The present disclosure relates to a vertical takeoff and landing (VTOL) aircraft (100) and a propulsion system (600) thereof. The propulsion system (600) comprises a primary rotor (108) configured to couple to an airframe (102) and oriented to generate a vertical thrust relative to the airframe (102), a drivetrain (626) operably coupled to an engine (602) and configured to mechanically drive the primary rotor (108), and a plurality of tiltable secondary rotor assemblies (114) configured to be disposed about the primary rotor (108). The primary rotor (108) comprises a plurality of collective-only variable-pitch blades. Each of the plurality of tiltable secondary rotor assemblies (114) may have a secondary rotor (116) and an electric motor (608) to drive the secondary rotor (116). An electric generator (606) operably coupled to the engine (602) or to the drivetrain (626) may be configured generate electric power for each electric motor (608) of the plurality of tiltable secondary rotor assemblies (114). Each of the plurality of tiltable secondary rotor assemblies (114) is configured to tilt between a vertical configuration (200b) and a horizontal configuration (200a) as a function of a phase of flight of the VTOL aircraft (100).

Fan module with variable-pitch blades for a propulsion system that includes: a rotor supporting the blades, and including an internal shaft and an external shroud, defining between them a space; a pitch control device (22) of the blades that includes a load transfer bearing; a feathering device of the blades; said feathering device includes at least one lever that is articulated around a fixed axis (A) in relation to the rotor, where said lever features a first end located outside said space and a second end located inside said space, and where a flyweight is fastened to the first end and the second end is coupled to said bearing.

This patent discloses improvements over a mechanism to modulate the pitch of the blades of a fan, turbine or propeller driven by a rotating shaft bearing a helical thread onto which a nut made of a ferromagnetic material was threaded; this nut was spun by electromagnets disposed about it on the stator system and its resultant axial motion manipulated the blades' pitch. This patent discloses refinement of control of the electromagnets employed to spin the axial modulator by embedding a plurality of ferrous protuberances in this nutthe rotational position of which is determined via metallic edge detection sensors whose logic levels are used to selectively energize electromagnets that apply a force onto the protuberances in order to induce rotation and axial motion on the nut. This additional degree of rotational freedom is controlled by this reluctance-motor like configuration while a second motor is used to spin the blades.

This patent discloses improvements over a mechanism to modulate the pitch of the blades of a fan, turbine or propeller driven by a rotating shaft bearing a helical thread onto which a nut made of a ferromagnetic material was threaded; this nut was spun by electromagnets disposed about it on the stator system and its resultant axial motion manipulated the blades' pitch. This patent discloses refinement of control of the electromagnets employed to spin the axial modulator by embedding a plurality of ferrous protuberances in this nutthe rotational position of which is determined via metallic edge detection sensors whose logic levels are used to selectively energize electromagnets that apply a force onto the protuberances in order to induce rotation and axial motion on the nut. This additional degree of rotational freedom is controlled by this reluctance-motor like configuration while a second motor is used to spin the blades.

An electronic control system (35) for a turbopropeller engine (2) having a gas turbine (20) and a propeller assembly (3) coupled to the gas turbine (20), the control system (35) implementing a propeller control unit (PEC) to control propeller operation based on a pilot input request, via generation of a driving quantity (I.sub.p) for an actuation assembly (29) designed to adjust a pitch angle () of propeller blades (10). The control unit engages a mechanical lock determining a minimum flight value for the pitch angle during a flight operating mode, and disengages the mechanical lock and controls the pitch angle below the minimum flight value, up to a minimum ground value lower than the minimum flight value, during a ground operating mode; the propeller control unit, during a transition from the ground operating mode to the flight operating mode, engages the mechanical lock, thereby causing an increase of the pitch angle towards the minimum flight value independently from the control action. In particular, the control unit anticipates the increase of the pitch angle in a time period (T) before the mechanical lock engagement due to transition from the ground operating mode to the flight operating mode.

Rotor hubs having pitch control systems and related methods are disclosed herein. An example apparatus includes a housing including a first housing arm to support a first blade grip and a first blade spindle and a second housing arm to support a second blade grip and a second blade spindle. The example apparatus includes a first pitch link and a second pitch link. The example apparatus includes a first pitch arm coupled to the first pitch link and one of the first blade grip or the first blade spindle and a second pitch arm coupled to the second pitch link and one of the second blade grip or the second blade spindle. The second pitch arm is to extend past the first housing arm to couple with the one of the second blade grip or the second blade spindle.

Rotor hubs having pitch control systems and related methods are disclosed herein. An example apparatus includes a housing including a first housing arm to support a first blade grip and a first blade spindle and a second housing arm to support a second blade grip and a second blade spindle. The example apparatus includes a first pitch link and a second pitch link. The example apparatus includes a first pitch arm coupled to the first pitch link and one of the first blade grip or the first blade spindle and a second pitch arm coupled to the second pitch link and one of the second blade grip or the second blade spindle. The second pitch arm is to extend past the first housing arm to couple with the one of the second blade grip or the second blade spindle.

A propeller provided with interchangeable blades, and to a method of mounting such interchangeable blades on the propeller. The propeller comprises a hub, fastening fittings, rotation guide devices for guiding the fastening fittings in rotation relative to the hub, locking parts, and blades. The fastening fittings are configured to be assembled into the hub from the inside of the hub, and the locking parts lock respective ones of the fastening fittings onto the hub. The blades are fastened to respective ones of the fastening fittings outside the hub and can thus easily be replaced with other blades without removing the propeller.

A propeller provided with interchangeable blades, and to a method of mounting such interchangeable blades on the propeller. The propeller comprises a hub, fastening fittings, rotation guide devices for guiding the fastening fittings in rotation relative to the hub, locking parts, and blades. The fastening fittings are configured to be assembled into the hub from the inside of the hub, and the locking parts lock respective ones of the fastening fittings onto the hub. The blades are fastened to respective ones of the fastening fittings outside the hub and can thus easily be replaced with other blades without removing the propeller.

A multi-blade rotor of a rotary wing aircraft, the multi-blade rotor comprising at least one rotor blade that defines a pitch axis and that is provided with an associated pitch-control lever that is operatively coupled to a pitch link rod, the pitch link rod defining a longitudinal axis, wherein the associated pitch-control lever comprises an accommodation that is located on the longitudinal axis of the pitch link rod at a predetermined distance from the pitch axis of the at least one rotor blade, the pitch link rod being operatively coupled to the associated pitch-control lever at the accommodation of the associated pitch-control lever, wherein the predetermined distance is adjustable in order to enable adjustment of track and balance of the multi-blade rotor.