EP4683851A2

EP4683851A2 - Vertical take-off and landing craft systems and methods utilizing tilting propellers

Info

Publication number: EP4683851A2
Application number: EP24775618.2A
Authority: EP
Inventors: Michael RUITH; Bryan Marshall
Original assignee: Supernal LLC
Current assignee: Supernal LLC
Priority date: 2023-03-21
Filing date: 2024-03-20
Publication date: 2026-01-28
Also published as: WO2024197012A2; WO2024197012A3

Abstract

A craft includes a body, a first wing extending from a first side of the body of the craft such that the first wing has a first boom, and a second wing extending from a second side of the body of the craft such that the second wing has a second boom. The first boom includes a first front upward-tilting tiltrotor and a first rear downward-tilting tiltrotor. The second boom includes a second front upward-tilting tiltrotor and a second rear downward- tilting tiltrotor. The craft further includes a tail aft of the body of the craft.

Description

Vertical Take-off and Landing Craft Systems and Methods Utilizing Tilting Propellers

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to provisional U.S. Application No. 63/453,684 filed March 21, 2023 and provisional U.S. Application No. 63/534,254 filed August 23, 2023, the contents of each of which are hereby incorporated by reference in their entirety.

BACKGROUND

[0002] An aircraft, such as a vertical takeoff and landing (VTOL) aircraft, a helicopter, a drone, a fixed-wing aircraft, or the like can be used to facilitate transportation of passengers and/or cargo, could serve as an Intelligence, Surveillance, and Reconnaissance (ISR) platform, or could be a vertical launch platform for other aircraft such as but not limited to fixed-wing aircraft. A variety of aircraft are currently known, falling into general categories of horizontal thrust aircraft (e.g., fixed wing aircraft) and vertical thrust aircraft (e.g., helicopters). The benefits of horizontal thrust aircraft are speed and efficient structures to transfer thrust to generate lift under wings. However, horizontal thrust aircraft suffer certain drawbacks, such as requiring specific landing areas, such as runways, to generate or deplete speed during take-off and landing. Vertical thrust aircraft have the benefit of being able to quickly gain lift without horizontal movement, and thus can take off from and land in relatively small areas (e.g., helipads). However, vertical thrust aircraft also suffer from certain drawbacks, such as the inability to carry large loads or travel horizontally at significant speed over longer distances.

[0003] Thus, there is an increasing need for efficient, scalable, safe, easily manufactured, and economically feasible vertical take-off and landing craft that are suited to efficiently generate horizontal thrust capability at speed, as well as to take off and land with minimal infrastructure requirements. There is demand for such craft (whether it be autonomous, piloted, or a combination of both) capable of traveling a variety of distances for a variety of applications, including but not limited to package delivery, photography, and shuttling/taxiing individuals or goods. A person of ordinary skill in the art will realize that, to improve aircraft efficiency, it is important to minimize the weight of the components of the aircraft. In addition, in the interest of efficiency, it is also important to include components on the aircraft that may be able to improve range of the aircraft and conserve power on the aircraft such that the aircraft may be configured to be more effectual.

[0004] Accordingly, some embodiments of the present application seek to improve the efficiency of the aircraft by eliminating lift rotors from the configuration of the aircraft, common on most aircraft, in favor of an all tiltrotor configuration. A tiltrotor, sometimes called a proprotor, is an aircraft component that generates both lift and propulsion by way of one or more powered rotors mounted on rotating shafts or nacelles. One benefit of tiltrotor design is that each rotor is capable of generating both lift power, such as in the VTOL capability of a helicopter, and “forward” power, such as in powering the speed and range of a conventional fixed-wing aircraft. Because each tiltrotor has a dual purpose, the need for rotors exclusively designed to generate lift are able to be eliminated, thus improving the efficiency of the aircraft. A further benefit of eliminating lift rotors from the aircraft configuration is that lift rotors generate substantial edgewise flow during forward flight, which in turn leads to large dynamic loads that typically are reacted through cyclic pitch or teetered rotor systems. The first introduces additional complexity and weight, the latter, in forward flight, leads to additional drag, powerdraw, and noise. Utilizing tiltrotors that align the inflow perpendicular to the rotor disk instead of lift rotors avoids these issues. It also minimizes vibrations during transition from wingborne to thrustborne operation and improves ride quality, electronic component life, and fatigue life of the aircraft structure.

SUMMARY

[0005] Some embodiments described herein relate to methods and systems of aircraft that are configured to eliminate the need for lift-specific rotors in favor of an all tiltrotor configuration of the aircraft.

[0006] An example embodiment includes a craft having a body. The craft also has a first wing extending from a first side of the body of the craft such that the first wing has a first boom. The first boom includes a first front rotor coupled to a front end of the first boom such that the first front rotor includes an upward-tilting tiltrotor. The first boom also includes a first rear rotor coupled to a rear end of the first boom such that the first rear rotor includes a downward-tilting tiltrotor. The craft also has a second wing extending from a second side of the body of the craft, where the second side is opposite the first side, such that the second wing has a second boom. The second boom includes a second front rotor coupled to a front end of the second boom such that the second front rotor includes an upward-tilting tiltrotor. The second boom also includes a second rear rotor coupled to a rear end of the second boom such that the second rear rotor includes a downward-tilting tiltrotor. The craft further includes a tail aft of the body of the craft.

