Abstract: The rotor consists of two airfoils symmetrically disposed around an axis of rotation. Each airfoil consists of an outer vane having a leading edge and a trailing edge and an inner vane having a trailing edge and having a leading edge attached to the trailing edge of the outer vane. The outer vane has a radius R and extends not more than 90 degrees around the axis of rotation. The inner vane extends 180 degrees around an axis that is parallel to but displaced from the axis of rotation. The radius of the inner vane is a fraction, between 0.6 and 0.8, of the radius of the outer vane. Automatic limitation of the speed of rotation is achieved in one embodiment by letting centrifugal force deform the inner vanes so as to reduce the cross sectional area of the air flow path through the rotor.

Abstract: The thrust of a Magnus propeller is made reversible by reversing the rotation of the Magnus cylinders independently of the direction of rotation of the propeller shaft. Reversible drives for the cylinders are provided that are mechanical, fluid or electric. Reversible motors for the propeller shaft are provided as an alternative reversing mechanism while the cylinders continue to rotate in the same direction. Separate motor drives are provided for the Magnus cylinders and the propeller shaft.

Abstract: Magnus cylinders are mounted for rotation at right angles to shafts that are revolved about a generally vertical axis. The shafts are free to rotate 180.degree.. The Magnus cylinders are continuously rotated in the same angular direction. At one position of revolution of the shafts, the cylinders rotate on an axis generally parallel to the axis of revolution of the shafts. When the apparatus is immersed in a fluid flow (gaseous or liquid) a torque of rotation is developed when the shafts are aligned with the fluid flow, and this torque of rotation is reduced as the shaft approaches a position transverse to the fluid flow. As the shafts pass this transverse position, a torque is developed by the rotating cylinder that rotates the shafts 180.degree. until the formerly downwardly depending cylinder is now upright and the formerly upright cylinder is now downwardly depending on its shaft.