Showing papers on "Propulsion published in 1976"

Flywheel drive system having a split electromechanical transmission

Abstract: A vehicle propulsion system including a split path, electromechanical transmission for use with a flywheel as a power source. One path comprises a mechanical drive train extending between the flywheel power source and the vehicle drive wheels or other power output. The other path comprises an electromechanical drive train of which the mechanical portion is shared with the mechanical drive train by virtue of a common planetary gear arrangement for dividing or combining the power transmitted from or to the flywheel. A battery may be included in the system to make up certain losses from operation and to provide the initial start-up power. A simplified control system is provided to control the transmission of power over the separate parallel paths.

High speed transit system

Abstract: A high speed ground transportation system, is suspended in an underground vacuum tube by a frictionless magnetic suspension system and propelled by gravity. The tubes are suspended inside deep underground tunnels from anchor points near each adjacent station and follow smooth catenary curves similar to the main suspension cables of a suspension bridge. Gravity propulsion is accomplished by allowing the vehicle to coast down the descending arc of the tube, during which time it is accelerated by gravity, and decelerating by gravitational braking while coasting up the tube's ascending arc. Thus, the trip is accomplished by transforming the vehicle's gravitational potential energy at one station into kinetic energy and back into gravitational potential energy at the next station. Excess kinetic energy arising from coasting between stations having different elevations is supplied or absorbed by on-board linear motor/generators that provide supplementary propulsion or regenerative braking. These linear motor/generators draw and return energy to an on-board flywheel kinetic energy storage system. Passenger and cargo transfer between the vehicle's interior and station is made without removing the vacuum environment of the vehicle, by providing air-locks through the tube walls at the station.

Supersonic combustion ramjet /scramjet/ engine development in the United States

Abstract: This survey of supersonic combustion ramjet (scramjet) engine development in the United States covers development of this unique engine cycle from its inception in the early 1960's through the various programs currently being pursued and, in some instances, describing the future direction of the programs. These include developmental efforts supported by the U.S. Navy, National Aeronautics and Space Administration, and U.S. Air Force. Results of inlet, combustor, and nozzle component tests, free-jet engine tests, analytical techniques developed to analyze and predict component and engine performance, and flight-weight hardware development are presented. These results show that efficient scramjet propulsion is attainable in a variety of flight configurations with a variety of fuels. Since the scramjet is the most efficient engine cycle for hypersonic flight within the atmosphere, it should be given serious consideration in future propulsion schemes

Combustion Measurements in Air Breathing Propulsion Engines. Survey and Research Needs

Abstract: —The current measurement needs of the jet engine combustion engineers and scientists are considered. An assessment is made of the potential of probe and optical technologies to meet them. In the first part, the available instrumentation are evaluated and compared for the following criteria: non-interfering access to the flow, specificity, accuracy, sensitivity, space and time resolution, and cost effectiveness. The flow properties of interest are: velocity, pressure, temperature and the components of the flow (N2, O2, CO2, H2O, CO, NO, NO2, OH, THC's and smoke). In the second part, the different needs of the development engineer, the combustor researcher and the fundamental combustion scientist are established separately. Desirable levels of measurement criteria are proposed for all three situations. Several experiments are suggested.

Bicycle propulsion and speed change means

Abstract: The invention relates to a novel propulsion means and first and second speed change means for a bicycle. The propulsion means comprises lever means adapted to be pumped up and down by the operator for driving the rear wheel of a bicycle through the speed change means, a propulsion wheel, and sprocket means.

Multi-bladed, high speed prop-fan

Abstract: A small diameter, highly loaded multiple bladed variable pitch propulsor having swept blades with thin advanced airfoil sections, integrated with a nacelle contoured to retard the airflow through the blades thereby reducing compressibility losses and designed to operate with a turbine engine and using a single stage reduction gear resulting in a high performance, lightweight propulsion system providing a substantial improvement in efficiency over the high bypass ratio turbofan engine.