[0007] Another example embodiment includes a craft having a body. The craft also has a first wing extending from a first side of the body of the craft such that a first inboard boom is mounted through the first wing and a first outboard boom is mounted at a first distal end of the first wing. A first front rotor is coupled to a front end of the first inboard boom such that the first front rotor includes an upward-tilting tiltrotor and a first rear rotor is coupled to a rear end of the first inboard boom such that the first rear rotor includes a downward-tilting tiltrotor. A second front rotor is coupled to a front end of the first outboard boom such that the second front rotor includes an upward-tilting tiltrotor and a second rear rotor is coupled to a rear end of the first outboard boom such that the second rear rotor includes a downward-tilting tiltrotor. The craft also has a second wing extending from a second side of the body of the craft such that the second side is opposite the first side and such that a second inboard boom is mounted through the second wing and a second outboard boom is mounted at a second distal end of the second wing. A third front rotor is coupled to a front end of the second inboard boom such that the third front rotor includes an upward- tilting tiltrotor and a third rear rotor is coupled to a rear end of the second inboard boom such that the third rear rotor includes a downward-tilting tiltrotor. A fourth front rotor is coupled to a front end of the second outboard boom such that the fourth front rotor includes an upward-tilting tiltrotor and a fourth rear rotor is coupled to a rear end of the second outboard boom such that the fourth rear rotor includes a downward-tilting tiltrotor. The craft further includes a tail aft of the body of the craft.

[0008] An example method of flying includes providing a craft having a front plurality of tiltrotors mounted to a front side of at least two booms extending through a lift surface of the craft and a rear plurality of tiltrotors mounted to a rear side of the at least two booms. The method also includes rotating the front plurality of tiltrotors upwards and rotating the rear plurality of tiltrotors downwards for vertical take-off mode. After reaching a cruise altitude, the method includes rotating the front plurality of tiltrotors forward and rotating the rear plurality of tiltrotors backward for horizontal flight mode. And after reaching a desired destination, the method includes rotating the front plurality of tiltrotors upwards and the rear plurality of tiltrotors downwards for vertical landing mode.

[0009] These as well as other aspects, advantages, and alternatives will become apparent to those of ordinary skill in the art by reading the following detailed description, with reference, where appropriate, to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 A is a perspective view of a craft, according to an exemplary embodiment of the present disclosure.

[0011] FIG. IB is an additional perspective view of the craft of FIG. 1A, according to an exemplary embodiment of the present disclosure.

[0012] FIG. 1C is an additional perspective view of the craft of FIGS. 1A & IB, according to an exemplary embodiment of the present disclosure.

[0013] FIG. 2A is a top view of a craft, according to an exemplary embodiment of the present disclosure.

[0014] FIG. 2B is a perspective view of the craft of FIG. 2A, according to an exemplary embodiment of the present disclosure.

[0015] FIG. 2C is a rear perspective view of the craft of FIG. 2A, according to an exemplary embodiment of the present disclosure.

[0016] FIG. 3 A is a perspective view of a craft, according to an exemplary embodiment of the present disclosure.

[0017] FIG. 3B is front view of the craft of FIG. 3 A, according to an exemplary embodiment of the present disclosure.

[0018] FIG. 4 is perspective view of an alternate tail configuration, according to an exemplary embodiment of the present disclosure.

[0019] FIG. 5 is a rear perspective view of the craft of FIG. 2A, according to an alternative embodiment of the present disclosure.

[0020] FIG. 6A is a perspective view of a craft, according to an exemplary embodiment of the present disclosure.

[0021] FIG. 6B is a top view of the craft of FIG. 6A, according to an exemplary embodiment of the present disclosure.

[0022] FIG. 6C is view of some components of the craft of FIG. 6A, according to an exemplary embodiment of the present disclosure.

[0023] FIG. 6D is view of some components of the craft of FIG. 6A, according to an exemplary embodiment of the present disclosure.

[0024] FIG. 7 is a perspective view of a craft, according to an exemplary embodiment of the present disclosure.

[0025] FIG. 8A is a perspective view of a craft, according to an exemplary embodiment of the present disclosure. [0026] FIG. 8B is view of some components of the craft of FIG. 8 A, according to an exemplary embodiment of the present disclosure.

[0027] FIG. 8C is view of some components of the craft of FIG. 8 A, according to an exemplary embodiment of the present disclosure.

[0028] FIG. 8D is view of some components of the craft of FIG. 8 A, according to an exemplary embodiment of the present disclosure.

[0029] FIG. 9 is a perspective view of a craft, according to an exemplary embodiment of the present disclosure.

[0030] FIG. 10 is a method of flying a craft, according to an exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION

[0031] Disclosed herein are examples of crafts utilizing tilting propeller and lift propeller configurations to improve efficiency of the craft by saving weight and improving both range and power of the craft. As a person of ordinary skill in the art will recognize, in an all-tilting propellers configuration, the tilting propellers are able to serve a dual purpose on an aircraft. For instance, in vertical flight, the tilting propellers are angled so the plane of rotation is horizontal to the ground in order to generate lift the way a conventional helicopter rotor generates lift. However, as the aircraft gains speed, the tilting propellers are progressively tilted forward or aft as appropriate, with the plane of rotation eventually becoming vertical, substantially perpendicular to the ground. In this manner, the tilting propellers provide thrust such as is typically provided by a propeller, and the airfoil of the aircraft wings become the main source of providing lift via the forward motion of the entire aircraft. Further, by the nature of the substantial thrust distribution to many tilting propellers, the configurations described herein are more robust towards failure of any one (or two) proprotors on a standard craft, which in turn leads to safer flight and landing conditions of the craft. In a craft that utilizes both tilting propellers and lift propellers, the sources of lift may be divided between some or all of the propellers.

