Showing papers on "Propulsion published in 1988"

Control means for marine propulsion system

Abstract: A marine vessel propulsion system includes port and starboard drive systems, each including an engine, an engine throttle, and a transmission furnishing drive power to a propeller on a drive shaft. Each transmission includes forward and reverse clutches, and each clutch can be fully engaged, fully disengaged and modulated. Two alternately usable separate control stations operate the throttles and clutches to control vessel speed and direction. Each control station comprises port and starboard sets of manually operable control devices, and each set includes a mode selector switch for selecting cruise mode or troll mode for its respective throttle and a manually operable direction/speed control lever. In troll mode the lever selects and modulates the selected respective clutch to control propeller speed. In cruise mode the lever fully engages the selected respective clutch and also regulates the engine throttle to control propeller speed. Port and starboard manually operable power-link function selector switches at each control station enable one direction/speed control lever to control both drive systems simultaneously in the forward cruise mode. Electronic controllers process control station output signals and feedback signals indicative of engine speeds and propeller direction and speeds and then provide drive system control signals. Transfer of control to one station from another is possible.

Propeller arrangement, in particular for ship propulsion plants

Abstract: Conventional propellers are borne on a hub bearing in their centre. The axial forces acting on the blade tips (3) in particular subject the blades (7) to a large bending moment. Therefore, the blades have to be of very massive construction, which however increases the stresses on the propeller due to centrifugal forces. So the size of such propellers is limited. Furthermore, the cost of the materials for manufacturing conventional propellers is comparatively high. In order to overcome these disadvantages, it is proposed that a propeller (2) equipped with an outer ring (4) be mounted, together with this outer ring (4), in a housing (5), so that a hub bearing can be dispensed with. The axial bending moments acting on the blades (7) of the propeller (2) are reduced, so the blades (7) can be made lighter. The centrifugal forces thus reduced also make larger propeller diameters possible than in the current state of the art. The propeller arrangement (1) can be utilised for ship propulsion and wind generators.

Propulsion system for a small vehicle

Abstract: The invention is vehicle propulsion system having a pump driven by an engine, a hydraulic motor driven by the pump, and a ground engaging wheel driven by the hydraulic motor. On the drive shaft connected between the engine and the pump is a flywheel whose moment of inertia is varied by radially translating weights on the flywheel. Under normal vehicle operating conditions, the weights are translated outward, whereby rotational energy is stored in the flywheel. When more power is needed then the engine can provide, the weights on the flywheel translate inwardly so that the flywheel imparts rotational energy to the pump through the drive shaft. The propulsion system has means to maintain the engine in a narrow r.p.m. range where the engine is most efficient. Vehicle speed and direction is varied by controlling the flow speed and direction from the pump, which determines the speed and direction of the hydraulic motor. The system also has an override mode wherein the engine speed is set at a new, higher level when a foot pedal operated by the vehicle operator exceeds a given range of movement.

Posture control device for marine vessels

Abstract: A number of embodiments of watercraft propulsion unit controls for optimizing watercraft performance and maintaining stability. Performance is optimized in the illustrated embodiments by adjusting the trim angle of the propulsion device and stability is maintained by changing either the trim condition or the speed of the propulsion unit. The desired posture may either be preset in response to an earlier stable condition or may be set upon reaching of optimum performance.

Performance and lifetime assessment of MPD arc thruster technology

Abstract: A summary of performance and lifetime characteristics of pulsed and steady-state magnetoplasmadynamic (MPD) thrusters is presented. The technical focus is on cargo vehicle propulsion for exploration-class missions to the Moon and Mars. Relatively high MPD thruster efficiencies of 0.43 and 0.69 have been reported at about 5000 s specific impulse using hydrogen and lithium, respectively. Efficiencies of 0.10 to 0.35 in the 1000 to 4500 s specific impulse range have been obtained with other propellants (e.g., Ar, NH3, N2). Thermal efficiency data in excess of 0.80 at MW power levels using pulsed thrusters indicate the potential of high MPD thruster performance. Extended tests of pulsed and steady-state MPD thrusters yield total impulses at least two to three orders of magnitude below that necessary for cargo vehicle propulsion. Performance tests and diagnostics for life-limiting mechanisms of megawatt-class thrusters will require high fidelity test stands which handle in excess of 10 kA and a vacuum facility whose operational pressure is less than 3 x 10 to the -4 torr.

