Convertible biplane aircraft for autonomous cargo delivery

An autonomous cargo delivery aircraft operable to transition between thrust-borne lift in a VTOL orientation and wing-borne lift in a biplane orientation. The aircraft includes a fuselage having an aerodynamic shape with a leading edge, a trailing edge and first and second sides. First and second wings are coupled to the fuselage proximate the first and second sides, respectively. A distributed thrust array includes a first pair of propulsion assemblies coupled to the first wing and a second pair of propulsion assemblies coupled to the second wing. A flight control system is operably associated with the distributed thrust array and configured to independently control each of the propulsion assemblies. The first side of the fuselage includes a door configured to provide access to a cargo bay disposed within the fuselage from an exterior of the aircraft with a predetermined clearance relative to the first pair of propulsion assemblies.

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 biplane orientation and, in particular, to aircraft operable for autonomous cargo delivery.

BACKGROUND

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 thrust from one or more jet engines or propellers. The wings generally have an airfoil cross section that deflects air downward as the aircraft moves forward, generating the lift force to support the airplane in flight. Fixed-wing aircraft, however, typically require a runway that is hundreds or thousands of feet long 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 lift and thrust to the aircraft. The rotors not only enable hovering and vertical takeoff and landing, but also enable, forward, backward and lateral flight. These attributes make helicopters highly versatile for use in congested, isolated or remote areas where fixed-wing aircraft may be unable to take off and land. Helicopters, however, typically lack the forward airspeed of fixed-wing aircraft.

A tiltrotor aircraft is another example of a VTOL aircraft. Tiltrotor aircraft generate lift and propulsion 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 vertical takeoff, hovering and landing and a generally vertical plane of rotation for forward flight, wherein the fixed wing provides lift and the proprotors provide forward thrust. In this manner, tiltrotor aircraft combine the vertical lift capability of a helicopter with the speed and range of fixed-wing aircraft. Tiltrotor aircraft, however, typically suffer from downwash inefficiencies during vertical takeoff and landing due to interference caused by the fixed wing. A further example of a VTOL aircraft is a tiltwing aircraft that features a rotatable wing that is generally horizontal for forward flight and rotates to a generally vertical orientation for vertical takeoff and landing. Propellers are coupled to the rotating wing to provide the required vertical thrust for takeoff and landing and the required forward thrust to generate lift from the wing during forward flight. The tiltwing design enables the slipstream from the propellers to strike the wing on its smallest dimension, thus improving vertical thrust efficiency as compared to tiltrotor aircraft. Tiltwing aircraft, however, are more difficult to control during hover as the vertically tilted wing provides a large surface area for crosswinds typically requiring tiltwing aircraft to have either cyclic rotor control or an additional thrust station to generate a moment.

SUMMARY

In a first aspect, the present disclosure is directed to an aircraft operable to transition between thrust-borne lift in a VTOL orientation and wing-borne lift in a biplane orientation. The aircraft includes a fuselage having an aerodynamic shape with a leading edge and a trailing edge separated by a chord length and first and second sides separated by a span length. The fuselage having a first cargo bay. First and second wings are coupled to the fuselage proximate the first and second sides, respectively. A distributed thrust array includes a first pair of propulsion assemblies coupled to the first wing and a second pair of propulsion assemblies coupled to the second wing. A flight control system is operably associated with the distributed thrust array and configured to independently control each of the propulsion assemblies. The first side of the fuselage includes a first door configured to provide access to the first cargo bay from an exterior of the aircraft with a predetermined clearance relative to each of the propulsion assemblies of the first pair of propulsion assemblies.

In some embodiments, in the VTOL orientation, the first wing may be substantially forward of the fuselage and the second wing may be substantially aft of the fuselage. In such embodiment, in the biplane orientation, the first wing may be substantially below the fuselage and the second wing may be substantially above the fuselage. In certain embodiments, the first and second wings may be substantially parallel to each other. In some embodiments, the first and second wings may be swept wings. In such embodiments, each of the first and second wings may have an apex proximate the leading edge of the fuselage such that, in the VTOL orientation, the propulsion assemblies are below the apexes of the first and second wings and such that, in the biplane orientation, the propulsion assemblies are aft of the apexes of the first and second wings. In certain embodiments, in the VTOL orientation, the propulsion assemblies may be below the leading edge of the fuselage and, in the biplane orientation, the propulsion assemblies may be aft of the leading edge of the fuselage.

In some embodiments, the fuselage may have a second cargo bay and the first side of the fuselage may include a second door configured to provide access to the second cargo bay from the exterior of the aircraft with the predetermined clearance relative to each of the propulsion assemblies of the first pair of propulsion assemblies. In certain embodiments, a power system may be disposed within the fuselage such as a plurality of batteries. In some embodiments, each of the propulsion assemblies may include an electric motor and a rotor assembly coupled to the electric motor. In certain embodiments, the distributed thrust array may be a two-dimensional thrust array. In some embodiments, the flight control system may be configured for autonomous flight control and/or unmanned cargo delivery.

