Showing papers on "Propulsion published in 1991"

Thrust stand for high‐power electric propulsion devices

Abstract: This paper describes a new high-power thrust stand developed for use with high-power (up to 250 kW) magnetoplasmadynamic (MPD) thrusters, which is installed in a high-vacuum MPD facility at Lewis Research Center. The design of the stand is based on inverted pendulum configuration, with the result of large displacements and high resolution. Calibration results showed that thrust measurements were linear and repeatable to within a fraction of 1 percent. The thrust stand was used for testing water-cooled MPD thrusters at power levels up to 125 kW. The thruster, however, is quite well suited for testing other types of electric propulsion devices.

Review of Propulsion Applications and Numerical Simulations of the Pulsed Detonation Engine Concept

Abstract: Here we review experimental and computational studies of the pulsed detonation engine concept (PDEC) and present results of our recent numerical study of this concept. The PDEC was proposed in the early 1940s for small engine applications; however, its potential was never realized due to a complicated, unsteady operation regime. In this study, we demonstrate the use of current advances in numerical simulation for the analysis of the PDEC. The high-thrust/engine volume ratio obtained in our simulations demonstrates promising potential of the pulsed detonation engine concept.

Electric and pedal driven bicycle with solar charging

Abstract: The invention relates to an electric propulsion system for a multi-wheeled vehicle including though not limited to a bicycle. The preferred embodiment consists of a standard street bicycle with multi-speed transmission, plus an electrical propulsion system and a solar charging apparatus. This preferred embodiment is normally powered by a combination of motor and pedals, coupled such that either or both may provide power at any time. The electrical propulsion system consists of: a) a DC electric motor, B) a plurality of batteries, C) a hand lever operating a throttle means, D) a throttle means which controls a battery switching circuit for altering the plurality of batteries into a parallel configuration for a lower voltage to facilitate regenerative charging at times, and into a series configuration at other times for a higher drive voltage for the motor, as well as controls a voltage regulating circuit which regulates voltage to the motor, E) a continuously variable automatic transmission which selects the correct ratio for conditions between a high and a low limit without intervention by the operator, as well as automatically regulates clutching friction, and F) A regenerative braking arrangement which converts forward momentum of bicycle and rider into a charging current for the plurality of batteries during braking or slowing. The solar apparatus consists of a plurality of solar cells mounted on a disc fitted outside the spokes on either or both sides of either or both wheels. A rotatable coupler conducts the solar charging current from the solar cells to the plurality of batteries.

Propulsion system for a vertical and short takeoff and landing aircraft

Abstract: The invention is a propulsion system for a V/STOL type aircraft. In detail, the invention comprises a turbofan engine (31) including a fan section (46), compressor section (65), combustion section (74), turbine section (58) and nozzle section (34). The turbine section (58) comprises a low-pressure turbine portion (56) coupled to and driving the fan section (46) and a high-pressure turbine portion (68) coupled to and driving the compressor section (65). A lift fan (36) is coupled to the fan section (46) by means of a drive shaft (52). A clutch (108) is incorporated for de-coupling the lift fan (36) from the fan section (46). A mechanism (80) is incorporated for extracting additional power from the low-pressure turbine portion (56) of the turbine section (58) to drive the lift fan (36) that augments the basic engine thrust for V/STOL operation.

Wake ingestion propulsion benefit

Abstract: It is well-known that the efficiency of propulsion is improved if part or all of the propulsive fluid comes from the wake of the craft being propelled. In this article this propulsion benefit is quantified in terms of wake parameters and propulsor properties. The formulations apply directly to unducted fans or propellers, but the conclusions are also relevant to ducted propulsors. It is found that the power saving is greatest when the propulsor disk loading is high, when the wake form factor is high (flow near separation), and when the propulsor design is such that the wake profile tends to be flattened as it passes through the propulsor (high wake recovery). Examples are given showing that the benefit can be in the 20% range in some cases. Propeller design parameters that lead to high wake recovery are also given.

