Showing papers on "Propulsion published in 1972"

Generalized simulation technique for turbojet engine system analysis

Abstract: A nonlinear analog simulation of a turbojet engine was developed The purpose of the study was to establish simulation techniques applicable to propulsion system dynamics and controls research A schematic model was derived from a physical description of a J85-13 turbojet engine Basic conservation equations were applied to each component along with their individual performance characteristics to derive a mathematical representation The simulation was mechanized on an analog computer The simulation was verified in both steady-state and dynamic modes by comparing analytical results with experimental data obtained from tests performed at the Lewis Research Center with a J85-13 engine In addition, comparison was also made with performance data obtained from the engine manufacturer The comparisons established the validity of the simulation technique

Linear motor propulsion system

Abstract: A tracked vehicle propulsion system employs a plurality of linear synchronous motors, each having a thruster module, and all fixed in mutually spaced relation along a track. Trains of cars, mounted to ride along the track and each bearing a linear rotor having interdigitated magnetic poles, are propelled by successive thruster modules. Each thruster module is provided with a thruster control that is connected to establish interthruster logic and all modules are driven with three-phase stator drive signals from one or another of a group of thrust controllers. Velocity of this synchronous motor system is controlled open loop by direct control of stator drive signal frequency. Velocity changes are achieved by sweeping the stator frequency from synchronism with one frequency to synchronism with another frequency. The system operates a number of trains at a slow speed in a near bumper-to-bumper relation during a travel through a station and decelerates incoming trains for operation at station speed and position. Various methods of operation and control are provided, including, among others, a normal cyclic mode as the trains run from station to station and back, increasing or decreasing number of trains in service, manual or operator control of train movement, emergency stop, emergency start, and start for groups of trains.

Magnetic Suspension and Propulsion Systems for High‐Speed Transportation

Abstract: High‐speed transportation vehicles (trains) carrying superconducting magnets can be levitated by repulsion from diamagnetic currents induced in a conducting track. Various approximate methods are presented for calculating the lift and drag forces for such magnetic suspensions. Fourier analysis of periodic train magnet fields is used to analyze ``image‐force'' and ``hybrid null‐flux'' systems which involve homogeneous conducting sheet tracks. A lumped circuit analysis is used to discuss the ``null‐flux'' principle and related systems with structured tracks. The stability and efficiency of linear induction and linear synchronous motor propulsion systems are studied using related methods.

Increased or variable bypass ratio engines

Abstract: Air breathing gas turbine engine design concepts, methods and apparatus for economically increasing the bypass ratio of conventional engine designs and/or for providing a variable bypass ratio feature. The disclosed preferred embodiments each involve a flow control system for internal management of intake and exhaust air within the engine comprising separated annular first and second duct means shaped and arranged to cross-over or invert air flow patterns within the confines of an annular passageway having an area substantially equal to the combined area of the two separated flow patterns. In this manner the quantities of air which pass to or from the various engine components can be routed without interference, necking down, or departure from the confines of the annular passageway. The system may be modified to achieve variable bypass ratio by providing a means for switching flow patterns between adjacent duct means of separated upstream and downstream portions to switch from inverted to straight through flow. The duct means comprise a plurality of conformably nesting basic duct elements of unique configuration and have utility in solving a variety of engine air flow control problems. The disclosed variable bypass engine concepts can be used in present aircraft propulsion systems to reduce jet and turbomachinery noise, to improve the installed drag characteristics of multimission propulsion units, and to improve fuel consumption rates.

Propulsion arrangement equipped with a linear motor

Abstract: A propulsion arrangement for a body movable along a track defining a direction of motion is disclosed. The arrangement includes a winding carrier assembly which coacts with a ferromagnetic return to develop a propulsion force for moving the body. The carrier assembly has two stacks of laminations carrying windings for developing a travelling wave; these windings are displaced with respect to each other by one pole pitch. The ferromagnetic return includes bars arranged transversely to the direction of motion. The arrangement of the bars constitutes a substantial simplification of the magnetic return and enables a simplified track switch layout to be obtained.

