An aircraft capable of carrying at least 400 pounds of payload, has four rotors systems, each of the rotor systems being independently driven by an electric motor or other torque-producing source. Each of the rotor systems provide sufficient thrust such that the aircraft is capable of controlled vertical takeoff and landing, even if one of the variable pitch rotor is inoperable. An electronic control system is configured to control the rotational speed and pitch of at least one of the rotor systems in each of the first and second rotor pairs. The rotors may be arranged in coaxial stacks or maybe otherwise configured.

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 turbomachine including at least two unducted propellers, one of which is an upstream propeller and one a downstream propeller, the upstream propeller including a plurality of blades, at least one first blade of which has a different length from that of a second blade.

A turbomachine including at least two unducted propellers, one of which is an upstream propeller and one a downstream propeller, the upstream propeller including a plurality of blades, at least one first blade of which has a different length from that of a second blade.

The aircraft thrust control system comprises a central power unit and peripheral power units. The central power unit comprises upper and lower propellers arranged one above the other and adapted to rotate in opposite directions, while propellers of the peripheral power units are located outside the aerodynamic operating range of the central power unit propellers.

The aircraft thrust control system comprises a central power unit and peripheral power units. The central power unit comprises upper and lower propellers arranged one above the other and adapted to rotate in opposite directions, while propellers of the peripheral power units are located outside the aerodynamic operating range of the central power unit propellers.

An aircraft having a fixed wing is operative to perform vertical takeoff and landing while positioned in a nose-down orientation. The aircraft has a fixed wing having a leading edge and a trailing edge; a propulsion system operative to selectively provide forward propulsion and rearward propulsion; and a controller operative to control operation of the propulsion system. The propulsion system provides rearward propulsion during takeoff of the aircraft to move the aircraft in a direction of the trailing edge of the fixed wing, and provides forward propulsion during flight of the aircraft to move the aircraft in a direction of the leading edge of the fixed wing. The aircraft maintains the wing substantially vertical with the trailing edge facing upwards during takeoff, and transitions to having the wing substantially horizontal during flight. A vertical landing procedure is also provided.

An aircraft having a fixed wing is operative to perform vertical takeoff and landing while positioned in a nose-down orientation. The aircraft has a fixed wing having a leading edge and a trailing edge; a propulsion system operative to selectively provide forward propulsion and rearward propulsion; and a controller operative to control operation of the propulsion system. The propulsion system provides rearward propulsion during takeoff of the aircraft to move the aircraft in a direction of the trailing edge of the fixed wing, and provides forward propulsion during flight of the aircraft to move the aircraft in a direction of the leading edge of the fixed wing. The aircraft maintains the wing substantially vertical with the trailing edge facing upwards during takeoff, and transitions to having the wing substantially horizontal during flight. A vertical landing procedure is also provided.

The aircraft comprises a fuselage defining a fuselage main axis. The fuselage comprises a docking system for fixing removable nacelles. The aircraft has wings equipped with tilting actuators for rotating wings about rotation axes parallel to the fuselage main axis and at least six propellers mechanically connected to the fuselage. The aircraft also has at least one cryo-hydrogen tank and at least one fuel cell for supplying power to the propellers, and

A capacitor for supplying power to the propellers, charged by at least one fuel cell. This capacitor stores electrical energy greater than the energy needed by all the propellers for ten seconds of hovering flight. Each propeller is equipped with a tilting actuator for rotating the propeller about a rotation axis making an angle of less than 45 degrees with a plane perpendicular to the fuselage main axis. The fuselage having a forward and a rear portion defining a forward to rear order of the propellers, in cruise flight, the two forward propellers are activated to provide vertical thrust, the intermediate propellers between the forward and rearmost propellers are not activated and the two rearmost propellers are activated to provide horizontal thrust.

The aircraft comprises a fuselage defining a fuselage main axis. The fuselage comprises a docking system for fixing removable nacelles. The aircraft has wings equipped with tilting actuators for rotating wings about rotation axes parallel to the fuselage main axis and at least six propellers mechanically connected to the fuselage. The aircraft also has at least one cryo-hydrogen tank and at least one fuel cell for supplying power to the propellers, and

A capacitor for supplying power to the propellers, charged by at least one fuel cell. This capacitor stores electrical energy greater than the energy needed by all the propellers for ten seconds of hovering flight. Each propeller is equipped with a tilting actuator for rotating the propeller about a rotation axis making an angle of less than 45 degrees with a plane perpendicular to the fuselage main axis. The fuselage having a forward and a rear portion defining a forward to rear order of the propellers, in cruise flight, the two forward propellers are activated to provide vertical thrust, the intermediate propellers between the forward and rearmost propellers are not activated and the two rearmost propellers are activated to provide horizontal thrust.