In certain embodiments, in the biplane orientation, the first door may be configured for cargo drop operations. In such embodiments, a first door actuator may be configured to receive commands from the flight control system and operate the first door between open and closed positions during the cargo drop operations. In some embodiments, in the VTOL orientation, a trailing edge door may be configured for cargo drop operations. In such embodiments, a trailing edge door actuator may be configured to receive commands from the flight control system and operate the trailing edge door between open and closed positions during the cargo drop operations.

In a second aspect, the present disclosure is directed to an autonomous cargo delivery aircraft operable to transition between thrust-borne lift in a VTOL orientation and wing-borne lift in a biplane orientation. The aircraft includes a fuselage having an aerodynamic shape with a leading edge and a trailing edge separated by a chord length and first and second sides separated by a span length. The fuselage having a first cargo bay. First and second swept wings are coupled to the fuselage proximate the first and second sides, respectively. A distributed thrust array includes a first pair of propulsion assemblies coupled to the first swept wing and a second pair of propulsion assemblies coupled to the second swept wing. A flight control system is operably associated with the distributed thrust array and configured to independently control each of the propulsion assemblies. The first side of the fuselage includes a first door configured to provide access to the first cargo bay from an exterior of the aircraft with a predetermined clearance relative to each of the propulsion assemblies of the first pair of propulsion assemblies. In the VTOL orientation, the first swept wing is substantially forward of the fuselage, the second swept wing is substantially aft of the fuselage and the propulsion assemblies are below the leading edge of the fuselage. In the biplane orientation, the first swept wing is substantially below the fuselage, the second swept wing is substantially above the fuselage, the propulsion assemblies are aft of the leading edge of the fuselage and the first door is configured for cargo drop operations.

DETAILED DESCRIPTION

While the making and using of various embodiments of the present disclosure are discussed in detail below, it should be appreciated that the present disclosure provides many applicable inventive concepts, which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative and do not delimit the scope of the present disclosure. In the interest of clarity, not all features of an actual implementation may be described in the present disclosure. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming but would be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

In the specification, reference may be made to the spatial relationships between various components and to the spatial orientation of various aspects of components as the devices are depicted in the attached drawings. However, as will be recognized by those skilled in the art after a complete reading of the present disclosure, the devices, members, apparatuses, and the like described herein may be positioned in any desired orientation. Thus, the use of terms such as “above,” “below,” “upper,” “lower” or other like terms to describe a spatial relationship between various components or to describe the spatial orientation of aspects of such components should be understood to describe a relative relationship between the components or a spatial orientation of aspects of such components, respectively, as the device described herein may be oriented in any desired direction. As used herein, the term “coupled” may include direct or indirect coupling by any means, including moving and/or non-moving mechanical connections.

Referring toFIGS. 1A-1Gin the drawings, various views of an autonomous cargo delivery aircraft10operable to transition between thrust-borne lift in a VTOL orientation and wing-borne lift in a biplane orientation are depicted.FIGS. 1A, 1C and 1Edepict aircraft10in the VTOL orientation wherein the propulsion assemblies provide thrust-borne lift.FIGS. 1B, 1D and 1Fdepict aircraft10in the biplane orientation wherein the propulsion assemblies provide forward thrust with the forward airspeed of aircraft10providing wing-borne lift enabling aircraft10to have a high speed, high endurance and/or high efficiency forward flight mode. In each orientation, aircraft10has a longitudinal axis10athat may also be referred to as the roll axis, a lateral axis10bthat may also be referred to as the pitch axis and a vertical axis10cthat may also be referred to as the yaw axis, as best seen inFIGS. 1E and 1F. When longitudinal axis10aand lateral axis10bare both in a horizontal plane and normal to the local vertical in the earth's reference frame, aircraft10has a level flight attitude.

In the illustrated embodiment, aircraft10has an airframe12including wings14,16and fuselage18. Wings14,16each have an airfoil cross-section that generates lift responsive to the forward airspeed of aircraft10in the biplane orientation. Each of wings14,16may be formed as single members or may be formed from multiple wing sections such as left and right sections. The outer skins for wings14,16are preferably formed from high strength and lightweight materials such as fiberglass, carbon, plastic, metal or other suitable material or combination of materials. As best seen inFIG. 1F, in the biplane orientation of aircraft10, wing14is an upper wing having a swept wing configuration and wing16is a lower wing having a swept wing configuration. In the illustrated embodiment, wings14,16have a quarter chord sweep angle between twenty-five degrees and forty-five degrees such as a quarter chord sweep angle between thirty degrees and forty degrees or a quarter chord sweep angle of about thirty-five degrees. In the illustrated embodiment, the leading edge sweep angle is greater than the quarter chord sweep angle and the trailing edge sweep angle is less than the quarter chord sweep angle. As illustrated, the sweep angle progressively decreases from the leading edge to the trailing edge forming a tapered swept wing design. In other embodiments, the sweep angle may remain constant from the leading edge to the trailing edge forming a simple swept wing design, the leading edge may have a sweep angle and the trailing edge may not have a sweep angle forming a delta swept wing design or the leading edge may have a positive sweep angle and the trailing edge may have a negative sweep angle forming a trapezoidal swept wing design. In other embodiments, wings14,16could have straight wing designs. In still other embodiments, wings14,16could have other designs such as anhedral and/or dihedral wing designs. The specific design of wings14,16including the sweep angle, the anhedral and/or dihedral orientation, the wingspan and the like will be determined based upon aerodynamic loads and performance requirements, as will be understood by those having ordinary skill in the art.