Unmanned multimode helicopter

Abstract: An unmanned helicopter capable of controlled free flight comprises a plurality of separable modules arranged in a substantially vertically stacked assembly symmetrical about a vertical axis. The modules include an uppermost propulsion module, a central fuel tank module and a lowermost control and payload module.

Accessory wheel and drive device for a motor vehicle

Abstract: In a preferred embodiment an automobile having four extra accessory utility wheels mounted on hydraulic jacks, with the back two accessory wheels being connected for synchronized steering thereof in both lateral and forward directions of movement of the car as well as the forward two wheels being synchronized with one another for synchronized steering in both lateral and forward directions and there being switch means whereby the front wheels and the rear wheels may be synchronized to one another for the forward and/or lateral steering, and at least one of the sets of front and back accessory wheels being connected for and including propulsion means alternately drivable by the regular automobile motor or by an electrical motor, the electrical motor-including embodiment also including accessory batteries connected to provide electricity to any accessory electrical motor and also connected to continually charged if necessary by the generator of the automobile, this above described combination of this invention providing both parking advantages and emergency power and wheels in the event of flat tires or other mechanical difficulty requiring supplemental driving power for propulsion of the automobile for reasonably short periods of time to remove the automobile from hazardous traffic locations or to propel the automobile to an appropriate next-occurring filling station or repair facility.

Comparison of advanced propulsion concepts for deep space exploration.

Abstract: Equations and charts are presented that permit rapid estimation of propulsion-system performance requirements for some typical deep-space missions. A number of advanced propulsion concepts for which performance estimates are available are compared with respect to their capability for flyby, rendezvous, and roundtrip planetary missions. Based on these estimates, the gas-core nuclear fission rocket and the pulsed fusion rocket yield the fastest trip times to the near planets. For round trips to Jupiter and beyond, the controlled fusion rocket shows progressively superior capabilities. Several propulsion concepts based on use of impinging laser beams are found to be noncompetitive with the other advanced concepts for deep space missions. Requirements for attainment of interstellar distances within a human lifetime are found to be some orders of magnitude beyond the capabilities of any propulsion concepts for which performance estimates are now possible.

Propulsion nozzle and actuator system employed therein

Abstract: A propulsion nozzle is described in combination with a gas turbine engine. The hot gas stream of the engine is discharged through the nozzle for forward propulsion, or may be discharged laterally thereof for reverse thrust. The nozzle is of the variable geometry, plug type wherein flaps are pivotal to vary the discharge and throat areas thereof for different flight conditions spanning subsonic and supersonic operation. The flaps for controlling discharge area are pivotally mounted on a frame which is longitudinally displacable to uncover ports in the sides of the pod or nozzle structure. The hot gas stream may then be laterally and forwardly discharged therethrough for reverse thrust. Axial movement of this frame is controlled by a set of first actuators. Pivotal movement of the flap is controlled by a set of second actuators. The first and second set of actuators are sequentially interconnected in such a fashion that both sets may be powered from a single source of pressurized hydraulic fluid through ''''hard'''' conduits. Valves are employed to enable independent operation of each set of actuators in providing the varying thrust capabilities of the nozzle.

Propulsion by impinging laser beams.

Abstract: Evaluation of the best mission performance of a 'photon sail' system using an impinging laser beam. The results of calculations of nondimensional time history of distance, velocity, and acceleration for propulsion by laser beam reflection are presented. These calculations show that propulsion by impinging laser beams is not competitive with advanced onboard propulsion concepts for missions in the solar system.

Dual thrust level monopropellant spacecraft propulsion system

Abstract: A flight auxiliary propulsion system for velocity trim, station keeping, momentum adjustment for a spacecraft comprising rocket or reaction motors, also designated thrusters, utilizing thermally decomposable monopropellants such as hydrazine and other derivatives, thereof hydrogen peroxide, and isopropyl nitrate. The thrusters are arranged in a distribution or manifold system so that one set of thrusters provides for relatively large thrusts of force in the order of 1 to 5 pounds and another set of thrusters develop low thrusts in the millipound range. The large thrusts are developed by the catalytic decomposition of the monopropellant into a thrust chamber and through a throat and expansion nozzle to the ambient externally of the spacecraft. The low level thrusts are developed by heating catalytically or thermally decomposed monopropellant by electrical heating elements more commonly known as resisto-jet elements. Dual thrust levels may also be achieved by a common motor with a controllable resisto-jet and variable throat-area control.

