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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 1,621 records · Page 90

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NASA NTRS1984

A high energy stage for the National Space Transportation System

The Shuttle/Centaur is an expendable hydrogen/oxygen cryogenic upper stage for use with the National Space Transportation System. It is a modification of the existing Atlas/Centaur which was used by NASA since 1966 to launch interplanetary and earth orbital payloads for numerous organizations. Two configurations of the Shuttle/Centaur are being developed. Vehicle capability includes placing approximately 4500 kg (10,000 lb) in geostationary orbit, and initial applications will be for the interplanetary Galileo and Ulysses Missions in 1986. The Shuttle/Centaur development program is discussed, the configurations and performance are described, and the unique integration and operations requirements related to the Shuttle are indicated. Design changes to the current Atlas/Centaur required for Shuttle operation are described here, and include those related to Orbiter cargo bay dimensions, environment, and safety considerations.

Stofan, A. J.↗

NASA NTRS1984

Commercial launch vehicles and upper stages

Since the beginning of the space age in October 1957, a family of expendable launch vehicles, capable of launching a wide range of payloads, was developed along with the Space Shuttle and a number of upper stages. A brief description is presented of selected orbits which have proved to be most useful for initial or conceptual understanding of space operations, taking into account direct injection and Hohman transfers, and synchronous and sun-synchronous orbits. Early American boosters are discussed along with current expendable launch vehicles, giving attention to the Vanguard, Redstone and Juno, Saturn 1B and Saturn V, Scout, the Atlas booster, Atlas Centaur, Delta, Titan IIIC, and Ariane. Details regarding the Space Shuttle are considered along with PAM-D, PAM-A, PAM-DII, TOS, IUS, Centaur-G, and Syncom-IV and Intelsat-VI.

Mahon, J.↗

NASA NTRS1985

Two-stage models for lunar and terrestrial anorthosites Petrogenesis without a magma ocean

The most popular model of early lunar differentiation is that of a globe-encircling magma ocean tens, if not hundreds, of kilometers deep which produced a floating anorthositic crust and a complementary plagioclase-depleted interior during solidification. Shirley (1983) attempted to show a process by which some of the oldest rocks, lunar ferroan anorthosites (LFA), might have formed from a partially molten 'magma ocean'. The present investigation is concerned with a process by which ferroan anorthosites might have formed without a magma ocean. Attention is given to the magma ocean hypothesis, a hypothesis proposed by Wetherill (1975) regarding a petrogenesis without a magma ocean, two-stage lunar anorthosites, and terrestrial anorthosites.

Longhi, J.↗

NASA NTRS1982

Computer program for prediction of fuel consumption statistical data for an upper stage three-axes stabilized on-off control system

A FORTRAN coded computer program and method to predict the reaction control fuel consumption statistics for a three axis stabilized rocket vehicle upper stage is described. A Monte Carlo approach is used which is more efficient by using closed form estimates of impulses. The effects of rocket motor thrust misalignment, static unbalance, aerodynamic disturbances, and deviations in trajectory, mass properties and control system characteristics are included. This routine can be applied to many types of on-off reaction controlled vehicles. The pseudorandom number generation and statistical analyses subroutines including the output histograms can be used for other Monte Carlo analyses problems.

Source record↗

NASA NTRS1982

Computer program for post-flight analysis of rigid body moments acting on a launch vehicle first stage

A FORTRAN coded computer program and method for evaluation of the rigid body disturbing moments for a launch vehicle first stage based on post-flight measurements is described. The technique is a straightforward deterministic approach. Residual moments are computed to satisfy the equations of motion. Residuals are expressed in terms of altered vehicle characteristics; the aerodynamic coefficients, thrust misalignment, and control effectiveness. This method was used on the Scout launch vehicle and uncovered several significant differences between flight data and wind tunnel data. The computer program is written in FORTRAN IV for a CDC CYBER 173 computer system.

