Showing papers on "Propulsion published in 1987"

Aircraft engine design

Abstract: Keywords: thermodynamique ; propulsion ; conception ; turboreacteurs ; hors design ; analyse ; cycles Note: avec disquette Reference Record created on 2005-11-18, modified on 2016-08-08

Helicopter rotor speed changing transmission

Abstract: A helicopter has two engines adapted to drive a main sustaining rotor and a plurality of auxiliary propulsion means through a transmission system that is selectively operable to vary the relative speeds of rotation of the sustaining rotor and the auxiliary propulsion means depending upon operating conditions.

A comparison of fusion/antiproton propulsion systems for interplanetary travel

Abstract: Rocket propulsion driven by either thermonuclear fusion or antiproton annihilation reactions is an attractive concept because of the large amount of energy released from a small amount of fuel. Charged particles produced in both reactions can be manipulated electromagnetically making high thrust/high specific impulse (7sp) operation possible. A comparison of the physics, engineering, and costs issues involved in using these advanced nuclear fuels is presented. Because of the unstable nature of the antiproton-proton (pp) reaction products, annihilation energy must be converted to propulsive energy quickly. Antimatter thermal rockets based on solid and liquid fission core engine designs offer the potential for high thrust (~10 Ibf)/ high 7sp (up to -2000 s) operation and 6 month round trip missions to Mars. The coupling of annihilation energy into a high-temperature gaseous or plasma working fluid appears more difficult, however, and requires the use of heavily shielded superconducting coils and space radiators for dissipating unused gamma ray power. By contrast, low-neutron-producing advanced fusion fuels (Cat-DD or DHe) produce mainly stable hydrogen and helium reaction products which thermalize quickly in the bulk plasma. The energetic plasma can be exhausted directly at high 7sp (. 10s) or mixed with additional hydrogen for thrust augmentation. Magnetic ftision rockets with specific powers (ocp) in the range of 2.5 to 10 kW/kg and 7sp in the range of 20,000-50,000 s could enable round trip missions to Jupiter in less than a year. Inertial fusion rockets with ocp > 100 kW/kg and 7sp > 10s could perform round trip missions to Pluto in less than 2 years. On the basis of preliminary fuel cost and mission analyses, fusion systems appear to outperform the antimatter engines for difficult interplanetary missions. *Senior Research Scientist, Advanced Nuclear Propulsion; currently, NASA Lewis Research Center, Cleveland, Ohio; Senior Member of AIAA. Copyright ©1987 by Aerojet TechSystcms Co. Published by the American Institute of Aeronautics Astronautics, Inc. with permission. 89 Purchased from American Institute of Aeronautics and Astronautics

Dual mode diesel electric power system for vehicles

Abstract: A diesel-electric propulsion and operating system may be used alone or in combination with another power supply. It has particular application to a dual mode, trolley and diesel bus. The diesel engine is controlled to supply only that power demanded by the electrical systems, including the traction motor, and to operate on a fixed power curve. This provides an optimized efficiency. Other novel characteristics include a two-speed drive axle limited to the mode selector, a backup hydraulic motor and pump, a dual mode passenger compartment tester, and a diesel engine pretester.

An application of the weis-fogh mechanism to ship propulsion

Abstract: A mechanism of hovering flight of small insects which is called the Weis-Fogh mechanism is applied to ship propulsion. A model of the propulsion mechanism is proposed, which is based on a two-dimensional model of the Weis-Fogh mechanism and consists of one or two wings in a square channel. The dynamic properties of the model are studied experimentally, and the propulsive efficiency obtained is as high as 75 percent. A model ship equipped with this propulsion mechanism was made, and working tests performed. The model ship sailed very smoothly and the moving speed of the wings was small compared with the advancing speed of the ship.

Marine propelling apparatus

Abstract: This disclosure relates to a marine propulsion system including a double propeller. To obtain a forward thrust, the two propellers are driven in opposite directions while producing forward propulsion forces. To obtain a rearward thrust, only one propeller is driven in the direction to produce a rearward force. The two propellers are attached to coaxial inner and outer horizontal shafts. A single vertical shaft is coupled by bevel gears to the shafts, and movable clutches couple the driving force to the horizontal shafts.

