An aerial vehicle is provided including rotor units connected to the aerial vehicle, and a control system configured to operate at least one of the rotor units. The rotor unit includes rotor blades, wherein each rotor blade includes a surface area, and wherein an asymmetric parameter is defined, at least in part, by the relationship between the surface areas of the rotor blades. The value of the asymmetric parameter is selected such that the operation of the rotor unit: (i) moves the rotor blades such that each rotor blade produces a respective vortex and (ii) the respective vortices cause the rotor unit to produce a sound output having an energy distribution defined, at least in part, by a set of frequencies, wherein the set of frequencies includes a fundamental frequency, one or more harmonic frequencies, and one or more non-harmonic frequencies having a respective strength greater than a threshold strength.

A telescopic spar mechanism is provided. The telescopic spar mechanism comprises a housing, an outer tube rotatably coupled to the housing, and an inner tube received within the outer tube. The outer tube having flat walled threads formed on an inside. The inner tube having a plurality of spaced apart bearings secured to an outside of the inner tube, where the plurality of bearings are received within lands of the threads of the outer tube. The telescopic spar mechanism is used in combination with a wing assembly to increase the wing size of VTOL aircrafts.

To provide an unmanned aerial vehicle that eliminates or minimizes the laboriousness involved in optimal pitch adjustment of propellers while eliminating or minimizing complexity and instability in airframe structure and/or flight programs. This object is solved by an unmanned aerial vehicle that is provided with a plurality of rotors and that includes: a center frame that is a central portion of an airframe of the unmanned aerial vehicle; and a plurality of arms extending radially from the center frame in plan view. A plurality of motors that are driving sources of the respective rotors are provided in the center frame. The plurality of rotors are supported by the respective arms. Each arm of the arms has a hollow cylindrical structure. A motive power transmission member configured to transmit a driving force of each motor of the motors to the each rotor is provided in the each arm.

Aircraft are configured to facilitate propeller blade pitch adjustability. According to one example, an aircraft can include a plurality of propellers, where each propeller includes plurality of blades. At least one pitch adjust mechanism may be associated with at least on propeller, where the pitch adjust mechanism is configured to adjust a pitch of the plurality of blades for at least one propeller in response to airflow from at least one other propeller influencing an airflow at the at least one propeller. Other aspects, embodiments, and features are also included.

A multimodal unmanned aerial system includes a fuselage forming a payload bay, a control wing forward of the fuselage including a first plurality of propulsion assemblies and a primary wing aft of the fuselage including a second plurality of propulsion assemblies. The primary wing has a greater wingspan than the control wing. The multimodal unmanned aerial system includes linkages rotatably coupling the fuselage to the control wing and the primary wing. The fuselage, the control wing and the primary wing are configured to synchronously rotate between a vertical takeoff and landing flight mode and a forward flight mode. The fuselage, the control wing and the primary wing are substantially vertical in the vertical takeoff and landing flight mode and substantially horizontal in the forward flight mode.

A propeller system with directional thrust control comprising a hub, a plurality of blade attachment apparatuses attached to the hub, and a plurality of blades, each blade of the plurality of blades being attached to a blade attachment apparatus of the plurality of blade attachment apparatuses. The hub is operable to rotate about a rotation axis thereof. The plurality of blades is attached to the hub via the plurality of blade attachment apparatuses such that the plurality of blades rotates about the rotation axis of the hub when the hub rotates about the rotation axis thereof. Each blade attachment apparatus of the plurality of blade attachment apparatuses is operable to rotate the blade attached thereto about a blade rotation axis.

According to various embodiments, there is provided a multi-rotor aircraft for a multiple payload delivery comprising a morphing mechanism having an airframe and at least three support arms coupled to the airframe wherein each support arm is configured for rotating about a vertical axis of the aircraft relative to the morphing mechanism. The aircraft further includes a payload bay coupled to the morphing mechanism for engaging and disengaging a plurality of payloads and a control system communicatively coupled with the morphing mechanism and the payload bay, wherein the control system is configured to cause each of the support arms to rotate by a predetermined angle about the vertical axis of the aircraft, wherein the predetermined angle is determined based on a change in distance between a neutral point and a centre of gravity of the aircraft.

A line-replaceable thrust module includes a nacelle configured to be mechanically connected to an anchoring location of an unmanned aerial vehicle (UAV), an electric motor coupled to the nacelle, an electric speed controller configured to control the speed of the electric motor and configured to be electrically connected to a communication network of the UAV, and a fuel cell system configured to produce electrical energy from an electrochemical reaction between hydrogen and oxygen. The fuel cell system includes a fuel cell, a hydrogen tank, a pressure regulator coupled to the hydrogen tank, and a supply line coupled between the pressure regulator and the fuel cell.

A collapsible unmanned aerial vehicle has: a cylindrical structural body; a plurality of deployable mechanisms laterally distributed about the cylindrical structural body; a control unit; a portable power source; each of the plurality of deployable mechanisms comprising a lift-generating device, a pliable pylon and an actuation mechanism, the cylindrical structural body being terminally mounted to the pliable pylon, the lift-generating device being terminally mounted to the pliable pylon, the actuation mechanism being operatively integrated along the pliable pylon, the pliable pylon being selectively configured to be radially straightened from the cylindrical structural body and to arcuately collapsed into the cylindrical structural body via the actuation mechanism, the control unit and the portable power source each being electrically connected to the actuation mechanism; the control unit and the portable power source being mounted within the cylindrical structural body; and the portable power source being electrically connected to the control unit.

According to a first aspect of the invention, there is provided a method for operating a multicopter experiencing a failure during flight, the multicopter comprising a body, and at least four effectors attached to the body, each operable to produce both a torque and a thrust force which can cause the multicopter to fly when not experiencing said failure. The method may comprise the step of identifying a failure wherein the failure affects the torque and/or thrust force produced by an effector, and in response to identifying a failure carrying out the following steps, (1) computing an estimate of the orientation of a primary axis of said body with respect to a predefined reference frame, wherein said primary axis is an axis about which said multicopter rotates when flying, (2) computing an estimate of the angular velocity of said multicopter, (3) controlling one or more of said at least four effectors based on said estimate of the orientation of the primary axis of said body with respect to said predefined reference frame and said estimate of the angular velocity of the multicopter. The step of controlling one or more of said at least tour effectors may be performed such that (a) said one or more effectors collectively produce a torque along said primary axis and a torque perpendicular to said primary axis, wherein (i) the torque along said primary axis causes said multicopter to rotate about said primary axis, and (ii) the torque perpendicular to said primary axis causes said multicopter to move such that the orientation of said primary axis converges to a target orientation with respect to said predefined reference frame, and (b) such that said one or more effectors individually produce a thrust force along said primary axis.