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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 829 records · Page 46
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Space shuttle: Longitudinal and lateral aerodynamic characteristics of the 0.0035-scale GD/C aerospace booster (B-15B-1)

Force tests on a 0.0035-scale model of the General Dynamics/Convair space shuttle B-15B-1 booster were conducted in the MSFC trisonic wind tunnel during February and March 1971. Longitudinal and lateral characteristics were obtained at Mach numbers from 0.6 to 4.96. The configuration tested had a low delta wing, all-movable canard controls of delta planform, and a single vertical tail. Most of the test was devoted to obtaining data relevant to the transition from atmospheric reentry to subsonic cruise. In that portion of the test the angles of attack ranged from 6 degrees to 60 degrees, and yaw runs were made at angles of attack of 15 and 35 degrees. The rest of the test was devoted to obtaining booster-alone buildup data relevant to the launch phase. For the launch phase, the Mach number range was from 0.6 to 2.0, the angles of attack were from -10 to +10 degrees, and yaw runs were made at zero angle of attack.

Debevoise, J. M.↗
NASA NTRS1972

Stability of water-lubricated three-lobe journals mated with plain bearings at zero load

Tests were conducted with plain bearings running with three types of three-lobe journals. The bearings, with a nominal 3.8-centimeter (1.5-in.) diameter and L/D of 1, were tested at 300 K (80 F) under stable conditions to 5400 rpm. The lobed configurations tested, in order of diminishing stability, were a tilted-lobe journal with grooves, a tilted-lobe journal without grooves, and a centrally lobed journal without grooves. A previously tested three-tilted-lobe bearing with grooves, running with a plain journal, was somewhat more stable than the tilted-lobe or centrally lobed journals.

Schuller, F. T.↗
NASA NTRS1970

Hypersonic research engine project. Phase 2: Structures and cooling development

The structures assembly model (SAM) was installed, and wind tunnel systems were checked out. The first run, with hydrogen cooling and SAM inserted in the wind tunnel stream (M = 7.7, P sub TOTAL = 900 psia, T sub TOTAL = 2500 deg R), was accomplished. The condition of the SAM after the run was satisfactory, with no visible signs or data indications of overheating or overloading.

Jilly, L. F.↗
NASA NTRS1972

Space shuttle: Static aerodynamic characteristics and control effectiveness of the GAC H-33 orbiter at Mach numbers from 0.6 to 4.96

A .003366 scale model of the Grumman H-33 orbiter was tested in the MSFC 14 inch Trisonic Wind Tunnel. Six-component aerodynamic force and moment data was recorded over a Mach number range of 0.6 to 4.96. Both pitch runs and yaw runs at various constant angles of attack were completed. The basic model configuration was investigated. The effects of a component build-up and of various control deflections were obtained. The elevons were deflected symmetrically and asymmetrically to determine elevator and aileron effectiveness. The rudder was tested both flared and unflared and the effects of deflections were determined in the flared case. The model was tested in pitch in two intervals. The first interval was from 0 to 20 deg. Then an adaptor was set to give the sting an offset angle and 20 to 40 deg angle of attack was obtained. Characteristics in sideslip were determined by varying sideslip angle from -4 deg to 10 deg with angle of attack set at 0 deg, 10 deg, 15 deg, and 30 deg.

Krepski, R.↗
NASA NTRS1972

Comparative lubrication studies of OH-58A tail rotor drive shaft bearings

Comparative lubrication tests were run with OH-58A helicopter tail rotor drive shaft bearings. The tests were run in an outdoor environment with ambient temperatures ranging from 10 to 75 F. Dust was periodically applied to the bearings to simulate field conditions. The cause of bearing failure was associated with dust penetration. Rotor shaft failure was found to be caused by the shaft rotating in the standard rubber collar due to seizure of the bearings. Bearings with a positive rubbing seal having a MIL-G-81322 grease produced lives greater than with bearings having labyrinth seals and a mineral oil paste lubricant. An elongated collar prevented failure of the rotor shaft during bearing seizure. In a limited test, installation of tail boom shrouds over the bearings which excluded dust and water resulted in bearing lives in excess of 1800 hours or 1200 hours greater than the current 600 hours TBO, regardless of the lubricant-bearing combination used.