High-Speed Flight Propulsion Systems

Abstract: This text provides a cohesive treatment of the complex issues in high-speed propulsion, as well as introductions to the recent capabilities for addressing several fundamental aspects of high-speed vehicle propulsion development. It includes 185 equations.

Track-laying vehicle electric drive system

Abstract: An electric drive system for track-laying vehicles includes a pair of electric motors for respectively driving the two vehicle tracks in low range forward and reverse, variable speed propulsion and steer. The output of a third electrical motor is additively combined with the outputs of the pair of motors to provide high range forward and reverse, variable speed propulsion and steer.

Electric drive system for track-laying vehicles

Abstract: An electric drive system for tracklaying vehicles includes a pair of electric motors and an infinitely variable speed, hydromechanical steering transmission including a pair of hydrostatic propulsion units and a plurality of planetary gears sets. The hydrostatic units are driven by one or both of the electric motors to produce separate hydrostatic propulsion outputs which are combined with the mechanical outputs of the motors by the planetary gear sets to generate separate hydromechanical propulsion outputs on right and left transmission output shafts for vehicle propulsion and steer in two speed ranges.

Design and Modeling Issues for Integrated Airframe/Propulsion Control of Hypersonic Flight Vehicles

Abstract: TraditionaLly the systems integration process in aerospace controls is to make individually desig subsystems work together, that is, to ensure functional compatibility and minimize adverse interactions. With large hypersonic vehicles the aerodynamic, propulsion, structural, and controls features are intrinsically highly interactive dynamically over a wide range of frequencies. Consequently, systems integration activities must be enormously expanded in scope and degree to assure a successful result. In essence the new goal of dynamic systems integration is to carry out concurrent multidisciplinary design of the highly interactive systems to maximize overall aircraft performance in its broadest terms. Cooperative consolidation and interaction of functions and subsystems to achieve performance levels and design synergism greater than would be possible with independent, individual subsystem designs are the natural consequences desired.

Marine jet drive

Abstract: This invention relates to a marine jet drive having improved operation, especially in regard to having efficient adaptation to propulsion engine and hull design; having a drive shaft with flexible coupling at each end, internal to the jet drive; having through-the-nozzle engine exhaust; having simplified, combined means of steering and reversing; having controllable nozzle aperture and trim control; having combination reverse flow deflector and trim plane; having means to disengage the engine from the jet to obtain true neutral; having protection from and removal of debris in the water intake duct; generally having fewer overhauls, easier serviceability and lighter weight.

Hybrid propulsion system for vehicles, in particular for road vehicles

Abstract: In a hybrid propulsion system for vehicles in which a first propulsion unit, of internal combustion type (10) transmits motion to at least one wheel (26) of the vehicle via transmission members including at least one clutch (14), a second propulsion unit (20) of electrical type, is connected to the driven element of said clutch via means such that the motion generated by one of said propulsion units when the other is deactivated is transmitted only to the transmission members located downstream of said clutch.

Paired motor system for small boat propulsion and steerage

Abstract: Paired spaced electrically driven motors provide a steerable propelling system for small boats. Each motor drives a propeller carried in an elongate channel, communicating from each lateral side of a boat beneath the water line to one boat end, to move water through such channels for boat propulsion. The electrical motors are of variable speed, reversible, and separately controlled by a joystick type control device to provide differential control of motor speed to allow steerage. The propelling system provides a low speed, maneuverable propulsion system for fishing use, as an auxiliary power system for boats having a separate principal powering system, and to aid maneuverability alone or in conjunction with the principal powering system.

Integrated flight/propulsion control system design based on a centralized approach

Abstract: An integrated flight/propulsion control system design is presented for the piloted longitudinal landing task with a modern, statically unstable, fighter aircraft. A centralized compensator based on the Linear Quadratic Gaussian/Loop Transfer Recovery methodology is first obtained to satisfy the feedback loop performance and robustness specificiations. This high-order centralized compensator is then partitioned into airframe and engine sub-controllers based on modal controllability/observability for the compensator modes. The order of the sub-controllers is then reduced using internally-balanced realization techniques and the sub-controllers are simplified by neglecting the insignificant feedbacks. These sub-controllers have the advantage that they can be implemented as separate controllers on the airframe and the engine while still retaining the important performance and stability characteristics of the full-order centralized compensator. Command prefilters are then designed for the closed-loop system with the simplified sub-controllers to obtain the desired system response to airframe and engine command inputs, and the overall system performance evaluation results are presented.

