Patent ID: 8640984

Claim:
A stator for a counter-torque device of a helicopter, said stator comprising: a hub; and a plurality of vanes distributed around said hub, wherein said vanes are angularly modulated around said hub such that the angular spacing between adjacent vanes of said vanes varies around said hub for each pair of said adjacent vanes, wherein said vanes are non-radial with respect to a center point of said hub such that each vane centerline passes through the hub and each vane centerline is tangent to a respective circle having a center positioned at the center point of the hub; wherein at least one of said vanes is modulated in a first direction such that said at least one of said vanes is slanted in said first direction, which is transverse to a central axis of said hub and the remaining ones of said vanes are modulated such that they are slanted in a second direction that is opposite to said first direction.