Knauber, R. N.↗

NASA NTRS1986

Thrust vectoring for single-stage-to-orbit, horizontal takeoff, horizontal landing, space vehicles

The preliminary design of a horizontal takeoff, horizontal landing, single-stage-to-orbit, rocket-powered space vehicle was performed. The purpose was to examine technology requirements for future small payload launch vehicles. The distinguishing aspect of the design was the utilization of thrust vectoring to provide half of the lift at takeoff. The inclusion of a canard was necessary to provide additional lift at takeoff and to balance the moments produced with thrust vectoring. A weights estimation, an aerodynamic assessment, a trajectory analysis, and a gear weight analysis were performed. The takeoff weight of the resulting vehicle was approximately 1.26 million pounds, based on advanced technology structures and subsystems. The vehicle was designed to deliver a 5000-pound payload to a polar orbit.

Cunningham, M. J.↗

NASA NTRS1986

Turbine-stage heat transfer - Comparison of short-duration measurements with state-of-the-art predictions

Comparisons are made between calculated and measured heat-transfer distributions on the midspan locations of the stators and rotors of two turbine stages. The agreement is generally good, except in regions near the leading edge, and is better for blading of higher aspect ratio. It is suggested that the discrepancies near the leading edge are caused by free-stream turbulence, and attempts to improve the modeling of this factor show improved agreement.

Rae, W. J.↗

NASA NTRS1986

Heat-flux measurements for the rotor of a full-stage turbine. I - Time-averaged results

Blade measurements of time-averaged flux distribution are obtained with and without gas injection for a full-stage rotating turbine. Results are presented along the blade in the flow direction at 10, 50, and 90 percent span locations for both the pressure and suction surfaces; enough measurements were obtained to present spanwise distributions as well. The results suggest that the suction surface laminar flat plate prediction is in reasonable agreement with the data from the stagnation point up to about 10 percent of the wetted distance. The influence of upstream nozzle guide vane injection is to significantly increase the local blade heat flux in the immediate vicinity of the leading edge.

Dunn, M. G.↗

NASA NTRS1986

Heat-flux measurements for the rotor of a full-stage turbine. II - Description of analysis technique and typical time-resolved measurements

An analytical technique for obtaining the time-resolved heat flux of a turbine blade is applied to the case of a TFE 731-2 hp full-stage rotating turbine. In order to obtain the heat flux values from the thin film gage temperature histories, a finite difference procedure is used to solve the heat equation with variable thermal properties. After setting out the data acquisition and analysis procedures, their application is illustrated for three midspan locations on the blade and operation at the design flow function. Results demonstrate that the magnitude of the heat flux fluctuation due to vane-balde interaction is large by comparison to the time-averaged heat flux at all investigated locations; FFT of a portion of the heat flux record illustrates that the dominant frequencies occur at the wake-cutting frequency and its harmonics.

Dunn, M. G.↗

NASA NTRS1987

Effect of Gimbal friction modeling technique on control stability and performance for Centaur upper-stage

The powered-phase autopilot for the Centaur upper stage rocket uses an autopilot forward loop gain scheduler that decreases the proportional gain as propellant mass is depleted. Nonlinear time response simulation studies revealed that Centaur vehicles with low-gain autopilots would have large attitude error limit cycles. These limit cycles were due to the assumed presence of Coulomb friction in the engine gimbals. This situation could be corrected through the use of an harmonic dither, programmed into the on-board digital computer and added to the engine command signal. This would introduce impending motion to the engines, allowing control of the engines even under small commands. Control authority was found to be restored when dither was used. A concern arose that the Centaur could be unacceptably excited at resonances near the dither frequency, if the dither amplitude was to be chosen on the basis of friction level present, a test was conducted to measure this level. Dither characteristics were to be based on the test results. The test results showed that the gimbal friction characteristic was actually hysteretic rather than the assumed Coulomb friction. The simulation results showed that, using this new model of gimbal friction, dither would no longer be necessary.

Graham, Ronald E.↗

NASA NTRS1986

Uprated OMS engine for upper stage propulsion

The results of a pre-development component demonstration program on the use of a gas generator-driven turbopump that increases the Space Shuttle's Orbital Maneuvering Engine (OME) operating pressure are given. Tests and analysis confirm the the capability of the concept to meet or exceed performance and life requirements. Storable propellant upper stage concepts are also discussed.