Space electric propulsion plasmas

Abstract: Electric thrusters offer the promise of a substantial improvement in performance over that of conventional chemical rockets currently used in space propulsion applications. There are three basically different ways in which electrical power and propellant inputs might be combined to produce thrust: (1) propellant can be heated electrically and then expanded through a nozzle; (2) electromagnetic body forces can be applied to accelerate a plasma to the desired exhaust velocity; or (3) electrostatic body forces can be applied to accelerate charged particles. Electric thrusters are classified in accordance with the mechanism by which they induce thrust as electrothermal, electromagnetic, and electrostatic. The characteristics of plasmas in electric thrusters along these lines are considered. >

Launch vehicle performance using metallized propellants

Abstract: Metallized propellant propulsion systems are considered as replacements for the solid rocket boosters and liquid sustainer stages on the current launch vehicles: both the Space Transportation System (STS) and the Titan 4. Liquid rocket boosters for the STS were analyzed as replacements for current solid rocket boosters. These boosters can provide a liquid propulsion system within the volume constraints of a solid rocket booster. A replacement for the Space Shuttle Main Engines using metallized O2/H2/Al was studied. The liquid stages of the Titan 4 were also investigated; the Aerozine-50 (A-50) fuel was replaced with metallized storable A-50/Al. A metallized propellant is similar to a traditional liquid propellant. However, it has metal particles, such as aluminum, that are suspended in a gelled fuel, such as hydrogen, RP-1, A-50 or monomethyl hydrazine (MMH). The fuels then undergo combustion with liquid oxygen or nitrogen tetroxide (NTO). These propellants provide options for increasing the performance of existing launch vehicle chemical propulsion systems by increasing fuel density or specific impulse or both. These increases in density and specific impulse can significantly reduce the propulsion system liftoff weight and allow a liquid rocket booster to fit into the same volume as an existing solid rocket booster. Also, because gelled fuels are akin to liquid propellants, metallized systems can provide enhanced controllability over solid propulsion systems. Gelling of the propellant also reduces the sensitivity to impacts and consequently reduces the propellant explosion hazard.

Dynamics and control of hypersonic vehicles - The integration challenge for the 1990's

Abstract: The dynamic characteristics of hypersonic vehicles are reviewed, with special attention to the interactions between the airframe, engine, and structural dynamics. Based on a preliminary investigation of the dynamics of a generic vehicle configuration similar to the X-30 with Scramjet propulsion, an assessment of these interactions is presented. The control effectors include aerodynamic pitch-control surfaces, as well as engine fuel flow and diffuser area ratio. The study configuration is statically instable in pitch, and exhibits strong airframe/engine/elastic coupling in the attitude dynamics and engine responses. This strong coupling will require a highly integrated airframe-engine control system, and the performance of the attitude control system will be contingent upon the ability to adequately deal with the structural aeroelastic response and engine dynamics.

Nuclear electric propulsion mission performance for fast piloted Mars missions

Abstract: A mission study aimed at minimizing the time humans would spend in the space environment is presented. The use of nuclear electric propulsion (NEP), when combined with a suitable mission profile, can reduce the trip time to durations competitive with other propulsion systems. Specifically, a split mission profile utilizing an earth crew capture vehicle accounts for a significant portion of the trip time reduction compared to previous studies. NEP is shown to be capable of performing fast piloted missions to Mars at low power levels using near-term technology and is considered to be a viable candidate for these missions.

