An inner middle rotor is rotated while an inner front rotor, an inner back rotor, and an outer rotor are not rotated. The inner middle rotor is surrounded by the inner front rotor, the inner back rotor, the outer rotor, and a fuselage. After rotating the inner middle rotor while not rotating the inner front rotor, the inner back rotor, and the outer rotor, the inner middle rotor, the inner front rotor, the inner back rotor, and the outer rotor are simultaneously rotated.

A device for sealing a space at a juncture between elements of a nacelle, the device being non-flammable by heat, having a predetermined shape, and having a proximal end configured to be inserted into the space to be sealed so as to seal it, and a distal end configured to be fastened to an element of the nacelle at a fire area.

An elastomeric bearing assembly has a housing, a centrifugal force bearing axially captured relative to the housing, and a sliding cap disposed between the housing and the centrifugal force bearing.

A rotary wing aircraft with a fuselage that forms an aircraft interior region, the fuselage comprising an upper primary skin that separates the aircraft interior region from an aircraft upper deck arranged above the fuselage, wherein the aircraft upper deck comprises an engine accommodating region with a firewall arrangement, the engine accommodating region accommodating at least one aircraft engine within the firewall arrangement, wherein the firewall arrangement comprises at least one gasket for tightening pass-through of a torque tube that connects the at least one aircraft engine to a main gear box of the rotary wing aircraft, and wherein the at least one gasket comprises at least two fire proof shells and a ring-shaped flexible fire proof bellows.

A rotary wing aircraft with a fuselage that forms an aircraft interior region, the fuselage comprising an upper primary skin that separates the aircraft interior region from an aircraft upper deck arranged above the fuselage, wherein the aircraft upper deck comprises an engine accommodating region with a firewall arrangement, the engine accommodating region accommodating at least one aircraft engine within the firewall arrangement, wherein the firewall arrangement comprises at least one gasket for tightening pass-through of a torque tube that connects the at least one aircraft engine to a main gear box of the rotary wing aircraft, and wherein the at least one gasket comprises at least two fire proof shells and a ring-shaped flexible fire proof bellows.

A stowable lift rotor is coupled to an airframe of a VTOL aircraft. The VTOL aircraft is convertible between a VTOL flight mode and a forward flight mode. The stowable lift rotor includes a lift arm. The proximal end of the lift arm is coupled to the airframe of the VTOL aircraft. The stowable lift rotor also includes a rotor assembly including rotor blades coupled to the distal end of the lift arm. The lift arm is movable between various positions including an extended position in the VTOL flight mode, a stowed position in the forward flight mode and intermediate positions therebetween such that the distance between the rotor assembly and the airframe is greater in the extended position than in the stowed position.

A tunable mass damper assembly is attachable to a rotor blade. The tunable mass damper assembly comprises a base configured to be attached to the rotor blade and a pendulum mass structure movably attached to the base and configured to move relative to the base in accordance with a rotational speed of the rotor blade about a rotor axis. The pendulum mass structure is configured to reduce vibratory forces of the rotor blade induced by a rotation of the rotor blade about the rotor axis. An entirety of the pendulum mass structure being configured to be contained within and enclosed by the rotor blade.

A fail safety apparatus of the air mobility is provided. Locations of propeller modules are adjusted by rotation parts and length adjustment units to evenly distribute thrust of the re-located propeller modules so that the attitude of the air mobility is stabilized. In particular, when one propeller module among a plurality of propeller modules fails, the attitude of the air mobility is normalized by adjusting a location of the failed propeller module and locations of remaining normal propeller modules so that flight safety of the air mobility is secured.

An aircraft includes an electronically controlled engine (ECE) and a first and a second throttle control assembly. The first throttle control assembly includes a first throttle fly button configured to command a FLY mode and a first throttle idle button configured to command an IDLE mode. The second throttle control assembly includes a second throttle fly button configured to command the FLY mode and a second throttle idle button configured to command the IDLE mode.

A wind estimation system for an aircraft includes a first sensor configured to sense a first position associated with an aircraft control component in a wind condition, a second sensor configured to sense a first configuration associated with a rotor system of the aircraft in the wind condition, and at least one controller in communication with at least one of the first sensor or the second sensor. The at least one controller is configured to determine a tip-path-plane angle of the aircraft based on the first position and the first configuration, and determine at least one of a current wind speed or current wind direction based on the tip-path-plane angle.