Boyd, William C.↗

NASA NTRS1986

Mutual downwash interference effects on the normal force and roll driving coefficients of multi-stage rockets

For several years, the TAD2 computer program has been used to calculate the aerodynamic properties of sounding rockets. This program was limited, however, in that a maximum of two fin sets could be accommodated analytically. In addition, the roll moment coefficients did not consider downwash effects. Techniques are developed and equations derived for the expansion of capability to include three fin sets. The effects of downwash on the roll moment coefficients are also treated analytically for two and three stage rockets.

Ward, P. R.↗

NASA NTRS1986

Dislocation mechanism based model for stage II fatigue crack propagation rate

Repeated plastic deformation, which of course depends on dislocation mechanism, at or near the crack tip leads to the fatigue crack propagation. By involving the theory of thermally activated flow and the cumulative plastic strain criterion, an effort is made here to model the stage II fatigue crack propagation rate in terms of the dislocation mechanism. The model, therefore, provides capability to ascertain: (1) the dislocation mechanism (and hence the near crack tip microstructures) assisting the crack growth, (2) the relative resistance of dislocation mechanisms to the crack growth, and (3) the fracture surface characteristics and its interpretation in terms of the dislocation mechanism. The local microstructure predicted for the room temperature crack growth in copper by this model is in good agreement with the experimental results taken from the literature. With regard to the relative stability of such dislocation mechanisms as the cross-slip and the dislocation intersection, the model suggests an enhancement of crack growth rate with an ease of cross-slip which in general promotes dislocation cell formation and is common in material which has high stacking fault energy (produces wavy slips). Cross-slip apparently enhances crack growth rate by promoting slip irreversibility and fracture surface brittleness to a greater degree.

Mazumdar, P. K.↗

NASA NTRS1986

Performance studies on an axial flow compressor stage

A low-speed, medium loaded axial flow compressor stage is studied experimentally and theoretically. The flow compressor facility, composed of an inlet guide vane row, a rotor blade row, and a stator blade row, and the principles of the streamline curvature method (SCM) and the Douglas-Neumann cascade program are described. The radial distribution of the flow properties, the rotor blade static pressure distribution, and the lift coefficient and relative flow angle derived experimentally and theoretically are compared. It is determined that there is good correlation between the experimental flow properties and the SCM data, the Douglas-Neumann cascade program and experimental rotor blade static pressure data, and the experimental and theoretical lift coefficients only in the midspan region. Modifications to the SCM and the Douglas-Neumann cascade program in order to improve their accuracy are discussed.

Sitaram, N.↗

NASA NTRS1987

From earth to orbit in a single stage

The National Aerospace Plane (NASP) program's preliminary analyses indicate that the ability to reach orbit is governed by average thrust/drag, average propulsion efficiency, and the ratio of takeoff fuel weight to total takeoff weight; examinations of each of the governing parameters have in turn pointed to the technology development efforts that must be undertaken for the realization of such a single-stage-to-orbit airbreathing vehicle. The key to the achievement of high thrust/drag, in particular, is the integration of engine intake compression and exhaust expansion functions with the airframe. The portion of the vehicle cross-sectional area thus employed in leading the airstream into the engine inlet should be as close to 100 percent as possible.

Jones, Robert A.↗

NASA NTRS1987

Effect of gimbal friction modelling technique on control stability and performance for Centaur upper stage

Graham, Ronald E.↗

NASA NTRS1988

Computer Program Predicts Turbine-Stage Performance

MTSBL updated version of flow-analysis programs MERIDL and TSONIC coupled to boundary-layer program BLAYER. Method uses quasi-three-dimensional, inviscid, stream-function flow analysis iteratively coupled to calculated losses so changes in losses result in changes in flow distribution. Manner effects both configuration on flow distribution and flow distribution on losses taken into account in prediction of performance of stage. Written in FORTRAN IV.

Boyle, Robert J.↗

NASA NTRS1988

Stabilizing Silicon-Ribbon Growth At Early Stages

Device mechanically stabilizes buttons from which silicon ribbons grown by dendritic-web process. Eliminates tendency for button to tip and interrupt pull because of asymmetry. Silicon seed hangs from holder through stabilizing tube. While button growing, tube elevated above melt surface. When ready for pulling of ribbon, tube comes to rest on button and prevents tipping. Large button used. Even if button assumes highly-asymmetrical weight distrubtion in early stages of growth, little danger of tipping and breakage of nascent ribbon.

Henry, Paul K.↗