Abstract: Biomimetic fish-like propulsion using polyelectrolyte ion-exchange membrane metal composites as a propulsion fin for a robotic swimming structure, such as a boat swimming in water medium, was investigated. The membrane was chemically plated with platinum. The resulting membrane was cut in a strip to resemble fish-like caudal fin for propulsion. A small function generator circuit was designed and built to produce approximately /spl plusmn/2.0 V amplitude signal at desired frequency up to 50 Hz. The circuit board was mounted on a buoyant Styrofoam shaped like a boat or a tadpole. The fin was attached to the rear of the boat. By setting the signal frequency to the desired value and thereby setting the frequency of bending oscillation of the membrane, a proportional forward propulsion speed could be obtained. The speed was then measured using a high speed camera. Several theoretical hydrodynamic models were then presented to characterize speed-frequency of the forward motion using available theories on biological fish motion. The results were compared to experimental data which showed close agreement.

Abstract: At the MIT Sea Grant College Program, Autonomous Surface Craft (ASCs) have been under development since 1993. An ASC is a small vessel outfitted with navigation and control systems which permit it to carry out functions autonomously. The first ASC developed was the ASC ARTEMIS, which was used to study command and control architectures, navigation systems, and basic data collection techniques. This vehicle successfully demonstrated the ability to operate autonomously and collect hydrographic data. ARTEMIS served well as a test platform but its small size made it unsuitable for coastal and open ocean research. Cruising speed, range, payload, and stability were all improved in the second generation ASC platform. The ASC ACES (Autonomous Coastal Exploration System) will provide better cruising speed, significantly more payload, longer mission endurance, and better seakeeping characteristics when compared to ARTEMIS. This was achieved within the primary design constraint of a 300 pound maximum weight chosen so that ACES could be easily deployed by a two member operations team. This paper describes the development of ACES. The challenge of designing a small lightweight platform with the required performance is explained and the solution implemented on ACES is described. Primary components of the design described include the hull and structural members, propulsion and power systems, and steering systems.

Abstract: The optimum mission performance is addressed, and a simple, robust, multivariable  ight-guidance law for following the prescribed optimum trajectory of an airbreathing, single-stage-to-orbit launch vehicle is proposed. Discussion focuses on the critical scramjet-powered phase of  ight for a hydrogen-fueled vehicle. The performance analysis,basedonenergy-statearguments,suggests that,whereas stationkeeping andorbitalmaneuverswill clearly require rocket propulsion, low-Earth-orbital energy can be achieved with scramjet propulsion. The feedback guidance law for trajectory following is also synthesized using total-energy concepts, along with an approach consistent with quantitative feedback theory. The open-loop system in the guidance analysis is multivariable, unstable, andnonminimumphase. Furthermore, the vehicle characteristics lead to signiŽ cant interactions between the inputs and responses. The guidance law developed relies on an integrated  ightand propulsion-control inner loop to stabilize the attitude dynamics and regulate the engine performance. It is shown that this hierarchical integrated synthesis technique yields simple, classical-looking compensation that robustly stabilizes the system and delivers very good performance.

Abstract: A fuel cell engine for a vehicle comprises at least one fuel cell stack for producing electric power from a fuel and an oxidant, a propulsion motor, for propelling the vehicle. The propulsion motor is connected to receive electric power from the at least one fuel cell stack and is operatively connected to mechanically drive a device for directing a fluid stream into the fuel cell stack. In preferred embodiments the propulsion motor is operatively connected to drive a device for directing at least one reactant fluid stream into the fuel cell stack.

Abstract: Production and trapping of small numbers of antiprotons for space applications are feasible, setting the stage for antiproton-catalyzed microfission/fusion (ACMF) reactions as a source of propulsive power. A spacecraft designed around an ACMF engine has been designed. Details, including Isp, thrust, structural features, power systems, radiation shields, ion drivers, payload and system masses, will be reviewed. Staging of the spacecraft in space, including requisite propulsion and trajectory parameters and scientific goals for aggressive (Isp=10,000 sec, thrust=150 kN, ΔV=100 km/sec) outer solar system and extraplanetary missions will be discussed.

