Abstract: A control system for use with a wind turbine is provided. The wind turbine includes a rotor, a blade coupled to the rotor, a sensor configured to obtain a measurement of the wind turbine, and an active flow control system at least partially defined within the blade. The control system is configured to operate the active flow control system in a first mode, receive a signal from the sensor indicating a load imbalance on the rotor, and change an operation of the active flow control system from the first mode to a second mode based on the signal. The second mode is configured to reduce the load imbalance on the rotor.

Abstract: A rotor blade fold system for an aircraft includes one or more actuators operably connected to one or more blade components of one or more rotor blades of the aircraft. One or more sensors are located at the one or more rotor blades and are configured to sense operation of the one or more blade components. A fold control system is configured to monitor output from the one or more sensors and is capable of stopping operation of the blade fold system, via communication with the one or more actuators, if the one or more blade components are not operating within predetermined limits.

Abstract: A personal motorized cooling fan designed to retract and fold into a vertical tower for economy of shipping, storage and desk space. Each fan blade includes a blade portion and a root portion that rides in a race that guides the blades as they splay during rotation. When the fan is turned on, the rotation of the shaft and therefore race, combined with centrifugal force, causes the blades to splay forming a radial array. A protective cage including an array of longitudinal members expands in a fan-like manner. The cage is engaged with ribbons of stretch fabric that retract and fold along with the cage and blades after use. The entire assembly folds tidily into a slender tower.

Abstract: A control system for mitigating the effects of a wind turbine on a radar system is disclosed. The control system includes a sensor configured to detect an operating condition of the radar system; a processor configured to receive an operating condition of the wind turbine and determine a rotation modification sequence based on the operating condition of the radar system and the operating condition of the wind turbine; and a controller configured to apply the rotation modification sequence to the wind turbine. A method of mitigating the effects of a wind turbine on a radar system is also disclosed.

Abstract: A method of controlling a wind turbine, where a control signal for a controllable parameter of the wind turbine is determined repeatingly at successive time steps, and a control history including respective control values derived from or included in past control signals is stored. These control values stored in the control history are then used to determine an alert parameter for the controllable parameter, the alert parameter being a function of the variations of the control signals over time. The wind turbine is then controlled according to the most recent control signal only if the alert parameter is below an alert threshold, and otherwise according to a modified control strategy. The control method may be performed on pitch reference signals for controlling the individual and/or collective pitch of the blades. The invention further relates to a control system configured to perform the above control method, and a wind turbine comprising such system.

Abstract: The present invention relates to a yaw system 5 for a windmill 1, the windmill comprising a tower 2 and a nacelle 3, the tower and the nacelle being joined by the yaw system and the yaw system further comprising a bearing fixed to the tower, on which bearing the nacelle rests and slides in a yawing movement, and at least one yaw motor arranged to allow the nacelle to perform a rotary motion along the bearing, wherein the yaw system 5 further comprises control means 8 for continuously operating the at least one yaw motor in such a way that the yaw motor strives to manoeuvre the nacelle according to a setpoint.

Abstract: A blade structure for a torque converter, produced by a process including the steps of: stamping a flat blank into a first annular plate that includes a first connecting ring portion, a second connecting ring portion, and a plurality of blades spaced from each other in a circumferential direction of the first and second connecting ring portions; bending the blades into a curved shape curved with respect to the first annular plate; bending the blades to be inclined by a predetermined angle with respect to the first and second connecting ring portions; and expanding the first annular plate outwardly in a radial direction thereof to thereby form a predetermined annular shape that has a larger radial dimension than the first annular shape and a larger circumferential distance between respective adjacent two of the blades than that in the first annular plate.

Abstract: Controller for a blade adjustment angle for at least one rotor blade of a wind power plant, in which a first controller branch is switched for the determination of the blade adjustment angle depending on the operating states of the wind power plant, wherein at least one differentiating member is provided in the switched first controller branch.

