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At least 991 records · Page 55
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Aeroacoustic research in wind tunnels: A status report

The increasing attention given to aerodynamically generated noise brings into focus the need for quality experimental research in this area. To meet this need several specialized anechoic wind tunnels have been constructed. In many cases, however, budgetary constraints and the like make it desirable to use conventional wind tunnels for this work. Three basic problems are inherent in conventional facilities: (1) high background noise, (2) strong frequency dependent reverberation effects, and (3) unique instrumentation problems. The known acoustic characteristics of several conventional wind tunnels are evaluated and data obtained in a smaller 4- x 5-foot wind tunnel which is convertible from a closed jet to an open jet mode are presented. The data from these tunnels serve as a guideline for proposed modifications to a 7- x 10-foot wind tunnel. Consideration is given to acoustic treatment in several different portions of the wind tunnel.

Bender, J.↗
NASA NTRS1972

Nozzle extension design status report

Twenty possible concepts of a possible nozzle/nozzle extension interface were originated. Not all of the concepts were considered worthy of analysis time. Six of them were thermally analyzed and three were stress analyzed. These analyses were done to determine which of the concepts would have the best chance of succeeding, that is, they were a screening process which was to allow rating of one concept against another. This was done because adequate material properties to determine absolute stress levels were not available at the time of the analyses. Through all of the concepts still exhibit some areas of negative margin of safety, concept no. 1 shows good promise that, with slight modifications, it could have all positive margins of safety. Another significant question, regarding these designs, has to do with the Grafoil seals and insulators. Some additional data was just recently received on Grafoil properties, but it was too late to incorporate in the analyses. The new data were not significantly different from the properties which were used.

Classen, L. B.↗
NASA NTRS1973

Determination of the relativistic time delay for Mariner 9: A status report on the JPL analysis of normal points

The procedure which has been chosen to accomplish a reduction of the Mariner 9 tracking data makes use of Doppler data over relatively short arcs of about one to nine orbital revolutions to determine the orbit of the spacecraft about Mars. Next, with the knowledge of the Mars-centered orbit, it is possible to use the range data to the spacecraft to determine the distance between the center of earth and the center of Mars for each short interval of tracking data. These reduced range measurements between the centers of the two planets make up the basic data for the relativity test.

Anderson, J. D.↗
NASA NTRS1973

Status report on Skylab project.

The major objectives of the Skylab project are to examine the medical aspects of what happens to man in long duration space flight, to make long-duration studies of the active and the quiet sun, and to gather data in the study of the ocean and the land masses of the earth. Corollary experiments use either the fact that they are to be performed in a complete vacuum, or the fact that the stars and the ultraviolet can be much more extensively studied. Some experiments in metal processing will make use of the zero force field.

Conrad, C., Jr.↗
NASA NTRS1973

Status report on shuttle program.

Following a brief summary of previous work, major attention is given to Phase-B extension, the Request for Proposal (RFP), the selected configuration and associated activities, and the future. NASA extended Phase-B contracts to examine other options that might lower peak annual funding and decrease program risk. Most of the discussion deals with the shuttle and orbiter systems. The efforts of the shuttle program in the past year have seen the completion of numerous trade studies and the selection of a prime shuttle contractor.

Swigert, J. L., Jr.↗
NASA NTRS1973

Space Shuttle status report.

A description is given of the design evolution during 1972-1973 of a reusable transportation system intended to place payloads of up to 65,000 lb in a 100 nm 28-degree inclination orbit, and to retrieve and return to earth 25,000 lb from orbit. The shuttle will be launched vertically as a rocket and will land horizontally as an airplane at about 170 kts with a cross range sufficient to return to the launch site after one orbit. The shuttle system is comprised of a reusable orbiter, two recoverable solid-propellant boosters, and an expendable liquid-propellant tank.

Peil, N. G.↗
NASA NTRS1973

Mariner 9 celestial mechanics experiment - A status report.

There are two basic efforts in the Mariner 9 celestial mechanics experiment: the determination of the gravity field of Mars and the performance of a very precise test of the theory of general relativity. In addition, there are a number of astrodynamic constants that are being determined. All the analyses are based on the Mariner 9 radio tracking data.

Lorell, J.↗
NASA NTRS1972

Wind speeds in lower atmosphere of Venus: Status report on possible measurement via differential VLBI tracking of entry probes

The potential of very-long-baseline interferometry (VLBI) is examined for use in the determination of wind speeds in Venus' lower atmosphere via the differential tracking of entry probes. A simplified mathematical model is presented in detail. An incomplete error analysis based on this model permits an educated guess to be made: an uncertainty in wind speed determination of no more than about 100/t m/sec, where t l is the corresponding time resolution in seconds, is an achievable goal, without the use of transponders on the miniprobes. If transponders are available on all probes, there should be little difficulty in estimating wind speeds with useful precision.

Shapiro, I. I.↗
NASA NTRS1974

Advances in measuring techniques for turbine cooling test rigs - Status report

Instrumentation development pertaining to turbine cooling research has resulted in the design and testing of several new systems. Pressure measurements on rotating components are being made with a rotating system incorporating ten miniature transducers and a slip-ring assembly. The system has been tested successfully up to speeds of 9000 rpm. An advanced system development combining pressure transducer and thermocouple signals is also underway. Thermocouple measurements on rotating components are transferred off the shaft by a 72-channel rotating data system. Thermocouple data channels are electronically processed on board and then removed from the shaft in the form of a digital serial train by one winding of a rotary transformer.

