Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Staging”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,477 records · Page 82
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Two-Stage Fan I: Aerodynamic and Mechanical Design

A two-stage, highly-loaded fan was designed to deliver an overall pressure ratio of 2.8 with an adiabatic efficiency of 83.9 percent. At the first rotor inlet, design flow per unit annulus area is 42 lbm/sec/sq ft (205 kg/sec/sq m), hub/tip ratio is 0.4 with a tip diameter of 31 inches (0.787 m), and design tip speed is 1450 ft/sec (441.96 m/sec). Other features include use of multiple-circular-arc airfoils, resettable stators, and split casings over the rotor tip sections for casing treatment tests.

Messenger, H. E.↗
NASA NTRS1972

Optimal ascent trajectories of a two stage space shuttle vehicle

The effects of aerodynamic lift on the performance capability of a two stage space shuttle are discussed. The performance program uses three degrees of freedom to describe the trajectory of a point mass moving over the rotating earth. Two cases of ascent modes are described and compared. It is concluded that significant improvements in performance through the use of lift appear to be configuration dependent, and for this reason cannot be generalized for all spacecraft configurations.

Wilson, R. A.↗
NASA NTRS1972

Preliminary performance of a low loading high tip speed fan stage

Limited data indicates the feasibility of designing fan stages for operation with weak oblique shocks in the rotor blade tip region. A 1600 ft/sec rotor tip speed fan indicated an overall efficiency of 0.846 at a pressure ratio of 1.51 even though the rotor blades had incurred damage in the leading edge tip region prior to obtaining the design speed performance. After the test it was observed that a number of the rotor blade mid-span dampers had failed, subsequently damaging a number of rotor blades in the leading edge tip region.

Bailey, E. E.↗
NASA NTRS1972

Coupling between structure and liquids in a parallel stage space shuttle design

A study was conducted to determine the influence of liquid propellants on the dynamic loads for space shuttle vehicles. A parallel-stage configuration model was designed and tested to determine the influence of liquid propellants on coupled natural modes. A forty degree-of-freedom analytical model was also developed for predicting these modes. Currently available analytical models were used to represent the liquid contributions, even though coupled longitudinal and lateral motions are present in such a complex structure. Agreement between the results was found in the lower few modes.

Kana, D. D.↗
NASA NTRS1972

High-loading, 1800 ft/sec tip speed transonic compressor fan stage. 1: Aerodynamic and mechanical design

A single stage fan with a tip speed of 1800 ft/sec (548.6m/sec) and hub/tip ratio of 0.5 was designed to produce a pressure ratio of 2.285:1 with an adiabatic efficiency of 84.0%. The design flow per inlet annulus area is 38.7 lbm/sq ft-sec (188.9KG/sqm-sec). Rotor blades have modified multiple-circular-arc and precompression airfoil sections. The stator vanes have multiple-circular-arc airfoil sections.

Morris, A. L.↗
NASA NTRS1971

Chimpanzee sleep stages.

The electroencephalogram and electro-oculogram of two unrestrained juvenile chimpanzees was monitored for 7 consecutive nights using telemetry methods. Of the sleeping time, 23% was spent in the rapid eye movement of REM type of sleep, whereas 8, 4, 15, and 10% were spent in non-REM stages 1 through 4, respectively. Seven to nine periods of REM sleep occurred per night. The average time from the beginning of one REM period to the beginning of the next was approximately 85 min.

Freemon, F. R.↗
NASA NTRS1972

A ten-stage electrostatic depressed collector for improving klystron efficiency.

A ten-stage electrostatic depressed collector, designed with the aid of an analog computer, was tested on a 1-kW CW 750-MHz klystron. Excellent correlation was achieved between computed and measured performance under varying conditions of RF drive. At full RF power output approximately 60 per cent of the spent beam energy was recovered by use of the depressed collector. The net power conversion efficiency of the tube was raised from its undepressed value of 54.3 per cent to approximately 70.9 per cent. At one-half full power output, a collector efficiency of 70 per cent was measured. At zero RF power output collector efficiency was 80 per cent. To achieve these results it was necessary to install a small focusing coil between the final drift tube and the collector. No spurious oscillations or instabilities were detected when collector depression was employed, nor was electron backstreaming increased significantly. Intentional short circuiting of adjacent collector electrode pairs was shown to cause only minor degradation in collector performance.

