Abstract: A variable pitch propeller assembly is disclosed for a power boat. Three blades are mounted on a housing carried by the propeller shaft. Each blade has an axle received in the housing. Each axle has a slot receiving a dowel carried in the housing so the blade can rotate about 5.degree. between two pitch positions. A centrifugally-operated, spring biased latch carried in the housing locks the shaft in each pitch position. The blade is released from the latch by a predetermined change in the hydrodynamic force acting on the blade surface. The propeller shaft is connected to the propeller assembly by three plastic keys which shear to permit the propeller assembly to spin with respect to the propeller shaft when the propeller assembly strikes a predetermined resistance, such as a rock or the like.

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: A system for changing pitch in aircraft propfans is disclosed, in which a motor, located at a stationary position, changes pitch of the blades by of a gear train. Three features of the system are that a feather brake can override the motor and drive the blades toward feather; a unison brake can prevent pitch from undergoing excursions toward fine pitch when propeller speed exceeds a limit; and the motor is non-rotating in the absence of pitch change. A pair of such systems can be used in a counterrotating propfan system, in order to independently change pitch of the propfans.

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 pitch change actuation system for changing the pitch of the blades (16) of a prop-fan propulsor (10) comprises a translating pitch change actuator (30) and a flexible feather latch member (50) including a feather stop (56) and a feather latch (58), the feather latch member (50) being selectively releasable so as to permit the pitch change actuator (30) to drive the blades (16) through feather to a desired reverse pitch setting. Pitchlock lugs (96) and (98) operatively engage a pitchlock screw lug (97) on a pitchlock screw (80) to provide pitchlock screw stops at full reverse pitch and feather, respectively, with the pitchlock lug (98) being selectively displaceable so as to permit the pitchlock screw (80) to rotate when the pitch change actuator (30) is translated to drive the blades (16) through feather to reverse pitch.

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.

Abstract: An aircraft propeller has adjustable pitch blades which are reset from a low pitch in-flight idle position to a lower pitch ground idle position by a beta feedback and reset mechanism. The reset mechanism includes a set of cam elements supported for movement in response to rotation of the blades and positioned to engage a follower plate adjustably mounted on the beta feedback control rods.

Abstract: There is provided a self-actuating, variable pitch propeller having a plurality of blades. All of the blades are automatically movable between a first, relatively lower pitch position and a second, relatively higher pitch position, substantially simultaneously and equally in response to achieving a predetermined combination of propeller rotational speed and hydrodynamic loading on the propeller blades. The blades are releasably locked to prevent pivoting of the blades, at least in the lower pitch position, but preferably can be locked in both the high and low pitch positions. More preferably, a feedback force is transmitted from the blade to the locking mechanism to vary the locking force in response to the net turning moment on the blade. The locking mechanism are released in response to the combined effects of centrifugal force generated by the blades and other portions of the propeller and the hydrodynamic loading on the blades.

Abstract: Governor stability of a propeller pitch controlled speed governor is improved by dynamically compensating a turbine engine speed error signal employed in determining fuel flow. The fuel flow requirement is a function of the dynamically compensated turbine engine speed error signal, an indicated air speed signal, and a power lever angle signal.

Abstract: A propeller system has a pair of hub assemblies driven in counter-rotation, each hub assembly having a mechanical pitch change actuator, each actuator being provided with a pitch lock that rotates simultaneously with the motion of the actuator to allow the actuator to set propeller blade pitch, but locks the propeller blade positionally when not rotating simultaneously with the actuator, and a differential for transmitting a pitch change signal across a rotating gap between the two hub assemblies and for providing power to a means for providing the pitch change signals. A pair of motors provide the rotative signal to set the pitch of the blades in each hub assembly. One of the pair of motors drives the actuator towards high pitch and the other motor drives the actuator towards low pitch. A synchronizer coordinates the signals of the first and second motors so that a pitch lock moves simultaneously with the actuator.