Gasoline engine and electric motor system for boats or the like

Abstract: A combination propulsion system for boats or the like is provided comprising a first, gasoline engine, a second, electric motor and means for coupling the motor to the engine whereby the electric motor may be reversed and used as a generator when the gasoline engine is running for recharging a battery.

Design and Performance of Bow Thrusters

Abstract: This paper concerns the hydrodynamic forces and moments produced by a bow thruster. Several broad problem areas are discussed and the extent of present-day knowledge indicated. These include general duct arrangement, duct shape, and impeller design. A step-by-step design procedure is outlined that permits the selection of a practical bow thruster. This procedure is described for a minimum number of operational requirements; e.g., single bow thruster, a specified turning rate when the ship is dead in the water, and a duty cycle that requires thruster operation at ahead speed for control capability in canals, harbors, and other restricted waterways. At the present time conventional circular transverse bow thrusters dominate the field of maneuvering propulsion devices (MPD) with respect to units installed. The literature on bow thrusters is replete with experimental and analytical data concerned with performance information and design criteria. Since many of these data can be generalized it is believed timely to review and tie together this information in one paper. The performance of some bow thrusters probably could have been improved if certain information and knowledge had been available during their design. This is especially true with regard to duct size and the importance of the free-stream velocity in relation to the thruster outflow velocity in determining the total body force. Many types of thrusters have been installed and proposed for consideration and development. Included are: single and multiple units installed near the ship's bow and/or stern, axial-flow propellers (embracing fixed pitch, controllable pitch, contrarotating), cycloida] propellers, and jet configurations such as ejector, ram, etc. In order to keep the present paper of reasonable length, emphasis is placed on the hydrodynamically applied forces and moments due to a single bow thruster duct with a single fixedpitch propeller (impeller). The combined action of multiple thruster units or coupling with rudder action is not considered. Such factors as wind, water current, ship motions, etc. that require a knowledge of ship particulars and ship response are not within the scope of the present paper. However, ship rotation rates that have been used satisfactorily in the past for bow thruster installations will be introduced. The paper presents and discusses: performance factors or parameters which describe or aid in the evaluation of thruster performance, the extent of present knowledge and design criteria as related to configuration arrangement, duct geometry, propeller design, added resistance at ahead s~ip speed, and interaction of thruster jet flow with the mainstream. Particular details encompassed in this paper are recommendations or criteria for the following design quantities: duct immersion, duct diameter, duct length, duct lip radius or shape, propeller hub-pod and fairwater effects, propeller blade shape, and propeller pitch-diameter ratio. A step-by-step design procedure which permits the selection of a practical bow thruster is outlined. This procedure is described for a minimum number of operational requirements; e.g., single bow thruster, a specified turning rate when the ship is dead in the water, and a duty cycle that requires thruster operation at ahead speed for control capability in canals, harbors, and other restricted waterways.

Inboard propulsion system for a boat

Abstract: An inboard propulsion system for a boat utilizing a water jet propulsion characterized by a pair of spaced nozzles each provided with individually controlled deflecting hoods to enable providing both a reverse thrust for backing the boat and to selectively reverse the water jet of a single nozzle to provide a turning force for steering the boat. Preferably, each of the nozzles is provided with a servo system which varies the effective opening of the nozzle in response to changes in the pressure differential between the intake pressure to the main impeller unit and the discharge pressure of the impeller unit to attempt to maintain a constant quantity flow from the nozzles independent or regardless of any variations in the intake pressure of the impeller unit.