In the illustrated embodiment, wings14,16are substantially parallel with each other with fuselage18extending substantially perpendicularly therebetween. Fuselage18has an aerodynamic shape with a leading edge18aand a trailing edge18bwith a fuselage chord length extending therebetween, two sides18c,18dwith a fuselage span length extending therebetween and a front18eand back18fwith a fuselage thickness extending therebetween. The aerodynamic shape of fuselage18is configured to minimize drag during high speed forward flight. In addition, the fuselage span length is configured to minimize interference drag between wings14,16. For example, the fuselage span length may have a ratio to the wingspan of wings14,16of between 1 to 2 and 1 to 3 such as a ratio of about 1 to 2.5. In other embodiments, the ratio of the fuselage span length to the wingspan may be either greater than 1 to 2 or less than 1 to 3. Fuselage18is preferably formed from high strength and lightweight materials such as fiberglass, carbon, plastic, metal or other suitable material or combination of materials. In the illustrated embodiment, wing14is coupled to fuselage18proximate side18dand wing16is coupled to fuselage18at proximate to side18cforming stiff connections therebetween. In the VTOL orientation, wing16is substantially forward of fuselage18and wing14is substantially aft of fuselage18. In the biplane orientation, wing16is substantially below fuselage18and wing14is substantially above fuselage18.

In the illustrated embodiment, fuselage18contains a power system20depicted as a plurality of batteries, as best seen inFIG. 1C. In the illustrated embodiment, batteries20may be rechargeable batteries or may be hot swappable batteries to enable a quick return to flight after the currently installed batteries have been discharged. As discussed herein, power system20supplies electrical power to flight control system30, the distributed thrust array of aircraft10and other power consumers of aircraft10such that aircraft10may be referred to as an electric vertical takeoff and landing (eVTOL) aircraft. In other embodiments, some or all of power system20maybe located within wings14,16and/or the nacelles of aircraft10. In some embodiments, aircraft10may have a hybrid power system that includes one or more internal combustion engines and an electric generator. Preferably, the electric generator is used to charge the batteries. In other embodiments, the electric generator may provide power directly to a power management system and/or the power consumers of aircraft10. In still other embodiments, aircraft10may use fuel cells as the electrical power source.

In the illustrated embodiment, fuselage18houses the flight control system30of aircraft10. Flight control system30is preferably a redundant digital flight control system including multiple independent flight control computers. For example, the use of a triply redundant flight control system30improves the overall safety and reliability of aircraft10in the event of a failure in flight control system30. Flight control system30preferably includes non-transitory computer readable storage media including a set of computer instructions executable by one or more processors for controlling the operation of aircraft10. Flight control system30may be implemented on one or more general-purpose computers, special purpose computers or other machines with memory and processing capability. For example, flight control system30may include one or more memory storage modules including, but is not limited to, internal storage memory such as random access memory, non-volatile memory such as read only memory, removable memory such as magnetic storage memory, optical storage, solid-state storage memory or other suitable memory storage entity. Flight control system30may be a microprocessor-based system operable to execute program code in the form of machine-executable instructions. In addition, flight control system30may be selectively connectable to other computer systems via a proprietary encrypted network, a public encrypted network, the Internet or other suitable communication network that may include both wired and wireless connections.

Wings14,16contain a communication network that enables power system20and flight control system30to communicate with the distributed thrust array of aircraft10. In the illustrated embodiment, aircraft10has a two-dimensional distributed thrust array that is coupled to airframe12. As used herein, the term “two-dimensional thrust array” refers to a plurality of thrust generating elements that occupy a two-dimensional space in the form of a plane. A minimum of three thrust generating elements is required to form a “two-dimensional thrust array.” A single aircraft may have more than one “two-dimensional thrust array” if multiple groups of at least three thrust generating elements each occupy separate two-dimensional spaces thus forming separate planes. As used herein, the term “distributed thrust array” refers to the use of multiple thrust generating elements each producing a portion of the total thrust output. The use of a “distributed thrust array” provides redundancy to the thrust generation capabilities of the aircraft including fault tolerance in the event of the loss of one of the thrust generating elements. A “distributed thrust array” can be used in conjunction with a “distributed power system” in which power to each of the thrust generating elements is supplied by a local or nacelle-based power element instead of a centralized power system.