Integrated divergent exhaust nozzle thrust reverser

Abstract: A relatively simple variable area divergent exhaust nozzle and low drag afterbody integrated with a target-type thrust reverser and used in conjunction with a convergent nozzle for application to the propulsion system of a high performance jet powered aircraft. Two or more aerodynamically shaped afterbody surfaces may be pivoted with a common actuation system to form: first an efficient nozzle-afterbody suitable for subsonic operation; second, a divergent nozzle-afterbody for efficient supersonic operation and; third, a target-type thrust reverser for in-flight or ground roll deceleration.

A report on the aerodynamic design and wind tunnel test of a Prop-Fan model

Abstract: Recent transport aircraft system studies have shown that the Prop-Fan propulsion system offers the potential for significant fuel savings over high bypass turbofans employing the same core engine technology for each. This important finding has encouraged more detailed study of the Prop-Fan aerodynamics and has led to NASA sponsorship of a wind tunnel research program to explore the projected high efficiency levels of advanced propeller configurations for 0.80 Mach number, high-altitude cruise operation. The aerodynamic design philosophy for the Prop-Fan model is discussed. The geometric characteristics and predicted performance of the wind tunnel model are presented. Finally, the preliminary test results are reviewed and compared to the performance goals originally projected.

Deformable plug for an aircraft engine exhaust nozzle

Abstract: A deformable plug for use within an aircraft engine exhaust nozzle system having thrust vectoring and thrust reversing capability, as well as the capability to vary the nozzle area thereby improving propulsion efficiency. This invention utilizes an exhaust nozzle passageway having a rectangular nozzle exit area with the aerodynamically shaped plug centrally located in the path of the engine exhaust gases. The portion of the plug extending aft of the nozzle exit plane comprises of a pair of oppositely facing flaps that can be actuated to provide thrust vector and thrust reversal control as desired. The portion of the plug extending forward of the nozzle exit plane provides for variable throat area control.

Design Considerations for Dynamically Positioned Utility Vessels

Abstract: Automatic stationkeeping alongside an offshore stucture represents a particularly demanding requirement for a dynamically positioned utility vessel. The adequacy of existing conventional position determination methods is reviewed and the potential of new, but unproven, radar-ranging techniques is discussed. The effects of utility vessel drag, mass, and propulsion characteristics on stationkeeping performance are described and compared to "ballpark" requirements anticipated for positioning alongside both stationary and floating platforms.

Flight experience with a digital integrated propulsion control system on an F-111E airplane

Abstract: A digital integrated propulsion control system (IPCS) installed in the left side of an F-111 E aircraft was tested in flight. The F-111 aircraft was selected for the IPCS program because it incorporated a variable geometry inlet and an afterburning turbofan engine and had two engines, one of which could remain in the normal configuration to ensure flight safety. Flight data were compared with results of tests run in an altitude test chamber. The digital system was found to be capable of duplicating the standard engine and inlet control systems. Instabilities such as inlet buzz and afterburner rumble were detected and controlled. The usefulness of an altitude chamber for developing a software and testing hardware was proven. The flexibility of IPCS was demonstrated when an autothrottle, an in-flight thrust calculation, and a coannular noise study capability were added at the end of the flight tests.

Marine propulsion system

Abstract: A jet propulsion system for boats in which the thrust force center line is below the boat reaction center line to urge the propulsion system thrust line to tilt downwardly The tilting of the propulsion system thrust line downwardly lifts the stern of the hull to create a suitable vertical vector As a consequence thereof, the boat is urged into a planing position for the reduction of drag on the boat in the lower speed range At the higher speeds, dynamic water pressure reacts on the intake to urge the tilting of the thrust force center line upwardly toward a horizontal position to reduce the depth of the bow of the boat submerged in water for reducing the drag on the boat A tension spring controls the angle of the tilting of the thrust force center line to attain the changeover at a selected speed for optimum operation

F100 Multivarible Control System Engine Models/Design Criteria.