Wave powered propulsion system for watercraft

Abstract: A watercraft is provided with a propulsion system having a hydraulic power plant driving a propeller through a transmission. The power to operate hydraulic pumps in the power plant is derived from wave motion by buoyant members connected to the power plant by outrigger arms. Undulation of the waves is converted to fluid pressure by the vertical movement of the buoyant members reciprocating pistons in the hydraulic pumps. Pressurized fluid is applied to a fluid motor driving the transmission. A steering assembly is operatively associated with one of the buoyant members.

Results of NASA's Energy Efficient Engine Program

Abstract: The major activity undertaken in the NASA Energy Efficient Engine Program has been completed. This paper reports on the progress made toward achieving the program goal of developing advanced technology to significantly reduce fuel consumption and operating costs of future subsonic transport-type propulsion systems. An additional goal was that the advanced concepts be compatible with future environmental regulations. Along with the results obtained, a brief overview of the design details of both the General Electric and Pratt and Whitney energy efficient engines and the overall program scope are presented. Overall, this program has been highly successful; the technology developed during its course is, and will continue to be, effectively employed in both current and future advance transport aircraft engine designs.

Aircraft automatic flight control system with model inversion

Abstract: A simulator study was conducted to verify the advantages of a Newton-Raphson model-inversion technique as a design basis for an automatic trajectory control system in an aircraft with highly nonlinear characteristics. The simulation employed a detailed mathematical model of the aerodynamic and propulsion system performance characteristics of a vertical-attitude takeoff and landing tactical aircraft. The results obtained confirm satisfactory control system performance over a large portion of the flight envelope. System response to wind gusts was satisfactory for various plausible combinations of wind magnitude and direction.

Microwave-powered aircraft

Abstract: A microwave-powered aircraft has lifting surfaces for exerting lifting forces on the aircraft in response to the propulsion of the aircraft and a rectenna array for receiving and rectifying microwave energy transmitted to the aircraft from a location remote from the aircraft. An electric motor for driving a propeller is energized by microwave energy received by the rectenna array, which is provided in a body at the underside of the aircraft. The body has its major dimensions extending horizontally and is relatively shallow with a periphery which is vertically curved so as to reduce turbulence in the airstream over the body during flight. The body is separate from the lifting surfaces and shaped to at least substantially avoid the generation of lifting forces by the body.

Drive system for track-laying vehicles

Abstract: A drive system for track-laying vehicles utilizes a pair of separate and independent motors (M1, M2) to drive a multi-range, infinitely variable steering transmission pursuant to developing two track driving transmission outputs. The transmission includes a pair of interconnected output planetary gears sets (20, 20) which are separately driven by the two motors to develop first range forward and reverse propulsion and steering at the transmission outputs (32, 34) as sun to carrier reductions. The transmission is shiftable into a second, higher speed range, wherein the two motor outputs are combined in one (30) of the output planetary gear sets constructed to produce second range forward propulsion and steering power, as well as steer canceallation at the transmission outputs.

Field Emission Electric Propulsion: Emission Site Distribution of Slit Emitters

Abstract: Field emission electric propulsion is the technological application of the principle of liquid metal ion sources as thrusters in electric space propulsion. Research work sponsored by the European Space Agency (ESA) on a slit-type field ion thruster is reported and discussed. The most significant new features of its emission performance are as follows: For the first time, a slit emitter with a closed propellant supply system was fired in any optional direction, requiring, in principle, no gravitational forces. Quantitative data relating the constituents of the residual gas atmosphere to the wetting behavior of the liquid metal propellant and the emission site distribution were obtained. A homogeneous distribution of equally spaced emission sites was observed; the measured spacing is in good agreement with a simple hydrostatic model of wavelike instabilities on electrically stressed surfaces of fluids.