Abstract: A self-locking pitch change actuator is configured to fit within an annular hub (34). A ring gear (40) is driven circumferentially by a tangentially oriented ballscrew (42) and traveler (44). The ballscrew (42) is driven by a hydraulic motor (50) controlled responsive to an electric pitch change motor (74). A pitchlock (62) is positioned by the collective actions of the ballscrew (42) and pitch change motor (74), with any movement relative to a preselected null position driving the hydraulic motor beta control valve (60) into an operative position.

Abstract: There is provided a self-actuating, variable pitch propeller having a plurality of blades. All of the blades are automatically movable between a first, relatively lower pitch position and a second, relatively higher pitch position, substantially simultaneously and equally in response to achieving a predetermined combination of propeller rotational speed and hydrodynamic loading on the propeller blades. The blades are releasably locked to prevent the pivoting of each blade when in the locked position. The locking means are released by actuating means activated by the combined effects of centrifugal force and hydrodynamic loading.

Abstract: A cam mechanism enabling the pilot to automatically advance the propeller low pitch stop with the engine power lever on airplanes with multibladed propeller systems having a beta control mechanism for adjusting the blade angle. The cam provides an inexpensive and reliable alternative to costly and complex automatic feathering systems.

Abstract: An aircraft propeller has adjustable pitch blades which are reset from a low pitch in-flight idle position to a lower pitch ground idle position by a beta feedback and reset mechanism. The reset mechanism includes a set of cam elements supported for movement in response to rotation of the blades and positioned to engage a follower plate adjustably mounted on the beta feedback control rods.

Abstract: An improved no-back mechanism for propeller pitch control comprises a brake which resists motion of a first member and a uni-directional coupling between the first member and a drive connecting a pitch control prime mover to an adjustable pitch propeller. The coupling permits limited movement of the drive with respect to the first member during back driving as in dither cycling of the blade while coupling the drive and first member for braking the back driving after the limited movement. As a result, dither cycling can occur during normal operation without release or slipping of the brake, thereby effecting a substantial wear reduction of brake plates of the brake.

Abstract: An inboard servo for a controllable pitch propeller of the force rod type comprises a feedback device having at least two feedback rods connected to the piston and extending through the cylinder end wall and an output ring connected to the rods. An emergency lock-up includes at least two threaded locking rods fastened to the cylinder and passing freely through holes in the feedback ring, each of which receives one or more nuts that can be threaded along the rod for engagement with the feedback ring to lock the piston in a desired position.

Abstract: A bladed rotor assembly comprising:a bladed rotor;an actuator for effecting a change of blade pitch;a first valve member connected to, and movable with, the actuator and having first and second passageways;anda second valve member co-operable with the first valve member and having first and second passageway systems formed therein for communication with the first and second passageways of the first valve member.The first passageway system of the second valve member includes first and second independent passageways, and is provided with a valve, and a bypass incorporating a non return valve. The valve is positioned so that when in a closed position fluid is prevented from entering the first independent passageway.

Abstract: A mechanical pitch lock includes a pitch lock screw (60) that simultaneously rotates within an actuator (42) while the actuator moves to change the pitch of a propeller blade (16). While rotating simultaneously with the motion of the pitch actuator, the pitch lock screw maintains a longitudinal position allowing the actuator to move. If the pitch lock screw does not rotate simultaneously with the actuator, the pitch lock screw moves longitudinally with the actuator until it abuts a projection 66 thereby preventing further movement by the actuator.

Abstract: A modular, easily replaceable, pitch actuation system is removably secured within the hub of an aircraft. The modular system houses a driving system which provides a rotational output to set the pitch of propeller blades mounted to the hub, and a pitch changing system that controls the driving system. The driving system includes a high-speed, low-torque hydraulic motor that drives an harmonic drive to amplify the torque of the motor. The pitch changing system includes an actuator which positions a valve that controls the hydraulic motor, and a nulling gear which repositions the valve and acts as a pitch lock.

