Propeller

Abstract

The inventive propeller consists of a shaft comprising at least two hubs which are mounted thereon and provided with blades fixed to each of them. Each blade has a front and rear sharp edges and is embodied in such a way that the greater airfoil thickness thereof is equal to (0.10-0.25)b along the blade span, wherein b is the mean chord of the blade. The greatest airflow thickness of each blade is located in the middle of each mean chord and is twisted around an axis passing through the middles of the mean chords along the blade span. The blade can be fixed to each hub at an angle of <90° with respect to the radius thereof, thereby reducing a local aerodynamic drag and aerodynamic loads. The inventive propeller can be provided with a fixed cylindrical enclosure which embraces all blades and extended in front of the blades of the front hub at a distance which is equal to or greater than the blade span, thereby increasing a torque effect value.

1 - 3 . (canceled) 
   
   
       4 . A propeller, comprising a shaft; at least two hubs arranged on said shaft; blades fixed on each of said hubs uniformly over a circumference, each of said blades having sharp front and rear edges and configured along an extension of a corresponding one of said blades with a maximum thickness of profiles (0.10-0.25)b wherein b is a length of a local chord of said blade, and being twisted relative to an axis extending through a middle of said local chords along said extension of said blade, wherein said maximum thickness of said profile is located in the middle of each of said local chords. 
   
   
       5 . A propeller as defined in  claim 4 , wherein said blades are fixed on each of said hubs inclinedly in a direction opposite to a direction of rotation. 
   
   
       6 . A propeller as defined in  claim 4 ; and further comprising an immovable cylindrical casing which surrounds all said blades and is moved out in front of said blades of a front hub not less than by length of said blade.