The NASA Electric Propulsion Program

Abstract: The NASA OAST Propulsion, Power and Energy Division supports electric propulsion for a broad class of missions. Concepts with potential to significantly benefit or enable space exploration and exploitation are identified and advanced toward applications in the near to far term. Recent program progress in mission/system analyses and in electrothermal, ion, and electromagnetic technologies are summarized.

Orbital system including a tethered satellite

Abstract: An orbital system comprising a main platform and a satellite tethered by a long cable which may be used to perform measurements in the upper layers of the atmosphere. Air drag on the satellite causes the orbit parameters to decay, and means of regenerating the orbit parameters by electro-dynamic propulsion are provided. The cable is electrically conductive and, in a propulsion configuration, a current is passed through the cable to provide electro-geomagnetic thrust. Winches enable the cable to be wound in and out, either constantly, or in synchronization with angular oscillation of the system to damp the oscillations. On an east-bound orbit, the satellite may be transferred from a measurement configuration, where it is below the platform, to a propulsion configuration, where it is above the platform. This is achieved by winding the cable in synchronism to excite the oscillations until it swings above the platform and then to damp the oscillations so that it remains above the platform. The opposite transfer is obtained symmetrically.

Trimming device for marine propulsion apparatus

Abstract: A trimming device for a marine propulsion apparatus wherein the operator may effect manual trim-up or trim-down adjustment to predetermined positions. In addition, a device is incorporated for automatically trimming down the outboard drive when the speed of the propulsion unit falls below a predetermined value.

An outlook on hypersonic flight

Abstract: The NASA Langley Research Center has been active in hypersonic research since the 1950's. A central part of the research conducted since 1970 has focussed on high speed airbreathing propulsion - in particular on supersonic combustion ramjets or scramjets. Renewed interest in very high speed flight in the 1980's has led to some expansion and broadening of this activity with particular attention to extreme speeds approaching orbital velocity. The purpose of this paper is to review the impact of extreme speed on the potential of scramjet propulsion. The implications of system performance objectives on propulsion and vehicle requirements will be explored. Some pertinent results from past studies will be summarized along with examples of engineering design and detailed analysis methods applied to typical scramjet components. Critical areas where fundamental knowledge is lacking will be highlighted, and some proposed studies to deal with these uncertainties will be outlined.

Basic processes of plasma propulsion

Abstract: : The report resumes the theoretical and analytical works, which accompanies the experimental development work on plasma thrusters done at the Institute of Space Systems, University of Stuttgart

Propulsion system for a buoyant vehicle

Abstract: The invention is a propulsion system for a buoyant aircraft. The invention comprises a gas storage container filled with a lighter-than-air gas and having outer walls of which at least a portion thereof are flexible. A system is provided to move the flexible portions of the walls alternately inward and outward varying the internal volume of the container, thus, varying the buoyancy of the aircraft and providing a propulsive force. Air foils mounted on the aircraft are adapted to provide trimming forces as the aircraft descends and ascends.

Modification to the Langley 8-Foot High Temperature Tunnel for hypersonic propulsion testing

Abstract: Described are the modifications currently under way to the Langley 8-Foot High Temperature Tunnel to produce a new, unique national resource for testing hypersonic air-breathing propulsion systems. The current tunnel, which has been used for aerothermal loads and structures research since its inception, is being modified with the addition of a LOX system to bring the oxygen content of the test medium up to that of air, the addition of alternate Mach number capability (4 and 5) to augment the current M=7 capability, improvements to the tunnel hardware to reduce maintenance downtime, the addition of a hydrogen system to allow the testing of hydrogen powered engines, and a new data system to increase both the quantity and quality of the data obtained.

Fluid propulsion engine with flow exit control device

Abstract: A common mechanism enables both throat area change in either a fan duct or an exhaust gas duct and flow deflection at the nozzle of the duct.

