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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 1,081 records · Page 60
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Depolarization measurements on the ATS-6 20 GHz downlink A description of the VPI&SU experiment and some initial results

The experiment considered is mainly concerned with the depolarizing effects of precipitation at millimeter wavelengths. Excessive depolarization introduces cross talk into communication systems which employ orthogonal polarization for frequency reuse. An understanding of atmospheric depolarization phenomena is, therefore, required for the design of future earth-satellite communications systems. Attenuation and cross polarization ratio data obtained under various meteorological conditions, including rain and a snowstorm, are presented.

Bostian, C. W.↗
NASA NTRS1975

The large coronal transient of 10 June 1973. I - Observational description

Ground-based and Skylab coronagraph observations are used to trace a coronal loop transient from its inception near the surface to a distance of 5 solar radii. Events in the lower solar atmosphere associated with this feature are outlined chronologically, and its physical appearance is described. The densities, mass, and energy of the transient are estimated, its shape is determined, and its typical and atypical characteristics are noted. It is inferred that this transient was caused by the emergence of an active region. It is shown that it was not immediately preceded by a flare and that the material at its leading edge did not decelerate appreciably, even at approximately 5 solar radii.

Hildner, E.↗
NASA NTRS1975

A description of hardware and mission planning for the Apollo-Soyuz Test Project

The Apollo-Soyuz Test Program (ASTP) is scheduled for flight in July 1975. This paper will describe briefly the mission planning and hardware associated with the program. Of interest are modifications to the basic Apollo and Soyuz vehicles as well as the newly developed docking module and docking system. Joint aspects of the mission profile are explained. Science objectives and corresponding experiments are described. Utilization of the ATS-6 Satellite for relay of TV, voice, and data to the ground is also a topic. The paper concludes with a discussion of the joint flight control interface.

Littleton, F. C.↗
NASA NTRS1975

Theoretical description of the 2A/double prime/ and 2A/prime/ states of the peroxyformyl radical

Simple orbital ideas are used to describe the lowest two states of the peroxyformyl radical, and ab initio Hartree-Fock calculations in these states are reported. It is found that both states may be formed exothermically by association of O2 and HCO in their ground states; however, the excited state may decompose readily to OH and CO2. The possible role of such processes in oxidation of aldelydes is discussed.

Winter, N. W.↗
NASA NTRS1975

Probing a planetary atmosphere - Pioneer Venus spacecraft description

This paper describes the four Pioneer Venus probe spacecraft which will explore the atmosphere of Venus in mid-December, 1978. The probes, one large and three small, will carry a complement of sixteen scientific instruments which will make measurements from entry (200 km-altitude) down to the planet surface. The surface environment, approximately 770 K temperature and 95 bar. pressure, leads to a design in which the equipment complement is housed in internally insulated, spherical pressure vessels. Entry deceleration and stabilization are provided by 45 deg. half-angle conical forebodies, heat protected by carbon phenolic ablative heat shields. For the large probe, a parachute provides additional retardation between 67 and 44 km altitude, a region of extreme scientific interest.

Nolte, L. J.↗
NASA NTRS1975

Pioneer Jupiter Orbiter/Probe mission. I - Spacecraft system description

This paper discusses the Pioneer Jupiter Orbiter/Probe mission with emphasis on the orbiter spacecraft system. In this mission, the atmosphere of Jupiter will be investigated for physical and chemical structure by a probe which survives entry and transmits data while descending below the 10-bar level. The spacecraft deflects after probe separation to a nonimpacting approach trajectory, acts as a communications relay for data from the descending probe, and propulsively enters an orbit about Jupiter. As an orbiter, it explores the environment of Jupiter for three years, making in situ measurements of the particles and fields of the Jovian magnetosphere together with remote measurements (including images) of Jupiter and the Galilean satellites. The spacecraft system is logically based on the design of Pioneers 10 and 11 with modifications for these different mission requirements: antenna, receiver, and memory for the probe-spacecraft data link; a retropropulsion system for the high velocity-change requirements of orbit insertion; a data system consistent with the requirements of a line-scan imaging system; and an improved complement of radioisotope-thermoelectric-generator power sources to provide adequate power six years after launch.

Lassen, H. A.↗
NASA NTRS1975

Description of the Space Shuttle Reaction Control System

The Space Shuttle RCS (reaction control system) is required to provide propulsion thrust for precise attitude control and three-axis translation. This capability must be provided for external tank separation, on-orbit operation, deorbit, and reentry. In order to meet these requirements a bipropellant, pressure-fed system utilizing monomethylhydrazine as fuel, and nitrogen tetroxide as oxidizer has been selected. The RCS engines include 38 primary thrusters rated at 870 lbf thrust and 6 vernier thrusters rated at 25 lbf thrust. The system is divided into three removable modules (one forward and two aft) to achieve maintenance and turnaround requirements. In order to provide additional mission flexibility, the aft modules can be connected together or interconnected with the OMS (orbital maneuvering system).

Blevins, D. R.↗
NASA NTRS1975

Description and calibration of the Langley 6- by 28-inch transonic tunnel

The Langley 6 by 28 inch transonic tunnel is described. The tunnel is a two dimensional facility with slotted top and bottom walls, used for testing two dimensional airfoil sections. Basic tunnel-empty Mach number distributions, noise surveys, and test section total pressure surveys are presented. The Mach number capability of the facility is from about 0.3 to 1.2. The stagnation pressure can be varied from 207 kN/sq m (30 lb/sq in) absolute to 620 kN/sq m (90 lb/sq in) absolute. This range of pressure can provide a Reynolds number of about 10 million, based on a 15.2 cm (6.0 in.) model chord at Mach numbers from 0.5 to 1.0. The maximum Reynolds number capability at a Mach number of 1.0 is about 15 million, based on the same model chord.