Abstract: Electrostatic propulsion systems for spacecraft include a plurality of electrostatic thrusters that are continuously coupled to power forms of a power supply system Ionizable gas is fed to a selected one of the thrusters to selectively initiate the thrust of that electrostatic thruster In other embodiments, heater power forms are coupled only to the selected thruster to reduce power consumption and increase cathode lifetime The propulsion system has a reduced complexity and is especially suited for spacecraft in which only one thruster is ever fired at a given time

Abstract: The invention relates to an engine control system for an internal combustion engine for propulsion of an associated watercraft. The engine includes an air intake in communication with a combustion chamber of the engine and an air intake adjustment means for altering the amount of air let into the combustion chamber of the engine. There is also an operation device controlling a water propulsion device of the watercraft. The device is movable between a forward, a neutral or a reverse position. A first control means for controls the air intake adjustment means based upon the position of the movable operating device. A second control means controls the air intake adjustment means independent of the first control means based upon a set of predetermined conditions.

Abstract: An intelligent control system for reusable rocket engines is under development at the NASA Lewis Research Center. The primary objective is to extend the useful life of a reusable rocket propulsion system while minimizing flight maintenance and maximizing engine life and performance through improved control and monitoring algorithms and additional sensing and actuation. The main result of this work is the successful integration and real-time demonstration of model-based fault detection with a reconfigurable control as a new technique for valve fault accommodation on a reusable rocket engine. The focus here is on detecting and accommodating a frozen (stuck in a fixed position) oxidizer valve during a down-thrust and up-thrust manoeuvre by examining fault parameters produced by the algorithm. The detection scheme estimates the position of the frozen valve as a function of the fault parameters. Real-time simulation results demonstrate the effectiveness of the approach for two fault scenarios during a typical throttling manoeuvre.

Abstract: An environmentally compatible propulsion system for low maintenance and long term durations at high altitudes is provided which is capable of utilizing high altitude ambient gas as fuel and producing ozone as a by-product of propulsion. The ion engine propulsion system ionizes a portion of an ambient atmospheric fuel to create a negative ionic plasma for bombarding and accelerating the remaining portion of the ambient atmospheric gas in a focused and directed path to an ion thruster anode. The novel ion engines provided create a negative ionic plasma between a cathode ion thruster and a ring-shaped anode in a housing composed of an electrical insulative material in which the cathode ion thruster is charged to -18 to -110 kilovolts (kv) to utilize ambient atmospheric gas as the propellant.

Abstract: A self-propelled, walk-behind traction vehicle includes a power source, a pair of drive wheels and an improved operator-manipulated drive control mechanism for selectively coupling the drive wheels to the power source in a manner that allows the operator to control propulsion and steering of the vehicles. The drive control mechanism includes a friction drive unit having a pair of reversible, variable speed transmissions associated with respective ones of the drive wheels for selectively coupling the drive wheels to the power source. The control mechanism further includes a pair of independently swingable control handles configured to be gripped by the operator and operably coupled to respective ones of the transmissions so that the speed and direction of rotation of each of the drive wheels is controlled by swinging a respective one of the handles.

Abstract: Electrolysis propulsion has been recognized over the last several decades as a viable option to meet many satellite and spacecraft propulsion requirements. This technology, however, was never used for in-space missions. In the same time frame, water based fuel cells have flown in a number of missions. These systems have many components similar to electrolysis propulsion systems. Recent advances in component technology include: lightweight tankage, water vapor feed electrolysis, fuel cell technology, and thrust chamber materials for propulsion. Taken together, these developments make propulsion and/or power using electrolysis/fuel cell technology very attractive as separate or integrated systems. A water electrolysis propulsion testbed was constructed and tested in a joint NASA/Hamilton Standard/Lawrence Livermore National Laboratories program to demonstrate these technology developments for propulsion. The results from these testbed experiments using a I-N thruster are presented. A concept to integrate a propulsion system and a fuel cell system into a unitized spacecraft propulsion and power system is outlined.