Abstract: An overspeed protection system is provided for a turboprop engine. The engine includes a governor pump and a constant speed governor both of which are driven by the turbine through a gear reduction assembly. The constant speed governor is in communication with the pitch adjustment means of the propeller and is operative to effect adjustments in the propeller pitch. The system further includes a pressure sensitive switch that is operative to sense a decrease in pressure of the fluid flow produced by the governor pump and thereby sensing a system failure. A solenoid is provided and is operative to prevent pitch adjustments after a system failure sensed by the pressure sensitive switch.

Abstract: Apparatus for controlling the pitch of the blades of a variable pitch, governor controlled, aerial propeller of which the pitch of the blades is variable between a coarse pitch limit and a fine pitch limit to match the torque of its prime mover has holding means (A) to maintain a forward thrust-generating blade pitch angle greater than the fine pitch limit with the prime mover idling as when an aircraft propelled by the propeller is taxi-ing whereby the propeller rotates more slowly, and hence more quietly, than it would otherwise. Preferably the holding means is effective by actuating a lock pitch solenoid valve (21) and an autofeather valve (18).

Abstract: A windmill construction embodying an improved arrangement for driving a load through a centrifugal clutch and for adjusting the pitch angle of the blades. The adjusting mechanism is responsive to speed so as to increase the pitch angle as the speed increases and further incorporates a latch mechanism for latching the blades in a maximum feathering pitch angle and for introducing a hysteresis effect into the mechanism.

Abstract: A propeller hub supports a plurality of adjustable pitch propeller blades which are rotated by a hydraulic cylinder and control system between a feather position and a reverse position through low and high pitch positions. The reverse pitch position is precisely set by axially adjusting a tubular sleeve threadably connected to the hydraulic cylinder and having an inner end surface forming a stop for the piston within the cylinder. The feather position is precisely set by axially adjusting lock nuts mounted on a threaded end portion of the piston rod projecting forwardly beyond the forward end of the sleeve. The hub also encloses feedback control rods which carry externally adjustable nuts providing for pilot control of the blade pitch into the reverse position.

Abstract: A variable pitch propeller, particularly suited for use with turbine engines, includes a range of beta control in low pitch and reverse pitch positions, in which the pilot can obtain a ground angle range with substantially lower angles in relation to the flight idle position. This is accomplished by the provision of lost motion connections in the form of sliding sleeves mounted on the beta feedback rods which come into operation at a particularly defined low pitch angle, under control of the pilot, and permits the blades to move to a still lower pitch angle for ground operations, by providing for relative movement between the blade yoke and the beta feedback rods.

Abstract: A propeller pitch control system having a mechanical low pitch stop which includes an electrical backup therefor. The backup comprises an electrically operatable means (245) to effect blade pitch adjustment toward feather under conditions of failure of the low pitch stop indicated by propeller operation at pitch angles in the range of beta operation, but power settings in the range of normal engine speed governor pitch control. Such operating conditions actuate a pair of switches (190 and 195) connecting the means (245) to a voltage source to increase blade pitch toward feather, thereby preventing overspeed operation of the propeller.

Abstract: A vertical axis windmill has a blade pivotally connected to a rotatable support structure on an axis passing through its center of gravity which is arranged to lie forward of its aerodynamic center whereby the blade automatically swings outwardly and inwardly when moving on the windward and leeward sides respectively of the axis of rotation of said support means.

Abstract: A variable pitch propeller is controlled by a hydraulic mechanism responsive to forces urging an unsymmetrically mounted propeller towards its maximum pitch. Spring bias means maintains the propeller at minimum pitch under conditions of rest. The propeller is prevented from increasing its pitch by the pressure produced on a closed hydraulic chamber until it reaches a predetermined r.p.m., when a centrifugal valve opens a first port and relieves the pressure in the cylinder and allows the propeller to increase in pitch. The increase in pitch opens a second port communicating with the pressure chamber, but that channel remains closed by a second valve that is normally closed but opens in response to a reduction in the throttle setting. The reduction in throttle setting closes the centrifugal valve so that the only channel from the pressure chamber is through the second port.

