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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 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Final analysis and design of a thermal protection system for 8-foot HTST combustor

The cylindrical shell combustor with T-bar supports in the 8-foot HTST at the NASA-Langley Research Center encountered vibratory fatigue cracking over a period of 50-250 tunnel tests within a limited range of the required operating envelope. A preliminary design study provided several suitable thermal protection system designs for the combustor, one of which was a two-pass regenerative type air-cooled omega-shaped segment liner. A final design layout of the omega segment liner was prepared and analyzed for steady-state and transient conditions. The design of a support system for the fuel spray bar assembly was also included. Detail drawings suitable for fabrication purposes were also prepared. Liner design problems defined during the preliminary study included (1) the ingress of gas into the attachment bulb section of the omega segment, (2) the large thermal gradient along the leg of the omega bulb attachment section and, (3) the local peak metal temperature at the radius between the liner ID and the leg of the bulb attachment. These were resolved during the final design task. Analyses of the final design of the omega segment liner indicated that all design goals were met and the design provided the capability of operating over the required test envelope with a life expectancy substantially above the goal of 1500 cycles.

Moskowitz, S.↗
NASA NTRS1973

Round trip Mars missions using looping trajectories in the 1980-2000 time period

Round trip Mars missions combining a standard trajectory leg and a looping trajectory leg are suggested as an alternative to the more conventional trajectories. Looping trajectories are shown to make it possible to trade a slight increase in total mission time for a significant reduction in Mars stay time, with the possible added benefit of a decrease in energy requirements.

Kibler, J. F.↗
NASA NTRS1974

Observations at Mercury encounter by the plasma science experiment on Mariner 10

A fully developed bow shock and magnetosheath were observed near Mercury, providing unambiguous evidence for a strong interaction between Mercury and the solar wind. Inside the sheath there is a distinct region analogous to the magnetosphere or magnetotail of earth, populated by electrons with lower density and higher temperature than the electrons observed in the solar wind or magnetosheath. At the time of encounter, conditions were such that a perpendicular shock was observed on the inbound leg and a parallel shock was observed on the outbound leg of the trajectory, and energetic plasma electron events were detected upstream from the outbound shock crossing. The interaction is most likely not atmospheric, but the data clearly indicate that the obstacle to solar wind flow is magnetic, either intrinsic or induced.

Ogilvie, K. W.↗
NASA NTRS1975

Study of bone mineral metabolism

The use of Sr-85 as an indicator of the skeletal location and relative amount of bone demineralization which occurs during immobilization of the body or body parts, bed-rest or space flight was studied. The bone mineral replacement which occurs after immobilization was measured rather than the bone loss which occurs during immobilization. In a study with two adult beagle dogs, the Sr-85 uptake in a leg which had been immobilized for two months was 400 percent higher than the uptake in the legs in regular use. This increased uptake probably resulted from only a few percent loss in bone mineral and indicates that losses less than one percent can be easily detected and located. The sensitivity, simplicity, and low radiation dose associated with the use of this method indicates that it should receive consideration for use on humans in bed-rest and space flight studies. Methods for measuring changes in total body nitrogen and in assisting the Johnson Space Center in calibrating a whole body counter for total body potassium measurements were also investigated.

Palmer, H. E.↗
NASA NTRS1974

Outer planet mission guidance and navigation for spinning spacecraft

The orbit determination accuracies, maneuver results, and navigation system specification for spinning Pioneer planetary probe missions are analyzed to aid in determining the feasibility of deploying probes into the atmospheres of the outer planets. Radio-only navigation suffices for a direct Saturn mission and the Jupiter flyby of a Jupiter/Uranus mission. Saturn ephemeris errors (1000 km) plus rigid entry constraints at Uranus result in very high velocity requirements (140 m/sec) on the final legs of the Saturn/Uranus and Jupiter/Uranus missions if only Earth-based tracking is employed. The capabilities of a conceptual V-slit sensor are assessed to supplement radio tracking by star/satellite observations. By processing the optical measurements with a batch filter, entry conditions at Uranus can be controlled to acceptable mission-defined levels (+ or - 3 deg) and the Saturn-Uranus leg velocity requirements can be reduced by a factor of 6 (from 139 to 23 m/sec) if nominal specified accuracies of the sensor can be realized.