Abstract: A method of determining fatigue load of at least one operative wind turbine, comprising: providing a transfer function that associates an obtained at least one measurement value of a first sensor to an obtained at least one measurement value of a second sensor the at least one measurement value of the first sensor and the at least one measurement value of the second sensor being obtained by use of a reference wind turbine at which the first sensor and the second sensor are located; obtaining at least one measurement value of a third sensor, wherein the third sensor is located at the at least one operative wind turbine, and wherein the third sensor corresponds in type and position to the first sensor at the reference wind turbine; calculating at least one transfer function value corresponding to the obtained at least one measurement value of the third sensor by use of the provided transfer function; calculating the fatigue load of the at least one operative wind turbine based on the calculated transfer functio

Abstract: In a method for blade load reduction control of a rotor of a wind turbine, the rotor includes a plurality of blades, and a pitch angle of each blade is controllable by an actuator. The method includes measuring mechanical load parameters on the rotor, providing control for a collective pitch blade setting based on a rotor speed; providing individual pitch control including transforming the mechanical load parameters from a rotational reference frame to a mechanical load on the rotor in a fixed reference frame; determining from the mechanical load two multi-blade pitches; correcting the multi-blade pitches to corrected multi-blade pitches using actuator limitations; inversely transforming the corrected multi-blade pitches to an individual pitch deviation for each blade in the rotational reference frame; adding up for each blade, the individual pitch deviation to the collective pitch to form an individual pitch; and setting each blade to the respective individual pitch.

Abstract: A method for monitoring wear of a blade pitch brake within a rotor blade pitch control system of a wind turbine is described. The rotor blade pitch control system includes a blade pitch actuator. The method includes engaging the blade pitch brake and measuring a blade pitch displacement while the blade pitch brake is engaged. The method further includes determining a brake wear level based on the measured blade pitch displacement while the blade pitch brake is engaged, and generating a brake wear level output signal corresponding to the brake wear level.

Abstract: Method and device for improving performance of an aircraft comprising at least one propeller engine without propeller fairing. According to the invention, the device (10) comprises means (2) for slaving, automatically and independently, blade setting angles (?), respectively associated with blades (B) of the propeller, to a constant reference control moment (Mc) predetermined, for a desired propeller thrust value, and intended to be applied on each blades (B), such that torsion aerodynamic moments (M) applied on blades (B) stay roughly equal to the reference control moment (Mc) whatever the angular position of blades (B) in the propeller plane of rotation is.

Abstract: A method for balancing a rotor of a rotary machine, wherein the rotor includes at least two rotor blades and a rotor shaft, includes receiving at least one measurement of either a load, an acceleration, or a displacement that pertains to at least one bending moment acting on the rotor shaft, determining at least one value of the at least one bending moment acting on the rotor shaft based, at least in part, on the received at least one measurement, and determining a pitch offset angle value of at least one rotor blade that facilitates reducing the at least one bending moment acting on the rotor shaft.

Abstract: A method for controlling a tip speed of a blade of a wind turbine. The method includes determining the wind speed proximate the wind turbine; maintaining a first substantially constant rotational speed of the tip of the blade during variable wind speeds above a first predetermined nominal wind speed and below the second predetermined nominal wind speed; maintaining a second substantially constant rotational speed of the tip of the blade during variable wind speeds above a second predetermined nominal wind speed. The noise generated by wind at the second predetermined nominal wind speed is greater than noise generated by the blade at the second constant rotational speed of the tip of the blade.

Abstract: A device for driving a first part of a wind turbine with respect to a second part of the wind turbine includes a driving element for engagement with the first part. The device also includes a driving unit including a housing to be fixedly connected to the second part, a motive generation means for generating motion of the motive element, and a motion transferring means for transferring the motion of the motive element to the driving element; and at least one slip coupling arranged between at least one of the motive element of the driving unit and the motion transferring means, the motion transferring means and the driving element, and within the motion transferring means, wherein the slip coupling is adjusted to slip if a torque acting on the slip coupling due to a movement force acting on the driving element exceeds a predetermined maximum torque.

