A method of flight control including having a vertical takeoff and landing aerial vehicle that has a plurality of lift propellers disposed on two linear support pieces, and there are two vertical stabilizers disposed at the rear of the two linear support pieces. A rotating shaft of each lift propeller from among the multiple lift propellers outwards forms an angle of 5 degrees to 15 degrees relative to a vertical plane of the aerial vehicle perpendicular to a horizontal plane of the aerial vehicle. The aerial vehicle of the present disclosure improves the heading axis control capacity of the aerial vehicle and reduces the restriction to the design size of the aerial vehicle.

One embodiment is an aircraft operable in a hover mode and a cruise mode and including a fuselage; wings connected on opposite sides of the fuselage; a canard connected to the fuselage forward of the wings; forward propulsion systems connected to a trailing edge of the canard on opposite sides of the fuselage; aft propulsion systems connected to trailing edges of the wings; and wing-mounted propulsion systems connected to leading edges of the wings. The aft propulsion systems are tiltable between a first position when the aircraft is in the hover mode and a second position when the aircraft is in the cruise mode. Each of the propulsion systems includes a rotor assembly comprising a plurality of rotor blades. The propulsion systems are substantially equidistant from a center of gravity (CG) of the aircraft.

A wing of an aircraft that includes a wing leading edge, a wing trailing edge, and a wing surface defined by a wing upper surface and a wing lower surface is described herein. The wing extends from the wing root to the wingtip, and the wingtip has a wingtip chord. A winglet extends from the wingtip and has a winglet leading edge, a winglet trailing edge, a winglet inboard surface, a winglet outboard surface, a winglet root having a winglet root chord, and a winglet tip. A flow fence is disposed on the wing surface inboard from the winglet and overlapping with the winglet. The flow fence is adapted to delay and/or prevent airflow separation on the winglet inboard surface at high angle of sideslip, increasing lateral stability and linearizing aircraft behavior at high angle of sideslip.

A wing of an aircraft that includes a wing leading edge, a wing trailing edge, and a wing surface defined by a wing upper surface and a wing lower surface is described herein. The wing extends from the wing root to the wingtip, and the wingtip has a wingtip chord. A winglet extends from the wingtip and has a winglet leading edge, a winglet trailing edge, a winglet inboard surface, a winglet outboard surface, a winglet root having a winglet root chord, and a winglet tip. A flow fence is disposed on the wing surface inboard from the winglet and overlapping with the winglet. The flow fence is adapted to delay and/or prevent airflow separation on the winglet inboard surface at high angle of sideslip, increasing lateral stability and linearizing aircraft behavior at high angle of sideslip.

Airframe localized keel structures are disclosed. An example aircraft includes an airframe, a first engine mounted on a first side of the airframe, a second engine mounted on a second side of the airframe, and an airframe keel positioned on at least one of a lower portion of the airframe or an upper portion of the airframe between the first engine and the second engine, the airframe keel to prevent an object from exiting the first engine and impacting the second engine.

An aircraft includes an airframe with first and second wings having a fuselage extending therebetween. A propulsion assembly is coupled to the fuselage and includes a counter-rotating coaxial rotor system that is tiltable relative to the fuselage to generate a thrust vector. First and second yaw vanes extend aftwardly from the fuselage. A flight control system is configured to direct the thrust vector of the coaxial rotor system and control movements of the yaw vanes. In a VTOL orientation of the aircraft, differential operation of the yaw vanes and/or differential operations of first and second rotor assemblies of the coaxial rotor system provide yaw authority for the aircraft. In a biplane orientation of the aircraft, collective operation of the yaw vanes provides yaw authority for the aircraft.

A vertical takeoff and landing aerial vehicle, including a plurality of lift propellers. A rotating shaft of each lift propeller from among the multiple lift propellers outwards forms an angle of 5 degrees to 15 degrees relative to a vertical plane of the aerial vehicle perpendicular to a horizontal plane of the aerial vehicle. The aerial vehicle of the present disclosure improves the heading axis control capacity of the aerial vehicle and reduces the restriction to the design size of the aerial vehicle.

A vertical takeoff and landing aerial vehicle, including a plurality of lift propellers. A rotating shaft of each lift propeller from among the multiple lift propellers outwards forms an angle of 5 degrees to 15 degrees relative to a vertical plane of the aerial vehicle perpendicular to a horizontal plane of the aerial vehicle. The aerial vehicle of the present disclosure improves the heading axis control capacity of the aerial vehicle and reduces the restriction to the design size of the aerial vehicle.

A method of using a split winglet includes providing an aircraft having a winglet attach fitting attaching a split winglet to a wing. The split winglet has an upper winglet and a lower winglet. The method additionally includes maintaining the winglet attach fitting and winglet at a first height relative to a fuselage when the aircraft is non-flying, and moving the winglet attach fitting and winglet to a second height relative to the fuselage when the aircraft is flying, the second height being higher than the first height.

A method of using a split winglet includes providing an aircraft having a winglet attach fitting attaching a split winglet to a wing. The split winglet has an upper winglet and a lower winglet. The method additionally includes maintaining the winglet attach fitting and winglet at a first height relative to a fuselage when the aircraft is non-flying, and moving the winglet attach fitting and winglet to a second height relative to the fuselage when the aircraft is flying, the second height being higher than the first height.