Boat propulsion device

Abstract: A propulsion device for a boat that mounts through a hole in a bottom surface of the boat. The engine is positioned inside the boat and the propeller drive is positioned under a bottom surface of the boat. The propulsion device includes a mounting assembly, a steering assembly rotatably connecting the drive to the mounting assembly for steering the propeller drive under the boat, a trimming assembly swingingly connecting the drive to the steering assembly for trimming/tilting of the propeller drive under the boat at any steered position, and a drive shaft means providing a drive connection between the engine and the propeller drive at any steered and trimmed position.

Propulsive options for a manned Mars transportation system

Abstract: In this investigation, five potential manned Mars transportation systems are compared. These options include: (1) a single vehicle, chemically propelled (CHEM) option, (2) a single vehicle, nuclear thermal propulsion (NTP) option, (3) a single vehicle solar electric propulsion (SEP) option, (4) a single vehicle hybrid nuclear electric propulsion (NEP)/CHEM option, and (5) a dual vehicle option (NEP cargo spacecraft and CHEM manned vehicle). In addition to utilizing the initial vehicle weight in low-earth orbit as a measure of mission feasibility, this study addresses the major technological barriers each propulsive scenario must surpass. It is shown that instead of a single clearly superior propulsion system, each means of propulsion may be favored depending upon the specified program policy and the extent of the desired manned flight time. Furthermore, the effect which aerobraking and multiple transfer cycles have upon mission feasibility is considered.

Optimizing Aircraft Performance With Adaptive, Integrated Flight/Propulsion Control

Abstract: The Performance-Seeking Control (PSC) integrated flight/propulsion adaptive control algorithm presented was developed in order to optimize total aircraft performance during steady-state engine operation. The PSC multimode algorithm minimizes fuel consumption at cruise conditions, while maximizing excess thrust during aircraft accelerations, climbs, and dashes, and simultaneously extending engine service life through reduction of fan-driving turbine inlet temperature upon engagement of the extended-life mode. The engine models incorporated by the PSC are continually upgraded, using a Kalman filter to detect anomalous operations. The PSC algorithm will be flight-demonstrated by an F-15 at NASA-Dryden.

Water jet propulsion unit

Abstract: A number of embodiments of watercraft having jet propulsion units contained within a tunnel in the hull and wherein the jet propulsion unit is pivotal about a first transversely extending horizontal pivot axis for bringing the jet propulsion unit through trim adjusted positions to an upward out of the water position. In addition, the jet propulsion unit is rotatable about a horizontal longitudinally extending axis so that its downwardly facing water inlet portion may be rotated upwardly for access through an access opening in the hull for servicing. In one embodiment, the jet propulsion unit is only rotatable about the horizontal longitudinally extending axis. A number of embodiments of rudder assemblies are also depicted supported by the steering nozzle for generating steering effects when the steering nozzle is not generating a significant steering effect and which may be pivoted to an out of the water position for protection when underwater obstacles are struck.

Automatic position controller for marine propulsions

Abstract: Several embodiments of automatic position controls for marine propulsion devices wherein the lift condition of the propulsion device is adjusted in response to a sensed running condition of the watercraft such as changes in acceleration, speed or planing condition. In some embodiments, the trim of the propulsion unit is also adjusted in response to the sensed conditions.

Production and use of metals and oxygen for lunar propulsion

Abstract: Production, power, and propulsion technologies for using oxygen and metals derived from lunar resources are discussed. The production process is described, and several of the more developed processes are discussed. Power requirements for chemical, thermal, and electrical production methods are compared. The discussion includes potential impact of ongoing power technology programs on lunar production requirements. The performance potential of several possible metal fuels including aluminum, silicon, iron, and titanium are compared. Space propulsion technology in the area of metal/oxygen rocket engines is discussed.

High-speed flight propulsion systems. Progress in Astronautics and Aeronautics. Vol. 137

Abstract: Various papers on high-speed flight propulsion systems are presented. The topics addressed are: propulsion systems from takeoff to high-speed flight, propulsion system performance and integration for high Mach air-breathing flight, energy analysis of high-speed flight systems, waves and thermodynamics in high Mach number propulsive ducts, turbulent free shear layer mixing and combustion, turbulent mixing in supersonic combustion systems, mixing and mixing enhancement in supersonic reacting flowfields, study of combustion and heat-exchange processes in high-enthalpy short-duration facilities, and facility requirements for hypersonic propulsion system testing.

