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US 4,370,096 AGranted
Marine propeller
AssigneePropeller Design Limited
InventorLeslie G. Church
Life of this patent
Estimating the term…
Abstract
A marine ring propeller comprising blades, each having parallel edges and a constant cross-section, and a ring in the form of an annular shroud fixed to the outer ends of the blades. The shroud is typically frusto-conical on its inner surface and curved on its outer surface to provide an aerofoil cross-section, apart from the leading edge which is provided with a concave bevel on either or both of the inner and outer surfaces.
Claims18
A marine ring propeller comprising:
- a plurality of elongated propeller blades positioned around a central hub, each blade having leading and trailing edges which are straight and parallel to each other, each blade being smoothly curved concavo-convex in cross-section with the leading edges being beveled to be substantially parallel to the plane of rotation of the propeller;
- the cross-section of each blade being constant along the length of the blade;
- a shroud shaped as an annular wall fixed to the outer ends of the blades and having an inner surface and outer surface, the inner surface being frusto-conical so as to be converging toward the downstream end of the propeller at an angle between 1.degree. and 15.degree. to the rotational axis;
- said inner surface being substantially flat from the trailing edge of the annular wall forward to a point axially forward of the point of contact with the leading edge of the propeller blade;
- said outer surface being essentially of smoothly curved convex shape when viewed in cross-section.
2 more elements
Dependencies are inferred from the claim text.