Abstract: Failures of aircraft primary flight-control systems to aircraft during flight have led to catastrophic accidents with subsequent loss of lives (e.g. , DC-1O crash, B-747 crash, C-5 crash, B-52 crash, and others). Dryden Flight Research Center (DFRC) investigated the use of engine thrust for emergency flight control of several airplanes, including the B-720, Lear 24, F-15, C-402, and B-747. A series of three piloted simulation tests have been conducted at Ames Research Center to investigate propulsion control for safely landing a medium size jet transport which has experienced a total primary flight-control failure. The first series of tests was completed in July 1992 and defined the best interface for the pilot commands to drive the engines. The second series of tests was completed in August 1994 and investigated propulsion controlled aircraft (PCA) display requirements and various command modes. The third series of tests was completed in May 1995 and investigated PCA full-flight envelope capabilities. This report describes the concept of a PCA, discusses pilot controls, displays, and procedures; and presents the results of piloted simulation evaluations of the concept by a cross-section of air transport pilots.

Abstract: Within the frame of the Future European Space Transportation Investigations Programme (FESTIP) technology developments on rocket and air breathing propulsion for reusable launch vehicles are presently being prepared by the European propulsion industry. In the FESTIP System Study [1] different reusable rocket-propelled vehicle concepts have been analysed. Based on the results of these investigations different reference high performance rocket engine concepts have been defined serving as a baseline for the technology work on engine component level initiated in this programme:

Abstract: A toy vehicle has a chassis, two axles, two pairs of wheels and four identical wheel support housings. Each wheel is mounted on a separate end of a separate one of the two axles by one of the wheel support housings. The wheels are mounted for rotation on the housings, which are mounted off center on the axles so as to rotate eccentrically around the axles with the wheels. Wheels on either lateral side of the chassis are driven by separate propulsion motors driving separate gear trains in the chassis to propel the vehicle. Collars around the axles and pairs of gears within the wheel support housings themselves couple the wheels with the gear trains. The axles are rotated together through a third shaft driven by a separate accessory motor to vary the eccentric position of the wheel support housings and thereby alter the appearance and performance of the vehicle. Slip clutches with angled, mating faces, effectively coupling the axles with the third shaft. The faces are spring biased together and remain engaged over limited ranges of angular movement. This permits each slip clutch to act as a suspension for the wheel support housings and the wheels supported on each axle protecting those downstream drive components from being overloaded and broken. The clutches further permit alteration of the phase between the wheel axles. Independent radio control of an accessory motor and two propulsion motors is provided.

Abstract: An electric vehicle propulsion system having a motor with first and second electrically isolated windings and a system control unit for controlling the motor, wherein the system control unit includes a first power bridge for driving the first windings and a second power bridge for driving the second windings.

Abstract: An auxiliary propulsion system for a boat or other marine vessel according to the invention incorporates an electric motor/transmission device (12) for generating locomotive force to propel the boat or vessel, an electrical power supply (27) for providing electrical energy to drive the electric motor/transmission device (12), at least one electrical energy generating device (24a, 24b) for generating electrical energy through conversion from one of at least sunlight, wind motion and water motion, a charging circuit (22) having means (22c) for controlling charging of the power supply with electrical energy from the energy generating device, and means (16) for controlling speed and direction operation of the electric motor/transmission device. In operation, electrical energy is inputted into the electric motor/transmission device from the electrical power supply and locomotive force is thereby generated by the electric motor/transmission device when the primary propulsion system of the boat or other marine vessel is inactive. Electrical energy to be stored in the electrical power supply is generated by converting at least one of sunlight, wind motion and water motion into electrical energy.