Abstract: : The objective of the F100 multivariable Control research program is to extend the linear quadratic regulator (LQR) theory to develop a 'practical' control system that can operate a state-of-the-art gas turbine engine over its entire flight envelope. The engine selected for this program is a Pratt and Whitney Aircraft F100 afterburning turbofan. To determine the adequacy of the control synthesis effort, the resulting control logic will be incorporated into a digital computer/controller, which then will be used to control a F100 engine in an altitude test facility at NASA Lewis Research Center. The F100 engine computer simulations, the control criteria for defining the basic requirements of a F100 control system, and a brief evaluation of the resulting LQR engine control system are presented in this report.

Optimal low-thrust orbital rendezvous

Abstract: The minimum propellant optimal rendezvous maneuver of two cosmic vehicles on circular and elliptical orbits is examined. It is assumed that the target without propulsion moves on an orbit around the Earth or other planets as a satellite, and the tracking vehicle with variable thrust propulsion moves on a close orbit. The problem of the determination of the optimal laws of variation which characterize the minimum propellant orbital rendezvous is formulated as an extremum variational problem with constraints, where the linear motion equations of the tracking vehicle are considered. On the basis of the optimal laws established in this manner numerical applications of practical interest are carried out.

Survey of Methods for Exhaust-Nozzle Flow Analysis

Abstract: accurate prediction of the range, payload, and operational economy of conventional, V/STOL, and supersonic jet aircraft, accurate knowledge of the velocity and discharge coefficients of the exhaust nozzle and the variation of these coefficients with nozzle pressure ratio is required. The need for high accuracy has become increasingly important because of the higher gross-to-net thrust ratios of today's high-bypass ratio turbofan engines and tomorrow's advanced supersonic jet engines. These high gross-to-net thrust ratios have the effect of greatly magnifying errors made in the prediction of the nozzle velocity coefficient. For example, studies of a Mach 2.2 supersonic transport aircraft conducted at the Douglas Aircraft Company have shown that a 1% variation in the nozzle thrust coefficient results in a 3.1% change in the direct operating cost of the airplane and a 2.3797o change in the specific fuel consumption. Thus, the analytical calculations that are used to provide initial design information, to guide the modification of existing nozzles, and to identify geometries for detailed experimental testing must be as accurate as possible. In addition, the wide variety of nozzle configurations that are now being considered dictates that the analytical methods must be flexible in the geometries that they can handle, and economic constraints dictate that the methods must be fast from the standpoint of computer time. In order to have a chance of developing an analytical method with good computational economy, it is necessary to exclude from consideration those phenomena which exercise a secondary effect on nozzle performance. Therefore, unless specifically mentioned, the methods considered in this paper will be restricted to those capable only of solving the problems of two-dimensional (planar or axisymmetric) isentropic (inviscid and shock-free) flow of a perfect gas. Because of the high pressure ratios at which modern jet engines operate, it is necessary that analytical methods be capable of handling mixed flows, that is, flows in which both subsonic and supersonic flow regions are present. Methods that are capable of treating such problems are commonly called transonic flow methods because there are regions where the flow is sonic and near sonic. Because nozzle analysis methods must have this capability, the method of characteristics will not be discussed (since it is limited to supersonic flows), nor will methods that are appropriate only for subsonic flows (such as the methods of classical hydrodynamics). Despite the mixed (subsonic-supersonic) nature of the flowfield, much progress has been made in recent years in the development of methods of solution appropriate for propulsion nozzle analysis. As an indication of this, the recent bibliography of Newman and Allison can be cited which, although restricted to external transonic flow problems, contains over 650 entries. Indeed one finds, as eloquently expressed by Murphy^ that " methods of obtaining numerical solutions of the equations of fluid flow have proliferated to the point where the number of different methods nearly equals the number of active workers in the field." Clearly against such a background, it is impossible to pretend that the survey presented here is complete. It is not the intention nor even the inclination of the authors to present a complete listing of all transonic nozzle analysis methods. The purpose of this survey, rather, is to classify and present critical com-

Marine propulsion plant with reversible propeller shaft connected thereto

Abstract: When reversing a marine power plant, due consideration must be given to the fact that the inertia of the ship will continue to force the ship through the water during a moment of time after the shut down of the prime mover, with the propeller then acting as a water turbine tending to rotate the propeller shaft in the same direction as before. If the propulsion plant includes a gas turbine and a reversing gear, the reversing gear is designed in such a manner that the part thereof connected to the turbine will represent, in use, a smaller inertia than the part connected to the propeller shaft, with the propeller shaft together with the propeller attached thereto representing a considerable rotating body. By suitable selection of the means engaging the parts of the reversing gear in their respective working positions for ahead and astern running, respectively, it will be possible to disengage the turbine part of the gear, to brake this part and then to re-engage the gear parts in their new relative position, thereafter braking the propeller connected part by the power of the turbine and finally bringing the whole system to rotate in the desired direction.

