Abstract: There is disclosed a propeller adapted for driving a vehicle, such as a boat. The propeller comprises a pair of pivotally mounted propeller blades which are adapted to assume an inactive position wherein the blades are substantially aligned with the direction of vehicle movement, and a working position wherein the blades are at an angle with respect to the direction of vehicle movement. A stop means on the propeller limits the forward pivotal movement of the propeller blades to those locations between the inactive position and a stop position wherein the propeller blades each forms an oblique angle with respect to the inactive position so the propeller blades can each assume a working position which is located on either side of a perpendicular position wherein the propeller blades are perpendicularly disposed to the direction of vehicle movement.

Abstract: An automotive engine cooling fan assembly including asymmetrical plastic fan blades and a torsion bar interconnecting each blade to the hub of the assembly, the asymmetrical blades responding to both aerodynamic and centrifugal forces to reduce the pitch thereof at high fan speeds, the entire fan blade subassembly being rotated as a result of the twisting of the torsion bar.

Abstract: A fully articulated helicopter rotor having an elastomeric type main bearing which is reactive of all blade motions about the intersecting blade pitch change, lead-lag, and coning axes, including blade droop supporting and limiting members for static and dynamic operating conditions wherein coupling influences between the separate blade motions are precluded. In reacting these blade weight loadings and dynamic thrust forces, the droop members specifically provide full area contact bearing surfaces to distribute the large forces from the blades into the rotor hub proper while avoiding scuffing or rolling contact between the parts, and the high bearing stresses which would result from either point or line contact only.