minimal thrust loss. This was accomplished by controlled solid body rotation (swirling) of the flow in the nozzle and jet exhaust. Relatively moderate angles of solid body rotation in the presence of temperature, density, pressure, and velocity gradients were utilized. Of great interest was the finding that significant reductions of sound pressure levels and sound power were obtained with only a small percentage of the total primary mass flow swirling at the exit of the nozzle. Therefore, tradeoffs between noise reduction and engine performance can be optimized to satisfy aircraft performance and federal noise standards with minimal wasted rotational kinetic energy.

Schwartz, I. R.↗

NASA NTRS1975

Stability characteristics of a single-phase free convection loop

Experiments investigating the stability characteristics of a single-phase free convection loop are reported. Results of the study confirm the contention made by previous workers that instabilities near the thermodynamic critical point can occur for ordinary fluids as well as those with unusual behavior in the near-critical region. Such a claim runs counter to traditional beliefs, but it is supported by the observation of such instabilities for water at atmospheric pressure and moderate temperatures in the present work.

Creveling, H. F.↗

NASA NTRS1975

Trajectory design of a solar electric propulsion Encke slow flyby mission

A slow flyby of the periodic comet, Encke, prior to its perihelion passage in 1980 has been shown to be a feasible mission for a solar electric propulsion spacecraft using a moderate power level of around 15 kw. The mission is accomplished in slightly less than two years with a planned miss distance and flyby speed of 1000 km and 4 km/s respectively. The results of a performance tradeoff study are presented together with a description of the nominal trajectory. The trajectories used in these mission studies were calculated using an updated model of the 30 cm mercury bombardment thruster's performance. The trajectory simulations include optimum staging of operating thrusters as a function of input power level constraints and limits on the variation of thruster specific impulse and efficiency as a function of thruster input power.

Sauer, C. G., Jr.↗

NASA NTRS1975

Circulation in the high-latitude thermosphere due to electric fields and Joule heating

Electric fields in the earth's upper atmosphere are capable of setting the neutral atmosphere in motion via ion-neutral collisions as well as pressure gradients from resultant Joule heating. By means of simple models for the high-latitude thermosphere and electric fields a simplified set of coupled equations is solved which show that moderate electric fields, when present for a period of several hours, are capable of displacing the neutral atmosphere of the order of 50 km in the vertical, a few hundred kilometers in the north-south direction and over 1000 km in the east-west direction.

Heaps, M. G.↗