Electronic power control and load rate circuit

Abstract: A control system for use in hybrid systems utilizing combustion engine, generator, and motor combinations for propulsion. The control system comprises a source of reference current for functional control of generator output and a circuit for bypassing a portion of the reference current away from the function controls in response to the position of an accelerator or brake pedal. The bypass circuit includes a capacitance network to generate a delay between any acceleration demands of the engine and a corresponding application of increased generator load, thereby eliminating engine bogging and reducing the production of smoke upon rapid increases of power demand. Potentiometers are adjustable to set the minimum idling speed of the engine and the maximum reference current to be applied for functional control. Fail safe circuitry is provided to assure that the system goes to a safe condition in the event of the failure of critical components.

Boat steering and reversing system

Abstract: A system for controlling the forward and reverse operation of a boat having a jet propulsion unit, which unit is mounted on the boat and swivelable to provide normal steering of the boat. Included is a mechanism for initiating a rapid turning of the propulsion unit through a turn of approximately one-half circle to redirect the force of propulsion forwardly and thus provide the reverse drive of the boat. The mechanism includes a means associated with the propulsion unit itself for generating and applying a turning moment of force or torque for reorienting it through the half-circle turn. A detent means is coupled to the unit and selectively positioned in the path of a stop mounted on the unit during its turning to retain it in either the forward or reverse operating position. The propulsion unit is of the thrust type in which a pressurized fluid flow is passed through a nozzle to provide the thrust force for propelling the boat.

Aircraft system lift ejector

Abstract: Apparatus and methods of operation are disclosed for combining high-energy primary flow fluid (normally a gaseous medium obtained from an aircraft system primary power plant or engine) and induced secondary flow fluid (ambient air) in the essentially conventional throat and diffuser sections of an ejector normally installed in an aircraft fixed wing, canard, or similar airfoil member to significantly increase ejector thrust augmentation ratio performance with a limited number of injection slots or openings of limited size to achieve high diffusion rates and substantially reduced propulsion energy losses attributed to flow resistance, flow backage, and flow separation, to permit ejector configurations of relatively small planform and relatively short diffuser lengths, to achieve apparatus stowability in conventional flight, to achieve design simplicity which allows variable geometry ejector for installation in aircraft system wing and canard airfoils, and to obtain other important aircraft system operating characteristics.

Comparison of the solar sail with electric propulsion systems

Abstract: The propulsive efficiencies of the solar sail and of electric propulsion systems are compared on the basis of specific impulse. It is shown that the solar sail is more efficient at one a.u. for mission durations greater than about two months, that the advantage is increased for missions toward the inner planets, and that the same conclusions are reached when the comparison is based on maximizing the momentum transferred to the payload. Other factors that will influence the choice of a propulsion system for a specific mission are mentioned.

Shoulder pack power unit for propelling water skis or surf boards

Abstract: A shoulder pack containing a light weight engine for propelling water skis or a surf board on which the operator stands, propulsion units being mounted under the skis or surf board and novel means being provided for operatively connecting the engine to the propulsion units with hand operated means for controlling the speed of the engine, thereby controlling the speed of the skis or surf board. The novel means that connects the engine to the propulsion units can be quickly disconnected from them for freeing the propulsion units and skis or surf board from the power pack when desired. I also provide novel means for quickly freeing the shoulder pack power unit from the back of the operator in case of an emergency and the power pack is so designed that it can float in water with the air intake to the engine and its exhaust pipes being positioned above the water surface so that the engine can still keep operating if desired. Automatic float controlled check valves prevent any entrance of water into the air intake or exhaust pipes and also prevent any spillage of gasoline into the water.

Prospects for Improvement in Efficiency of Flight Propulsions Systems

Abstract: A broad survey of aircraft gas-turbine propulsion trends is attempted, identifying the critical performance characteristics and indicating probable future improvements. Particular categories of propulsion system including those for V/STOL and supersonic transport aircraft are considered in more detail. Some discussion of special and multiple function powerplants is also included. Desirable engine characteristics for types of aircraft considered are discussed and problem areas identified. The powerplants are considered from the viewpoints of thermodynamics, noise and installation. Specific engine projects relevant to the survey are discussed.