[0032] In some embodiments, and as noted above, a vehicle may be a VTOL, which may or may not use electric power to hover, takeoff, and/or land. It should be understood that in other embodiments, the vehicle may be any other type of vehicle that may be able to utilize the advantages of the present invention, such as a ground vehicle (i.e., an automobile), a sea vehicle (such as a boat), or a flying craft (such as an aerial, floating, soaring, hovering, airborne, aeronautical aircraft, airplane, plane, spacecraft, a helicopter, an airship, or an unmanned aerial vehicle, or a drone).

[0033] For example, a vertical take-off and landing configuration according to some embodiments of the present disclosure may include, among other things, one or more lift surfaces, one or more lift propellers, one or more tilting propellers which may be mounted on respective hubs, a body, one or more booms, and a tail. The craft may be manned or unmanned. It is envisioned that the craft may be used for any purpose known to those skilled in the art, including for example, as a taxi, a delivery vehicle, an air ambulance, a personal vehicle, a cargo transport, a short or long-distance hauling aircraft, and/or a video/photography craft.

[0034] In some embodiments, a lift surface may extend relatively horizontally, when the craft is at rest, from one end to another. The lift surface may include an airfoil configured to generate lift when air flows past it. The lift surface may be a single continuous surface, or may include sections of lift surfaces, for example with one or more sections arranged inboard (e.g., towards a body) of booms (discussed below) and one or more sections arranged outboard (e.g., away from a body) of booms. Lift surface may incorporate portions of, or include shaped portions of, body, booms, and/or tilting propellers to generate lift and/or reduce drag as air flows past. In some embodiments, the lift surface may be forward-swept to maintain airflow over the lift surface at steeper climb angles than conventional crafts. In other embodiments, the lift surface may be aft-swept to maintain airflow over the lift surface for greater stability at lower speeds and higher angles of attack. The lift surface, in some embodiments, may include a first partial lift surface at a first end of the lift surface and a second partial lift surface at a second end of the lift surface. As will be understood by a person of ordinary skill in the art, the first and second partial lift surfaces may have any shape suitable to maximize lift and minimize drag, thereby reducing fuel consumption. For example, the partial lift surface may be rectangular, circular, triangular, or any combination thereof.

[0035] Lift propellers may be located at any position on the craft, as will be understood by a person of ordinary skill in the art. In some embodiments, a first lift propeller may be positioned forward of the lift surface on a first side of the body, a second lift propeller may be positioned aft of the lift surface on the first side of the body, a third lift propeller may be positioned forward of the lift surface on a second side of the body, and a fourth lift propeller may be positioned aft of the lift surface on the second side of the body. Lift propellers may also be mounted on one or more booms. The one or more booms may include a battery pack configured to supply electrical power to one or more electric motors or may be utilized for storage of goods, electrical or mechanical components of the craft, or any other items known to those skilled in the art. In some embodiments, two booms are configured substantially perpendicular to the top or bottom surface of the lift surface, but a person of ordinary skill in the art will understand that more or less than two booms may be utilized, and they may be attached using known attachment techniques and/or arranged in any suitable configuration. The one or more booms may include or connect to a tail that comprises one or more control surfaces (e.g., one or more of an elevator, a rudder, a ruddervators, a spoiler, or similar). Control surfaces may be on relatively vertical portions of tail or relatively horizontal portion of tail.

[0036] It should be understood that any suitable number of lift propellers may be incorporated (for example, more or less than four lift propellers may be utilized) on the craft. Lift propellers may be configured to generate substantially vertical thrust. Lift propellers may operate at a fixed pitch and/or a fixed rpm. In some embodiments, lift propellers may be positioned one either side of a lift surface and along booms. In some embodiments, lift propellers may be positioned on lift surface. In some embodiments, lift propellers may be driven by a gearbox, which in turn may be driven by an electric motor.

[0037] Tilting propellers may be configured to rotate or move about an axis parallel with the ground along with partial lift surfaces, where the tilting propellers and partial lift surfaces rotate outboard of booms. It should be understood that in other embodiments, the tilting propellers may also be referred to as a tilting prop, a rotor, or a proprotor, depending on their design details. In some embodiments, where a lift surface is a separate structure from booms, tilting propellers may move or rotate with the lift surface aside from portions of the lift surface that include a body. In some embodiments, the tilting propeller hub may move or rotate with the partial lift surface about an axis parallel to the ground. Based on the shape of lift surface, the lift surface not including body may rotate with tilting propellers to increase lift and decrease drag, thereby reducing fuel consumption. The lift surface shape may also vary throughout the length of boom. For example, the lift surface may be rectangular shaped to support the weight of body, and may be thinner out to tilting propeller to reduce drag when tilting propeller is configured for horizontal operation and wider when tilting propeller is configured for vertical operation. In other embodiments, tilting propellers may move or rotate such that only a portion of the components connected with a tilting propeller hub and blades of the tilting propeller move or rotate, such as a portion of a boom or other attachment mechanism between the tilting propeller and the craft.