The two-dimensional distributed thrust array of aircraft10includes a plurality of propulsion assemblies, individually denoted as34a,34b,34c,34dand collectively referred to as propulsion assemblies34. In the illustrated embodiment, propulsion assemblies34a,34bare coupled to wing14and propulsion assemblies34c,34dare coupled to wing16. More specifically, propulsion assembly34ais coupled to an upper or forward end of nacelle body36athat is fixably attached to wingtip14a, propulsion assembly34bis coupled to an upper or forward end of nacelle body36bthat is fixably attached to wingtip14b, propulsion assembly34cis coupled to an upper or forward end of nacelle body36cthat is fixably attached to wingtip16cand propulsion assembly34dis coupled to an upper or forward end of nacelle body36dthat is fixably attached to wingtip16d. By positioning propulsion assemblies34a,34b,34c,34dat wingtip14a,14b,16c,16d, the thrust and torque generating elements are positioned at the maximum outboard distance from the center of gravity of aircraft10located at the intersection of axes10a,10b,10c. The outboard locations of propulsion assemblies34provide dynamic stability to aircraft10in hover and a high dynamic response in the VTOL orientation of aircraft10enabling efficient and effective pitch, yaw and roll control by changing the thrust, thrust vector and/or torque output of certain propulsion assemblies34relative to other propulsion assemblies34.

Even though the illustrated embodiment depicts four propulsion assemblies34, the distributed thrust array of aircraft10could have other numbers of propulsion assemblies both greater than or less than four. Also, even though the illustrated embodiment depicts propulsion assemblies34in a wingtip mounted configuration, the distributed thrust array of aircraft10could have propulsion assemblies coupled to the wings in other configurations such as a mid-span configuration. In the illustrated embodiment, propulsion assemblies34are variable speed propulsion assemblies having fixed pitch rotor blades and thrust vectoring capability. Depending upon the implementation, propulsion assemblies34may have longitudinal thrust vectoring capability, lateral thrust vectoring capability or omnidirectional thrust vectoring capability. In other embodiments, propulsion assemblies34may be single speed propulsion assemblies, may have variable pitch rotor blades and/or may be non-thrust vectoring propulsion assemblies.

Propulsion assemblies34are independently attachable to and detachable from nacelle bodies36and are preferably standardized and/or interchangeable units such as line replaceable units or LRUs providing easy installation and removal from airframe12. The use of line replaceable propulsion units is beneficial in maintenance situations if a fault is discovered with one of the propulsion assemblies. In this case, the faulty propulsion assembly34can be decoupled from airframe12by simple operations and another propulsion assembly34can then be attached to aircraft10. In other embodiments, propulsion assemblies34may be integral with nacelle bodies36.

Aircraft10has a damping landing gear system that includes landing gear assembly38acoupled to a lower or aft end of nacelle body36a, landing gear assembly38bcoupled to a lower or aft end of nacelle body36b, landing gear assembly38ccoupled to a lower or aft end of nacelle body36cand landing gear assembly38dcoupled to a lower or aft end of nacelle body36d. By positioning landing gear assemblies38a,38b,38c,38dat wingtip14a,14b,16c,16dand by having a relatively low center of gravity, aircraft10maintains suitably high landing stability and tip-over stability. In the illustrated embodiment, each landing gear assembly38including a spring housing forming a spring chamber with a spring disposed therein and a plunger slidably coupled to the spring housing and movable between a compressed position and an extended position. The spring biases the plunger into the extended position during flight and the landing force compresses the plunger into the compressed position against the bias of the spring, thereby absorbing at least a portion of the landing force. In addition, the spring biasing force acting on the plunger when aircraft10is positioned on a landing surface generates a push-off effect to aid during takeoff maneuvers. In other embodiments, the landing gear assemblies may be passively operated pneumatic landing struts or actively operated telescoping landing struts. In still other embodiments, the landing gear assemblies may include wheels that enable aircraft10to taxi and perform other ground maneuvers. In such embodiments, the landing gear assemblies may provide a passive brake system or may include active brakes such as an electromechanical braking system or a manual braking system to facilitate parking during ground operations.

Aircraft10has a distributed array of aerodynamic control surfaces carried by landing gear assemblies38. More specifically, elevon40ais rotatably coupled to landing gear assembly38a, elevon40bis rotatably coupled to landing gear assembly38b, elevon40cis rotatably coupled to landing gear assembly38cand elevon40dis rotatably coupled to landing gear assembly38d. In the illustrated embodiment, elevons40are pivoting aerosurfaces that are rotatable about respective elevon axes. In the illustrated embodiment, elevons40a,40bhave a dihedral angle of about forty-five degrees relative to wing14and elevons40c,40dhave an anhedral angle of about forty-five degrees relative to wing16. In other embodiments, elevons40could have other angles relative to the wings such as angles less than or greater than forty-five degrees including being parallel to or perpendicular with the respective wings, such angles being adjustable during ground operation or during flight. The specific design of elevons40including the elevon angle relative to the wings, the elevon sweep angle, the elevon length and the like will be determined based upon aerodynamic loads and performance requirements, as will be understood by those having ordinary skill in the art. When operated collectively, elevons40serve as elevators to control the pitch or angle of attack of aircraft10, in the biplane orientation. When operated differentially, elevons40serve as ailerons to control the roll or bank of aircraft10, in the biplane orientation. In addition, elevons40may be used to generate yaw, roll and pitch control moments to complement other control authority mechanisms in hover or to provide standalone control authority in hover.