Dietrich, M. W.↗
NASA NTRS1971

Hydrocarbon polymeric binder for advanced solid propellant

Various experimental factors were examined to determine the source of difficulty in an isoprene polymerization in the 5-gallon reactor which gave a non-uniform product of low functionality. It was concluded that process improvements relating to initiator and monomer purity were desirable, but that the main difficulty was in the initiator feed system. A new pumping system was installed and an analog simulation of the reactor, feed system and initiator decomposition kinetics was devised which permits the selection of initial initiator concentrations and feed rates to use to give a nearly uniform initiator concentration throughout a polymerization run. An isoprene polymerization was run in which the process improvements were implemented.

Potts, J. E.↗
NASA NTRS1972

NASTRAN buckling analysis of a thin walled cylinder

The computer run time required for a buckling analysis using NASTRAN is considerably greater than for a linear static analysis of the same structure. It is very important to obtain an optimal model size for the structure being analyzed, such that the model is neither so large as to increase running time unnecessarily, nor so small as to hinder accuracy. The problem of critical load accuracy versus model complexity is considered for a thin walled cylinder, using both Level 12 and Level 15 NASTRAN releases.

Wight, R. B.↗
NASA NTRS1971

Rolling-element fatigue lives of through-hardened bearing materials.

Rolling-element fatigue tests were run with eight through-hardened bearing materials at 150 F. One-half in. dia balls of each material were run in five-ball fatigue testers. Care was taken to maintain constant all variables known to affect rolling-element fatigue life. The longest lives at 150 F were obtained with AISI 52100. Ten-percent lives of the other materials ranged from 7 to 78 percent of that obtained with 52100. A trend is indicated toward decreased rolling-element fatigue life with increased total weight percent of alloying elements. Three groups of 120-mm bore ball bearings made from AISI M-1, AISI M-50, and WB-49 were fatigue tested at an outer-race temperature of 600 F. The 10-percent lives of the M-50 and M-1 bearings exceeded the calculated AFBMA life by factors of 13 and 6, respectively. The bearings with WB-49 races showed lives less than AFBMA life. The results of the bearing tests at 600 F correlate well with the results of the five-ball fatigue data at 150 F.

Parker, R. J.↗
NASA NTRS1971

The series hybrid bearing - A new high speed bearing concept.

The series-hybrid bearing couples a fluid-film bearing with a rolling-element bearing such that the rolling-element bearing inner race runs at a fraction of shaft speed. A series-hybrid bearing was analyzed and experiments were run at thrust loads from 100 to 300 lb and speeds from 4000 to 30,000 rpm. Agreement between theoretical and experimental speed sharing was good. The lowest speed ratio (ratio of ball bearing inner-race speed to shaft speed) obtained was 0.67. This corresponds to an approximate reduction in DN value of 1/3. For a ball bearing in a 3 million DN application, fatigue life would theoretically be improved by a factor as great as 8.

Anderson, W. J.↗
NASA NTRS1972

Advanced ETC/LSS computerized analytical models, CO2 concentration. Volume 1: Summary document

Computer simulations have been prepared for the concepts of C02 concentration which have the potential for maintaining a C02 partial pressure of 3.0 mmHg, or less, in a spacecraft environment. The simulations were performed using the G-189A Generalized Environmental Control computer program. In preparing the simulations, new subroutines to model the principal functional components for each concept were prepared and integrated into the existing program. Sample problems were run to demonstrate the methods of simulation and performance characteristics of the individual concepts. Comparison runs for each concept can be made for parametric values of cabin pressure, crew size, cabin air dry and wet bulb temperatures, and mission duration.

Taylor, B. N.↗
NASA NTRS1972

An improved design method and experimental performance of two dimensional curved wall diffusers

A computer design program was developed to incorporate the suction slots in solving the potential flow equations with prescribed boundary conditions. Using the contour generated from this program two Griffith diffusers were tested having area ratios AR = 3 and 4. The inlet Reynolds number ranged from 600,000 to 7 million. It was found that the slot suction required for metastable operation depends on the sidewall suction applied. Values of slot suction of 8% of the inlet flow rate was required for AR = 4 with metastable condition, provided that enough sidewall suction was applied. For AR = 3, the values of slot suction was about 25% lower than those required for AR = 4. For nearly all unseparated test runs, the effectiveness was 100% and the exit flow was uniform. In addition to the Griffith diffusers, dump and cusp diffusers of comparable area ratios were built and tested. The results obtained from these diffusers were compared with those of the Griffith diffusers. Flow separation occurred in all test runs with the dump and cusp diffusers.