Device for control of an aircraft

Abstract: Control apparatus for an aircraft is provided which includes a gas-controlled housing disposed downstream of a gas turbine jet propulsion supply system. A propulsion nozzle is provided at the downstream end of a tubular member extending from the control housing in alignment with a longitudinal axis of the engine system. Lateral control outlets extend in opposite lateral directions from the gas-controlled housing. The flow of gases selectively to one or both of the control outlets and to the propulsion nozzle is effected by way of two part-spherical sector control valve members which are mounted for pivotal movement about an axis running perpendicular to the longitudinal axis. The control valve members are configured for selectively blocking the flow of propulsion gases to the propulsion nozzle and the respective lateral control outlets.

Development of a Five-Pound Thrust Bipropellant Engine

Abstract: The subject program advanced the technology for high-performance, rapid response, long-lived bipropellant engines in the 5-lb. thrust class. The results of design and development activities and the fire testing of fast response (0.005 sec), high-performance (300 sec 75p), 5 IbF bipropellant (N2O4/MMH) engines to obtain performance and life durability data are presented. Data were obtained from over 17,000 sec of firing duration and over 400,000 engine starts. Steady-state and pulsing performance, and engine response data were obtained over a range of tank pressures and at environmental temperatures ranging from 20-120° F. Thermal characteristics and heat rejection rates were experimentally evaluated as injector and chamber designs were varied. Simulated duty cycles were demonstrated with three engines. These data were utilized in the forecast of engine life and reliability and the assessment of exhaust plume contamination. Background P RIOR to 1963, few spacecraft missions required the injection of a payload into orbit. Furthermore, there was little need or room for an onboard propulsion system as part of an orbiting package. During the period 1963 to 1968, payload weights increased and a need for station-keeping developed as mission goals became more ambitious. Reaction control systems employed catalytic decomposition of hydrogen peroxide and/or cold gas jets. The instability of the hydrogen peroxide under storage and the need for pressure relief valves made the reliability of this system inherently low.

Future earth orbit transportation systems/technology implications

Abstract: Assuming Space Shuttle technology to be state-of-the-art, projected technological advances to improve the capabilities of single-stage-to-orbit (SSTO) derivatives are examined. An increase of about 30% in payload performance can be expected from upgrading the present Shuttle system through weight and drag reductions and improvements in the propellants and engines. The ODINEX (Optimal Design Integration Executive Computer Program) program has been used to explore design options. An advanced technology SSTO baseline system derived from ODINEX analysis has a conventional wing-body configuration using LOX/LH engines, three with two-position nozzles with expansion ratios of 40 and 200 and four with fixed nozzles with an expansion ratio of 40. Two assisted-takeoff approaches are under consideration in addition to a concept in which the orbital vehicle takes off empty using airbreathing propulsion and carries out a rendezvous with two large cryogenic tankers carrying propellant at an altitude of 6100 m. Further approaches under examination for propulsion, aerothermodynamic design, and design integration are described.

Improving aircraft energy efficiency

Abstract: Investigations conducted by a NASA task force concerning the development of aeronautical fuel-conservation technology are considered. The task force estimated the fuel savings potential, prospects for implementation in the civil air-transport fleet, and the impact of the technology on air-transport fuel use. Propulsion advances are related to existing engines in the fleet, to new production of current engine types, and to new engine designs. Studies aimed at the evolutionary improvement of aerodynamic design and a laminar flow control program are discussed and possibilities concerning the use of composite structural materials are examined.