Abstract: In recent years, research in the propulsion and maneuvering mechanisms used by fish has demonstrated the utility of biopropulsion for use on undersea vehicles. Despite recent advances in unmanned undersea vehicle (UUV) technology, little progress has been made in improving propulsive efficiency and maneuverability. Most underwater vehicle designs employ a conventional propeller as the main propulsor and shrouded thrusters and/or control fins for maneuvering. Two types of vehicle designs are prevalent: torpedo shaped bodies streamlined for speed and range, or box-shaped bodies designed for maneuvering and station keeping. Unfortunately, most future UUV missions require all of these capabilities: high transit speed, long range/duration, maneuverability and station keeping ability. Thus we look to fish as a potentially optimal UUV design in that they are able to cruise great distances at significant speed, maneuver in tight spaces and accelerate and decelerate quickly. This paper summarizes the relevant design issues and current work in the development of a flexible-hull UUV which propels and maneuvers like a fish. Following the morphology and kinematics of a yellowfin tuna, the Charles Stark Draper Laboratory Vorticity Control UUV (VCUUV) will be the first demonstration of a freely swimming Thunniform (tuna-like motion) robotic vehicle. Simulation of the required kinematics and loads indicate that Thunniform motion can be actuated with a r ind forebody comprising 60% of the total vehicle len~h and four rind links actuating the tail section and caudal fin. Three different actuation concepts were compared by analyzing possible components and arrangements to attain the required loads and mission duration. A recirculating hydraulics concept was chosen for prototyping due to the versatility of the design for study of a variety of swimming speeds and maneuvers. 82 Fish swimming, vorticity control, tuna, unmanned undersea vehicle (UUV). ROV INTRODUCTION Improvements in propulsive efficiency and maneuverability of unmanned undersea vehicles (UUV's) are necessary to achieve the challenging new missions in littoral zone warfare, mine reconnaissance and scientific missions in cluttered environments. Increasingly sophisticated (and power intensive) mission payloads, and the need for greater range and endurance compete for finite energy supplies on board UUV's. Improved propulsive efficiency and energy capacity will directly increase mission time and reduce the launch and recovery overhead. More work may be done in a vehicle deployment: a larger area may be surveyed, or perhaps more time may be spent in one location studying a site of interest. Even modest increases in mission duration will directly improve mission performance. Maneuverability has been a particularly vexing problem for underwater vehicle desig'ners. There are two common actuators for

Abstract: Wheelchair propulsion kinetic measurements require the use of custom pushrim force/moment measuring instruments which are not currently commercially available. With the ability to measure pushrim forces and moments has come the development of several dynamic metrics derived for analyzing key aspects of wheelchair propulsion. This paper presents several of the equations used to calculate or derive the primary variables used in the study of wheelchair propulsion biomechanics. The uncertainties for these variables were derived, and then numerically calculated for a current version of the SMART/sup Wheel/. The uncertainty results indicate that the SMART/sup Wheel/ provides data which has better than 5 to 10% uncertainty, depending upon the variable concerned, at the maximum, and during most of the propulsion phase the uncertainty is considerably smaller (i.e. approximately 1%). The uncertainty analysis provides a more complete picture of the attainable accuracy of the SMART/sup Wheel/ and of the degree of confidence with which the data can be recorded. The derivations and results indicate where improvements in measurement of wheelchair propulsion biomechanical variables are likely to originate. The most efficient approach is to address those variables in the design of the system which make the greatest contribution to the uncertainty. Future research will focus on the point of force application and examination of nonlinear effects.

Abstract: A rocket propulsion system for spacecraft achieves greater economy, reliability and efficiency rocket by incorporating monopropellant RCS thrusters (1a-1f) for attitude control and bipropellant SCAT thrusters (5a-5c) for velocity control. Both sets of thrusters are designed to use the same liquid fuel, supplied by a pressurized non-pressure regulated tank, and operate in the blow down mode. In the propulsion system such station keeping and attitude control thrusters may function in conjunction with a large thrust apogee kick engine, which may also be of the SCAT thruster construction, that uses the same propellent fuel. Hydrazine and Binitrogen tetroxide are preferred as the fuel and oxidizer, respectively. The new system offers a simple conversion of existing monopropellant systems to a high performance bipropellant dual mode system without the extreme complexity and cost attendant to a binitrogen tetroxide--hydrazine bipropellant system.

Abstract: A hybrid motor vehicle utilizing electric motor propulsion prior to cruise mode detection condition and internal combustion engine propulsion during cruise mode. The hybrid motor vehicle utilizing an information super highway for system diagnostics or operating mode control as between powering the hybrid motor vehicle by electric motor or internal combustion engine. The exhaust manifold external surface temperature may be utilized to heat a catalyst for processing ambient air surrounding the vehicle.

