Improved spar-to-hub joint for a flexbeam helicopter rotor

摘要

The flexbeam helicopter rotor has an improved connection between the flexbeam (20) and the hub (12) of the connecting pin variety but in which the high tensile fibers of the flexbeam (20) do not wrap around the connecting pin (22), wherein the blade centrifugal loads and the blade lead-lag loads are reacted by the connecting pin (22) at a station where it passes through drilled holes (58) in the flexbeam inner end, and wherein the blade flapping motion imposed loads are reacted through two load paths in the flexbeam-to-hub connection, the first load path being created by a prying reaction between the flexbeam (20) and the hub connecting flanges (16, 18), and the second load path being created by the differential bending reaction between the flexbeam (20) at the station of the drilled holes (58) and the connecting pins (22). Further, there are means (42, 44) to decouple the loads and decrease the maximum load in at least one of the load paths created by the aforementioned prying reaction and the aforementioned bending reaction so that they are substantially spaced along the flexbeam axis of rotation (34) from each other to thereby permit the use of a minimum thickness flexbeam (20), and gain the attended advantage of reduced rotor weight and size, and which flexbeam-to-hub connection has the additional advantage of a reduced flapping hinge effecting offset, or flapping axis, from the prior art type of connection.