Abstract: A method for doing an optimization of the performance envelope initially authorized for an existing rotorcraft engine (M) to enable the engine (M), to be used in an optimized performance envelope that is different from the performance envelope initially authorized for the engine, is remarquable in that this optimization is compensated by modifying the total service life of the engine (M).

Abstract: A shock absorbing device for a watercraft propeller is provided that can include an outer tube unitarily formed with blades of a propeller. An inner tube can be coupled with a propeller shaft. An intermediate tube can be positioned between the outer tube and the inner tube. A first damping means can be placed between the intermediate tube and the outer tube. A second damping means can be placed between the intermediate tube and the inner tube. One of the damping means can include a rubber damper interposed between the inner tube and the intermediate tube, and an engaging means for limiting an angle range in which the inner tube and the intermediate tube can be rotatable relative to each other to a predetermined angle range. The rubber damper can have a spring constant with which elastic deformation thereof begins at a moment that the propeller shaft initiates its rotation.

Abstract: A system for determining wind turbine tower base torque loads including a controller configured to determine a torque load of a base of a tower of a wind turbine according to a computation of an effective height of the wind turbine multiplied by a wind force upon a rotor of the wind turbine, and generate a control signal representing the torque load. A method for determining wind turbine tower base torque loads including determining a torque load of a base of a tower of a wind turbine according to the foregoing computation, and generating a control signal representing the torque load.

Abstract: A wind turbine pitch control system is disclosed that provides a pulsed torque to the blade pitch actuator if continuous torque fails to adjust the blade pitch angle to a commanded pitch angle. This invention provides a cost-effective way to increase peak torque capability for existing wind turbines that have problems, under certain operating conditions, moving blades per the control command.

Abstract: A method of determining fatigue load of at least one operative wind turbine, comprising: providing a transfer function that associates an obtained at least one measurement value of a first sensor to an obtained at least one measurement value of a second sensor the at least one measurement value of the first sensor and the at least one measurement value of the second sensor being obtained by use of a reference wind turbine at which the first sensor and the second sensor are located; obtaining at least one measurement value of a third sensor, wherein the third sensor is located at the at least one operative wind turbine, and wherein the third sensor corresponds in type and position to the first sensor at the reference wind turbine; calculating at least one transfer function value corresponding to the obtained at least one measurement value of the third sensor by use of the provided transfer function; calculating the fatigue load of the at least one operative wind turbine based on the calculated transfer functio

Abstract: A method for correcting offsets in sensors includes mounting, on a rotating machine, a first set of sensors in locations selected to measure vector loads in a first set of coordinates. The method further includes mounting, on the rotating machine, a second set of sensors in locations selected to measure vector loads in a second set of coordinates, wherein the first set of coordinates and the second set of coordinates rotate with respect to one another when the rotating machine is operating. The method also includes utilizing measurements from either or both of the two sets of sensors to correct offset errors in vector loads measured by the other set of sensors.

Abstract: A wind turbine rotor blade root load sensor is provided. The sensor is configured to be internally mounted within an insert of a root portion of a wind turbine rotor blade. The sensor comprises a carrier member which is configured to be fixedly connected to the insert so that loads can be transmitted therebetween and the sensor further comprises a sensing element, supported by the carrier member.

Abstract: The present invention relates to a method and a system for operating a Wind Turbine (WTG), which WTG comprises a rotor comprising at least two blades, which blades are pitch regulated, where the rotor is connected to a shaft, which shaft is supported by bearings, and which shaft drives at least one generator, where the WTG uses a load regulation system for regulating the individual pitch of at least two blades. The object of the invention is to compensate for asymmetric load on the rotor in a wind turbine, a second object is to reduce wearing at shaft bearings in the wind turbine, and a third object is to increase the power production of a wind turbine. This can be achieved if the load regulation system measures the actual rotor load by at least one displacement sensor, which displacement sensor is measuring the bending of the main shaft, where the load regulation system based on the shaft bending regulates the individual pitch of the blades for compensating asymmetric load at the rotor.