Pollack, F. G.↗
NASA NTRS1974

Stall/spin research status report

Description of a program aimed at improving the design and evaluation techniques relative to stall/spin characteristics of general-aviation aircraft. The program encompasses analytical studies, full-scale and model wind-tunnel tests, a radio-control model, and full-scale flight tests. Initial spin-tunnel results of several tail designs on a representative light aircraft are discussed.

Bowman, J. S., Jr.↗
NASA NTRS1974

Polybenzimidazoles, status report

Particular attention is given to polybenzimidazoles derived from the condensation of tetraaminobiphenyl and diphenylisophthalate. The polybenzimidazoles can be prepared by the condensation of equimolar amounts of the monomers in the absence of solvent. However, the polymerization has also been carried out in a variety of solvents. The polybenzimidazoles have excellent technical possibilities. These possibilities have currently not yet been commercially realized.

Leal, J. R.↗
NASA NTRS1974

Status report on Astronaut Maneuvering Equipment

The objectives of the Skylab experiment M509 were related to the development and the use of an Astronaut Maneuvering Unit (AMU). Through the actual orbital flight tests, the experiment has produced invaluable data to verify and extend previous ground-based research. AMU equipment and operating modes are considered along with flight plans, crew operations, and the maneuvering test plan. Attention is also given to orbital test results, a subjective evaluation, and actual and simulator flight assessment.

Mccandless, B., II↗
NASA NTRS1975

An evaluation of various ball bearing lubricants operating in various environments /A status report/

Testing of both fluid and solid lubricants in small ball bearings is reported for a period of up to one year in various environments. The testing equipment, procedures and detailed results of five different lubricants, operating in a vacuum at ambient temperature, are described. Specially made motors were shimmed to maintain a 2.27 kg thrust load on both bearings, having a speed of 3600 rpm allowing 216,000 revolutions on each bearing per hour until failure. The commercial perfluoropolyether (PFPE-1) grease, having the best results, was recommended for long term bearing operation under hard vacuum conditions. It had an average life of over 8760 hrs. The ester based grease was recommended for moderate life requirements in vacuum conditions, while the silicone based grease and the fluorosilicone based grease were not recommended for vacuum operation due to extensive metal damage in the bearings.

Demorest, k. E.↗
NASA NTRS1975

Status report on NASA two-segment approach program

NASA, in cooperation with the FAA, is evaluating the two-segment approach as a routine procedure for reducing aircraft noise. The program calls for separate flight evaluations using a 727 and a DC-8, and an extrapolation of these results to determine the adaptability of the technique to the rest of the fleet. After a review of the total program, this paper presents (1) the profile and procedures developed and the noise reduction achievable, (2) the vortex characteristics behind an aircraft on a two-segment path, and (3) cost estimates for retrofitting aircraft with two-segment avionics.

Denery, D. G.↗
NASA NTRS1975

Relativity experiment on Helios - A status report

The relativity experiment on Helios (Experiment 11) uses S-band and Doppler data, and spacecraft-solar-orbital data to measure the effects of general relativity in the solar system and the quadrupole moment in the solar gravitational field. Specifically, Experiment 11 is converned with measuring the following effects: (1) relativistic orbital corrections described by two parameters of the space-time metric which are both equal to unity in Einstein's theory; (2) orbital perturbations caused by a finite quadrupole moment of an oblate sun, described by zonal harmonics in the solar gravitational field.

Anderson, J. D.↗
NASA NTRS1975

Status report on nuclear electric propulsion systems

Progress in nuclear electric propulsion (NEP) systems for a multipayload multimission vehicle needed in both deep-space missions and a variety of geocentric missions is reviewed. The space system power level is a function of the initial launch vehicle mass, but developments in out-of-core nuclear thermionic direct conversion have broadened design options. Cost, design, and performance parameters are compared for reusable chemical space tugs and NEP reusable space tugs. Improvements in heat pipes, ion engines, and magnetoplasmadynamic arc jet thrust subsystems are discussed.

Stearns, J. W.↗
NASA NTRS1976

The NASA Pollution-Reduction Technology Program for small jet aircraft engines - A status report

A three-phase experimental program is described which has the objective of enabling EPA Class T1 jet engines to meet the 1979 EPA emissions standards. In Phase I, three advanced combustor concepts, designed for the AiResearch TFE 731-2 turbofan engine, were evaluated in screening tests. Goals for carbon monoxide and unburned hydrocarbons were met or closely approached with two of the concepts with relatively modest departures from conventional combustor design practices. A more advanced premixing/prevaporizing combustor, while appearing to have the potential for meeting the oxides of nitrogen goal as well, will require extensive development to make it a practical combustion system. Smoke numbers for the two combustor concepts which will be carried forward into Phase II of the program were well within the EPA smoke standard. Phase II, Combustor-Engine Compatibility Testing, which is in its early stages, and planned Phase III, Combustor-Engine Demonstration Testing, are also described.

Fear, J. S.↗