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Results for “HIGH THRUST”

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 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Design, fabrication, and operation of dished accelerator grids on a 30-cm ion thruster.

Several closely-spaced dished accelerator grid systems have been fabricated and tested on a 30-cm diameter mercury bombardment thruster and they appear to be a solution to the stringent requirements imposed by the near-term, high-thrust, low specific impulse electric propulsion missions. The grids were simultaneously hydroformed and then simultaneously stress relieved. The ion extraction capability and discharge chamber performance were studied as the total accelerating voltage, the ratio of net-to-total voltage, grid spacing, and dish direction were varied.

Rawlin, V. K.↗
NASA NTRS1972

Analytical solutions of a class of optimum orbit modifications.

A space vehicle in an orbit around a spherical planet is considered. It is proposed to bring the vehicle, by a series of orbital maneuvers, into a final orbit. It is sought to minimize the total characteristic velocity for the maneuver. Since for a high-thrust propulsion system the characteristic velocity provides a direct measure of the fuel consumption, the optimal trajectory considered yields the minimum fuel expenditure. It is assumed that the planet is surrounded by a spherical atmosphere.

Vinh, N. X.↗
NASA NTRS1973

Experimental cold-flow evaluation of a ram air cooled plug nozzle concept for afterburning turbojet engines

A concept for plug nozzles cooled by inlet ram air is presented. Experimental data obtained with a small scale model, 21.59-cm (8.5-in.) diameter, in a static altitude facility demonstrated high thrust performance and excellent pumping characteristics. Tests were made at nozzle pressure ratios simulating supersonic cruise and takeoff conditions. Effect of plug size, outer shroud length, and varying amounts of secondary flow were investigated.

Straight, D. M.↗
NASA NTRS1973

Ballistic mode Mercury orbiter mission opportunity handbook

Significant payloads in Mercury orbit can be achieved through use of high-thrust, chemical propulsion systems on ballistic trajectories. Interplanetary trajectory characteristics are presented, for Venus swingbys to Mercury, were multiple revolutions about the sun are allowed on each leg to provide low energy mission in 1977, 1980, 1985 and 1988. Guidance and navigation results are shown for each opportunity. Additionally, the use of midcourse maneuvers and multiple Venus swingbys are explored as means of further reducing the energy requirements.

Hollenbeck, G. R.↗
NASA NTRS1974

Rotating and positive-displacement pumps for low-thrust rocket engines. Volume 2: Fabrication and testing

Rotating and positive displacement pumps of various types were studied for pumping liquid fluorine for low thrust high performance rocket engines. Included in the analysis were: centrifugal, pitot, Barske, Tesla, drag, gear, vane, axial piston, radial piston, diaphragm and helirotor pump concepts. The centrifugal and gear pumps were carried through detail design and fabrication. After preliminary testing in Freon 12, the centrifugal pump was selected for further testing and development. It was tested in Freon 12 to obtain the hydrodynamic performance. Tests were also conducted in liquid fluorine to demonstrate chemical compatibility.

Csomor, A.↗
NASA NTRS1974

A study of unmanned mission opportunities to comets and asteroids

Several unmanned multiple-target mission opportunities to comets and asteroids were studied. The targets investigated include Grigg-Skjellerup, Giacobini-Zinner, Tuttle-Giacobini-Kresak, Borrelly, Halley, Schaumasse, Geographos, Eros, Icarus, and Toro, and the trajectories consist of purely ballistic flight, except that powered swingbys and deep space burns are employed when necessary. Optimum solar electric rendezvous trajectories to the comets Giacobini-Zinner/85, Borrelly/87, and Temple (2)/83 and /88 employing the 8.67 kw Sert III spacecraft modified for interplanetary flight were also investigated. The problem of optimizing electric propulsion heliocentric trajectories, including the effects of geocentric launch asymptote declination on launch vehicle performance capability, was formulated, and a solution developed using variational calculus techniques. Improvements were made to the HILTOP trajectory optimization computer program. An error analysis of high-thrust maneuvers involving spin-stabilized spacecraft was developed and applied to a synchronous meteorological satellite mission.