Integrated Flight/Propulsion Control Design for a STOVL Aircraft using H-Infinity Control Design Techniques

Abstract: Results are presented from an application of H ? control design methodology to a centralized integrated flight/propulsion control (IFPC) system design for a supersonic Short Take?Off and Vertical Landing (STOVL) fighter aircraft in transition flight. The emphasis is on formulating the H ? control design problem such that the resulting controller provides robustness to modelling uncertainties and model parameter variations with flight condition. Experience gained from a preliminary H ? based IFPC design study performed earlier is used as the basis to formulate the robust H ? control design problem and improve upon the previous design. Detailed evaluation results are presented for a reduced order controller obtained from the improved H ? control design showing that the control design meets the specified nominal performance objectives as well as provides stability robustness for variations in plant system dynamics with changes in aircraft trim speed within the transition flight envelope. A controller scheduling technique which accounts for changes in plant control effectiveness with variation in trim conditions is developed and off-design model performance results are presented with the scheduled controller.

Composite road vehicle with electric and thermal propulsion means

Abstract: A transport method is disclosed wherein relatively slow displacements with frequent stops and relatively rapid displacements with few stops may be efficiently performed with the same vehicle or the same vehicle unit The slow displacements are made by means of one or more electric batteries and the rapid displacements are made by means of one or more thermal engines

Twenty First Century Propulsion Concept

Abstract: : This contract explored the Biefield-Brown effect which allegedly converts electrostatic energy directly into a propulsive force in a vacuum environment The program emphasized the the experimental exploration of this electrostatic thrust-generation concept to confirm or deny its existence, to verify its operation under high vacuum conditions, and to establish an experimental database via tests with candidate devices to permit the nature and magnitude of its thrust to be determined An improved laboratory test configuration was developed for quantifying electrostatically induced propulsive forces on selected devices This configuration used a vacuum chamber and diffusion pump arrangement which extended conditions to the 1 microtorr range While attempts were made to increase the driving DC voltage to 50 kV or more, the driving voltages were generally limited to about 19 kV to avoid electrical breakdown problems Boundary effects arising from the presence of induced surface charges on the walls of the vacuum chamber surrounding the test devices were significant, and had to be taken into account in using the torsion pendulum system to make thrust force measurements Direct experimental results indicate that no detectable propulsive force was electrostatically induced by applying a static potential difference up to 19 kV between the electrodes of test devices under conditions in which electrical breakdowns did not occur

Automatic trim system

Abstract: A marine propulsion device comprising a propulsion unit adapted to be mounted to a boat for pivotal movement about a generally horizontal tilt axis, and for pivotal movement about a generally vertical steering axis, the propulsion unit including a propeller shaft adapted to support a propeller for rotation therewith, the marine propulsion device further comprising a steering mechanism for pivoting the propulsion unit about the steering axis, and a control system including structure for sensing force applied on the steering mechanism by the propulsion unit, and structure for pivoting the propulsion unit about the tilt axis in response to the force sensed by the force sensing structure.

Hybrid chemical/electromagnetic propulsion system

Abstract: A hybrid chemical/electromagnetic propulsion system which combines thermal expansion of a chemically-reacted propellant with electromagnetic acceleration of the propellant to provide an efficient propulsion system that operates in the specific impulse I sp range of 800 to 2500 seconds. The hybrid chemical/electromagnetic propulsion system includes a reaction chamber, an expansion nozzle mounted to the exit of the reaction chamber, and an induction coil wound around a portion of the expansion nozzle. The reaction chamber supports the combustion or chemical reaction of a propellant to form high-temperature ionizable reaction products. The expansion nozzle then expands these high-temperature reaction products to generate thrust. The induction coil generates a varying electric and magnetic field which ionizes and magnetically accelerates the reaction products to generate additional thrust. A drive circuit supplies current to the induction coil in a manner that maximizes this additional thrust.