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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Final design proposal: Theta Group-The Hotbox. A proposal in response to a commercial air transportation study

The Hotbox is a 40 passenger commercial aircraft designed to have a minimum range of 5500 ft and cruise at a velocity of 30 ft/sec. The aircraft is designed to serve the longer range overseas market in Aeroworld. In order to serve all the airports in the overseas market, the Hotbox was required to be able to use a five foot gate. A weight requirement was set a 4.5 lbs in order to maximize aircraft efficiency. Finally, a single engine system was chosen because it minimized system weight, complexity and cost. The Hotbox is estimated to cost $152,000 Aeroworld dollars and will sell for $200.000. The propulsion system for the Hotbox consists of a nose mounted Astro 15 electric powered motor and a Top Flight 12-6 propeller. A Spica airfoil was selected for the Hotbox based on the ease of construction of its flat bottom and its positive lift and drag characteristics. A fuselage of rectangular cross section will internally contain the propulsion system, control system, and a passenger bay with 2x20 seating. A combination of directional and longitudinal control will enable the Hotbox to maneuver. The final design of the Hotbox provides for takeoff distance in 26.5 ft and normal cruise range of 17,000 ft.

Source record↗
NASA NTRS1994

The quiescent and flaring EUV spectrum of Algol and its relationship to other active coronae. EUV spectroscopy of bright hyades coronae: 71 Tauri and Theta 1 Tauri

This program involves analysis and interpretation of EUVE spectrometer observations of the active stars Algol (beta Per) and 71 Tauri. The EUVE satellite spectrometers observed the prototype eclipsing binary Algol over nearly 1.5 orbital periods. Effective exposure times were 100 ksec and 89 ksec in the short wave (70-180 A) and medium wave (140-370 A) channels. High temperature (up to 20 MK) Fe XVI-XXIV emission lines are clearly detected in the overall spectrum. In addition, a quiescent continuum is present which increases towards shorter wavelengths. Using synthesized spectra of optically thin line and continuum emission folded through the instrumental response, we have examined constraints on the (Fe/H) coronal abundance in Algol. We find that the coronal Fe is underabundant by factors that approximately equal 2-4 relative to solar photospheric values, unless an unreasonably large quantity of coronal plasma at T greater than 30 MK is present in the quiescent spectrum. The latter possibility is, however, inconsistent with available X-ray data. Lightcurves of the high temperature EUV lines compared to line emission at He II 304 A show considerable differences, with much deeper minima present in the He II line during both primary and secondary eclipses. Toward the end of the observation a moderate flare lasting approximately 6 hours was detected in the high temperature Fe emission lines. The 71 Tau observation, for about the same exposure time, revealed only a handful of weak emission lines; however, the strongest lines were also those of Fe XXIII/XX, suggesting a hot coronal plasma. No obvious flaring or other variation was present in the 71 Tau Deep Survey lightcurve.

Stern, Robert A.↗
NASA NTRS2000

The Visual Orbit of theta(sup 2) Tauri and the Distance to the Hyades

Comparisons of measurements from interferometry, spectroscopy, precision photometry, lunar occultation, and Hipparcos not only checks the accuracy of the distance to the Hyades, but also provides an accurate empirical mass-luminosity relation, and a good estimate of the age of the Hyades.

binaries visual-instrumentation interferometers st↗
NASA NTRS2010

Thrust Stand Measurements of the Conical Theta Pinch FARAD Thruster

It is found that the impulse of a pulsed inductive plasma thruster utilizing preionization is maximized for a particular ratio of the stored energy in the capacitor to the injected propellant mass. The fact that the impulse depends on the ratio of the initial stored energy to injected propellant mass agrees with previous current sheet studies, supporting the idea that a Townsend-like breakdown process strongly influences current sheet formation, and in turn, current sheet formation strongly affects the operational efficiency of the device. The optimum in half cone angle of the inductive coil can be explained in terms of a balance between the direct axial acceleration and the radial pinching contribution to thrust. From the trends in these data we conclude that operation at the correct ratio of capacitor energy to propellant mass is essential for efficient operation of pulsed inductive plasma thrusters employing a preionized propellant.

Hallock, Ashley K.↗
NASA NTRS2013

Single and Multi-Pulse Low-Energy Conical Theta Pinch Inductive Pulsed Plasma Thruster Performance

Fabricated and tested CTP IPPTs at cone angles of 20deg, 38deg, and 60deg, and performed direct single-pulse impulse bit measurements with continuous gas flow. Single pulse performance highest for 38deg angle with impulse bit of approx.1 mN-s for both argon and xenon. Estimated efficiencies low, but not unexpectedly so based on historical data trends and the direction of the force vector in the CTP. Capacitor charging system assembled to provide rapid recharging of capacitor bank, permitting repetition-rate operation. IPPT operated at repetition-rate of 5 Hz, at maximum average power of 2.5 kW, representing to our knowledge the highest average power for a repetitively-pulsed thruster. Average thrust in repetition-rate mode (at 5 kV, 75 sccm argon) was greater than simply multiplying the single-pulse impulse bit and the repetition rate.

Hallock, Ashley K.↗
NASA NTRS2023

Short-Transverse Tensile Fracture Behavior of Thick AA2219 Plate - Effects of Theta (Al2Cu) Particle Size and Distribution

An investigation was conducted to obtain a better understanding on the microstructural characteristics of 5-inch-thick AA2219-T87 plate material and the mechanism that led to the unexpected low ductility in the short-transverse (ST) orientation. Materials characterization techniques were utilized to observe the microstructure of fractured tensile specimens and remnant plate material. The mechanism and cause of low ST ductility in the thick plate material is presented and discussed in this report.

Short-Transverse Orientation↗
DOE OSTI2013

CO Oxidation on supported single Pt atoms - Experimental and Ab Initio density functional studies of CO interaction with Pt atom on theta-alumina(010) surface

Although there are only a few known examples of supported single atoms, they are unique because they bridge the gap between homogenous and heterogeneous catalysis. The metal center is single supported atoms can be isoelectronic with their homogenous catalyst counterpart and may allow mechanistic pathways normally seen in homogenous catalysts. Here, we report CO oxidation activity of mono-disperse single Pt atoms supported on an inert substrate, -alumina (Al2O3), in the presence of stoichiometric oxygen. Since CO oxidation on single Pt atoms cannot occur via a conventional Langmuir-Hinshelwood scheme (L-H scheme) which requires at least one Pt-Pt bond, we have carried out a first principles density functional theoretical study of a proposed pathway which is a variation on the conventional L-H scheme and is inspired by organometallic chemistry of platinum. We find that a single supported Pt atom prefers to bond to O2 over CO. The CO then bonds with the oxygenated Pt atom and forms a carbonate which dissociates to liberate CO2, leaving an oxygen atom on Pt. A subsequent reaction with another CO molecule regenerates the single atom catalyst. An in-situ diffuse reflectance infrared study of CO adsorption on the catalyst s supported single atoms has been carried out to infer information on CO absorption modes and compare the observed spectra with calculated ones for intermediates in the proposed CO oxidation pathway. Our results clearly show that supported Pt single atoms are catalytically active and that this catalytic activity can occur without involving the substrate. Characterization by electron microscopy and X-ray absorption studies of the mono-disperse Pt/ -Al2O3, synthesized by solution methods, are also presented.

single atom catalysis↗