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U.S. Department of Energy
Office of Scientific and Technical Information

Windmill

Patent ·
OSTI ID:6267662
A windmill, a variable pitch air-screw is described comprising a hub, a generally horizontally-supported stationary shaft on which the hub is mounted for free rotation. A resilient support for connecting the shaft to a ground-standing supports tower; at least two rotatable blades, each blade radially extending from the hub and defining a root radially spaced from the hub; one and another collar fixedly mounted axially spacedly on the hub on respective opposite sides of the rotational plane on the blades; each blade has an air foil profile with a thicker leading edge; a thinner trailing edge; a main concave surface and an opposite convex surface; first and second resilient strips for each blade, the first strip rigidly connected at one end to the one collar and as its other end to the convex surface of one blade root proximate the blade leading edge. The second strip is rigidly connected at one end to the another collar and at its other end to the concave surface of the same one blade root proximate its trailing edge; the strips are oppositely inclined to each other and each crossing the rotational plane of the blades; increase of the centrifugal force exerted on the blades decreases the inclination of the strips and causes rotation of each blade about its longitudinal axis relative to the hub. This increases the pitch of the blades with increase of the rotational speed of the air-screw.
Assignee:
NOV; NOV-87-072014; EDB-87-147304
Patent Number(s):
US 4678923
OSTI ID:
6267662
Country of Publication:
United States
Language:
English

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