Land gear assemblies38are independently attachable to and detachable from nacelle bodies36and are preferably standardized and/or interchangeable units such as line replaceable units or LRUs providing easy installation and removal from airframe12. The use of line replaceable land gear units is beneficial in maintenance situations if a fault is discovered with one of the land gear assemblies. In this case, the faulty land gear assembly38can be decoupled from airframe12by simple operations and another land gear assembly38can then be attached to aircraft10. In other embodiments, land gear assemblies38may be integral with nacelle bodies36.

In the illustrated embodiment, the outer housings of each group of a propulsion assembly34, a nacelle body36and a land gear assembly38form a nacelle such as nacelle42a, nacelle42b, nacelle42cand nacelle42d. Each nacelle42houses an electronics node including sensor, controllers, actuators and other electronic components used to operate systems associated with the respective propulsion assembly34and a land gear assembly38. For example, nacelle42dhouses a gimbal actuator44d, an electronic speed controller46d, a sensor array48dand an elevon actuator50d, as best seen inFIG. 1A. In other embodiments, each nacelle42may house one or more batteries for aircraft having a distributed power system for the distributed thrust array.

Each propulsion assembly34includes a rotor assembly that is coupled to an output drive of a respective electric motor that rotates the rotor assembly in a rotational plane to generate thrust for aircraft10. For example, propulsion assembly34dincludes rotor assembly52dand electric motor54d. In the VTOL orientation of aircraft10, the uppermost part of rotor assemblies52is below the apexes of wings14,16and leading edge18aof fuselage18. Likewise, in the biplane orientation of aircraft10, the forwardmost part of rotor assemblies52is aft of the apexes of wings14,16and leading edge18aof fuselage18. In other embodiments, the rotors assemblies could extend beyond the apexes of wings14,16and/or beyond leading edge18aof fuselage18. In the illustrated embodiment, rotor assemblies52each include four rotor blades having a fixed pitch. In other embodiments, the rotor assemblies could have other numbers of rotor blades including rotor assemblies having less than or more than four rotor blades. Alternatively or additionally, the rotor assemblies could have variable pitch rotor blades with collective and/or cyclic pitch control. As best seen inFIG. 1B, rotor assemblies52a,52drotate in the counterclockwise direction and rotor assemblies52b,52crotate in the clockwise direction when viewed from above, as indicated the motion arrows. In the illustrated embodiment, each rotor blade has a root to tip twist between thirty degrees and fifty degrees.

Together, each respective electric motor and rotor assembly forms a propulsion system. In the illustrated embodiment, each propulsion system has mounted to a nacelle42on a gimbal56, such as gimbal56d, that provides a two-axis tilting degree of freedom such that the electric motor and rotor assembly tilt together relative to the nacelle enabling propulsion assemblies34to have omnidirectional thrust vectoring capability. In the illustrated embodiment, the maximum angle of the thrust vector may be between 10 degrees and 30 degrees such as between 15 degrees and 25 degrees or about 20 degrees. Notably, using a 20-degree thrust vector yields a lateral component of thrust that is about 34 percent of total thrust. In other embodiments, the propulsion systems may have a single-axis tilting degree of freedom in which case, the propulsion assemblies could act as longitudinal and/or lateral thrust vectoring propulsion assemblies.

Aircraft10may be a manned or unmanned aircraft. Flight control system30may autonomously control some or all aspects of flight operations for aircraft10. Flight control system30is also operable to communicate with remote systems, such as a ground station via a wireless communications protocol. The remote system may be operable to receive flight data from and provide commands to flight control system30to enable remote flight control over some or all aspects of flight operations for aircraft10. The remote flight control and/or autonomous flight control may be augmented or supplanted by onboard pilot flight control during manned missions. Regardless of the input, aircraft10preferably utilizes a fly-by-wire system that transmits electronic signals from flight control system30to the actuators and controllers of aircraft systems to control the flight dynamics of aircraft10including controlling the movements of rotor assemblies52, gimbals56and elevons40. Flight control system30communicates with the controlled systems via a fly-by-wire communications network within airframe12. In addition, flight control system30receives data from a plurality of sensors58such as one or more position sensors, attitude sensors, speed sensors, altitude sensors, heading sensors, environmental sensors, fuel sensors, temperature sensors, location sensors and the like to enhance flight control capabilities. Flight control system30receives sensor data from and sends flight command information to the electronics nodes such that each propulsion assembly34and each land gear assembly40may be individually and independently controlled and operated. For example, flight control system30is operable to individually and independently control the speed and the thrust vector of each propulsion assembly34and the position of each elevon40.

Referring additionally toFIGS. 2A-2Iin the drawings, a sequential flight-operating scenario of aircraft10is depicted. As best seen inFIG. 2A, aircraft10is in a tailsitter position on a surface such as the ground or the deck of an aircraft carrier. In this tailsitter position, the weight of aircraft10has caused the plungers of landing gear assemblies38to compress the springs disposed therein such that the plungers are in retracted positions. In addition, elevons40are rotated to point in an upward direction to provide ground clearance. When aircraft10is ready for a mission, flight control system30commences operations providing flight commands to the various components of aircraft10. Flight control system30may be operating responsive to autonomous flight control, remote flight control or a combination thereof. For example, it may be desirable to utilize remote flight control during certain maneuvers such as takeoff and landing but rely on autonomous flight control during hover, high speed forward flight and transitions between wing-borne flight and thrust-borne flight.

