GB1245168A - Improvements in/or relating to rotors - Google Patents

Abstract

1,245,168. Helicopter rotor hubs. SOC. DE CONSTRUCTION ET D'EXPLOITATION DE MATERIELS ET MOTEURS. 10 Feb., 1969 [12 Feb., 1968], No. 7107/69. Heading B7W. A hub for a helicopter variable pitch rotor comprises a rotary axle, a hub member rigidly secured to this axle and to arm means at the free ends of which are attached the rotor blades, each arm means comprising at least three bundles of strips, the bundles being distributed about the pitch variation axis and being connected to each other and to the hub member by holding means in such a way that the arm means possesses a high resistance to bending and a relatively low resistance to torsion. The bundles 5, 6, 7, 8 of each arm are composed of laminated piled strips to prevent fatigue cracks spreading, each of constant thickness and all having the same shape in plan, and the holding means are constituted by rigid sheets 9 and 10 and a plurality of rigid collars spaced along the length of the arm means in planes normal to the pitch axis. The sheet 9 has the same profile as the arm means 3 and is inserted between two consecutive median strips of the bundles 5 and 7, and a second sheet 10 which intercepts the sheet 9 at right angles and is formed in two parts (see Fig. 3) and riveted together. Each collar is formed of a group of four braces 11 in the form of channel bars of U-cross-section provided with recesses 18 enabling them to bear against two consecutive bundles of strips such as 5 and 6. The braces are riveted together through the sheet 9 or 10 by rivets 20 and clamp the strips of the bundles. The strips of the bundles are further clamped by forks 10 also in the form of channel bars of U-crosssection which are riveted through sheets 9 or 10 by rivets 21. The hub member 2 is constituted by a pile of sheets which can be glued to each other.