Abstract: Analyses were conducted which indicate that sub kW-class ion thrusters may provide performance benefits for near-Earth space commercial and science missions. Small spacecraft applications with masses ranging from 50 to 500 kg and power levels less than 0.5 kW were considered. To demonstrate the efficacy of propulsion systems of this class, two potential missions were chosen as examples; a geosynchronous north-south station keeping application, and an Earth orbit magnetospheric mapping satellite constellation. Xenon ion propulsion system solutions using small thrusters were evaluated for these missions. A payload mass increase of more than 15% is provided by a 300-W ion system for the north-south station keeping mission. A launch vehicle reduction from four to one results from using the ion thruster for the magnetospheric mapping mission. Typical projected thruster performance over the input power envelope of 100-300 W range from approximately 40% to 54% efficiency and approximately 2000 to 3000 seconds specific impulse. Thruster technologies required to achieve the mission-required performance and lifetime are identified.

Abstract: The gasdynamic fusion propulsion system utilizes a simple mirror magnetic geometry in which a highdensity plasma is cone ned long enough to generate fusion energy while ejecting charged particles through one end to generate thrust. At high densities the collision mean free path becomes much shorter than the length, making the plasma behave much like a continuous medium, a e uid. Under these conditions the escape of the plasma is analogous to the e ow of a gas into a vacuum from a vessel with a hole. With the mirror serving as a magnetic nozzle the plasma-charged particles are ejected at very high energies, giving rise to specie c impulses of well over 200,000 s, but at modest thrusts because of the smallness of their mass. We examine methods by which the thrust of this engine can be enhanced. On the one hand we explore the use of a hydrogen propellant that is heated by the radiation emanating from the plasma, which, upon exhausting through a nozzle, generates the additional thrust. On the other hand we focus purely on changing the properties of the injected plasma to achieve the same objectives. We e nd in the case of a deuterium‐ tritium plasma that the use of hydrogen results in a degradation of the propulsive capability of the system, but we e nd it quite suitable for an engine that burns a mixture of deuterium and helium 3. The same results can be achieved by simply increasing the density of the injected plasma without encountering major adverse consequences. Because of engineering considerations, however, the use of a hydrogen propellant may prove to be inevitable if no other means are found to protect the walls of the reactor chamber against large heat loads.

Abstract: Introduction In Chapters 5–8, various control laws were presented for attitude stabilization and maneuvering. The hardware used to implement the control laws were principally momentum exchange devices as well as magnetic and solar torque controllers. Such controllers work in a linear continuous mode. The torques that they can provide are in the range of 0.02–1 N-m for momentum exchange devices, 10 −2 –10 −3 N-m for magnetic torque controllers, and 10 −5 –10 −6 N-m for solar torque controllers. This form of attitude control has two major disadvantages. First, the speed of attitude maneuvering is limited by the low-level maximal torques that can be delivered to the ACS. The second but no less important difficulty was encountered in orbit-maneuvering tasks. The high-level liquid thrusters (or solid propulsion motors) used for orbit changes induce parasitic torques due to physical irregularities of the propulsion system. The level of induced parasitic torques is of the order of several newton-meters. The only way to control the attitude of the spacecraft under such disturbance conditions is to use reaction thruster controllers (see also Section 8.8). Reaction thrusters used in attitude control are activated in a pulsing mode only. There are no linear, continuous reaction thrust controllers. This fact somehow complicates the analytical treatment of attitude control systems using them as torque controllers. However, they can provide almost any torque level, as surveyed in Appendix C. Reaction torque levels ranging between 0.01 N-m and 30 N-m are very common in most spacecraft. For practical considerations, it is convenient to use thrusters of the same thrust level for all control tasks in the satellite, but if this is not feasible then thrusters with different thrust levels can be incorporated as part of a unified propulsion system. This chapter deals with the analysis and design of reaction thruster attitude control. It also covers two principal difficulties caused by the pulsing mode of thruster firing: the limits on attitude accuracy that can be achieved with a given thruster, and the fuel penalty associated with sensor noise.

