TECHNICAL FIELD OF THE DISCLOSURE

The present disclosure relates, in general, to aircraft configured to convert between thrust-borne lift in a VTOL orientation and wing-borne lift in a forward flight orientation and, in particular, to aircraft having a quadcopter configuration in the VTOL orientation and both a monoplane configuration and a biplane configuration in the forward flight orientation.

BACKGROUND

Unmanned aircraft systems (UAS), also known as unmanned aerial vehicles (UAV) or drones, are self-powered aircraft that do not carry a human operator, uses aerodynamic forces to provide vehicle lift, are autonomously and/or remotely operated, may be expendable or recoverable and may carry lethal or nonlethal payloads. UAS are commonly used in military, commercial, scientific, recreational and other applications. For example, military applications include intelligence, surveillance, reconnaissance and attack missions. Civil applications include aerial photography, search and rescue missions, inspection of utility lines and pipelines, humanitarian aid including delivering food, medicine and other supplies to inaccessible regions, environment monitoring, border patrol missions, cargo transportation, forest fire detection and monitoring, accident investigation and crowd monitoring, to name a few.

Fixed-wing aircraft, such as airplanes, are capable of flight using wings that generate lift responsive to the forward airspeed of the aircraft, which is generated by forward thrust from one or more jet engines or propellers. The wings generally have an airfoil cross section that generates the lift force to support the airplane in flight. Fixed-wing aircraft, however, typically require a runway for takeoff and landing. Unlike fixed-wing aircraft, vertical takeoff and landing (VTOL) aircraft do not require runways. Instead, VTOL aircraft are capable of taking off, hovering and landing vertically. One example of VTOL aircraft is a helicopter which is a rotorcraft having one or more rotors that provide vertical thrust to enable VTOL operations as well as lateral thrust to enable forward, backward and sideward flight. These attributes make helicopters highly versatile for use in congested, isolated or remote areas where fixed-wing aircraft may be unable to takeoff or land. A tiltrotor aircraft is another example of a VTOL aircraft. Tiltrotor aircraft generate vertical and forward thrust using proprotors that are typically coupled to nacelles mounted near the ends of a fixed wing. The nacelles rotate relative to the fixed wing such that the proprotors have a generally horizontal plane of rotation for VTOL operations and a generally vertical plane of rotation for forward flight during which the fixed wing provides lift.

SUMMARY

In a first aspect, the present disclosure is directed to an aircraft having multiple wing planforms. The aircraft includes an airframe having first and second half-wings with first and second pylons extending therebetween. A distributed thrust array is attached to the airframe. The thrust array includes a first plurality of propulsion assemblies coupled to the first half-wing and a second plurality of propulsion assemblies coupled to the second half-wing. A flight control system coupled to the airframe is configured to independently control each of the propulsion assemblies and control conversions between the wing planforms. The aircraft is configured to convert between thrust-borne lift in a VTOL orientation and wing-borne lift in a forward flight orientation. The aircraft is also configured to convert between a biplane configuration and a monoplane configuration in the forward flight orientation.

In some embodiments, the first and second pylons may be pivotably coupled between the first half-wing and the second half-wing. In certain embodiments, in the forward flight orientation, the first half-wing may be an upper half-wing and the second half-wings may be a lower half-wing. In such embodiments, the upper half-wing may have a low wing configuration with the propulsion assemblies attached thereto and the lower half-wing may have a high wing configuration with the propulsion assemblies attached thereto. In other embodiments, each of the half-wings may have two wingtips and each of the propulsion assemblies may be a wingtip mounted propulsion assembly.

In certain embodiments, the aircraft may have a multicopter configuration, such as a quadcopter configuration, in the VTOL orientation. In some embodiments, in the biplane configuration, the thrust array may form a two-dimensional thrust array and in the monoplane configuration, the thrust array may form a one-dimensional thrust array. In certain embodiments, the each of the propulsion assemblies may be a non-thrust vectoring propulsion assembly, a unidirectional thrust vectoring propulsion assembly or an omnidirectional thrust vectoring propulsion assembly. In some embodiments, the flight control system may be configured to convert the aircraft between the biplane configuration and the monoplane configuration during forward flight. In certain embodiments, the flight control system may be configured for remote flight control, for autonomous flight control or combinations thereof. In some embodiments, a pod assembly may be coupled to the airframe. For example, the pod assembly may be coupled between the first and second pylons or the pod assembly may be coupled between the first and second half-wings.

In a second aspect, the present disclosure is directed to an aircraft having multiple wing planforms. The aircraft includes an airframe having first and second half-wings with first and second pylons extending therebetween. A distributed thrust array is attached to the airframe. The thrust array includes two propulsion assemblies coupled to the first half-wing and two propulsion assemblies coupled to the second half-wing. A flight control system is coupled to the airframe and is configured to independently control each of the propulsion assemblies. The aircraft is configured to convert between thrust-borne lift in a VTOL orientation and wing-borne lift in a forward flight orientation. In the VTOL orientation, the distributed thrust array has a quadcopter configuration. In the forward flight orientation, the first and second half-wings have a biplane configuration in a first planform with the thrust array configured as a two-dimensional thrust array and the first and second half-wings have a monoplane configuration in a second planform with the thrust array configured as a one-dimensional thrust array. The flight control system is configured to convert the first and second half-wings between the first and second planforms during forward flight.