Multipurpose modular spacecraft

Abstract: A multipurpose modular spacecraft is adaptable quickly and easily for performing a variety of short- and long-range space missions, such as on-orbit maintenance missions and the like. The multipurpose modular spacecraft comprises a fully integrated short-range space vehicle including one or more relatively small modular propulsion sets which provide propulsion capability for relatively short-range missions and close-in maneuvering requirements. Longer-range propulsion capability is provided by a comparatively larger propulsion module designed for removable nested mounting within an open-sided chamber in the short-range vehicle. Relatively simple and easily operated latch mechanisms retain the propulsion sets and the propulsion module on the short-range space vehicle in preselected positions with relatively simple electrical fittings connected together to provide a control interface with the short-range space vehicle. The propulsion sets and/or the propulsion module can be replaced or removed as required to refuel the modular spacecraft or to adapt the spacecraft for a particular space mission.

Magnetohydrodynamic ship propulsion with superconducting magnets

Abstract: The feasibility of magnetohydrodynamic (MHD) ship propulsion using superconducting magnets is reviewed in light of recent advances in high-temperature superconductivity. The scaling relations for the electrical and hydraulic efficiencies of MHD pump-jets show that overall efficiencies >50% are feasible at speeds of 40 knots and higher provided that magnetic fields >5T can be maintained over volumes of the order of 100 m3. The development of large-scale electrical machinery and magnets using the high-temperature superconductors now under development could make it practical to construct submersibles for high-speed and silent operation. Low-speed tankers for movement of bulk cargo would be efficient with even lower fields.

Low pressure reaction control propulsion system for a spacecraft

Abstract: A spacecraft propulsion system which integrates the function of the apogee kick motor (AKM) and reaction control system (RCS) is disclosed. In accordance with this invention, a pump-fed AKM is employed which results in lightweight main tanks and pressurization systems. The RCS thrusters are operated by small bellows tanks which are intermittently pressurized by a gas pressurization system to provide high pressure for operation of the RCS thrusters. The system according to this invention enables use of lighter weight main propellant tanks since they do not have to withstand high internal pressures and also enables realization of the numerous advantages of a pump-fed AKM. Several embodiments describe various methods for cycling the bellows tanks.

Experimental and numerical study of the propeller/fixed wing interaction

Abstract: With the advent of high-efficiency propellers as a propulsion alternative for the future, it has become necessary for the nature of the slipstream and its interference with aircraft components to be known over a wide range of operating conditions. A complementary experimental and computational investigation of the interaction between a propeller and a fixed wing is reported here. The experimental investigation is conducted on a propeller/nacelle wing configuration at low subsonic speeds

The ram accelerator - A chemically driven mass launcher

Abstract: The ram accelerator, a chemically propelled mass driver, is presented as a viable new approach for directly launching acceleration-insensitive payloads into low earth orbit. The propulsion principle is similar to that of a conventional air-breathing ramjet. The cargo vehicle resembles the center-body of a ramjet and travels through a tube filled with a pre-mixed fuel and oxidizer mixture. The launch tube acts as the outer cowling of the ramjet and the combustion process travels with the vehicle. Two drive modes of the ram accelerator propulsion system are described, which when used in sequence are capable of accelerating the vehicle to as high as 10 km/sec. The requirements are examined for placing a 2000 kg vehicle into a 500 km orbit with a minimum of on-board rocket propellant for circularization maneuvers. It is shown that aerodynamic heating during atmospheric transit results in very little ablation of the nose. An indirect orbital insertion scenario is selected, utilizing a three step maneuver consisting of two burns and aerobraking. An on-board propulsion system using storable liquid propellants is chosen in order to minimize propellant mass requirements, and the use of a parking orbit below the desired final orbit is suggested as a means to increase the flexibility of the mass launch concept. A vehicle design using composite materials is proposed that will best meet the structural requirements, and a preliminary launch tube design is presented.

Field tests on a MAGLEV with passive guideway linear inductor motor transportation system

Abstract: A passive guideway linear inductor motor MAGLEV research vehicle intended primarily for urban transportation applications is presented. Solutions for magnetic levitation and propulsion control together with the main sensors (airgap, acceleration, and position) are described. Preliminary field tests on a 4-t 4-m-long research vehicle, named Magnibus-01, are given. Vehicle take-off and landing, response to perturbations in levitation, vehicle acceleration, and electrical braking at low speeds were recorded and are presented. >

High performance sea-going craft

Abstract: A sea-going craft has a main central body with two wings affixed to the body and extending horizontally away to either side. A catamaran-type hull is attached to each wing end, and provides flotation. The rearward edge of each wing is generally closer to the water than the forward edge when the craft is under power, thus adding lift due to the ground-effect phenomenon. A hydrofoil is affixed to each hull and extends downwardly, and a third hydrofoil is affixed to the central body, extending downwardly. The craft includes propulsion apparatus.