High-performance missile synthesis with trajectory and propulsion system optimization

Abstract: Synthesis of a high-performance two-pulse-motor-propelled missile by simultaneous optimization of trajectory and propulsion systems in two operational scenarios is described. This work employed a quasiNewton parameter optimization scheme with penalty functions to meet terminal and path constraints. The trajectory control variables were parameterized using piecewise linear open-loop commands and piecewise constant linear feedback gains. The pulse motor parameters optimized were pulse split, average thrust levels, neutrality factors, pulse burn times, and the interpiilse delay. Optimization of the rocket motor thrust time curve in addition to the trajectory increased the range by up to 11% when compared with the trajectories optimized with originally specified rocket motor propulsion data.

Motorised propulsion unit for a motor vehicle arranged transversely

Abstract: The motorised propulsion unit is arranged transversely and includes an output shaft 1 connected coaxially, on the one hand, by means of a differential, to two axially aligned transmission shafts 3, 4 carried by two bearings P1, P2 secured to the unit and respectively coupled to the two wheels of a first set of wheels of the vehicle, and, on the other hand, to transmission means particularly for driving the wheels of a second set of wheels. The motorised propulsion unit is characterised in that the said transmission means are formed by a hydrostatic pump H which is located between the two bearings P1, P2 and whose shaft 16 is tubular, traversed by one 3 of the transmission shafts and capable of being coupled to the output shaft 1. The invention may be used for driving two sets of wheels.

The supersonic through-flow turbofan for high Mach propulsion

Abstract: A study was done to evaluate the potential improvements in aircraft turbine engine performance by incorporating unique supersonic through-flow fans Engine performance, weight, and mission studies were carried out for conventional turbofan engines using supersonic through-flow fans A Mach 3 commercial transport mission was considered The advantages of the supersonic fan engines were evaluated in terms of mission range comparisons between the supersonic fan engines and conventional engines The installed specific fuel consumption of the supersonic fan engines was 12 percent better than the conventional engines and the installed weight was projected to be 25 percent lighter For a takeoff gross weight of 550,000 lbs, the aircraft powered by supersonic fan engines had a range capability of 6600 nm compared to 5300 nm (a 25% improvement) for conventional engines

Nuclear powered Mars cargo transport mission utilizing advanced ion propulsion

Abstract: Nuclear-powered ion propulsion technology was combined with detailed trajectory analysis to determine propulsion system and trajectory options for an unmanned cargo mission to Mars in support of manned Mars missions. A total of 96 mission scenarios were identified by combining two power levels, two propellants, four values of specific impulse per propellant, three starting altitudes, and two starting velocities. Sixty of these scenarios were selected for a detailed trajectory analysis; a complete propulsion system study was then conducted for 20 of these trajectories. Trip times ranged from 344 days for a xenon propulsion system operating at 300 kW total power and starting from lunar orbit with escape velocity, to 770 days for an argon propulsion system operating at 300 kW total power and starting from nuclear start orbit with circular velocity. Trip times for the 3 MW cases studied ranged from 356 to 413 days. Payload masses ranged from 5700 to 12,300 kg for the 300 kW power level, and from 72,200 to 81,500 kg for the 3 MW power level.

Submersible drive means

Abstract: A submersible drive unit for propelling a scuba diver through water. The propulsion device comprises a shrouded propeller which is removably and adjustably attached to the diver's air tank. Removably attached to the propeller shroud is a waterproof motor housing for encasing a motor to drive the propeller. Batteries for driving the motor are enclosed within two kidney-shaped cases, one located on each side of a conventional diver's weight belt. A hand grip having at least one switch is used to activate/deactivate the unit as well as to control the speed.

Method and device for controlling propulsion

Abstract: For controlling the propulsion of vehicles which are equipped with permanent single axle drive and engagable all wheel drive, the rotational behaviour of the wheels (11-14) is measured, the measurement signals electronically processed and brake pressure applied to the relevant wheel brake (11 or 12) in the event of excessive wheel slip. In addition the second drive axle (HA) is automatically switched on and back off as required, that is as a function of the wheel slip of the permanently driven wheels (11, 12).

Vehicle, especially a rail vehicle

Abstract: A vehicle, especially a rail vehicle, with a low floor throughout (Fig. 1; 21) and with driven single-wheel propulsion mechanisms (Fig. 2; 7) and/or non-driven single-wheel running mechanisms.