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Device for controlling the pitch of the blades of a convertible aircraft rotor

  • US 20030183722A1
  • Filed: 03/20/2003
  • Published: 10/02/2003
  • Est. Priority Date: 03/29/2002
  • Status: Active Grant
First Claim
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1. A pitch control device for controlling pitch of blades of a rotor of a convertible aircraft, where the rotor comprises:

  • a rotor mast having a base and a longitudinal axis, the rotor mast being designed to be driven in rotation by said base about said longitudinal axis, a hub, driven in rotation by the mast, and connected to the mast by a tilting arrangement allowing the hub as a whole to tilt about any flapping axis passing through the axis of the mast and perpendicular to the axis of the mast, at least two blades, each of which is connected to the hub by a coupling retaining and hingeing said blade in pitch about a longitudinal pitch change axis of said blade, which pitch change axis extends it a plane of rotation of the rotor, wherein the pitch control device is external to the hub and comprises, for each blade of the rotor;

    a pitch change lever integral in rotation with a root of said blade about said pitch change axis, and projecting on a side of a plane of rotation of the rotor which faces towards the base of the mast, a pitch control rod, which is movable in a direction substantially parallel to the longitudinal axis of rotation of the mast, a bellcrank, mounted so as to pivot, about a pivot pin substantially contained in a radial plane relative to the longitudinal axis of rotation of the mast, on a fixed point of a drive plate, integral in rotation with the mast, said pitch control rod being hinged to said bellcrank at least so as to pivot about a pin substantially parallel to the pivot pin of the bellcrank on the drive plate and at a point offset radially outwardly of said pivot pin relative to the longitudinal axis of rotation of the mast, and a link rod, hinged at least so as to pivot at one end on said pitch change lever, about a pin substantially parallel to said pitch change axis, and at an other end of said link rod, to the bellcrank, at a fixed point on the bellcrank situated between said plane of rotation of the rotor and the point at which the bellcrank is hinged to the drive plate, so that said link rod is slightly inclined to any radial plane relative to the longitudinal axis of rotation of the mast, and that the bellcrank converts any movement of the pitch control rod into movement of the link rod in a direction substantially transverse to the direction of the longitudinal axis of the mast.

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