Abstract: A method and device for reducing vibratory noise in a system with an integral rotating member includes independently operable drive systems for controlling the angular velocity of at least two independently rotatable masses. Control signals manipulate the drive system to rotate each mass at optimal speed, direction and phase to reduce noise induced in the system by the rotating member.

Abstract: Operations of a turbine to generate energy from a relatively slow fluid flow, such as wind and water, are described. The turbine has a plurality of foils rotating about a central axis at a rotational velocity, each of the foils having a length and a foil axis parallel to the length and the central axis with each of the foils rotatable about its foil axis. From determinations of a velocity of the fluid flow, and angular location of each foil and the rotational velocity about the central axis, an attack angle of each foil is controlled with respect to the direction of fluid flow about the foil axis responsive to the velocity of the fluid flow, the angular location of the foil and the rotational velocity as the foil rotates about the central axis.

Abstract: Disclosed is a method of reducing a structural unbalance in a wind turbine rotor with pitch control and a control device for performing the method are provided. The method comprises the steps of: detecting a magnitude of the structural unbalance and its phase in relation the rotor's azimuth (?) on the basis of a measurement of the rotor's azimuth (?) and a measurement of the rotor speed or the generator speed (?), establishing individual pitch angle offsets for each blade of the rotor on the basis of the magnitude and the phase, and adding the individual pitch angle offsets to the respective pitch angles of the blades of the rotor.

Abstract: The invention relates to a wind power current generator comprising a bearing, a tubular stator that carries a race of the bearing, a tubular rotor coaxial with the tubular stator that can rotate in relation to the stator, a hub connected to the rotor, and at least two blades radially extending away from the hub. According to the invention, the stator and the rotor are formed with substantially tubular cross sections and are concentric to one another. The opposing surfaces of the rotor and stator carry permanent magnets and windings. The stator and rotor extend beyond either side of the magnets and the windings in order to accommodate an antifriction bearing on at least one side. The tubular nature of the rotor and stator allows easy passage of workers within the generator for maintenance thereof and of the blades. Additionally, the tubular nature facilitates air flow through the structure and out the blades, cooling equipment within the structure and aiding de-icing of the blades.

Abstract: A wind energy plant with a nacelle, the azimuth orientation of which is motor-driven adjustable via an adjustment device, the adjustment device having at least one asynchronous motor with gearbox and at least one holding brake, wherein a control unit for the asynchronous motor is provided, which limits the moment occurring on the asynchronous motor to a predetermined maximum value.

Abstract: A method for optimization of operating parameters of a wind energy installation defines an upper and a lower interval limit value for a parameter to be optimized. The method includes carrying out a cycle with alternate operations of the wind energy installation with the interval limit values, with a data record in each case being produced with a target variable over a variable number of repetitions. The data records relating to the interval limit values are evaluated to form a quality measure, and the interval limit value with the poorer quality measure is identified. Then, at least the interval limit value with the poorer quality measure is replaced by shifting through a step value ? in a direction of another interval limit value. The cycle is then repeated.

Abstract: A method for limiting loads in a wind turbine by using measured loads or wind speed to increase the minimum pitch angle for extended periods. The minimum pitch angle will be allowed to relax down to the default when load excursions diminish. The method will allow turbines to capture more energy by operating in higher wind speeds and/or utilizing larger rotors without additional loss of fatigue life.

Abstract: The present invention provides a device enabling the collective pitch of the blades of the main rotor of a single-engined rotorcraft to be reduced automatically in the event of an engine failure. The device comprises an actuator which increases the collective pitch of the blades above a predefined threshold, and which decreases the collective pitch below the predefined threshold. The actuator is arranged on a bell crank of the mixing unit of the rotorcraft.