Ladson, C. L.↗
NASA NTRS1975

The experimental clean combustor program: Description and status to November 1975

The generation of technology was studied for the development of advanced commercial CTOL aircraft engines with lower exhaust emissions than current aircraft. The program is in three phases. Phase 1, already completed, consisted of screening tests of low pollution combustor concepts. Phase 2, currently in progress, consists of test rig refinement of the most promising combustor concepts. Phase 2 test results are reported. Phase 3, also currently in progress, consists of incorporating and evaluating the best combustors as part of a complete engine. Engine test plans and pollution sampling techniques are described in this report. Program pollution goals, specified at engine idle and take-off conditions, are idle emission index value of 20 and 4 for carbon monoxide (CO) and total unburned hydrocarbons (THC), respectively, and at take-off are an oxides of nitrogen (NOx) emission index level of 10 and a smoke number of 15. Pollution data were obtained at all engine operating conditions. Results are presented in terms of emission index and also in terms of the Environmental Protection Agency's 1979 Standards Parameter.

Niedzwiecki, R. W.↗
NASA NTRS1976

Description of a landing site indicator (LASI) for light aircraft operation

An experimental cockpit mounted head-up type display system was developed and evaluated by LaRC pilots during the landing phase of light aircraft operations. The Landing Site Indicator (LASI) system display consists of angle of attack, angle of sideslip, and indicated airspeed images superimposed on the pilot's view through the windshield. The information is made visible to the pilot by means of a partially reflective viewing screen which is suspended directly in frot of the pilot's eyes. Synchro transmitters are operated by vanes, located at the left wing tip, which sense angle of attack and sideslip angle. Information is presented near the center of the display in the form of a moving index on a fixed grid. The airspeed is sensed by a pitot-static pressure transducer and is presented in numerical form at the top center of the display.

Fuller, H. V.↗
NASA NTRS1975

Process description

The production of hydrogen from coal by hydrogasification and subsequent steam hydrocarbon reforming was studied. Process heat and power requirements are supplied by an HTGR. The process is examined as a function of a maximum reforming (process) temperature of 922 K (1200 F) to 1367 K (2000 F). The major parameters for the five cases selected are summarized in a table. A fixed thermal capacity of 3000 MW for the HTGR heat source was used as a basis. The resulting hydrogen production rates and the corresponding hydrogen purity are also given in a table.

Source record↗
NASA NTRS1976

Artwork Interactive Design System (AIDS) program description

An artwork interactive design system is described which provides the microelectronic circuit designer/engineer a tool to perform circuit design, automatic layout modification, standard cell design, and artwork verification at a graphics computer terminal using a graphics tablet at the designer/computer interface.

Johnson, B. T.↗
NASA NTRS1976

Pines nonsingular gravitational potential derivation, description and implementation

An engineering interpretation of and some minor corrections to previously completed work on a uniform representation of the gravitational potential and its derivatives (with emphasis on avoiding the usual singularity at the pole) were presented. The physical meaning of the variables was explained, the derivation of results was separated into smaller parts for easier reading, some additional recurrence relations for the derived Legendre polynomials were included and compared, and a computer program implementing this formulation was presented. Numerical experiments have shown that the use of this representation, besides removing the singularity, substantially increases the speed of the computation.

Spencer, J. L.↗
NASA NTRS1975

Description of a computerized method for predicting thermal fatigue life of metals

A computer program is described which can be used to predict the thermal fatigue life of metals and structural components from conventional metal properties. A unique feature of TFLIFE is that it calculates lives according to several different failure criteria for the same input data. These criteria are surface crack initiation, interior crack initiation, and complete fracture of both unnotched and notched fatigue specimens. Sample output tables are shown, together with results for two typical problems: (1) Thermal-mechanical fatigue of bar specimens of the tantalum alloy T-111, and (2) thermal-stress fatigue of wedge specimens of the nickel alloy B-1900.

Spera, D. A.↗
NASA NTRS1975

Technical description of space ultra reliable modular computer (SUMC), model 2 B

The design features of the SUMC-2B computer, also called the IBM-HTC are described. It is general purpose digital computer implemented with flexible hardware elements and microprograming to enable low cost customizing to a wide range of applications. It executes the S/360 standard instruction set to maintain problem state compability. Memory technology, extended instruction sets, and I/O channel variations are among the available options.

Source record↗
NASA NTRS1975

UHMLE: Program description user guide

A program which computes maximum likelihood estimates for the general normal mixture is introduced. The program allows the user to fix any subsets of the mixture parameters; this fixed set may be redefined at various times in the iteration process. There is considerable time saved in computing the likelihoods if the diagonal form is specified. Hence, in the early iterations the diagonal assumption might be used, changing over to the full covariance mode later in the iteration process for a more refined solution. This flexibility allows the user to choose the sequence of parameter configurations in the iteration process which he feels will optimize the computation time required as well as possibly avoid convergence to suboptimal local maxima of the likelihood function.

Cobely, W. A.↗