Abstract: A helicopter transmission mounting structure is disclosed in which at least three decoupled inertial isolators (26,38,30,32) are connected to the transmission (12) to support the helicopter fuselage. Each of the inertial isolators (26,28,30,32) is mounted in the nodal plane of the transmission (12) to absorb inplane vibrations generated by a rotor blade and transmitted through a rotor mast (10). The inertial isolators (26,28,30,32) respond individually to applied vibrations which have predetermined frequencies and generate counteracting forces to reduce the amplitude of vibrations transmitted to the fuselage. In an alternative embodiment beam input links (134,136,138,140) are connected from the nodal plane of the transmission to inertial isolators (142,144,146,148). The beam input links (134,136,138,140) are connected to transmit only those forces parallel to the rotor mast (10).

Abstract: A vibration isolator (10) includes an outer housing (14) with an inner housing (16) supported for reciprocation therein. The inner housing (16) includes an elastomeric spring (32) supporting a sleeve or inner cylinder (30) with a passage (44) extending therethrough interconnecting a pair of spaced apart chambers (40,42) defined between the housings (14, 16). A tuning mass including liquid is disposed in the chambers (40,42) and the passage (44). The inner housing (16) functions as a piston to move the tuning mass through the inner cylinder (30) between the chambers (40,42) and generate amplified counter-inertial forces to cancel vibration.

Abstract: A helicopter having a lift unit including a multiblade helicopter main rotor system and a nodalized module including a beam driven in response to blade developed vertical forces has a fuselage unit connected to the beam only at vibration nodal points along the beam. The coupling between the lift unit and the fuselage comprises two rigid arms which form the beam and which extend toward one another from the nodal points. A multilayered flexible beam section interconnects the arms to accommodate beam bending in the flexible section. A rigid member is attached to each of the arms at drive points intermediate the nodal points in supporting relation from the lift unit.