Abstract: A wind turbine with at least one blade having a pitch axis that is offset laterally so that the blade does not intersect with an axis of rotation of the wind turbine, and a center of mass and an aerodynamic center are offset from the pitch axis in the direction parallel to the axis of rotation of the wind turbine. The blade is arranged so that the blade can pitch towards stall against the action of a resilient device and also so that the centrifugal loading on at least one of the blade and one or more components optionally attached to the blade, acts against the spring in a direction to shed power by pitching the blade towards stall and also so that the torque loading provided by a power conversion device acts to pitch the blade in the opposite direction, so as to reduce the amount of load shedding whenever the power is being extracted from the wind turbine.

Abstract: Vertical and horizontal wind shears, yaw misalignment and/or turbulence act together to produce asymmetric loading across a wind turbine rotor. The resultant load produces bending moments in the blades that are reacted through the hub and subsequently to the low-speed shaft. As a result, the main shaft and main shaft flange are displaced from their at rest or non-aerodynamic load positions. The amount of shaft flange displacement is measured using one or more sensors. The output signals from the sensors are used to determine the magnitude and/or the orientation of the resultant rotor load. This information is used to effect the blade pitch change needed to reduce the load and thereby reduce fatigue and loading on various turbine components.

Abstract: The invention described here offers a low-cost method of remote flight control suitable for use in toy airplanes and ornithopters (flapping-wing aircraft). To accomplish this, the aircraft is powered by a reversible electric motor. The propeller or flapping wing produces a torque force, which is dependent upon the direction of motor rotation. This torque force is used to bank the aircraft and cause a turn. In the case of an airplane, a reversible-pitch propeller enables the propeller to produce thrust in either rotational direction. In the case of an ornithopter, the torque force results from an asymmetrical motion of the wings. By reversing the motor direction, the asymmetry is reversed and the ornithopter turns in the opposite direction. This control method reduces costs, because unlike other toy aircraft control systems, it provides full directional control of the aircraft without the need for any servo or actuator in addition to the drive motor.

Abstract: A method for controlling a wind turbine having twist bend coupled rotor blades on a rotor mechanically coupled to a generator includes determining a speed of a rotor blade tip of the wind turbine, measuring a current twist distribution and current blade loading, and adjusting a torque of a generator to change the speed of the rotor blade tip to thereby increase an energy capture power coefficient of the wind turbine.

Abstract: A method is provided for controlling a wind turbine, and a wind turbine is provided with a control device for controlling a wind turbine. A method and a wind turbine are developed so that losses of yield, particularly as a result of variations in the conversion of the kinetic energy of the wind into electrical energy, e.g., in the rotor, drive train and generator, are minimized as far as possible. A method is provided for controlling a wind turbine, wherein at least one operational setting is varied within predefined limits.

Abstract: Vertical and horizontal wind shears, yaw misalignment and/or turbulence act together to produce asymmetric loading across a wind turbine rotor. The resultant load produces bending moments in the blades that are reacted through the hub and subsequently to the main shaft. As a result, the main shaft may be radially displaced from its at rest positions. The amount of radial displacement is measured using two or more sensors. The output signals from the sensors are used to determine the magnitude and/or the orientation of the resultant rotor load. This information is used to affect the blade pitch change or other action with similar system effect to reduce the asymmetric load and thereby reduce fatigue and loading on various turbine components.

Abstract: In one aspect, the present invention relates to a system for monitoring wind turbines, wherein image and acoustic monitoring, in particular, is performed. In order to further improve, for example, the maintenance, safety and efficiency of a wind turbine, it is desirable to monitor additional parameters of the wind turbine. A wind turbine is provided, wherein acoustic and optical sensors are employed to monitor the operation of the wind turbine. In one embodiment, the optical sensor images a particular location in the nacelle housing when the acoustic sensor detects a sound emanating from that location in the nacelle housing. A method for monitoring a wind turbine is described wherein when a deviation between the operating acoustic spectrum and the reference acoustic spectrum exceeds the threshold, the component that generated the operating acoustic spectrum is imaged.