[0038] In some embodiments, tilting propellers may be connected to lift surface through a rotating linkage such as a rotating spar, and/or extending linkages. In some embodiments, the rotating spar may be actuated to rotate tilting propeller relative to lift surface. Any number of tilting propellers may be positioned at any suitable location on the craft, including on the lift surface, on one or more sides of a body, on a boom, or any other location. In some embodiments, extending linkages may be actuated to rotate tilting propeller relative to lift surface. Actuators configured to actuate spars and/or rotating linkages may comprise one or more of a rotating actuator or a linear actuator. Tilting propellers may be configured in one configuration to rotate around and/or relative to an axis substantially parallel with a ground surface and/or a lift surface, considered when the aircraft is at rest on the ground surface.

[0039] Improved craft, consistent with each of the various disclosed embodiments, may include tiltrotors configured to rotate from one position when the craft is in a vertical thrust configuration to another position when the craft is in a horizontal thrust configuration, thereby allowing the aircraft to both land in small clearances and efficiently and quickly travel horizontally.

[0040] Both lift propellers and/or tilting propellers may be positioned above or away from control surfaces and/or portions of body such that a blade strike is unlikely or not possible. For example, tilting propellers may be spaced above a tilting propeller hub and/or lift propellers, when in a vertical take-off and landing configuration. Further, tilting propellers may be spaced along lift surface and substantially above body, and/or lift propellers may be spaced along booms and substantially above body. Tilting propellers may be spaced along lift surface away from tail (e.g., outboard) to avoid a blade strike on tail. For example, each tilting propeller may be positioned at more than half the distance of one wing from body or, in some embodiments, more than two-thirds the distance of one wing from body. Tilting propellers, lift propellers, and/or controls may be operable by an onboard pilot, an onboard computer (e.g., autonomously), or from a control outside of the craft (e.g., remotely), or a mixture of one or more of an onboard pilot, an onboard computer, and/or a control outside of the aircraft. A tilting propeller may be configured to be controlled through a power control (e.g., throttle), a pitch control (e.g., collective) and/or an angle of attack control (e.g., cyclically), or any suitable combination of these controls. Each of these controls may comprise mechanical and electrical actuators, switches, or other controls known to one of ordinary skill in the art, in conjunction with one or more processors (e.g., within controllers, computers) to effect operation and management of each individual control or as a subset of controls or all controls altogether.

[0041] Both lift propellers and tilting propellers may be mechanically powered by one or more electric motors. It is contemplated that, in some embodiments, each lift propeller and/or tilting propeller may be powered by a dedicated motor, or one or more lift propellers and/or tilting propellers may be powered by a shared motor. As one example, two lift propellers along one boom may share a motor. It is contemplated that the motors discussed herein could be traditional fuel powered motors, electric motors, and/or hybrid motors. In some embodiments, a motor and rotor may be connected to a transmission that controls the use power generated by the motor. The transmission may be a continuously variable transmission (CVT), or an automatic transmission, or a manual or semi-manual transmission to shift one or more gears to output differing amounts of power. Lift propellers and/or tilting propellers may be constant speed rotors or variable speed rotors. Lift propellers and/or tilting propellers may be at a constant angle of attack or have a changeable angle of attack (e.g., changeable through one or more actuators).

[0042] Both lift propellers and tilting propellers may include various numbers, types, materials, and shapes of propeller blades. For instance, in some embodiments, each blade of a propeller may have a curved shape. In other embodiments, each blade of a propeller may include a winglet at an exterior end of the blade that is largely perpendicular to the remainder of the blade. Other examples are possible.

[0043] Speed, position and/or angle of attack may be changed and/or gear may be shifted individually, as a set at the same time, or for all tilting propellers and/or all lift propellers simultaneously. For example, four lift propellers may all change speed at once to initiate a takeoff sequence and/or landing sequence. As another example, tilting propellers may be shifted from a take-off and landing configuration to a cruise condition simultaneously. As another example, two tilting propellers and four lift propellers may all change speed and/or angle of attack to affect a take-off and landing sequence simultaneously.

[0044] In some embodiments, the tilting propellers may include a first tilting propeller attached to the first partial lift surface such that the first partial lift surface moves with tilting propellers during movement of the tilting propeller relative to and/or rotation about an axis parallel to the ground. A second tilting propeller may be attached to the second partial lift surface such that the second partial lift surface moves with tilting propellers during movement of the tilting propeller relative to and/or rotation about an axis parallel to the ground. The partial lift surfaces may include one or more control systems which may be operable by the pilot located in a cabin. The partial lift surfaces may be operated via actuators, active inceptors, sidesticks, switches, and/or buttons and may be configured to generate lift for vertical take-off and/or landing craft in a horizontal thrust configuration. The partial lift surfaces may also be configured to generate lift in a vertical thrust configuration. The partial lift surfaces may comprise a wing portion with a similar cross-sectional area and/or airfoil shape to the rest of lift surface (e.g., partial lift surfaces may comprise a continuation of lift surface). In some embodiments, the partial lift surfaces may comprise winglets, may consist of winglets, and in other embodiments, the partial lift surfaces may not have winglets. Whether the partial lift surfaces have winglets may depend on the type of cargo, travel time, and/or tilting propeller size. Partial lift surfaces may each comprise a winglet and a wing portion. Winglets may extend generally vertically from the end of the wing portions. Winglets may be configured to reduce drag, as will be understood by a person of ordinary skill in the art.

