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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Quiescent Galaxy Size, Velocity Dispersion, and Dynamical Mass Evolution

Abstract We use surveys covering the redshift range 0.05 < z < 3.8 to explore quiescent galaxy scaling relations and the redshift evolution of the velocity dispersion, size, and dynamical mass at fixed stellar mass. For redshift z < 0.6, we derive mass-limited samples and demonstrate that these large samples enhance constraints on the evolution of the quiescent population. The constraints include 2985 new velocity dispersions from the SHELS F2 survey. In contrast with the known substantial evolution of size with redshift, evolution in the velocity dispersion is negligible. The dynamical-to-stellar-mass ratio increases significantly as the universe ages, in agreement with recent results that combine high-redshift data with the Sloan Digital Sky Survey. Like other investigators, we interpret this result as an indication that the dark matter fraction within the effective radius increases as a result of the impact of the minor mergers that are responsible for size growth. We emphasize that dense redshift surveys covering the range 0.07 < z < 1 along with strong and weak lensing measurements could remove many ambiguities in evolutionary studies of the quiescent population.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1963

ELECTRON TEMPERATURES IN THE UPPER ATMOSPHERE

Energy loss processes for fast electrons, electron heating efficiency, heat input to the electron gas, effect of thermal coupling, and electron thermal conductivity above the f2 peak

F- 2 LAYER↗
NASA NTRS1968

Aircraft without wings.

Lifting body type M2-F1 and M2-F2 aircraft enabling astronauts to make own landings at choice airport

Syvertson, C. A.↗
NASA NTRS1969

Lifting body flight tests and analysis

Reusable lifting entry vehicle flight tests, investigating handling qualities and subsonic- transonic aerodynamics of M2-F2 /M2-F3/, HL-10 and X-24A

Layton, G. P., Jr.↗
NASA NTRS1970

Background and current status of the lifting body program

The lifting body concept was originally conceived by the Ames Research Center, and the design was developed over a period of years, from 1957 to 1964. By using a cone as a basic entry shape and modifying it to obtain lift and control, the M-2 shape evolved. In a cooperative venture with the NASA Ames Research Center to determine if a pilot could maneuver, flare, and land this class of vehicle, the Flight Research Center constructed a lightweight version of the lifting body, the M2-F1 vehicle. This vehicle was constructed during the fall of 1962 and spring of 1963 and extensively flight tested during the summer of 1963. Because of the success of the M2-F1 flight program, the research program was extended to include vehicles that would be representative of mission weight and wing loading. Figure 1 shows the three vehicles in the present lifting body program. On the left is the X-24A vehicle, which evolved from the U. S. Air Force's SV-5 PRIME vehicle; in the center is the M2-F3 vehicle, which is a modified version of the M2-F2 vehicle; and on the right is the HL-10 vehicle, which evolved from work at the NASA Langley Research Center.

John G McTigue↗
NASA NTRS1970

Stability and control derivatives of the lifting body vehicles

Predictions of the flight characteristics of lifting bodies have been based almost exclusively on wind-tunnel data for small-scale models. A need thus exists to compare the results from small-scale and full-scale wind-tunnel tests with results from flight tests to establish some measure of the accuracy of the predictions and to assess the sensitivity of the vehicle's handling qualities to typical discrepancies between flight and wind-tunnel results. Comparisons of these types have been one of the primary objectives of the M2-F2, HL-10, and X-24A flight programs. In this paper the more important longitudinal and lateral-directional aerodynamic stability and control derivatives obtained from flight are compared with small- and full-scale wind-tunnel results where applicable. Significant trends and important differences are pointed out, and the implications discussed.

Robert W Kempel↗
NASA NTRS1970

Correlation of flight-test loads with wind- tunnel predicted loads on three lifting body vehicles

An essential area of research with the unique M2-F2, HL-10, and X-24A lifting body configurations is the assessment of the ability to predict flight loads from wind- tunnel tests. Flight measurements and correlation with predictions are necessary in verifying the structural integrity of existing vehicles and establishing the groundwork for weight savings on future vehicles of similar shapes. As part of the overall lifting body flight investigation at the Flight Research Center, detailed aerodynamic-load studies are being made on each of the three vehicles. This paper presents the preliminary results from these studies

Ming H Tang↗
NASA NTRS1971

Twilight and nighttime ionospheric temperatures from oxygen wavelengths 6300 and 5577 spectral line profiles

Fabry-Perot interferometer measurements of atomic oxygen 6300 A and 5577 A line profiles from twilight and nightglow are used to determine the neutral temperatures in F2 and E regions of the earth's ionosphere. The exospheric temperatures T sub n (infinity) determined from the 6300 A profiles are usually somewhat higher than those calculated from Jacchia's model, with differences as large as approximately 300 K noted when T sub n (infinity) = 1500 to 1600 K. The post-sunset and pre-dawn rate of change of T sub n (infinity) is often substantially larger than the Jacchia prediction. The 5577 A (E-region) measured temperatures range from 200 to 220 K on quiet nights to 500 to 600 K during geomagnetic storms.