Abstract: In the method for the determination of the pressure (p) in and/or of the through-flow (Q) of a liquid through a pump having at least one magnetic bearing for the axial journaling of the pump rotor (1), axial forces act on the rotor (1) of the pump during operation. The axial forces which act on the rotor are utilised for the determination of the pressure (p) and/or of the through-flow (Q).

Abstract: An airplane engine control method and apparatus are provided which form an engine control system easy to operate, which set a reciprocating engine of an airplane in such an operating condition in a partial power mode as to maximize the efficiency of the airframe and the engine as a whole, and which enable setting of suitable partial power in a reciprocating engine with a variable-pitch propeller in such a manner that, when predetermined partial power is set, a relationship expressed by Te ∝ &rgr;N2 is established with respect to the engine torque (Te), the number of engine revolutions (N) and the atmospheric density (&rgr;).

Abstract: A mechanism for automatically changing the pitch of propeller blades employing engine torque alone which increases with air speed. A powered hub mounts at least two blades and includes blade pitch changing elements automatically responsive to engine torque for changing blade pitch. The elements include a gear train having a drive gear and several driven gears with flexible coupling components interconnected therebetween. The flexible coupling includes a number of compressible components disposed in cavities in a circular array between the driving gear and the driven gears and which distort under torsional loads at a pre-determined rate.As engine torque changes due to aerodynamic loads on the blades, the flexible coupling components distort causing the blades to change pitch angle.

Abstract: An improved electronic hydraulic propeller control designed as a retro-fit kit for existing Hamilton Standard Division 54460 and 54H60 propeller controllers includes an apparatus for controlling the pitch angle of a propeller blade. The retro-fit kit includes an electro-hydraulic servo valve, an electronic controller, a protection valve, and a propeller maintenance interface panel. These components functionally replace the existing hydromechanical propeller control system without reconfiguration of the existing interface. The apparatus converts mechanical inputs of the propeller and airframe systems to electronic signals, which can be measured by the electronic control. The apparatus also receives and converts the electronic control's commands into hydraulic pressure and flow changes through an electro-hydraulic servo valve. The electronic controller performs the required calculations to interpret and then react to changes in the propeller/airframe systems.

Abstract: A variable speed helicopter rotor system and method for operating such a system are provided which allow the helicopter rotor to be operated at an optimal angular velocity in revolutions per minute (RPM) minimizing the power required to turn the rotor and thereby resulting in helicopter performance efficiency improvements, reduction in noise, and improvements in rotor, helicopter transmission and engine life. The system and method provide for an increase in helicopter endurance and. The system and method also provide a substantial improvement in helicopter performance during take-off, hover and maneuver.

Abstract: A variable pitch propeller apparatus for use with a motor is disclosed. The apparatus includes a housing having a plurality of blades mounted therein for rotation. Adjustable high pitch and low pitch stop rings are connected to the housing and a synchronizer ring is slidably received by the housing and positioned between the stop rings. The synchronizer ring is limited in movement by the desired position of the adjustable high pitch stop ring and adjustable low pitch stop ring. A plurality of springs are used to bias the blades in a low pitch position for trolling and when the spring force is overcome by the thrust on the blades, the blades pivot to a high pitch position. The springs are cooperatively connected to the synchronizer ring or to the blades so that blade movement is coordinated and simultaneous. A tensioning ring is connected to the housing for simultaneously adjusting the tension on the springs.