[0045] The body may be any suitable shape, size, or configuration suitable for the purpose of the craft, as will be understood by a person of ordinary skill in the art. For example, the body may be oval, square, triangular, or otherwise any appropriate shape sufficient to hold cargo and/or passengers while remaining structurally sound. Moreover, the body may include a gear for landing on land and/or water, which may or may not be retractable. The gear may be included at both the front and the back of the craft, and may include wheels, treads, pontoons, or other components that may aid the craft in landing in land and/or water. The body may also include a cockpit configured to hold a pilot, passenger(s), and/or cargo. In one example, the pilot may be located at the front of the aircraft and the passengers and/or cargo may be located behind the pilot. However, it is contemplated that the pilot could be located at any location within the body (or that the craft could be maneuvered without a pilot at least some of the time). [0046] The body may also include a windshield of any suitable shape and size; one or more doors configured to open and/or close (e.g., by swinging, sliding, and/or raising/lowering) to allow ingress/egress of persons and/or cargo; one or more seats; and controls and/or a computer system configured to communicate and/or control craft systems for the craft, including for example, tilting propellers, lift propellers, and/or one or more control surfaces (e.g., elevator, rudder, ruddervator, actuator, spoiler, or other known controls/surfaces). The body may include a fuselage configured to provide structure to connect and/or link a lift surface structure of lift surface. In some embodiments, the fuselage may be of truss, monocoque, or semi-monocoque construction. The fuselage may be constructed of aluminum of carbon fiber. [0047] Further, in some embodiments, the craft may include one or more battery modules and one or more energy management systems (EMSs) that are in communication with the battery modules and that are configured as electronic regulators to monitor and control the charging and discharging of the battery modules.

[0048] The booms may efficiently provide structure for tail structure, one or more electric motors for one or more lift propellers, and/or one or more batteries to power one or more lift propellers and/or one or more tilting propellers. The lift propellers may also be connected to the craft's electrical and control systems. The booms may be supported by lift surface and the internal structure of the lift surface. Thus, the structure of lift surface may efficiently provide lift to the craft to carry persons or cargo while incorporating structure to support booms, and/or additionally to support tilting propellers in horizontal thrust and vertical take-off and landing configurations. Additionally, tilting propellers can create stress on structure as it rotates, and it is thus advantageous to support tilting propellers through the lift surface that comprises internal structural components, such as spars and ribs, that are capable of withstanding the stress from tilting propellers as they operate to generate thrust and as they rotate between configurations. Efficient use of the structure in lift surface can provide for a lighter craft, leading to less use of fuel and travel at greater speeds.

[0049] The tail may be linked aft of booms. In some embodiments, the tail may be linked aft of a lift surface. The tail may comprise an elevator along the link between one boom and another boom. The tail structure may be aft of a body. The tail structure may comprise control surfaces such as rudders and/or ruddervators, where the control surfaces extend upwards and/or downwards from booms. In some embodiments, at least one control surface may be positioned at least partially above a rotation plane of the lift propellers. For example, a rudder, an elevator, or a ruddervators of the tail may extend partially above a body and/or lift propellers. The tail may be configured to provide control to the craft through control surfaces that are positioned in a freestream (e.g., relatively undisrupted air) when the craft is in a horizontal thrust configuration.

[0050] A number of tail configurations are contemplated, including a T-tail, cruciform tail, dual tail, triple tail, V-tail, Bronco tail, low boom tail, or high boom tail. A Bronco tail may have relatively perpendicular vertical and horizontal surfaces. The tail may have rounded edges between substantial vertical and horizontal surfaces to provide efficient support of substantially horizontal surfaces by the substantially vertical surfaces, considered when the craft is at rest on a ground surface. In some embodiments, a tail may extend from a body and booms may be connected above the tail extending from the body, where the connection of booms is separate from the tail extending from the body or connected to the tail extending from the body.

[0051] Improved craft, consistent with each of the disclosed embodiments, may also incorporate a variety of tail configurations. As a person of ordinary skill in the art will understand, various tail configurations may be desirable for various craft depending on the goals of the manufacturers, operators, and end-users. For example, certain tail configurations are desirable to reduce weight, reduce components, reduce interaction between rotors, stabilizers, and/or lift surfaces, reduce the tail area, improve the aesthetic look of an aircraft, provide ground clearance during take-off and/or landing, improve hub spacing to avoid potential blade strike, include an empennage shape to avoid blocking air to an elevator, and/or allow for a continuous structural wing box. Moreover, it is known that aircraft structure, including certain tail configurations, can be improved by streamlining the aircraft structure necessary to support heavy components such as tiltrotors, electric motors, and batteries. It is contemplated that the various embodiments disclosed herein may use any of the tail configurations disclosed herein, and to the extent a specific tail configuration is discussed with respect to a particular embodiment, that tail configuration is provided for illustrative purposes and is not intended to be limiting.

[0052] FIGS. 1A-1C include a craft 100, which may include any component described above. In some embodiments, craft 100 includes a body 102, a first wing 108 extending from a first side 104 of the body 102 of the craft 100, and a second wing 110 extending from a second side 106 of the body 102 of the craft 100 opposite the first side 104 of the body 102 of the craft 100. As such, in some embodiments, a first boom 120 is mounted through the first wing 108 and a second boom 122 is mounted through the second wing 110. The craft 100 also includes a tail 128 aft of the body of the craft 100 between the first boom 120 and the second boom 122.

