ELASTOMERIC HELICOPTER ROTOR HEAD WITH DYNAMIC AND STATIC BLADE CONING AND DROOP STOPS

摘要

1439237 Helicopter rotors UNITED AIRCRAFT CORP 5 Sept 1973 [5 Sept 1972 (2)] 41727/73 Heading B7W A helicopter rotor 10 has a hub 12 rotatable about an axis 14 and a plurality of blades 16 each extended inwardly by a yoke member 22 positioned between the arms of a yoke 20 extending from hub 12, a part-spherical laminated elastomeric bearing 18 being secured at 30 and 28 respectively to the yokes to give the blade universal freedom of movement about the point of intersection 37 of the pitch-change axis 32 lead-lag axis 34 and flapping axis 36. The point 37 is concentric with a part-spherical ball 56 bolted at 58 to the root end of the blade and forming the spigot of a centring bearing 27 which comprises alternate layers of elastomer and rigid laminates bonded to the outer surface of ball 56 and to an outer race 60 carried by yoke 20. A lag-lead damper (not shown) is connected to yoke 22 by an elastomeric bearing 94. Coning and droop stops are provided for each blade and so arranged that when the blade is at either its coning or droop stops leadlag motion of the blade does not change the angle of cone or droop. A ring 70 is mounted for free rotation on a bearing 72 and is formed with a frusto-conical face 80 profiled to cooperate with the surface 82 of a coning limit stop 84 secured to yoke 20. As shown in Fig. 11, yoke 20 carries also a bracket 102 which supports a barrel shape member 118 and a pivoted member 88 having faces 86 and 100 which respectively co-operate with the surface 80 of ring 70 and the outer surface of the barrel shape member 118, the member having a balance weight 123 and a balance spring 122, Fig. 8. When the rotor is stationary or operating at low speed spring 122 pulls the member 88 into position between ring 70 and member 118 to form a static droop stop. When rotor speed increases the centrifugal effect of the weight 123 overcomes the spring and moves the member 88 clear of the member 118 which then serves as a dynamic droop stop. An alternative construction of the centre spigot is described with reference to Fig. 1 (not shown).