Feibelman, W. A.↗
NASA NTRS1971

Proposed characterization of tornadoes and hurricanes by area and intensity

Results of the 1968 through 1970 Tornado Watch Experiment conducted jointly by NASA and NOAA suggested the necessity of characterizing individual tornadoes in order to improve the identity of tornado-producing nephsystems. An attempt was made, therefore, to categorize each tornado by its intensity and area. Fujita-scale wind and corresponding damage categories were devised to classify tornadoes as Gale (F0), Weak (F1), Strong (F2), Severe (F3), Devastating (F4), and Incredible (F5). Additionally, individual tornado areas were also categorized as Trace (TR), Decimicro (DM), Micro (MI), Meso (ME), Marco (MA), Giant (GI), and Decagiant (DG), thus permitting characterizing of a tornado by a combination of intensity and area, such as weak decimicro tornado, severe meso tornado, or incredible giant tornado. A test characterization of 156 Japanese tornadoes in 1950-69 was accomplished for comparison with 893 U.S. tornadoes in 1965. Unexpectedly, the percentage distribution of intensity and individual area of U.S. and Japanese tornadoes is very similar except for large and/or intense ones. Intensity distribution within the Dallas and Fargo tornadoes of 1957 was also studied in detail. It was also found that the F-scale variation along the paths of family tornadoes shows an intensity oscillation with a 45-min interval.

Fujita, T. T.↗
NASA NTRS1972

Statistical analysis of landing contact conditions for three lifting body research vehicles

The landing contact conditions for the HL-10, M2-F2/F3, and the X-24A lifting body vehicles are analyzed statistically for 81 landings. The landing contact parameters analyzed are true airspeed, peak normal acceleration at the center of gravity, roll angle, and roll velocity. Ground measurement parameters analyzed are lateral and longitudinal distance from intended touchdown, lateral distance from touchdown to full stop, and rollout distance. The results are presented in the form of histograms for frequency distributions and cumulative frequency distribution probability curves with a Pearson Type 3 curve fit for extrapolation purposes.

Larson, R. R.↗
NASA NTRS1972

The state of the ionosphere above Alma Ata

The basic patterns are described in the behavior of critical frequencies and minimum effective heights of the ionosphere's reflecting E, F1, and F2 layers, according to ionospheric recorder measurements from 1943 to 1967. The variations of critical frequencies and virtual heights are compared with the relative sunspot numbers and the flux of the sun's radio emission at 10.7 cm.

Rudina, M. P.↗
NASA NTRS1972

Occupancy of the radio frequency spectrum in the 16-23 MHz band

Measurement results are presented for actual utilization of the short wave frequency band, obtained by continuous registration of the number of radio stations in the 16-23 MHz band over an annual cycle (1965). It is shown that there is a relation between the number of radio stations and the variations of MUF-F2. During years of minimum solar activity and at night, segments free of radio stations operating by normal reflection, can be selected in the 18-23-MHz band for ionospheric-scattering links.

Ashkaliyev, Y. F.↗
NASA NTRS1972

Space Storable Propellant Performance Gas/Liquid Like-Doublet Injector Characterization

A 30-month applied research program was conducted, encompassing an analytical, design, and experimental effort to relate injector design parameters to simultaneous attainment of high performance and component (injector/thrust chamber) compatibility for gas/liquid space-storable propellants. The gas/liquid propellant combination selected for study was FLOX (82.6% F2)/ambient temperature gaseous methane. The injector pattern characterized was the like-(self)-impinging doublet. Program effort was apportioned into four basic technical tasks: injector and thrust chamber design, injector and thrust chamber fabrication, performance evaluation testing, and data evaluation and reporting. Analytical parametric combustion analyses and cold flow distribution and atomization experiments were conducted with injector segment models to support design of injector/thrust chamber combinations for hot fire evaluation. Hot fire tests were conducted to: (1) optimize performance of the injector core elements, and (2) provide design criteria for the outer zone elements so that injector/thrust chamber compatibility could be achieved with only minimal performance losses.

Falk, A. Y.↗