A passively varying pitch propeller includes a hub and a first and a second blade assembly. Each blade assembly respectively has a blade having an airfoil shape yielding a positive zero-lift pitching moment for the blade assembly, a pitching axis located such that a disturbance in pitch angle creates a restoring pitching moment, yielding static pitch stability, and a mass distribution resulting in a zero pitching moment contribution due to product of inertia in a plane normal to blade pitch rotation.

A curved body (830), for propelling fluids, crafts and harvesting fluid power, comprises a convex outer leading surface securely connected to a concave inner trailing surface to define an open vessel. Upon oscillation, ambient fluids are accelerated and ejected from the vessel to propel the vessel and the ambient fluids in opposite directions. Apparatus is secured to a motive power source directly or via actuating member (832), by fastening through aperture (834). The oscillating propulsor can be operated directly by a reciprocating motive power source, and indirectly by the reaction momentum imparted to a supporting base. Thrust may be vectored by rotation of the curved body (830) about the supporting base. Drag reduction using fluid dynamic shapes, intake openings, a fore fin (844), an aft fin (846), and a lubricant cavity, are embodied. Enhanced propulsion using multistage oscillating propulsors is embodied.

A device includes a hub and a blade. The hub has a cylindrical geometry. The blade extends radially from the hub. The blade has a helical structure. The blade includes a leading edge, a winglet, a trailing edge, and a trough. The leading edge is formed on the blade and has an arcuate geometry. The winglet of the blade is distal relative to the hub. The winglet angles away from a surface of the blade. The trailing edge is formed on the blade to be opposite the leading edge. At least a portion of the trailing edge forms a pitch-line cup that is angled with respect to the surface of the blade. The trough is formed in a transition between the pitch-line cup of the trailing edge and the winglet. The trough forms a recess that is relatively closer to the surface of the blade.

A method for controlling a thruster of a marine vehicle includes a body and a thruster mounted on the body of the vehicle, the vehicle being at least partially immersed in a liquid and moving with respect to the liquid along an axis of displacement in a direction of displacement and rotating about at least one axis of rotation perpendicular to the axis of displacement with a rotational speed, the thruster including an upstream propeller and a downstream propeller along the axis of displacement in the direction of displacement. The method including a stabilization step, in which the thruster is controlled such that the main axis of the upstream flow generated by the upstream propeller at a given instant t is an estimated main axis on which a position of a center of the downstream propeller, situated substantially on the axis of rotation of the downstream propeller, is estimated to be situated at a later instant t+dt at which the flow generated by the upstream propeller at the given instant t reaches the downstream propeller, the estimated main axis depending on the rotational speed of the vehicle.

A self-adjusting variable pitch propeller comprises a central hub with an axial propeller centre line defining the rotational axis of the propeller. A plurality of blades extend radially from the hub. The hub exhibits a central bore arranged to receive a rotating drive shaft. Each blade is pivotally fixed to the hub and pivotal about a respective blade pivot axis which extends radially from the hub through the respective blade. Each blade exhibits a leading edge, a trailing edge, a pressure side exhibiting a pressure side area and a suction side exhibiting a suction side area. The blades are mechanically interconnected to freely transfer pivotal movement of each blade to all other blades. The pivotal axis of each blade is positioned such that >50% of the suction side area and of the pressure side area is arranged between the trailing edge and the pivotal axis of the respective blade.

A self-adjusting variable pitch propeller included a central hub with an axial propeller centre line defining the rotational axis of the propeller. A plurality of blades extend radially from the hub. The hub exhibits a central bore arranged to receive a rotating drive shaft. Each blade is pivotally fixed to the hub and pivotal about a respective blade pivot axis which extends radially from the hub through the respective blade. Each blade exhibits a leading edge, a trailing edge, a pressure side exhibiting a pressure side area and a suction side exhibiting a suction side area. The blades are mechanically interconnected to freely transfer pivotal movement of each blade to all other blades. The pivotal axis of each blade is positioned such that >50% of the suction side area and of the pressure side area is arranged between the trailing edge and the pivotal axis of the respective blade.

A bistable pitch propeller includes a ball, a spring, and a clutch module where the clutch module has a range of rotational movement between a locked end position and a released end position. The clutch module includes a detent, where the ball sits inside and outside of the detent when the clutch module is in the locked end position and released end position, respectively. In response to an input torque and a spring force from the spring, the clutch module rotates toward the released end position and the locked end position, respectively. The bistable pitch propeller also includes an aircraft blade where the aircraft blade is at the first pitch angle and the second pitch angle when the clutch module is in the locked end position and the released end position, respectively.

A yoke plate arrangement may comprise a yoke plate, a wear plate comprising a wear surface and a contact surface, wherein a post extends from the contact surface, and a yoke plate ear extending from the yoke plate in a radial direction, wherein a first aperture is disposed in the yoke plate ear, the post located at least partially within the first aperture, the contact surface being in contact with the yoke plate ear. The yoke plate arrangement may further comprise a retaining feature for coupling the wear plate to the yoke plate. The wear surface may be for engaging a trunnion bearing.

A yoke plate arrangement may comprise a yoke plate, a wear plate comprising a wear surface and a contact surface, wherein a post extends from the contact surface, and a yoke plate ear extending from the yoke plate in a radial direction, wherein a first aperture is disposed in the yoke plate ear, the post located at least partially within the first aperture, the contact surface being in contact with the yoke plate ear. The yoke plate arrangement may further comprise a retaining feature for coupling the wear plate to the yoke plate. The wear surface may be for engaging a trunnion bearing.

A Pulsed Locomotor (120), for propelling media, fluids and crafts, in fluids and on land, comprising a blade (124) securely connected to a drive shaft (122). Upon reciprocation, the ambient medium is forced towards the trailing edge of the blade (124) thereby causing a reactive locomotion of the apparatus, substantially along the plane of the blade. Apparatus is secured to motor M by fastening through aperture (130). The apparatus can be operated directly by motor M, and indirectly by the reaction momentum imparted to a supporting platform P. Thrust is directed by steering handle (128) about a bearing (126), rotatably coupling to platform P and base C. Lubricant L is supplied to outlets (134) via conduit (136) and inlet (132), to coat the apparatus with a lubricant cavity, for drag reduction. The blade (124) planes along a figure 8 reciprocation path s1e1s2e2s1. Crafts are embodied.