As best seen inFIG. 2B, aircraft10has performed a vertical takeoff and is engaged in thrust-borne lift in the VTOL orientation of aircraft10. As illustrated, the rotor assemblies of propulsion assemblies34are each rotating in the same horizontal plane. As longitudinal axis10aand lateral axis10b(denoted as the target) are both in a horizontal plane H that is normal to the local vertical in the earth's reference frame, aircraft10has a level flight attitude. In the VTOL orientation, the plungers of landing gear assemblies38have moved to their extending positions responsive to the biasing force applied by the springs disposed therein. In addition, elevons40having been rotated to point in an downward direction which is the neutral configuration of elevons40in flight regimes, noting that rotation of one or more elevons40in the downwash of propulsion assemblies34may be used to provide hover stability as well as certain pitch, roll and yaw authority for aircraft10. In the VTOL orientation, wing16is the forward wing and wing14is the aft wing. As discussed herein, flight control system30independently controls and operates each propulsion assembly34including independently controlling speed and thrust vector. During hover, flight control system30may utilize differential speed control and/or differential or collective thrust vectoring of propulsion assemblies34to provide hover stability for aircraft10and to provide pitch, roll, yaw and translation authority for aircraft10.

After vertical ascent to the desired elevation, aircraft10may begin the transition from thrust-borne lift to wing-borne lift. As best seen from the progression ofFIGS. 2B-2E, aircraft10is operable to pitch down from the VTOL orientation toward the biplane orientation to enable high speed and/or long range forward flight. As seen inFIG. 2C, longitudinal axis10aextends out of the horizontal plane H such that aircraft10has an inclined flight attitude of about thirty degrees pitch down. As seen inFIG. 2D, longitudinal axis10aextends out of the horizontal plane H such that aircraft10has an inclined flight attitude of about sixty degrees pitch down. Flight control system30may achieve this operation through speed control of some or all of propulsion assemblies34, thrust vectoring of some or all of propulsion assemblies34, tilting of some or all of elevons40or any combination thereof.

As best seen inFIG. 2E, aircraft10has completed the transition to the biplane orientation with the rotor assemblies of propulsion assemblies34each rotating in the same vertical plane. In the biplane orientation, wing14is the upper wing positioned above wing16, which is the lower wing. By convention, longitudinal axis10ahas been reset to be in the horizontal plane H, which also includes lateral axis10b, such that aircraft10has a level flight attitude in the biplane orientation. As forward flight with wing-borne lift requires significantly less power than VTOL flight with thrust-borne lift, the operating speed of some or all of the propulsion assemblies34may be reduced. In certain embodiments, some of the propulsion assemblies of aircraft10could be shut down during forward flight. In the biplane orientation, the independent control provided by flight control system30over each propulsion assembly34and each elevon40provides pitch, roll and yaw authority for aircraft10.

As aircraft10approaches the desired location, aircraft10may begin its transition from wing-borne lift to thrust-borne lift. As best seen from the progression ofFIGS. 2E-2H, aircraft10is operable to pitch up from the biplane orientation to the VTOL orientation to enable, for example, a vertical landing operation. As seen inFIG. 2F, longitudinal axis10aextends out of the horizontal plane H such that aircraft10has an inclined flight attitude of about thirty degrees pitch up. As seen inFIG. 2G, longitudinal axis10aextends out of the horizontal plane H such that aircraft10has an inclined flight attitude of about sixty degrees pitch up. Flight control system30may achieve this operation through speed control of some or all of propulsion assemblies34, thrust vectoring of some or all of propulsion assemblies34, tilting of some or all of elevons40or any combination thereof. InFIG. 2H, aircraft10has completed the transition from the biplane orientation to the VTOL orientation and, by convention, longitudinal axis10ahas been reset to be in the horizontal plane H which also includes lateral axis10bsuch that aircraft10has a level flight attitude in the VTOL orientation. Once aircraft10has completed the transition to the VTOL orientation, aircraft10may commence its vertical descent to a surface. During this vertical descent, elevons40are rotated to point in the upward direction to provide ground clearance. As aircraft10is landing, the weight of aircraft10causes the plungers of landing gear assemblies38to compress the springs disposed therein such that the plungers are in retracted positions, thereby providing damping of the landing impact. As best seen inFIG. 2I, aircraft10has landed in a tailsitter orientation at the desired location.