Mann, F. I.↗
NASA NTRS1975

Gaseous fuel nuclear reactor research

Gaseous-fuel nuclear reactors are described; their distinguishing feature is the use of fissile fuels in a gaseous or plasma state, thereby breaking the barrier of temperature imposed by solid-fuel elements. This property creates a reactor heat source that may be able to heat the propellant of a rocket engine to 10,000 or 20,000 K. At this temperature level, gas-core reactors would provide the breakthrough in propulsion needed to open the entire solar system to manned and unmanned spacecraft. The possibility of fuel recycling makes possible efficiencies of up to 65% and nuclear safety at reduced cost, as well as high-thrust propulsion capabilities with specific impulse up to 5000 sec.

Schwenk, F. C.↗
NASA NTRS1975

Solar electric geocentric transfer with attitude constraints: Analysis

A time optimal or nearly time optimal trajectory program was developed for solar electric geocentric transfer with or without attitude constraints and with an optional initial high thrust stage. The method of averaging reduces computation time. A nonsingular set of orbital elements is used. The constraints, which are those of one of the SERT-C designs, introduce complexities into the analysis and the solution yields possible discontinuous changes in thrust direction. The power degradation due to VanAllen radiation is modeled analytically. A wide range of solar cell characteristics is assumed. Effects such as oblateness and shadowing are included. The analysis and the results of many example runs are included.

Sackett, L. L.↗
NASA NTRS1975

Design definition study of a lift/cruise fan technology V/STOL airplane: Summary

A two-engine three-fan V/STOL airplane was designed to fulfill naval operational requirements. A multimission airplane was developed from study of specific point designs. Based on the multimission concept, airplanes were designed to demonstrate and develop the technology and operational procedures for this class of aircraft. Use of interconnected variable pitch fans led to a good balance between high thrust with responsive control and efficient thrust at cruise speeds. The airplanes and their characteristics are presented.

Zabinsky, J. M.↗
NASA NTRS1975

Mechanically coupled lift fan propulsion and control for multimission V/STOL aircraft

A two-engine, three-fan V/STOL airplane was designed to fulfill naval operational missions. Use of interconnected variable pitch fans led to a good balance between the requirements for high thrust and responsive control at low speed, and efficient thrust at cruise speeds. Engine-out requirements, integration of propulsion and aerodynamic controls, and the propulsion installation were the major factors influencing the configuration. An airplane with a multimission capability from both vertical and short takeoff was conceived.

Zabinsky, J. M.↗
NASA NTRS1975

Simplified simulation models for control studies of turbojet engines

The essential dynamical characteristics of a simple single spool turbojet engine were determined through simulation of low order system models on an analog computer. An accurate model was studied and system complexity was reduced through various linearizations and approximations. A derivation of a seventh order simplified simulation model is presented with a derivation of an even simpler third order model, and simulation results from each. The control problem studied is one of getting from zero fuel flow equilibrium to a high thrust equilibrium while taking into account surge margin and turbine inlet temperature constraints.

Brennan, T. C.↗
NASA NTRS1980

Flexible sliding seal

Circular seal both slides and flexes to accomodate relative motion between two sealed members. Originally developed for Space Shuttle orbiter, it contains sliding seal to accommodate engine gimbaling and flexible seal that absorbs forward motion at high thrust of engine heat shield relative to airframe. Other possible applications are in support structures of heavy machinery and vehicle engines. Flexible sliding seal is ring about 7 feet in diameter and can withstand temperatures up to 1,600 F.

Wallenhorst, E. L.↗
NASA NTRS1978

Airframe-integrated propulsion system for hypersonic cruise vehicles

The paper describes a new hydrogen-burning airframe-integrated scramjet concept which offers good potential for efficient hypersonic cruise vehicles. The characteristics of the engine which assure good performance are extensive engine-airframe integration, fixed geometry, low cooling, and control of heat release in the supersonic combustor by mixed modes of fuel injection from the combustor entrance. The present paper describes the concept and presents results from inlet tests, direct-connect combustor tests, and tests of two subscale boiler-plate research engines currently underway under conditions which simulate flight at Mach 4 and 7. It is concluded that this engine concept has the potential for high thrust and efficiency, low drag and weight, low cooling requirement, and application to a wide range of vehicle sizes.