Hybrid electrothermal/electromagnetic arcjet thruster and thrust-producing method

Abstract: A hybrid electrothermal/electromagentic arcjet thruster has a cylindrical body with a longitudinal central axis, a plurality of electro-thermal propulsion mechanisms defined in the body in radially and circumferentially spaced relation about and extending along the central axis, and an electromagnetic propulsion mechanism defined in the body coaxially along the central axis thereof, between the electrothermal propulsion mechanisms and extending downstream thereof. Each electrothermal propulsion mechanism has tandemly-arranged constriction and expansion zones and are operable to concurrently receive a flow of gaseous propellant through the constriction zone and generate an electric arc therethrough to the expansion zone. The arcs interact with the propellant flows such that the latter are partially ionized and electrothermally accelerated through the expansion zones. The electromagnetic propulsion mechanism has an expansion chamber which communicates with, and extends downstream of, the expansion zones. The electromagnetic propulsion mechanism is operable to concurrently receive the flows of electrothermally-accelerated partially-ionized propellant in the expansion chamber and generate a radial current flux and an azimuthal magnetic field which interact with one another and with the flow of propellant such that the latter is electromagnetically accelerated at a higher rate than the electrothermal acceleration thereof.

Modular, Ion-Propelled, Orbit-Transfer Vehicle

Abstract: The design approach is presented for a modular, ion-propelled, orbit transfer vehicle (OTV). The OTV consists of a propulsion module that can be returned to Earth via the Shuttle for refueling and refurbishment, and a reusable power bus that mates to the spacecraft paylpad and remains in orbit. The technologies required to make the OTV concept both technically and economically feasible are identified. As an example of how the OTV could be applied, the NAVSTAR/Global Positioning System (GPS) Block 3 mission is examined using both conventional (expendable) chemical stages and the ion propulsion OTV. The OTV approach is shown to be particularly attractive, from a cost standpoint, for the specific application to GPS. The high specific impulse provided by ion propulsion is shown to result in a new reduction of $145 to 195 million in overall cost for the GPS Block 3 mission as compared with the cost using the Payload Assist Module (PAM) D-II chemical propulsion stage. This reusable OTV approach is believed to be equally attractive for other missions that require multiple launches.

Electromagnetic ground to orbit propulsion method and operating system for high mass payloads

Abstract: A reusable and regenerative electromagnetic propulsion method and operating system is provided for propelling high mass payloads to orbital velocities which does not require a vacuum environment. The propulsion system comprises a self supporting superconducting dipole coil several kilometers in diamater that is accelerated by magnetic repulsive forces generated by a plurality of giant superconducting field coils mounted in the underground tunnels. The propulsion dipole is mounted inside a circular hypersonic wing-like structure equipped with movable aerodyanmic control surfaces for guidance. The propulsion system can accelerate a payload with any desired launch azimuth by accelerating along a line of magnetic induction generated by the field coils having the desired azimuth angle. The payload is attached to the propulsion system by a plurality of cables. After reaching orbital velocity, the payload is detached from the propulsion system and the propulsion system is decelerated back to the earth's surface by magnetic repulsive forces generated by the field coils. A large fraction of the orbital energy of the propulsion system is reconverted back into electrical energy by the inductive coupling between the magnetically decelerated propulsion coil and the field coils which is used to launch another payload.

Composite fanjet/ramjet propulsion device

Abstract: Composite changeover-type reaction power plant for propelling aircraft and spacecraft operating in subsonsic, supersonic and hypersonic regions, embracing a turbofan bypass engine with front fan, and a ramjet engine with a cycle corresponding to that of the fan, where the fan has individually independently supported, operationally counterrotating statorless rotors and variable fan blades which are feathered and immobilized during ramjet operation for low drag during said ramjet operation.

Method and apparatus for determining slip thresholds for a propulsion slip control system of a motor vehicle

Abstract: Method of and apparatus for determining slip thresholds for a propulsion slip control system of a motor vehicle, whereby the instantaneously effective coefficient of friction between vehicle and road is determined from the measured values of vehicle speed and of the vehicle longitudinal acceleration and a slip value is associated therewith as a threshold value for the propulsion slip control system.

Pedal boat propulsion system

Abstract: A marine propeller equipped drive unit is provided for support from the transom of a boat in generally the same manner an outboard motor is supported from a boat transom and a pedal crank assembly is provided for mounting within a boat forward of a transverse seat thereof to be operated by the legs of a person supported from the seat, the pedal crank assembly including an output shaft and the drive unit including an upper end input shaft and there being provided an open drive shaft assembly extending between and operably connecting the output shaft to the input shaft.

