A rotorcraft including a fuselage, one or more motor-driven rotors for vertical flight, and a control system. The motors drive the one or more rotors in either of two directions of rotation to provide for flight in either an upright or an inverted orientation. An orientation sensor is used to control the primary direction of thrust, and operational instructions and gathered information are automatically adapted based on the orientation of the fuselage with respect to gravity. The rotors are configured with blades that invert to conform to the direction of rotation.

An assembly configured to prevent damage to an object during manufacture thereof is provided including a first housing having a substantially hollow interior. An exposed first planar surface of the first housing includes an inlet port and a plurality of small openings formed about the periphery. The inlet port, the hollow interior, and the plurality of small openings form a fluid flow path through the assembly. A second housing similar in size and shape to the first housing, has an exposed second planar surface. An intermediate layer is arranged between the first housing and the second housing. A cross-section of the intermediate layer is configured to change shape in response to a compression force applied thereto by the first housing and the second housing to form a seal separating an exterior portion of the object exposed to the plurality of small openings from an interior surface of the object.

A rotorcraft including a fuselage, one or more motor-driven rotors for vertical flight, and a control system. The motors drive the one or more rotors in either of two directions of rotation to provide for flight in either an upright or an inverted orientation. An orientation sensor is used to control the primary direction of thrust, and operational instructions and gathered information are automatically adapted based on the orientation of the fuselage with respect to gravity. The rotors are configured with blades that invert to conform to the direction of rotation.

A rotor blade is provided. The rotor blade includes a blade portion, a tip cap formed to define a dimple, a fastener and a doubler. The fastener includes a flat-headed shaft and is disposable such that the flat-headed shaft extends through the blade portion and the tip cap at the dimple. The fastener is configured to urge the blade portion toward the tip cap. The doubler includes a dimpled portion disposable between the tip cap and a portion of the flat-headed shaft at the dimple and an exterior portion. The exterior portion is disposable flush with respective exterior surfaces of the blade portion and the flat-headed shaft.

A rotor system is provided in one example embodiment and may include a rotor duct; at least one rotor blade, wherein the at least one rotor blade comprises a tip end; and a multi-material tip extension affixed at the tip end of the at least one rotor blade, wherein the multi-material tip extension comprises an inboard portion fabricated from a first material and an outboard portion fabricated from a second material, wherein the second material is different than the first material.

A blade spar for a rotor blade for a rotor of an aircraft or vessel, preferably wherein the rotor is a propeller, the blade spar comprising a laminate structure. The laminate structure includes a plurality of plies of fibres in a matrix, wherein the blade spar has generally a longitudinal axis defining a longitudinal direction, the longitudinal axis extending along a radial direction of the rotor. The blade spar includes at least a portion that is curved from the longitudinal axis, wherein the plurality of plies comprises a first ply comprising a plurality of first fibres, wherein an alignment of the first fibres varies along the longitudinal direction to align the first fibres to the curved blade spar.