Abstract: A propeller for a boat having a plurality of recesses and a plurality of land portions arranged circumferentially alternately around an outer periphery of a propeller boss which is fitted over and connected to a propeller shaft. A boss of each of propeller blades and each of blade shafts disposed parallel to an axis of the propeller boss to rotatably support such propeller blade are accommodated in each of the recesses, and each of the land portions is provided with an exhaust passage extending axially through the land portion to permit an exhaust outlet in a body of a propelling device to be opened at a rear end face of the propeller boss. Thus, it is possible to discharge an exhaust gas from an engine through the inside of the propeller boss into water.

Abstract: A control system is provided which prevents a powerful, propeller driven, jet training aircraft from requiring corrective action to throttling and gyroscopic effects when the student wishes to fly the aircraft in coordinated flight. The control system includes a digital memory having stored therein flight test generated data representative of the relationship between the amount of rudder trim required to maintain the aircraft in coordinated flight as a function of aircraft engine torque and airspeed. Sensors are provided to measure aircraft engine torque aircraft altitude aircraft speed, and pitch rate. The measured parameters are coupled to the digital computer. The digital computer combines the parameters provided by the sensors and data read from the memory to produce a composite rudder trim signal which automatically reduces rudder forces induced by throttling and gyroscopic effects produced in response to pilot commanded maneuvers to thereby maintain the aircraft in coordinated flight.

Abstract: A method and apparatus for controlling a propulsion engine output in a vessel, based on the net axial force on a propeller shaft in the vessel. The apparatus includes a regulating loop with a computer which continuously controls the delivery of fuel to the vessel's engine, and optionally controls the attack angle of the vessel's propeller blades. Control of the fuel delivery is performed in accordance with predetermined control algorithms, and optionally, by operator-set parameter values and maneuvering operations. The apparatus further includes at least one force sensor mounted to a bearing which supports the vessel's propeller shaft. The force sensor, which is preferably mounted to a thrust bearing, detects a net axial force on the propeller shaft. The net axial force detected is then used as a parameter in the control algorithms and therefore as a factor in controlling the delivery of fuel.

Abstract: There is provided a self-actuating variable pitch marine propeller which incorporates two or more blades, each independently rotatable, relative to the propeller hub, between a first lower and a second higher pitch. The blades are preferably mechanically linked by coordinating devices and are caused to move preferably by a combination of centrifugal force effect resulting from inertial masses means and the hydrodynamic forces acting upon the blade hydrodynamic surface. The rotation of the blades relative to the propeller hub is restrained until the restraint is overcome by the forces acting to pivot the blades to the higher pitch position. Most preferably there is also provided a mechanical bias, such as a spring to hold the blades in the lower pitch position. Initially, the hydrodynamic force can also tend to hold in the blades in the lower pitch position, or to move the blades towards the higher pitch.

Abstract: There is provided a self-actuating variable pitch marine propeller which incorporates two or more blades, each independently rotatable, relative to the propeller hub, between a first lower and a second higher pitch. The blades are preferably mechanically linked by coordinating means and are caused to move preferably by a combination of centrifugal force effect resulting from inertial mass means and the hydrodynamic forces acting upon the blade hydrodynamic surface. The rotation of the blades relative to the propeller hub is limited primarily as to speed of rotation by restricted viscous fluid flow damping means operably connected to the blades. In one preferred embodiment, the viscous flow means further acts as an initial restraint against all motion by closing off the viscous flow orifice until a certain minimum propeller rotational speed is achieved.

Abstract: A self-actuating variable pitch marine propeller which incorporates two or more blades having cylindrical shafts which are rotatably connected to a central hub via cylindrical joints; the blades rotate about and translate radially, relative to the hub center, along the blade shaft, or shank, axis. In operation, the blades move radially outwardly from the hub center as they rotate from lower to higher pitch. The blades are biased towards the lower pitch. As the propeller rotational speed increases, centrifugal forces act on the blade mass creating a radially directed outward force. This radially outward force, upon reaching a sufficient magnitude, causes the blades to move radially outward. A blade positioning mechanism connected between each blade and the hub directs the blades to rotate to a higher pitch angle as the blades move radially outward.