Patent ID: 6120251
Filing Date: 2000-09-19
Classification: B64C

Abstract:
A rotor for a rotorcraft of the type comprising:a mast intended to be driven by a mast base in rotation about a mast axis, which is the axis of rotation of the rotor,a hub, secured to the mast,at least two blades, each of which has a blade root connected to the hub by retaining and articulation means, allowing angular travel of the blade in terms of pitch, in terms of flapping and in terms of drag about a longitudinal axis for changing the pitch of the blade, an axis of flapping and an axis of drag of the blade respectively, which axes are perpendicular in pairs and meet at a center of articulation of said retaining and articulation means, the axis of drag being approximately parallel to said axis of the rotor, and, for each blade,a flap stops device in which inner fixed stops on the same side as the mast, and outer fixed stops on the opposite side to the mast and which are secured to the blade root bear directly against inner fixed stops and outer fixed stops respectively, which are secured to the hub, in order respectively to limit the negative and positive flappings of the blade, each of the inner and outer flap stops of the blade having a bearing surface at least a portion of which is planar, transverse with respect to the corresponding pitch axis and inclined to the axis of the rotor so that said blade flap stop approximately faces a corresponding respective inner or outer stop of the hub, and in which device each flap stop of the hub is curved into an arc of a circle with a convexness facing radially outwards with respect to the axis of the rotor,wherein each inner or outer flap stop of the hub has a bearing surface which is a portion of a torus-shaped surface, with convexity facing towards the opposite inner or outer flap stop belonging to a blade and which is centered on the axis of drag of said bladeswherein each inner or outer flap stop of the hub is substantially a quarter-torus segment,wherein the inner flap stop of each blade comprises a bearing surface, the planar portion of which is extended, on one side of the corresponding pitch axis by a portion of cylindrical surface.