Yang, T.↗
NASA NTRS1972

The X-ray system of crystallographic programs for any computer having a PIDGIN FORTRAN compiler

A manual is presented for the use of a library of crystallographic programs. This library, called the X-ray system, is designed to carry out the calculations required to solve the structure of crystals by diffraction techniques. It has been implemented at the University of Maryland on the Univac 1108. It has, however, been developed and run on a variety of machines under various operating systems. It is considered to be an essentially machine independent library of applications programs. The report includes definition of crystallographic computing terms, program descriptions, with some text to show their application to specific crystal problems, detailed card input descriptions, mass storage file structure and some example run streams.

Stewart, J. M.↗
NASA NTRS1972

Instantaneous distortion investigation

The results obtained in an inlet-engine compatibility test run in the 10x10 SWT of the NASA-Lewis Research Center are reviewed. This program was run to measure the time-variant distortions produced in a supersonic inlet and to relate a unique distortion peak, occurring in an instant of time, to the origin of stall in a compressor. The major stumbling block in this type of effort is the determination of a proper increment of time over which to average pressures before computing distortions. It is reasonable to expect that the proper averaging time is related to the particular compressor in question. The most significant point reported is that the proper averaging time may not be solely dependent on a particular compressor, and, in fact, may vary with operating conditions, even for the same inlet-engine combination.

Calogeras, J. E.↗
NASA NTRS1972

Acoustic fatigue and sound transmission characteristics of a ram composite panel design

An experimental study to determine the acoustic fatigue characteristics of a flat multi-layered structural panel is described. The test panel represented a proposed design for the outer skin of a research application module to be housed within the space shuttle orbiter vehicle. The test specimen was mounted in one wall of the Wyle 100,000 cu ft reverberation room and exposed to a broadband acoustic environment having an overall level of 145 db. The test panel was exposed to nine separate applications of the acoustic environment, each application consisting of 250 seconds duration. Upon completion of the ninth test run, the specimen was exposed to a simulated micrometeoroid impact near the panel center. One additional test run of 250 seconds duration was then performed to complete the overall simulation of 50 flight missions. The experimental results show that no significant fatigue damage occurred until the test specimen was exposed to a simulated micrometeoroid impact. The intermediate foam layer forming the core of the test specimen suffered considerable damage due to this impact, causing a marked variation in the dynamic characteristics of the overall test panel. During the final application of the acoustic environment, the strain and acceleration response spectra showed considerable variation from those spectra obtained prior to impact of the panel. Fatigue damage from acoustic loading however, was limited to partial de-bonding around the edges of the composite panel.

Cockburn, J. A.↗
NASA NTRS1973

Evaluation of load-life relation with ball bearings at 500 F

A survey of the literature suggests that a stress-life exponent of approximately 12 is typical of vacuum-processed steels for ball bearings rather than the exponent of 9 which has been generally accepted by the bearing industry and bearing users. Tests run with vacuum-degassed AISI 52100 balls in the five-ball fatigue tester at four maximum Hertz stress levels in the range from 650,000 to 875,000 psi showed good agreement with the literature. However, tests run with consumable-electrode vacuum melted AISI M-50 steel angular-contact ball bearings at 500 F at three thrust loads did not show significant deviation from the accepted ninth power stress-life relation.

Parker, R. J.↗
NASA NTRS1973

CIT photoheliograph functional verification unit test program

Tests of the 2/3-meter photoheliograph functional verification unit FVU were performed with the FVU installed in its Big Bear Solar Observatory vacuum chamber. Interferometric tests were run both in Newtonian (f/3.85) and Gregorian (f/50) configurations. Tests were run in both configurations with optical axis horizontal, vertical, and at 45 deg to attempt to determine any gravity effects on the system. Gravity effects, if present, were masked by scatter in the data associated with the system wavefront error of 0.16 lambda rms ( = 6328A) apparently due to problems in the primary mirror. Tests showed that the redesigned secondary mirror assembly works well.

Source record↗
NASA NTRS1973

A Quiet Engine for stilling complaints.

Two experimental Quiet Engines using derated CF6 cores are discussed. One engine has a low-speed fan running at a tip speed of 1160 fps; the other engine has a fan running at the high speed of 1550 fps. The two engines are expected to show the relative advantages of fans operating at low tip speeds with high lift coefficients in comparison with fans operating at high tip speeds with low lift coefficients. Test results obtained with full-scale (6-ft diameter) fans are examined.

Sanders, N. D.↗