Jones, R. A.↗
NASA NTRS1985

Radiation exposure and performance of multiple burn LEO-GEO orbit transfer trajectories

Many potential strategies exist for the transfer of spacecraft from low Earth orbit (LEO) to geosynchronous (GEO) orbit. One strategy has generally been utilized, that being a single impulsive burn at perigee and a GEO insertion burn at apogee. Multiple burn strategies were discussed for orbit transfer vehicles (OTVs) but the transfer times and radiation exposure, particularly for potentially manned missions, were used as arguments against those options. Quantitative results concerning the trip time and radiation encountered by multiple burn orbit transfer missions in order to establish the feasibility of manned missions, the vulnerability of electronics, and the shielding requirements are presented. The performance of these multiple burn missions is quantified in terms of the payload and propellant variances from the minimum energy mission transfer. The missions analyzed varied from one to eight perigee burns and ranged from a high thrust, 1 g acceleration, cryogenic hydrogen-oxygen chemical prpulsion system to a continuous burn, 0.001 g acceleration, hydrogen fueled resistojet propulsion system with a trip time of 60 days.

Gorland, S. H.↗
NASA NTRS1985

Laser propulsion for the orbital transfer mission

America's space activities in the 1990s and beyond will partly consist of missions involving the transportation of cargo from low earth orbit (LEO) to higher orbits or to an escape trajectory. Such missions are to be performed with the aid of an orbit transfer vehicle (OTV). The operation of the OTV can be based on different propulsion concepts. A chemical OTV is characterized by a high thrust and low specific impulse. The result is a short trip time at the cost of large quantities of propellant. On the other hand, low-thrust systems such as electric propulsion units, consume very little propellant, but would have a long trip time. The present paper is concerned with a compromise between these two extremes. The employed propulsion system utilizes laser thermal propulsion, in which a ground or space-based laser is used to beam energy to a thruster on the OTV. The laser light is absorbed by a propellant. The resulting heating of the propellant causes an expansion of the propellant through a nozzle to produce thrust. Details regarding this propulsion concept are discussed, taking into account operational questions and missions.

Frisbee, R. H.↗
NASA NTRS1985

Radiation exposure and performance of multiple burn LEO-GEO orbit transfer trajectories

Many potential strategies exist for the transfer of spacecraft from low Earth orbit (LEO) to geosynchronous (GEO) orbit. One strategy has generally been utilized, that being a single impulsive burn at perigee and a GEO insertion burn at apogee. Multiple burn strategies were discussed for orbit transfer vehicles (OTVs) but the transfer times and radiation exposure, particularly for potentially manned missions, were used as arguments against those options. Quantitative results concerning the trip time and radiation encountered by multiple burn orbit transfer missions in order to establish the feasibility of manned missions, the vulnerability of electronics, and the shielding requirements are presented. The performance of these multiple burn missions is quantified in terms of the payload and propellant variances from the minimum energy mission transfer. The missions analyzed varied from one to eight perigee burns and ranged from a high thrust, 1 g, acceleration, cryogenic hydrogen-oxygen chemical propulsion system for a continuous burn, 0.001 g acceleration, hydrogen, fueled resistojet propulsion system with a trip time of 60 days.

Gorland, S. H.↗
NASA NTRS1985

Analysis of the free-tip rotor wind-tunnel test results

The results from a wind tunnel test of a small scale free-tip rotor are analyzed. The free-tip rotor has blade tips that are free to weathervane into the tip's relative wind, thus producing a more uniform lift around the azimuth. The free-tip assembly, which includes the controller, functioned flawlessly throughout the test. In a test of the free-tip's response after passing through a vertical air jet, the tip pitched freely and in a controlled manner. Analysis of the tip's response characteristics showed the free-tip system's damped natural frequency to be 5.2 per rev. Tip pitch angle responses to the local airstream are presented for an advance-ratio range of 0.1 to 0.397 and for a solidity weighted rotor lift coefficient range of 0.038 to 0.092. Harmonic analysis of the responses showed a dominance by the first harmonic. As a result of the tip being free, forward flight power requirements were reduced by 8% or more. More power reduction was recorded for high thrust conditions. In addition to the power reduction, flatwise blade bending moments were reduced by as much as 30% at the inboard blade stations.

Stroub, Robert H.↗