Air Augmented Rocket Propulsion Concepts

Abstract: : This report presents the results of a study of five combined cycle propulsion systems capable of accelerating a single stage vehicle with lifting surfaces from ground launch to Earth orbit. The engines studied were airbreathing, rocket based combined cycle (RBCC) engines. 'Combined Cycle' engines integrate airbreathing and rocket propulsion systems into a single engine system. These engines transition from initial air-augmented rocket mode takeoff and initial acceleration to ramjet to scramjet and finally to rocket propulsion to orbital insertion velocity. Engine systems, engine/vehicle integration, vehicle structure, propellant storage systems and thermal protection system (TPS) design, sizing and weight estimation, overall performance on various trajectories, and ground support systems were studied. A technology assessment, subscale engine test plan, development program plan and life cycle costs estimates are presented. Keywords: Air augmented rockets, Ramjets, Scramjets, Orbit on demand, Combined cycle engines, Space vehicles.

A Free-Piston Engine Hydraulic Pump for an Automotive Propulsion System

Abstract: A free-piston engine hydraulic pump (FPEHP) is considered as a power source in the propulsion system of an automotive vehicle. The propulsion system uses a two-stroke spark-ignited free-piston engine coupled to a hydraulic pump and an accumulator where high pressure hydraulic fluid is stored for transmission of power. The energy in the accumulator is transmitted to hydraulic motors which provide the tractive effort

Aircraft pylon for engine support

Abstract: An aircraft propulsion system includes at least one pusher propeller mounted to a nacelle mounted to the aircraft by a pylon which produces a wake which impinges upon the propeller. The wake from the pylon is modified to reduce noise and vibration produced by the propeller interaction with the wake. The propulsion system may include a pair of counterrotating pusher propellers.

Highly compact inlet diffuser technology

Abstract: The potential benefits of short, highly compact inlet diffuser systems extend from efficient propulsion/airframe performance to improved survivability The cost of these benefits may be excessively high engine face distortion This highlights the importance of accurate preliminary design methods that assure low distortion engine face flow Therefore, compact/offset subsonic diffuser performance and operational characteristics have been investigated, with the general goal of developing preliminary design guidelines and providing a useful perspective for advanced aircraft designers Incorporated are important prior works that extend the database by introducing the results of recent experiments, including passive and active BLC methods for providing separation-free diffuser flow Diagnostic pressure measurements, in conjunction with CFD calculations, are used to demonstrate the flow mechanisms responsible for the engine face distortion profile Surprisingly good comparisons of measured engine face pressure characteristics with CFD results are shown for the severely separated flow of the test article

Motor vehicle propulsion control when accelerating from a stationary position

Abstract: In a system for controlling the propulsion on motor vehicles, by a reduction of the drive torque by an intervention in ignition, carburator or fuel injection and/or brakes, includes a first device which reduces the drive torque when the maximum adhesion coefficient is exceeded, and a second device which reduces the drive torque to a value associated with the measured maximum value of the vehicle acceleration when the monitored wheel variable exceeds the threshold value, as a result of which too great an excess of torque is prevented and sufficient traction and cornering stability are retained without unnecessarily slowing down a propulsion of the motor vehicle.

Light aircraft for short-distance takeoff and landing

Abstract: A light aircraft for short distance takeoff and landing includes an airplane having a propeller provided on a rear pedestal thereof for producing vertical propulsion and an airship having a propeller provided on a rear pedestal thereof for producing vertical propulsion and also having a flight attitude sensor provided within an operating compartment thereof. The flight attitude sensor is always directed in the vertical direction, detects forward and rearward inclinations of the airship, and transmits signals corresponding to the inclinations to the two propellers, thereby rotating the two propellers to produce downward or upward propulsion to maintain the aircraft at the normal horizontal attitude at all times.

Electrically conductive plastic bushings for marine propulsion devices

Abstract: A marine propulsion device is provided including a propulsion unit adapted to be mounted on a boat for pivotal movement relative thereto about a generally vertical steering axis, the propulsion unit having a propeller shaft supporting a propeller, an internal combustion engine drivingly connected to the propeller, and a corrosion protection system, which device also includes at least one bushing made of a conductive plastic to allow a path for electrical connection to the corrosion protection system to be established across the bushing.

Recent progress by JNR on Maglev

Abstract: An overview is given of the Japanese National Railways (JNR) Maglev system, which uses superconducting magnet levitation and linear synchronous motor (LSM) propulsion The progress made has included a speed of 517 km/h reached by experimental vehicle ML500, a three-car test run by the MLU001 vehicle, manned test runs, and test runs with aberrations purposely introduced into the guideway A maximum speed of 352 km/h was achieved for the three-car train After noting guideway and power supply facility components, the MLU001 and MLU002, the discussion centers on the vehicle body, carriages, superconducting magnets, and helium liquifier and refrigerator units >