Advanced Propulsion Concepts - Project Outgrowth

Abstract: : A study was conducted by an ad hoc group within the Air Force Rocket Propulsion Laboratory during the calendar year of 1970 in an attempt to predict the major propulsion developments that may occur in the next 30 to 40 years. The report evaluates the future of conventional chemical rocketry based on thermodynamic principles and revolutionary conceptual approaches to system applications. Advanced concepts falling under the general headings of Thermal, Field and Photon Propulsion are evaluated to a degree necessary to define their potential. The report does not define a long list of very near-term technology program subjects, but is designed to encourage and motivate talented and interested scientists and engineers to once again strive for advanced propulsion concepts.

Hydraulic front-wheel propulsion system for harvesting vehicles

Abstract: A hydraulic propulsion system utilized to propel and steer the front wheel of a harvesting vehicle under the control of a driver. The hydraulic system includes a manually operable forward-reverse-speed control mechanism, for selectively controlling a hydraulic motor which is operatively connected with the front wheel, as well as a foot-pedal operated steering mechanism whereby the driver can effectively control the propulsion of the vehicle and, at the same time, assist with the harvesting operation.

Propulsion requirements for communications satellites.

Abstract: The concept of characteristics thrust is introduced herein as a means of classifying propulsion system tasks related particularly to geosynchronous communications spacecraft. Approximate analytical models are developed to permit estimation of characteristic thrust for injection error corrections, orbit angle re-location, north-south station keeping, east-west station keeping, spin axis precession control, attitude rate damping, and orbit raising applications. Performance assessment factors are then outlined in terms of characteristic power, characteristic weight, and characteristic volume envelope, which are related to the characteristic thrust. Finally, selected performance curves are shown for power as a function of spacecraft weight, including the influence of duty cycle on north-south station keeping, a 90 degree orbit angle re-location in 14 days, and finally comparison of orbit raising tasks from low and intermediate orbits to a final geosynchronous station. Power requirements range from less than 75 watts for north-south station keeping on small payloads up to greater than 15 KW for a 180 day orbit raising mission including a 28.5 degree plane change.

Considerations in the design of drive systems for on-the-road electric vehicles

Abstract: The energy and power requirements of a class of on-the-road electric vehicles are developed, and acceleration and speed characteristics of such vehicles in urban traffic are discussed. Curves of average speed under different conditions of traffic are presented, as are curves of average power required during acceleration, average power required during cruising, and peak power required. A dc drive system for propulsion of such a vehicle and an ac drive system appropriate for such an application are described. The two kinds of system are then compared, on an economic as well as a technical basis. A procedure for designing an electric vehicle is outlined, pertinent fields in which research and development are needed are listed, and a reference list on electric vehicles is included.

Hydraulic propulsion unit

Abstract: Hydraulic propulsion apparatus particularly adapted for use on a marine vessel such as a barge comprises a propeller and hydraulic driving motor mounted at one end of the vessel for vertical adjustment and rotary steering movements The propeller is housed within a protective cage or shroud which normally extends below the level of the bottom of the vessel for engagement with the bottom of a shallow body of water whereupon the propeller may be adjusted vertically upwardly automatically A preferably hydraulically operated steering mechanism is connected to the propeller assembly for imparting rotary steering movements to the latter, the mechanism permitting vertical adjustment of the propulsion apparatus

Trajectory correction propulsion for TOPS

Abstract: A blowdown-pressurized hydrazine propulsion system was selected to provide trajectory correction impulse for outer planet flyby spacecraft as the result of cost/mass/reliability tradeoff analyses. Present hydrazine component and system technology and component designs were evaluated for application to the Thermoelectric Outer Planet Spacecraft (TOPS); while general hydrazine technology was adequate, component design changes were deemed necessary for TOPS-type missions. A prototype hydrazine propulsion system was fabricated and fired nine times for a total of 1600 s to demonstrate the operation and performance of the TOPS propulsion configuration. A flight-weight trajectory correction propulsion subsystem (TCPS) was designed for the TOPS based on actual and estimated advanced components.