Propeller

Abstract

A propeller. The blades of the propeller are characterized by a blade center axis which corresponds to a generator line of a cone to which the blade, or blade thrust surface, conforms. The propeller hub is fixed to the blade at the root, in line with the blade center axis, such that the hub axis and blade center axis lie in the same plane, and the leading edge of the blade is positioned forward (referring to the upstream direction of movement caused by the propeller) of the trailing edge of the blade.

1 . A propeller comprising:
 a hub operable to rotate about an axis of rotation in a direction of rotation, characterized by a forward end and an aft end; and   one or more blades characterized by a root, a tip, a leading edge and a corresponding trailing edge, and a thrust surface, wherein   the thrust surface of each blade conforms to a surface of a reference cone characterized by a vertex and a base and a reference cone circumference, and a generator line, wherein   a radial axis extending radially from the root of each blade corresponds to a generator line of the cone, and the root of each blade is fixed to the hub such that the axis of rotation is coplanar with the radial axis of each blade; wherein   each blade subtends no more than 90° of the reference cone circumference.   
     
     
         2 . The propeller of  claim 1  wherein:
 the axis of rotation and the radial axis of each blade are substantially perpendicular. 
 
     
     
         3 . The propeller of  claim 1  wherein:
 the axis of rotation and the radial axis of each blade are set at an angle of 45° or more. 
 
     
     
         4 . The propeller of  claim 1  wherein:
 the leading edge of each blade is forward of its corresponding trailing edge. 
 
     
     
         5 . The propeller of  claim 1  wherein:
 each blade is rotated about its generator line such that its average pitch angle relative to the hub is different from that which it would have had without such rotation. 
 
     
     
         6 . The propeller of  claim 1  wherein
 the average pitch angle between leading and trailing edges is 45° or less. 
 
     
     
         7 . The propeller of  claim 1  wherein:
 a line on the thrust surface, along the radial axis of each blade, is a straight line corresponding to a generator line of the cone. 
 
     
     
         8 . The propeller of  claim 1  wherein:
 a leading-to-trailing line on the thrust surface of each blade, perpendicular to the radial axis, is a circular arc. 
 
     
     
         9 . The propeller of  claim 1  wherein:
 each blade is symmetric about the radial axis of the blade. 
 
     
     
         10 . The propeller of  claim 1  wherein:
 each blade is asymmetric about the radial axis of the blade. 
 
     
     
         11 . The propeller of  claim 1  wherein:
 the plane containing the radial axis and axis of rotation is substantially parallel to a plane containing a portion of the trailing edge of the blade. 
 
     
     
         12 . The propeller of  claim 1  wherein:
 the hub is spaced apart from the vertex of the reference cone, such that the axis of rotation intersects a generator line at a distance of at least half the length of the distance from the blade root to the tip as measured along the generator line that passes through the axis of rotation. 
 
     
     
         13 . The propeller of  claim 1  wherein:
 a plane which passes through a portion of the blade near its trailing edge is substantially parallel to a plane containing the radial axis of the blade and its axis of rotation. 
 
     
     
         14 . A propeller characterized by a propeller axis, said propeller comprising:
 a blade having a thrust face which substantially conforms to an area of the curved surface of a cone, said blade having a radial axis;   said blade being disposed with respect to the propeller axis so that a plane containing the propeller axis will also contain a generator line of a reference cone which corresponds to a radial axis of the blade.   
     
     
         15 . The propeller of  claim 14  wherein:
 the blade has a circular curvature in directions transversely between the leading and trailing edges of the blade and no curvature in a direction radially of the blade. 
 
     
     
         16 . The propeller of  claim 14  wherein:
 the blade has the curvature of a conic section in directions transversely between the leading and trailing edges of the blade and no curvature along a radius of the blade. 
 
     
     
         17 . The propeller of  claim 14  wherein:
 the blade, in addition to being disposed with respect to the propeller axis so that a plane containing the propeller axis will also contain a generator line of the cone which corresponds to a long axis of the blade, is disposed such that the generator line of the cone is perpendicular to the propeller axis. 
 
     
     
         18 . The propeller of  claim 14  wherein:
 the blade, in addition to being disposed with respect to the propeller axis so that a plane containing the propeller axis will also contain generator line of the cone which corresponds to a long axis of the blade, is disposed such that the generator line of the cone is angled relative to the propeller axis such that the tip of the blade is forward or aft of the root of the blade. 
 
     
     
         19 . A propeller comprising:
 a hub operable to rotate about an axis of rotation in a direction of rotation, characterized by a forward end and an aft end; and   one or more blades characterized by a root, a tip, a leading edge and a corresponding trailing edge, and a thrust surface, wherein   the thrust surface of each blade conforms to a surface of a reference cone characterized by a vertex and a base and a reference cone circumference, and a generator line, wherein   a radial axis extending radially from the root of each blade corresponds to a generator line of the cone, and the root of each blade is fixed to the hub such that the axis of rotation is coplanar with the radial axis of each blade; wherein   the blade's axis of rotation intersects a generator line at a distance of at least half the length of the distance from the blade root to tip as measured along the generator line that passes through the axis of rotation and up to approximately the length of the blade's radial axis away from the cone's vertex.