Paul, C. K.↗
NASA NTRS1975

Apollo flight crew cardiovascular evaluations

The results of the lower body negative pressure (LBNP) and passive stand tests are presented, and the efficacy of the experimental antihypotensive garments is evaluated. Results of the tests are presented in tabular form. Postflight orthostatic evaluations during the Apollo program indicate that reduction in orthostatic tolerance is a consequence of space flight exposure. Heart rate, the most reliable index, was increased, while systolic and pulse pressures were decreased during immediate postflight evaluations using lower body negative pressure and passive standing as the orthostatic stress. Elevation in resting heart rate was a less frequent finding. There was considerable variability in the magnitude of these changes between individual crewmembers and in the persistence of the changes over subsequent postflight evaluations. Postflight changes in leg volume during LBNP were equal to or less than those seen during preflight baseline evaluations. Body weight, resting calf girth, supine leg volume, and cardiothoracic ratios were all diminished immediately postflight, and return to preflight values was not complete within the postflight testing time frame.

G.W. Hoffler↗
NASA NTRS1976

Device for installing rocket engines

A device for installing rocket engines is reported that is supported at a cant relative to vertical by an axially extensible, tiltable pedestal. A lifting platform supports the rocket engine at its thrust chamber exit, including a mount having a concentric base characterized by a concave bearing surface, a plurality of uniformly spaced legs extended radially from the base, and an annular receiver coaxially aligned with the base and affixed to the distal ends of said legs for receiving the thrust chamber exit. The lifting platform rests on a seat concentrically related to the pedestal and affixed to an extended end portion thereof having a convex bearing surface mated in sliding engagement with the concave bearing surface of the annular base for accommodating a rocking motion of the platform.

George, T. R., Jr.↗
NASA NTRS1976

Catheter tip force transducer for cardiovascular research

A force transducer for measuring dynamic force activity within the heart of a subject essentially consists of a U-shaped beam of low elastic compliance material. Two lines extend from the beams's legs and a long coil spring is attached to the beam. A strain gauge is coupled to one of the beam's legs to sense deflections thereof. The beam with the tines and most of the spring are surrounded by a flexible tube, defining a catheter, which is insertable into a subject's heart through an appropriate artery. The tines are extractable from the catheter for implantation into the myocardium by pushing on the end of the spring which extends beyond the external end of the catheter.

Feldstein, C.↗
NASA NTRS1975

Measurement of auroral Birkeland currents

Results are presented for measurements of the auroral current made with a rocket-borne experiment over Fort Churchill, Canada, during the February-May period in 1968. On the upward leg of the rocket flight there were detected a westward auroral current of 10,000 A near 96 km altitude and two oppositely directed Birkeland currents of about 0.00005 A per sq m at about 160 km altitude. On the downward leg there were revealed a westward filament of current of about 0.0008 A per sq m at about 220 km altitude, two oppositely directed Birkeland sheet currents of about 0.00014 A per sq m at about 230 km altitude, and two oppositely directed Birkeland currents of about 0.00007 A per sq m which fed a westward auroral electrojet of about 0.0010 A per sq m at about 100 km altitude and were associated with a bright rayed arc. A reversal in the Birkeland current system near midnight was also observed. These observations are probably manifestations of the complex nature of small-scale currents associated with complicated auroral forms.

Ifedili, S. O.↗
NASA NTRS1976

Regional measurement of body nitrogen

Studies of methods for determining changes in the muscle mass of arms and legs are described. N-13 measurements were made in phantom and cadaver parts after neutron irradiation. The reproducibility in these measurements was found to be excellent and the radiation dose required to provide sufficient activation was determined. Potassium-40 measurements were made on persons who lost muscle mass due to leg injuries. It appears that K-40 measurements may provide the most accurate and convenient method for determining muscle mass changes.

Palmer, H. E.↗
NASA NTRS1977

Automatic blood pressure measuring system (M091)

The Leg Volume Measuring System is used to measure leg calf girth changes that occur during exposure to lower body negative pressure as a result of pooling of blood and other fluids in the lower extremities.

Source record↗
NASA NTRS1977

Investigate methods for measuring muscle and bone mass changes in astronauts and animals which occur during space flight

Sodium-22 is being used as a tracer for bone mineral metabolism studies. Dogs are being grown from puppies to adulthood on a diet containing a constant level of sodium-22 in order to uniformly tag the entire skeleton with a long lived radionuclide. This study is still in progress and the dogs are still growing. Potassium-40 measurements were made on people, who are replacing muscle mass lost due to leg injuries, in a second study. It appears that potassium-40 measurements provide an accurate and convenient method for determining relative changes in the muscle content of the leg.

Palmer, H. E.↗
NASA NTRS1978

Influence of central venous pressure upon sinus node responses to arterial baroreflex stimulation in man

Measurements were made of sinus node responses to arterial baroreceptor stimulation with phenylephrine injection or neck suction, before and during changes of central venous pressure provoked by lower body negative pressure or leg and lower truck elevation. Variations of central venous pressure between 1.1 and 9.0 mm Hg did not influence arterial baroreflex mediated bradycardia. Baroreflex sinus node responses were augmented by intravenous propranolol, but the level of responses after propranolol was comparable during the control state, lower body negative pressure, and leg and trunk elevation. Sinus node responses to very brief baroreceptor stimuli applied during the transitions of central venous pressure also were comparable in the three states. The authors conclude that physiological variations of central venous pressure do not influence sinus node responses to arterial baroreceptor stimulation in man.