[0053] A front end 120a of the first boom 120 further includes a first front rotor 130 and a front end 122a of the second boom 122 further includes a second front rotor 134 such that the first front rotor 130 and the second front rotor 134 are each an upward-tilting tiltrotor. As an upward-tilting tiltrotor, the first front rotor 130 and the second front rotor 134 each are facing upward from the craft 100 during vertical take-off of the craft 100 such that a plane of rotation of the first front rotor 130 and the second front rotor 134 are each substantially- parallel to the ground when the first front rotor 130 and the second front rotor 134 each are tilted upward. As the craft 100 switches from vertical take-off mode to horizontal flight mode, each of the first front rotor 130 and the second front rotor 134 are progressively tilted downward to a forward-facing configuration until the plane of rotation of the first front rotor 130 and the second front rotor 134 are each substantially-perpendicular to the ground. As such, each of the first front rotor 130 and the second front rotor 134 are configured to be a puller tiltrotor for the craft 100 during horizontal flight mode. In some embodiments, a central component of each of the first front rotor 130 and the second front rotor 134 are in the same plane as the first boom 120 and second boom 122, respectively, when in this configuration. As the craft prepares for landing and switches from horizontal flight mode to vertical landing mode, each of the first front rotor 130 and the second front rotor 134 are again progressively tilted upward such that the plane of rotation of the first front rotor 130 and the second front rotor 134 are each again substantially-parallel to the ground.

[0054] Similarly, a rear end 120b of the first boom 120 further includes a first rear rotor 132 and a rear end 122b of the second boom 122 further includes a second rear rotor 136 such that the first rear rotor 132 and the second rear rotor 136 are each an downwardtilting tiltrotor. As a downward -tilting tiltrotor, the first rear rotor 133 and the second rear rotor 136 each are facing downward from the craft 100 during vertical take-off of the craft 100 such that a plane of rotation of the first rear rotor 132 and the second rear rotor 136 are each substantially-parallel to the ground when the first rear rotor 132 and the second rear rotor 136 each are tilted downward. As the craft 100 switches from vertical take-off mode to horizontal flight mode, each of the first rear rotor 132 and the second rear rotor 136 are progressively tilted upward to a rear-facing configuration until the plane of rotation of the first rear rotor 132 and the second rear rotor 136 are each substantially-perpendicular to the ground. As such, each of the first rear rotor 132 and the second rear rotor 136 are configured to be a pusher tiltrotor for the craft 100 during horizontal flight mode. In some embodiments, a central component of each the first rear rotor 132 and the second rear rotor 136 are in the same plane as the first boom 120 and second boom 122, respectively, when in this configuration. As the craft prepares for landing and switches from horizontal flight mode to vertical landing mode, each of the first rear rotor 132 and the second rear rotor 136 are again progressively tilted downward such that the plane of rotation of the first rear rotor 132 and the second rear rotor 136 are each again substantially-parallel to the ground.

[0055] In some embodiments, a third boom 124 is also mounted to or through the first wing 108 and a fourth boom 126 is also mounted through the second wing 110.

[0056] In such embodiments, a front end 124a of the third boom 124 further includes a third front rotor 138 and a front end 126a of the fourth boom 126 further includes a fourth front rotor 142 such that the third front rotor 138 and the fourth front rotor 142 are each an upward-tilting tiltrotor. As an upward-tilting tiltrotor, the third front rotor 138 and the fourth front rotor 142 each are facing upward from the craft 100 during vertical take-off of the craft 100 such that a plane of rotation of the third front rotor 138 and the fourth front rotor 142 are each substantially-parallel to the ground when the third front rotor 138 and the fourth front rotor 142 each are tilted upward. As the craft 100 switches from vertical take-off mode to horizontal flight mode, each of the third front rotor 138 and the fourth front rotor 142 are progressively tilted downward to a forward-facing configuration until the plane of rotation of the third front rotor 138 and the fourth front rotor 142 are each substantially-perpendicular to the ground. As such, each of the third front rotor 138 and the fourth front rotor 142 are configured to be a puller tiltrotor for the craft 100 during horizontal flight mode. In some embodiments, a central component of each of the third front rotor 138 and the fourth front rotor 142 are in the same plane as the third boom 124 and fourth boom 126, respectively, when in this configuration. As the craft prepares for landing and switches from horizontal flight mode to vertical landing mode, each of the third front rotor 138 and the fourth front rotor 142 are again progressively tilted upward such that the plane of rotation of the third front rotor 138 and the fourth front rotor 142 are each again substantially-parallel to the ground.

[0057] Similarly, a rear end 124b of the third boom 124 further includes a third rear rotor 140 and a rear end 126b of the fourth boom 126 further includes a fourth rear rotor 144 such that the third rear rotor 140 and the fourth rear rotor 144 are each an downward-tilting tiltrotor. As a downward -tilting tiltrotor, the third rear rotor 140 and the fourth rear rotor 144 each are facing downward from the craft 100 during vertical take-off of the craft 100 such that a plane of rotation of the third rear rotor 140 and the fourth rear rotor 144 are each substantially-parallel to the ground when the third rear rotor 140 and the fourth rear rotor 144 each are tilted downward. As the craft 100 switches from vertical take-off mode to horizontal flight mode, each of the third rear rotor 140 and the fourth rear rotor 144 are progressively tilted upward to a rear-facing configuration until the plane of rotation of the third rear rotor 140 and the fourth rear rotor 144 are each substantially-perpendicular to the ground. As such, each of the third rear rotor 140 and the fourth rear rotor 144 are configured to be a pusher tiltrotor for the craft 100 during horizontal flight mode. In some embodiments, a central component of each the third rear rotor 140 and the fourth rear rotor 144 are in the same plane as the third boom 124 and fourth boom 126, respectively, when in this configuration. As the craft prepares for landing and switches from horizontal flight mode to vertical landing mode, each of the third rear rotor 140 and the fourth rear rotor 144 are again progressively tilted downward such that the plane of rotation of the third rear rotor 140 and the fourth rear rotor 144 are each again substantially-parallel to the ground.

