Sounds are generated by an aerial vehicle during operation. For example, the motors and propellers of an aerial vehicle generate sounds during operation. Disclosed is an adjustable propeller that may alter shapes during operation or rotation of the propeller such that the sound generated by the rotation of the propeller changes. The propeller may include multiple sections and joints that allow movement of the sections in any direction. Likewise, the propeller may include one or more sound flaps that may be opened or closed to further alter the sound generated as the propeller rotates.

A pitch horn assembly for an aircraft including a blade attachment member having a first end, a second end configured to be coupled to a rotor blade; and a blade attachment axis extending between the first end and the second end of the blade attachment member; a moveable arm configured to be coupled to the blade attachment member at a pitch horn axis, the moveable arm having a first end configured to be coupled to a pitch link; a second end; and a moveable arm axis extending between the first end and the second end of the moveable arm; an extendable member configured to be coupled to the blade attachment member and the moveable arm of the pitch horn, wherein the extendable member moves the moveable arm about the pitch horn axis. An embodiment provides a method of adjusting a pitch-flap coupling in an aircraft.

A blade for an aircraft rotor has a trailing-edge tab, the tab being movable between a stowed position, in which substantially all of the tab is located within the blade, and a deployed position, in which at least a portion of the tab extends from a trailing edge of the blade. At least one actuator system is selectively operable to cause movement of the tab between the stowed position and the deployed position for changing a chord length of the blade.

A rotor system comprising hinged stabilizing flaps (6) which compensate for the torque generated by a main rotor of an air vehicle and provide the air vehicle with the rotation around its own axis, the rotor system further comprising deflecting flaps (12) which allow the air vehicle to move forward, backward, right and left.

A pitch horn assembly for an aircraft including a blade attachment member having a first end, a second end configured to be coupled to a rotor blade; and a blade attachment axis extending between the first end and the second end of the blade attachment member; a moveable arm configured to be coupled to the blade attachment member at a pitch horn axis, the moveable arm having a first end configured to be coupled to a pitch link; a second end; and a moveable arm axis extending between the first end and the second end of the moveable arm; an extendable member configured to be coupled to the blade attachment member and the moveable arm of the pitch horn, wherein the extendable member moves the moveable arm about the pitch horn axis. An embodiment provides a method of adjusting a pitch-flap coupling in an aircraft.

A rotary wing air vehicle has a body; at least one engine located on the body; a rotor that extends outwards from the body and rotates around its own axis in connection with the engine; at least one shaft extending outward from the rotor and triggered by the engine to rotate around an axis that the shaft extends from the rotor; at least two blades connected with the shaft and triggered by the shaft to move; at least one flap on the blade which provides drag force to the rotor by its movement to a closed position or an open position; at least one brake system which is located on the body in connection with the rotor to enable the flap to move to the closed position and/or open position so that a rotational speed of the rotor is adjusted by a user.

An edge morphing arrangement for an airfoil having upper and lower control surfaces is provided with an elongated edge portion that overlies the edge of the airfoil, the edge portion having a surface element having first and second edges that communicate with, and form extensions of, respective ones of the upper and lower control surfaces of the elongated airfoil. The surface elements are formed of deformable compliant material that extends cross-sectionally from the first surface element edge to an apex of the edge portion, and to the second surface element edge. There is additionally provided a driving link having first and second driving link ends, the first driving link end being coupled to the interior of one of the first and second rib portions. The second end is arranged to receive a morphing force, and the rib element is deformed in response to the morphing force.

An edge morphing arrangement for an airfoil having upper and lower control surfaces is provided with an elongated edge portion that overlies the edge of the airfoil, the edge portion having a surface element having first and second edges that communicate with, and form extensions of, respective ones of the upper and lower control surfaces of the elongated airfoil. The surface elements are formed of deformable compliant material that extends cross-sectionally from the first surface element edge to an apex of the edge portion, and to the second surface element edge. There is additionally provided a driving link having first and second driving link ends, the first driving link end being coupled to the interior of one of the first and second rib portions. The second end is arranged to receive a morphing force, and the rib element is deformed in response to the morphing force.