Referring next toFIG. 3, a systems diagram depicts one implementation of an aircraft100that is also representative of aircraft10discussed herein. Specifically, aircraft100includes four nacelle assemblies102a,102b,102c,102dthat respectively support four propulsion systems104a,104b,104c,104dthat form a two-dimensional thrust array of thrust vectoring propulsion assemblies and four landing systems106a,106b,106c,106deach of which includes a rotatable elevon as discussed herein. Disposed within respective nacelle assemblies102a,102b,102c,102dare electronics nodes108a,108b,108c,108deach of which includes one or more controllers, sensors, actuators and/or other electronic systems. In the illustrated embodiment, a power system110, such as a plurality of batteries, and a flight control system112are disposed with fuselage114. Power system110and flight control system112are operably associated with each of propulsion systems104a,104b,104c,104dand landing systems106a,106b,106c,106dand are communicably linked to electronic nodes108a,108b,108c,108dby a fly-by-wire communications network depicted as arrows116a,116b,116c,116d. Flight control system112receives sensor data from and sends commands to electronic nodes108a,108b,108c,108dto enable flight control system112to independently control each of propulsion systems104a,104b,104c,104dand landing systems106a,106b,106c,106d, as discussed herein.

Referring additionally toFIG. 4in the drawings, a block diagram depicts a control system120operable for use with aircraft100or aircraft10of the present disclosure. In the illustrated embodiment, system120includes two primary computer based subsystems; namely, an aircraft system122and a remote system124. In some implementations, remote system124includes a programming application126and a remote control application128. Programming application126enables a user to provide a flight plan and mission information to aircraft100such that flight control system112may engage in autonomous control over aircraft100. For example, programming application126may communicate with flight control system112over a wired or wireless communication channel130to provide a flight plan including, for example, a starting point, a trail of waypoints and an ending point such that flight control system112may use waypoint navigation during the mission. In addition, programming application126may provide one or more tasks to flight control system112for aircraft100to accomplish during the mission such as pickup and delivery of one or more packages. Following programming, aircraft100may operate autonomously responsive to commands generated by flight control system112.

Flight control system112preferably includes a non-transitory computer readable storage medium including a set of computer instructions executable by a processor. Flight control system112may be a triply redundant system implemented on one or more general-purpose computers, special purpose computers or other machines with memory and processing capability. For example, flight control system112may include one or more memory storage modules including, but is not limited to, internal storage memory such as random access memory, non-volatile memory such as read only memory, removable memory such as magnetic storage memory, optical storage, solid-state storage memory or other suitable memory storage entity. Flight control system112may be a microprocessor-based system operable to execute program code in the form of machine-executable instructions. In addition, flight control system112may be selectively connectable to other computer systems via a proprietary encrypted network, a public encrypted network, the Internet or other suitable communication network that may include both wired and wireless connections.

In the illustrated embodiment, flight control system112includes a command module132and a monitoring module134. It is to be understood by those skilled in the art that these and other modules executed by flight control system112may be implemented in a variety of forms including hardware, software, firmware, special purpose processors and combinations thereof. Flight control system112receives input from a variety of sources including internal sources such as sensors136, controllers/actuators138, propulsion systems102and landing systems106and external sources such as remote system124as well as global positioning system satellites or other location positioning systems and the like. For example, as discussed herein, flight control system112may receive a flight plan for a mission from remote system124. Thereafter, flight control system112may be operable to autonomously control all aspects of flight of an aircraft of the present disclosure.

For example, during the various operating modes of aircraft100including vertical takeoff and landing flight mode, hover flight mode, forward flight mode and transitions therebetween, command module132provides commands to controllers/actuators138. These commands enable independent operation of each propulsion system102including rotor speed and thrust vector and each landing system106including elevon position. Flight control system112receives feedback from controllers/actuators138, propulsion systems102and landing systems106. This feedback is processed by monitoring module134that can supply correction data and other information to command module132and/or controllers/actuators138. Sensors136, such as an attitude and heading reference system (AHRS) with solid-state or microelectromechanical systems (MEMS) gyroscopes, accelerometers and magnetometers as well as other sensors including positioning sensors, speed sensors, environmental sensors, fuel sensors, temperature sensors, location sensors and the like also provide information to flight control system112to further enhance autonomous control capabilities.

Some or all of the autonomous control capability of flight control system112can be augmented or supplanted by remote flight control from, for example, remote system124. Remote system124may include one or computing systems that may be implemented on general-purpose computers, special purpose computers or other machines with memory and processing capability. For example, the computing systems may include one or more memory storage modules including, but is not limited to, internal storage memory such as random access memory, non-volatile memory such as read only memory, removable memory such as magnetic storage memory, optical storage memory, solid-state storage memory or other suitable memory storage entity. The computing systems may be microprocessor-based systems operable to execute program code in the form of machine-executable instructions. In addition, the computing systems may be connected to other computer systems via a proprietary encrypted network, a public encrypted network, the Internet or other suitable communication network that may include both wired and wireless connections. The communication network may be a local area network, a wide area network, the Internet, or any other type of network that couples a plurality of computers to enable various modes of communication via network messages using suitable communication techniques, such as transmission control protocol/internet protocol, file transfer protocol, hypertext transfer protocol, internet protocol security protocol, point-to-point tunneling protocol, secure sockets layer protocol or other suitable protocol. Remote system124communicates with flight control system112via a communication link130that may include both wired and wireless connections.