[0058] Further, in such embodiments, the first boom 120, the second boom 122, the third boom 124, and the fourth boom 126 may each be mounted anywhere along a length of the first wing 108 and the second wing 110, respectively. For instance, a boom may be mounted through a wing such that there is no outboard portion of the wing extending beyond the boom, as shown in FIG. 1 A. In other embodiments, the boom may be mounted through the wing such that there is only a wing-tip portion of the wing extending outboard of the boom, such that there is a significant portion of the wing extending outboard of the boom, or such that there is a majority portion of the wing extending outboard of the boom. [0059] For example, in some embodiments, such as the embodiment shown in Figures 1 A-1C, the craft 100 includes the first boom 120 and the second boom 122 mounted through the first wing 108 and the second wing 110, respectively, at an intermediary location along the length of each respective wing. However, the third boom 124 is mounted at a first distal end of the first wing 108 and the fourth boom 126 is mounted at a second distal end of the second wing 110.

[0060] In these embodiments, the first boom 120 may be a first inboard boom, the second boom 122 may be a second inboard boom, the third boom 124 may be a first outboard boom, and the fourth boom 126 may be a second outboard boom.

[0061] It should be understood that other embodiments, there can be any number of booms, and the booms can be mounted anywhere along the length of either or both of the wings, and either in the same plane as the wings or in planes above or below the wings.

[0062] Further, in some embodiments, the inboard booms may each be mounted below a plane of the respective wings and the outboard booms may each be mounted in the plane of the respective wings, such as is shown in Figures 1A-1C. By raising the outboard booms to be in plane with the respective wings, the clearance between the landing gear touchpoint and the lowest point on the wing exterior may be maximized, which in turn increases the rollover angle of the craft 100. Specifically, on embodiments of the craft 100 when there are fewer rotors, each must have a larger diameter to equate to the same level of lift and/or propulsion, and therefore ground clearance becomes a bigger and bigger issue. Other configurations and mounting positions are possible.

[0063] Further still, in some embodiments, the inboard booms and the outboard booms may all be parallel with each other. In other embodiments, only some or none of the booms may be in parallel with each other.

[0064] Also in some embodiments, each inboard boom may have a first length and each outboard boom may have a second length that is shorter than the first length. In such embodiments, it may be desirable that each boom have the same overhang distance from the profile of the wing, but because the chord of the wing profile at the mounting location of the inboard booms is larger than the chord of the wing profile at the mounting location of the outboard booms, the overall length of the inboard booms must be longer than the outboard booms to achieve equal overhang lengths.

[0065] In other embodiments, the craft 100 may include more booms through each wing, each having an upward-tilting tiltrotor and a downward-tilting tiltrotor on a fore and aft end of each additional boom. As such, the tilting propellers connected at the respective front end of each boom may be configured to rotate upwards when transitioning from forward flight to thrustborne flight whereas the tilting propellers connected at the respective rear end of each boom may be configured to rotate downwards when transitioning from forward flight to thrustborne flight. Conversely, the tilting propellers connected at the respective front end of each boom may be configured to rotate back downwards when transitioning from thrustborne flight to forward flight to a forward-facing, puller configuration whereas the tilting propellers connected at the respective rear end of each boom may be configured to rotate back upwards when transitioning from thrustborne flight to forward flight to a rearfacing, pusher configuration.

[0066] In other embodiments, the craft 100 may only include one boom through each wing such that each boom is positioned, for instance, at a near end of each respective wing of the craft with the majority of each wing being inboard of each respective boom and a wingtip outboard of each respective boom. In such embodiments, a diameter of each rotor mounted on the fore and aft of each respective boom is able to be further increased without causing interference with other rotors or components of the craft 100.

[0067] In some embodiments, the craft 100 may have a total footprint spanning about 50 ft. In such embodiments, each rotor may have a diameter of about 11 ft. In other embodiments, each rotor may have a diameter between 5 ft and 20 ft. By utilizing fewer rotors on the craft 100, a larger disc area of each rotor is allowable, which in turn requires less power to operate. This type of minimization leads to higher levels of efficiency specifically in hover mode of the craft 100. Therefore, during the most critical power times such as take-off and landing, using fewer rotors allows for power efficiency in order to operate most effectively. Therefore, in some embodiments, it may be desirable to sacrifice some efficiency in forward motion flight for maximized efficiency during the most critical power times, such as in any hover configuration such as take-off and landing, by reducing from a 12 rotor configuration to an 8 rotor or a 4 rotor configuration of the craft 100.

Moreover, with this type of configuration having reduced number of rotors, the craft 100 may be able to carry more weight.

[0068] Further, in some embodiments, each rotor has four blades. In other embodiments, each rotor has between two and eight blades. Any of the blades on the rotor of the craft 100 may be a variable-pitch blade such that a pilot of the craft 100 or a controller of the craft 100 is able to adjust the blade pitch during flight of the craft 100. As such, the blade angle can thus be adjusted to its optimum value for the phase of flight, be it takeoff, climb, cruise, or landing.