Abstract: Two RL10A-3-3A rocket engines comprise the main propulsion system for the Centaur upper stage vehicle. Centaur is used with bod Titan and Atlas launch vehicles, carrying military and civilian payloads from high altitudes into orbit and beyond. The RL10 has delivered highly reliable service for the past 30 years. Recently, however, there have been two in-flight failures which have refocused attention on the RL10. This heightened interest has sparked a desire for an independent RL10 modeling capability within NASA and th Air Force. Pratt & Whitney, which presently has the most detailed model of the RL10, also sees merit in having an independent model which could be used as a cross-check with their own simulations. The Space Propulsion Technology Division (SPTD) at the NASA Lewis Research Center has developed a computer model of the RL10A-3-3A. A project team was formed, consisting of experts in the areas of turbomachinery, combustion, and heat transfer. The overall goal of the project was to provide a model of the entire RL10 rocket engine for government use. In the course of the project, the major engine components have been modeled using a combination of simple correlations and detailed component analysis tools (computer codes). The results of these component analyses were verified with data provided by Pratt & Whitney. Select modeling results and test data curves were then integrated to form the RL10 engine system model The purpose of this report is to introduce the reader to the RL10 rocket engine and to describe the engine system model. The RL10 engine and its application to U.S. launch vehicles are described first, followed by a summary of the SPTD project organization, goals, and accomplishments. Simulated output from the system model are shown in comparison with test and flight data for start transient, steady state, and shut-down transient operations. Detailed descriptions of all component analyses, including those not selected for integration with the system model, are included as appendices.

Abstract: The invention is a supersonic aircraft. In detail, the aircraft is in the form of a flying wing having a generally flat upper surface, a generally cosine shaped lower surface and a swept back leading edge. A propulsion system is mounted in the aircraft for providing forward thrust and is adapted to provide a source of pressurized air. A plenum is mounted under and behind the leading edge of the flying wing in a spaced relationship thereto, the plenum having a swept back leading edge and a length substantially equal to the length of the flying wing and a trailing edge in the form of an exhaust nozzle; the exhaust nozzle extending substantially over the entire length of the plenum. A duct system is coupled between the at least one engine and the plenum such that pressurized air from the engine can be provided to the plenum for ejection out the nozzle in the form of a sheet of pressurized air under the wing.

Abstract: A method and arrangement for propelling fluidborne vehicles is disclosed that results in reduction in the overall form drag of certain classes of vehicles. The method and arrangement consists of using a propulsion system with an inlet that circumscribes the transition region between a forebody section containing the widest part of the vehicle and a tapered afterbody section of the vehicle to remove fluid from the viscous boundary layer that is generated by the forward portion of the vehicle, and accelerates this boundary layer fluid through a propulsion system in the afterbody portion of the vehicle. Removal of boundary layer fluid can reduce momentum losses which occur in the wake created by various classes of vehicles.

Abstract: In a joint technology programme Daimler-Benz Aerospace (Dasa) and the German Aerospace Research Establishment (DLR) are presently investigating technologies for advanced thrust chambers of reusable, high performance cryogenic rocket engines. This Technology Programme on Cryogenic Rocket Propulsion (TEKAN) has been established in 1996 under sponsorship of the German Space Agency DARA. In this programme the extensive experience of Dasa with regeneratively cooled liquid rocket engine combustion chambers is combined with the research oriented activities of DLR in liquid rocket propulsion in order to reach the targets. The present paper describes and discusses the technology developments within TEKAN which have been initiated. Rocket engine cycle analyses for different reusable launch vehicle concepts are performed in order to define the requirements for the thrust chamber components of future launch vehicle propulsion systems. In addition, a simulation tool is developed for transient engine analysis. Basic theoretical and experimental work on combustion chamber heat transfer, cooling, lifetime, and combustion modelling is continued in this programme. Technology developments of the main thrust chamber components as injectors and combustion chamber technologies for high lifetime (thermal barrier coatings, elastic liner technologies) are investigated with experimental test programmes on subscale level and theoretical analyses. Technologies for expander cycle engines are developed and the applicability of carbon fibre reinforced composite materials in cryogenic thrust chambers is investigated.