Hydrodynamic transmission for ship propulsion

Abstract: The present invention relates to a hydrodynamic transmission for ship propulsion comprising a prime mover driving an axial flow pump in combination with an open, water-powered turbine for driving propeller blades. The power plant and the propeller are not mechanically connected, and power is transmitted through the hydrodynamic transmission. The invention also provides for a thrust-reversing mechanism specially adapted to the hydrodynamic transmission described herein.

Sonic responsive toy vehicle steering system

Abstract: The present invention relates to a toy vehicle provided with a chassis, a propulsion and guidance wheel mounted to the chassis for rotation to propel the vehicle along a surface and for turning to steer the vehicle, a propulsion mechanism within the chassis, a system for operatively connecting the wheel and the propulsion mechanism to rotate the wheel to propel the vehicle, a system for sensing predetermined sound waves and temporarily connecting the propulsion mechanism to the wheel to turn the wheel to steer the vehicle, and a handheld sound wave generating unit remote from the vehicle for generating the sound waves.

Series waterjet propulsion pumps for marine vehicles

Abstract: A waterjet propulsion system having at least two pumps in series so that low from a hull or other intake is directed through a first waterjet propulsion pump; and then via a two-position diverter valve, either out to a thrust nozzle, or to and through a second waterjet propulsion pump having a thrust nozzle. Subsequent series-pump units and diverter valves may follow to provide as many propulsion stages as required for power requirements. Each pump unit is driven by its own power unit which may be shut down when flow is diverted to the preceding unit's thrust nozzle. Good efficiencies are thereby attained over a wide range of power and speed requirements.

Development of an 8-cm engineering model thruster system

Abstract: Electric propulsion has been shown to offer major advantages over the techniques currently employed for the control of earth satellites. For a user to realize these advantages, however, requires the availability of a proven, operationally flight-ready propulsion system. Currently an Engineering Model of an 8-cm ion thruster propulsion system is under development. The system includes the thruster unit with its associated reservoir, thruster gimbaling subsystem, and power processing unit. This paper describes the EM System with special emphasis on hardware design and system performance.

Device for controlling boat speed

Abstract: Relates to attachments to a motor boat for reducing the speed of the boat below the idling speed sufficient to permit trolling for fish. The speed controlling device includes a plate member mounted for movement from a vertical position immediately aft of the propeller and across the path of the propeller wash, thereby to slow the speed of the boat, to a second position away from the propeller and out of the path of the propeller wash. Hydraulic mechanism including a piston-cylinder combination unit is connected to a fixed support, such as the propulsion unit of the boat, and to the plate member for moving the latter between the aforesaid two positions of movement. Ports are provided in the cylinder for admitting fluid under pressure to either side of the piston to impart movement of the piston in either direction in the cylinder and to impart corresponding movement to the plate member. A rotary hydraulic pump is driven by a reversible electric motor to provide not only the source of fluid pressure for moving the piston plate member but also the port in the cylinder into which the fluid pressure is introduced for determining the direction of movement of the piston. A three-position electric switch is provided for controlling the operation of the electric motor either in one or the other of its two directions of rotation or for rendering the motor inoperative.

Solid Propellant Pulsed Plasma Propulsion System Design

Abstract: Fundamental definitions, a few semiempirical correlations of experimental data, and two design constraints of solid propellant-pulsed plasma thrusters are used to illustrate the design analysis of such an electric propulsion system. The semiempirical relations presented have been generated from thruster data covering impulse bits extending from 2.7 dyne-sec (6/i Ib-sec) to 31 mN-sec (7 mlb-sec) and a specific impulse up to 5100 sec. They are descriptive to within about 8%.

Electron bombardment propulsion system characteristics for large space systems

Abstract: The results of an anlaysis of electron bombardment ion propulsion systems for use in the transportation and on-orbit operations of large space systems are presented. Using baseline technology from the ongoing primary propulsion program and other sources, preliminary estimates of the expected characteristics of key system elements such as thrusters and propellant storage systems were performed. Projections of expected thruster performance on argon are presented based on identified constraints which limit the achievable thrust and/or power density of bombardment thrusters. System characteristics are then evaluated as a function of thruster diameter and specific impulse.