Abstract: Wind turbine blade pitch control system including hydraulic actuators which pivotally drive the blades about the longitudinal axis thereof to adjust the blade pitch. The actuators are supplied with hydraulic fluid from independent sources thereof for normal blade pitch adjustment and feathering. Means are provided which, during feathering, isolate the pressurization and drain of the actuators from certain system components, whereby such pressurization and drain are not hampered by any malfunction of such components.

Abstract: A pitch control system for a multibladed variable pitch wind turbine. Each of the turbine blades is pivotally driven about the longitudinal axis thereof independently of the other blades by at least a pair of hydraulic actuators. The actuators are supplied with pressurized hydraulic fluid from a first source thereof under conditions of normal pitch change adjustment. Under conditions wherein feathering of the blades is required, the actuators are supplied with hydraulic fluid from second sources thereof such that one of the actuators associated with each of the blades is supplied with fluid from one second source and a second actuator is provided with fluid from a redundant second source whereby blade feathering may be effected despite a malfunction of one of the redundant sources or one of the actuators.

Abstract: This invention concerns devices for limiting the flapping movements of the blades of a rotary-wing aircraft main rotor. The device described has a well known reciprocal ring lower abutment common to all the blades. The disadvantages of this well known arrangement is obviated by the use of separate upper abutment devices for each blade. Each upper abutment device comprises a bent lever a first arm of which forms an abutment part and a second arm supports a weight. The lever can oscillate on a pivot and is acted upon by a spring which holds it in a stop position when the rotor stops so that the first arm of the lever extends almost parallel to the axial plane of symmetry of the associated blade. When the rotor rotates at sufficient speed centrifugal force pivots the lever away from the blade root.

Abstract: A propeller hub supports a plurality of angularly disposed propeller blades which are movable by a hydraulic cylinder between a high pitch position and a reverse position through a low pitch position. Hydraulic fluid is supplied to the cylinder from a governor unit driven by the aircraft engine, and a fluid pressure responsive relief valve controls the pressure of the hydraulic fluid. The pressure responsive relief valve is manually adjustable by the aircraft pilot to change the fluid pressure at which the valve responds in order to change the pitch of the propeller blades. The fluid pressure must be increased above a predetermined normal operating limit for actuating the cylinder against the bias of a spring within the propeller to move the blades to their reverse pitch position. In addition, a centrifugally actuated lock unit prevents actuation of the cylinder and movement of the blades to their reverse pitch position until the speed of the propeller is reduced to a slow idle.

Abstract: Control means, for effecting the pitch-adjustment of a rotor blade, includes an actuator urgeable by biassing means in one direction for adjusting pitch in one sense and being subjectable to fluid pressure for movement in the opposite direction, against the action of the biassing means, for adjusting pitch in the other sense. Stop means is provided which is also subjectable to said fluid pressure, being maintained in an inoperative position when the pressure is above a predetermined value and being movable into an operative position when the pressure falls below that predetermined value. Abutment means is engageable by the stop means, when in its operative position, to arrest movement of the actuator at a predetermined position when moving in said one direction.

Abstract: A rotary actuator, suitable for use with rotors having flow-varying blading, for effecting adjustment of the blading, including two relatively-rotatable and co-axially-disposed main actuator components. Each of the components carries a respective abutment means, one of which is axially-displaceable with respect to its component between an inoperative position and an operative position, and both of which are so disposed with respect to their components that during operation of the actuator with said one abutment means in its operative position, the two abutment means co-operate to arrest relative rotational movement of said components only upon said components reaching a pre-determined relative rotational position.

Abstract: A rotary actuator includes two relatively-rotatable main actuator components, abutment means being carried by the first component and displaceable axially with respect thereto, and further abutment means being carried by the second component. Holding means is operable for holding the displaceable abutment means out of engagement with respect to the further abutment means whereby relative rotational movement between the components occurs when one of them moves in either one of its two directions of rotation. Controlling means is operative, with the holding means inoperative, for urging the displaceable abutment means into engagement with the further abutment means at any relative rotational position of the components.