Neugebauer, W.↗
NASA NTRS1972

Coupling between structure and liquid propellants in a parallel-stage space shuttle design.

A study was conducted to determine the influence of liquid propellants on the dynamic loads for space shuttle vehicles. A parallel-stage configuration model was designed and tested to determine the influence of liquid propellants on coupled natural modes. A forty degree-of-freedom analytical model was also developed for predicting these modes. Currently available analytical models were used to represent the liquid contributions, even though coupled longitudinal and lateral motions are present in such a complex structure. Agreement between the results was found in the lower few modes.

Kana, D. D.↗
NASA NTRS1972

A common solar electric upper stage for multi-mission applications.

The concept of using a solar-electric upper stage for multi-mission application is practical, economical, and versatile approach to space expMission capabilities include a Mercury orbiter, asteroid and comet rendezvous, a solar probe, and extra-ecliptic probe, and outer planet flybys and orbiters. The 17.5-kw vehicle has an injected mass of 1500 to 2500 kg and carries up to 500 kg of attached or separable payload packages. Mission characteristics, performance tradeoffs and a concepegn configuration are presented, and program plans, cost estimates and advanced technology requirements are identified.

Meissinger, H. F.↗
NASA NTRS1972

One-stage model for color conversion.

Description of a one-stage approximation to the color-conversion model of Richards and Parks (1971). The modified model proposes three channels for color vision, each with different center-surround sensitivities. In its strongest form, the model predicts that the gain-setting control that alters the sensitivities of each channel is solely a function of achromatic contrast.

Richards, W.↗
NASA NTRS1972

Investigation of the aluminium-aluminium oxide reversible transformation as observed by hot stage electron microscopy.

Thin foils of high purity aluminium and an Al-Al2O3 SAP type of alloy were oxidised in a specially designed hot stage specimen chamber in an electron microscope. Below 450 C, amorphous aluminium oxide formed on the foil surface and was first detectable at foil edges, holes, and pits. Islands of aluminium then nucleated in this amorphous oxide. The aluminium islands displayed either a lateral growth with eventual coalescence with other islands, or a reoxidation process which caused the islands to disappear. The aluminium island formation was determined to be related to the presence of the electron beam. A mechanism based upon electron charging due to the electron beam was proposed to explain the nucleation, growth, coalescence, disappearance, and geometry of the aluminium islands.

Grove, C. A.↗
NASA NTRS1972

Plume impingement force during tandem stage separation at high altitudes.

An analytical technique is described for predicting the plume impingement force during tandem stage separation, including the reversed flow effects. Comparisons of predicted and measured impingement forces for various geometric and flow conditions show good correlation between the analytical technique and experimental data.

Su, M. W.↗
NASA NTRS1972

Wind-tunnel tests of a single stage to orbit space shuttle at Mach numbers of 2.60, 3.85, and 4.64

Wind tunnel tests were conducted to determine the static aerodynamic characteristics of a single-stage-to-orbit space shuttle model at Mach numbers of 2.60, 3.85, and 4.64. Test parameters included various payloads for the launch configurations and various corner radii for the entry configurations. The test results for the launch configurations generally indicated that a decrease in payload size resulted in a marked increase in axial force. Decreasing the corner radii of the entry configuration led to large increases in axial force. The results also indicated that the presence of an engine door on the entry configuration caused a measurable positive increment in pitching moment. Changing the entry configuration afterbody geometry from a biconic shape to a conic shape increased the normal-force and stability level.

Graves, E. B.↗
NASA NTRS1971

Expendable second stage reusable space shuttle booster. Volume 1: Executive summary

The development of an expendable second stage for use with a reusable space shuttle booster is discussed. The configuration of a low-cost, reusable multipurpose space transportation system for the 1980 time period is presented. A system capable of economically placing payloads in earth orbit which are larger and heavier than can be carried in the shuttle orbiter cargo bay is defined. The ESS/reusable shuttle system is complementary to the space shuttle system and provides mission flexibility to permit economical expansion of the overall space program.

Source record↗
NASA NTRS1971

Expendable second stage reusable space shuttle booster. Volume 12: Design data book

The general and design criteria for the expendable second stage of the reusable space shuttle booster are presented. The subjects discussed are: (1) trajectory development, (2) aerodynamic heating on basic payloads, (3) vehicle configurations, trajectory, and heat regimes, (4) orbit maneuvering system, (5) structural analysis, and (6) booster loads and structural sizing.

Source record↗