Mark, A. L.↗
NASA NTRS1978

Development of an hypothesis for simulating anti-orthostatic bed rest

The Guyton model, modified by the addition of leg compartments and the effect of the gravity vector, was used to evaluate hypotheses describing leg dehydration and fluid shifts. While the study is not complete, the basic approach was shown to be useful by identifying important mechanisms, identifying systems which need further experimental description and by assisting in the development of a general hypothesis.

Leonard, J. I.↗
NASA NTRS1979

Limb blood flow - Rest and heavy exercise in sitting and supine positions in man

The objectives of the study were twofold: (1) to determine the effect of body position (hydrostatic pressure) on total blood flow in active and passive limbs at rest and after severe exercise; and (2) to further evaluate the impedance technique for measurement of blood flow. To this end, the effect of body position on the redistribution of total blood flow in active (leg) and passive (forearm) limbs during exercise was determined by measuring total limb impedance (blood flow) in five male and one female subjects in sitting and supine positions with a modified Beckman BR-100 rheograph. The results show that, at rest and after exercise, the supine position induces significantly greater flows in the leg but not in the forearm. With severe exercise, blood flows are increased in both passive and active limbs, so that there is probably no net transfer of blood volume from passive to active muscles. The advantages of the impedance technique over other methods are stressed.

Greenleaf, J. E.↗
NASA NTRS1980

Saturn's magnetosphere, rings, and inner satellites

The discovery of the Saturn magnetosphere and its characterization by Pioneer 11 are reported, and findings on the planet's rings and satellites obtained by energetic charged particle measurements within the inner magnetosphere are presented. Bow shock crossings identified by the Pioneer plasma analyzer and magnetometer at distances of 24.1, 23.1 and 20.0 Saturn radii indicate the presence of a magnetosphere with physical dimensions and charged particle populations intermediate between those of the earth and Jupiter, with a scale more similar to that of the earth. Particle angular distributions on the inbound leg of the trajectory are consistent with a dipole magnetic field approximately perpendicular to the planet's equator, while on the outbound leg the distributions indicate the presence of an equatorial current sheet. Charged particle absorption features are detected at the orbits of Dione and Mimas, encompassing the orbits of Tethys and Enceladus, and at 2.534 and 2.343 Saturn radii indicating the presence of satellites of diameters greater than 170 km. Charged particle measurements also confirm the Pioneer division in the rings between 2.292 and 2.336 Saturn radii, a suspected satellite at 2.82 Saturn radii, the presence of the F ring between 2.336 and 2.371 Saturn radii and the outer radius of the A ring at 2.292 Saturn radii.

Van Allen, J. A.↗
NASA NTRS1980

Tolerance of Lower Body Negative Pressure (LBNP) in endurance runners, weightlifters, swimmers and nonathletes

Thirteen endurance runners (R), 12 weightlifters (WL), 12 swimmers (SW) and 10 nonathletes (NA) were tested for their tolerance of lower body negative pressure (LBNP) in consecutive 5 minute stages at -20, -30, -40, -50 and -60 torr. Each subject also performed an exercise test on a bicycle ergometer with progressive workloads to exhaustion to determined aerobic capacity. The R had a much higher aerobic capacity than any of the other groups, but a significantly lower LBNP tolerance. While responses in heart rate and pulse pressure were quite similar in all 4 groups, the rate of increase in leg volume relative to LBNP stress (leg compliance, LC) was considerably greater in R than in the other athletes and NA. The greater LC in R could be attributed not only to a more rapid shift of blood to the lower extremities but also to a greater tendency for edema formation, both contributing to a more rapid loss in effective central blood volume for a given LBNP stress. These results substantiate earlier observations which led to the conclusion that endurance running is not advisable as a training regimen for astronauts.

Source record↗
NASA NTRS1981

Turbine bypass engine: A new supersonic cruise propulsion concept

Engine performance and mission studies were carried out for a single-spool Turbine Bypass Engine concept. Comparisons were made between the TBE, a conventional single-spool turbojet, and the Pratt & Whitney Variable Stream Control Engine. The airplane assumed for the study was a Mach 2.32 commercial supersonic transport. The nominal mission was a 4000-nautical miles total range with a 300-nautical miles subsonic cruise leg. The figure of merit was the minimum takeoff gross weight for the mission. Comparisons of the three engines were also made for the 4000-nautical miles total range with longer subsonic cruise legs.

Franciscus, L. C.↗