While operating remote control application128, remote system124is configured to display information relating to one or more aircraft of the present disclosure on one or more flight data display devices140. Display devices140may be configured in any suitable form, including, for example, liquid crystal displays, light emitting diode displays or any suitable type of display. Remote system124may also include audio output and input devices such as a microphone, speakers and/or an audio port allowing an operator to communicate with other operators or a base station. The display device140may also serve as a remote input device142if a touch screen display implementation is used, however, other remote input devices, such as a keyboard or joystick, may alternatively be used to allow an operator to provide control commands to an aircraft being operated responsive to remote control.

Aircraft10may operate in many roles including military, commercial, scientific and recreational roles, to name a few. For example, as best seen inFIGS. 5A-5D, aircraft10may be a logistics support aircraft configured for cargo transportation such as performing autonomous package delivery operations between a warehouse and customers. In the illustrated implementation, aircraft10includes an upper cargo bay60aand a lower cargo bay60b. Upper and lower cargo bays60a,60bextend in the spanwise direction of fuselage18, as best seen inFIG. 5Din which a back access panel has been removed from fuselage18exposing batteries20and a plurality of packages62. Packages62may be loaded into and unloaded from upper cargo bay60aby opening a side door64a, as best inFIGS. 5A-5B. Likewise, packages62may be loaded into and unloaded from lower cargo bay60bby opening a side door64b, as best inFIGS. 5A-5B. As illustrated, any number of packages62may be loaded into cargo bays60a,60band transported by aircraft10from a departure location to one or more destination locations to accomplish one or more delivery operations. Once all packages62have been delivered, aircraft10may return to the departure location or other location to acquire more packages62for delivery. Preferably, packages62are fixably coupled within fuselage18by suitable means to prevent relative movement therebetween, thus protecting the contents of packages62from damage and maintaining a stable center of mass for aircraft10.

Even though fuselage18has been depicted and described as having two cargo bays60a,60band two side doors64a,64b, it should be understood by those having ordinary skill in the art that a fuselage of the present disclosure could have any number of cargo bays and/or any number of side doors both greater than or less than two without departing from the principles of the present disclosure. Also, even though fuselage18has been depicted and described as having side doors64a,64bon only one side of fuselage18, it should be understood by those having ordinary skill in the art that a fuselage of the present disclosure could have one or more side doors on each side of the fuselage such that access to each of the cargo bays is available from either side of the aircraft or a fuselage of the present disclosure could have one or more side doors on each side of the fuselage that provide access to only certain of the cargo bays from either side of the aircraft without departing from the principles of the present disclosure.

In the illustrated embodiment, fuselage18and side doors64a,64bare configured to provide access to upper and lower cargo bays60a,60bfrom the exterior of aircraft10while providing a predetermined clearance C relative to propulsion assemblies34c,34dand in particular to rotor assemblies52c,52d, as best seen inFIG. 5C. This configuration allows for ground personnel or automated loading and unloading equipment to safely approach aircraft10and easily access cargo bays60a,60bvia side doors64a,64bwithout interference with propulsion assemblies34c,34dor other parts of aircraft10. In the illustrated embodiment, the predetermined clearance C is between two feet and four feet such as about three feet. In other embodiments, the predetermined clearance C could have other dimensions including predetermined clearances of less than two feet or greater than four feet.

In addition to loading and unloading aircraft10while positioned on a surface, aircraft10of the present disclosure has package release capabilities in association with cargo transportation. This package release capability allows aircraft10to deliver cargo to a desired location following transportation thereof without the requirement for landing by opening any one of the side doors on the lower side of aircraft10during flight and releasing the desired package or packages. For example, as best seen inFIG. 6A, upon reaching the desired location in a package delivery operation, flight control system30provides commands for accomplishing the package release including commands to a side door actuator70to open side door64aduring forward flight. An automated package drop system then releases the desired package62from cargo bay60a. In the illustrated embodiment, package62is supported by a parachute66during its descent to the ground or other target location. Thereafter, side door actuator70causes side door64ato close. In another example, as best seen inFIG. 6B, upon reaching the desired location in a package delivery operation, aircraft10transitions from the biplane orientation to the VTOL orientation and engages in hover operations above the target location. Flight control system30then provide commands for accomplishing a package release including commands to a trailing edge door actuator72to open a trailing edge door68such as a clamshell type door. An automated package drop system then releases the desired package62from one of cargo bays60a,60b. In the illustrated embodiment, package62is supported by a parachute66during its descent to the ground or other target location. Thereafter, trailing edge door actuator72causes trailing edge door68to close and aircraft10transitions from the VTOL orientation to the biplane orientation for high speed, high endurance and/or high efficiency flight to the next package release location.

The foregoing description of embodiments of the disclosure has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the disclosure. The embodiments were chosen and described in order to explain the principals of the disclosure and its practical application to enable one skilled in the art to utilize the disclosure in various embodiments and with various modifications as are suited to the particular use contemplated. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the embodiments without departing from the scope of the present disclosure. Such modifications and combinations of the illustrative embodiments as well as other embodiments will be apparent to persons skilled in the art upon reference to the description. It is, therefore, intended that the appended claims encompass any such modifications or embodiments.