A compound helicopter includes a fuselage including a fuselage airframe, a translational thrust system coupled to the fuselage airframe and a pylon assembly subject to vibration. The pylon assembly includes a transmission and a rotor system having a main rotor assembly. The compound helicopter also includes a main rotor vibration isolation system including a plurality of augmented liquid inertia vibration eliminator units each having an isolation frequency and each coupled between the fuselage airframe and the pylon assembly to reduce transmission of the pylon assembly vibration to the fuselage airframe at the isolation frequency. Each augmented liquid inertia vibration eliminator unit includes at least one active tuning element movable to tune the isolation frequency thereof.

A vibration control assembly includes a housing having an interior region and an inner mass including a cage disposed within the interior region of the housing and being rotatable within the housing about a first axis and a gyroscope wheel disposed within the cage and rotatable about a second axis other than the first axis. At least one driving source includes a stator and is operable to interact with a magnetic field of the inner mass to drive rotation of the inner mass about at least one of the first axis and the second axis, wherein the at least one driving source is mounted within the interior region of the housing.

Aircraft support structures, systems, and methods are disclosed. In one embodiment, an aircraft system includes a rotating component and a support (e.g. strut) that supports the rotating component. The support includes a locking assembly (P1) that is configured to lock, automatically, an inner member (214) of the support with respect to an outer member (208) of the support for stiffening the support in response to reaching or exceeding a predetermined threshold amount of displacement, load, stress, or rotation. The aircraft support structures, systems, and methods herein utilize self-locking and self-unlocking supports (e.g. struts) for increasing or decreasing a stiffness of the support.

A strut for mounting an engine in an aircraft includes a first member and a second member. A friction material is coupled to a surface of the first member and is positioned between the first member and the second member. At least one attachment couples the first member, the second member, and the friction material. A biasing mechanism is associated with the at least one attachment. A biasing force of the biasing mechanism biases the second member into engagement with the frictional material to create a static frictional load between the first member and the second member.

A method and system to isolate vibrations, including a first pair of fluid chambers disposed to isolate first vibrations between a first body and a second body, wherein the first vibrations are parallel to a first axis, wherein the first body is a propeller hub, a rotor hub, a pylon attachment, or an engine, and wherein the second body is a propeller shaft, a rotor mast, or a body attachment; a second pair of fluid chambers disposed to isolate second vibrations between the first and second bodies, wherein the second vibrations are parallel to a second axis perpendicular to the first axis; first and second inertia tracks disposed to place the first and second pairs of chambers in fluid communication, respectively; and a plurality of elastic energy storage devices coupled to the first body and the second body and disposed to isolate vibrations between the first and second bodies.

A system for reducing the transmission of vibration from a first vibrating body to a second body, the system having a first part connected to the first vibrating body, a second part connected to the second body and an electro-hydrostatic actuator connected to the first and second parts, the electro-hydrostatic actuator being operable to continuously oscillate the first and second parts 10 relative to each other at a frequency substantially corresponding to the frequency of vibration of the first vibrating body.

A mounting system for a vibration isolation device comprises a support structure having an opening disposed therein, the opening having a concave recess; a thin elastomeric component attached to a surface of the concave recess; and a spherical elastomeric bearing disposed in the opening and attached to the thin elastomeric component, the spherical elastomeric bearing having a beveled upper portion, a middle portion and a beveled lower portion configured to engage the vibration isolation devices.

A mounting arrangement for mounting at least a gear box of a rotorcraft to a fuselage of a rotorcraft, the mounting arrangement comprising a gear box of a rotorcraft and at least two support plates that are rigidly attached to at least approximately opposing sides of the gear box, each one of the at least two support plates comprising at least two attachment means that are adapted to allow attachment of the at least two support plates to a fuselage of a rotorcraft by means of associated struts in order to enable transfer of induced loads occurring in operation, which are directed into a predetermined load direction, via the associated struts.

A helicopter is described that comprises: a rotor; a fuselage; a drive transmission unit operatively connected to the rotor; a support body, which supports the transmission unit; and constraining means interposed between the support body and the fuselage; the constraining means in turn comprise a crosspiece connected in a fixed manner with respect to the support body and having a first lying plane; the crosspiece is formed in part by a metallic material and in part by a visco-elastic material.

A vehicle load-limiting suspension apparatus comprises at least one shear tab for controlling an amount of impact load applied to a vehicle structure when a vehicle impact event occurs. The vehicle load-limiting suspension apparatus further comprises at least one crush tube for limiting the amount of impact load applied to the vehicle structure after the at least one shear tab shears in response to occurrence of the vehicle impact event.