[0069] In some embodiments, such as shown in FIGS. 1 A-1C, the tail 128 is in a V- tail configuration. In other embodiments, the tail 228 may have a T-tail configuration and, as such, may include a base component 228 connecting the body 202 of the craft 200 to the remaining components of the tail 228, such as is shown in the T-tail configuration here. Other tail configurations for tail 228 are possible, such as a Bronco tail, an X-tail, or an adjusted V- tail, where each prong of the “V” includes a kink and/or a horizontal, inward-directed flange at a top, for example. In some embodiments, the tail 128 may further include a lower fin, such as below the V-tail shown in Figures 1 A-1C. The lower fin may be included to increase directional stability of the craft 100, like a weather vane. Other additions for improved stability are also possible.

[0070] In some embodiments, the body 102 of the craft 100 further includes a fuselage 152 and landing gear 154. The fuselage 152 may largely include a cockpit 156 as well as other components described above. The landing gear 154 can be any reasonable type of landing gear, such as a fixed dorm of landing gear, a retractable form of landing gear, skids, floats, or the like. As shown in FIGS. 1 A-1C, in some embodiments, the landing gear 154 may include a tricycle landing gear, such that landing gear 154 has a three-pronged point of contact. In such embodiments, one prong may be substantially under a nose of the craft 100 and the other two prongs may be extended behind each respective wing of the craft 100. In some embodiments, the body 102 of the craft 100 may comprise a variety of other components, such as a cooling inlet. In some embodiments, the body 100 includes a cooling inlet on a top portion of the body 100 in a variety of locations. Ideally the cooling inlet can be positioned to most effectively ventilate a bay and battery of the craft 100. As such, a variety of positions, orientations, and dimensions of the cooling inlet are possible.

[0071] Further, various embodiments of the craft 100 may include any of the above characteristics in combination with each other.

[0072] Further, in some embodiments, front and rear ends of the booms are referred to as front and rear edges.

[0073] FIGS. 2A-2C includes a craft 200, which may include any component described above. In some embodiments, craft 200 includes a body 202, a first wing 208 extending from a first side 204 of the body 202 of the craft 200, and a second wing 210 extending from a second side 206 of the body 202 of the craft 200 opposite the first side 204 of the body 202 of the craft 200. As such, a first boom 220 and a third boom 224 are mounted through the first wing 208 and a second boom 222 and a fourth boom 226 are mounted through the second wing 210. The craft 200 also includes a tail 228 aft of the body of the craft 200 between the first boom 220 and the second boom 222.

[0074] In some embodiments, such as shown in FIGS. 2A-2C, the tail 228 is in a T- tail configuration. The tail 228 may include a base component 228 connecting the body 202 of the craft 200 to the remaining components of the tail 228, such as is shown in the T-tail configuration here. As such, the tail 228 may include a vertical stabilizer 254 and a horizontal stabilizer 256. The vertical stabilizer 254 of the tail 228 may be included to prevent a nose of the craft 200 from swinging from side to side in the yaw direction during flight, and may further include one or more rudder 258 as a movable surface mounted on the trailing edge of the vertical stabilizer 254 for controlling rotation about the vertical axis of the craft 200. The horizontal stabilizer 256 of the tail 228 may be included to prevent a nose of the craft 200 from undesirably pitching up or down during flight, and it may further include one or more elevators 260 to control the nose of the craft 200 and/or the angle of attack of one or more wings extending from the craft 200 by changing the inclination of the one or more wings to alter the amount of lift which each wing generates, causing the craft 200 to climb or dive accordingly. Other tail configurations for tail 228 are possible, such as a V-tail (shown as 502 in FIG. 5) or a Bronco tail for example.

[0075] A front portion 220a of the first boom 220 further includes a first propeller 230 and a front portion 222a of the second boom 222 further includes a third propeller 234 such that the first propeller 230 and the third propeller 234 are each a tilting propeller. The rear portion 220b of the first boom 220 and the rear portion 222b of the second boom 222 include a third propeller 232 and a fourth propeller 236, respectively. The third boom 224 mounted through the first wing 208 further includes a fifth propeller 238 mounted at a front portion 224a of the third boom 224 and a sixth propeller 240 mounted at a rear portion 224b of the third boom 224. The fourth boom 226 mounted through the second wing 210 further includes a seventh propeller 242 mounted at a front portion 226a of the fourth boom 226 and an eighth propeller 244 mounted at a rear portion 226b of the third boom 226. As such, in some embodiments, the tilting propellers connected at the respective front edge of each boom may be configured to rotate downwards when transitioning from thrustbome flight to forward flight whereas the tilting propellers connected at the respective rear edge of each boom may be configured to rotate upwards when transitioning from thrustborne flight to forward flight. [0076] FIGS. 3A-3B includes a craft 300, which may include any component described above. In some embodiments, the craft 300 includes a body 302, a first wing 304 extending from a first side of the body 302 of the craft 300, and a second wing 306 extending from a second side of the body 302 of the craft 300 opposite the first side of the body 302 of the craft 300. As such, a first boom 310 is mounted through the first wing 304 and a second boom 312 is mounted through the second wing 306. The craft 300 also includes a tail 308 aft of the body 302 of the craft 300 connecting a rear portion of the first boom 310 and a rear portion of the second boom 312. The tail 308 may have a variety of configurations, such as the V-tail configuration shown here. Other tail configurations for tail 308 are possible, such as a T-tail or a Bronco tail for example. The first boom 310 further includes a first propeller 318 and a second propeller 320 such that the first propeller 318 and the second propeller 320 are each tilting propellers. The second boom 312 further includes a third propeller 322 and a fourth propeller 324 such that the third propeller 322 and the fourth propeller 324 are each tilting propellers. Also included is a fifth propeller 314 mounted through the first wing 304 such that the fifth propeller 314 is a tilting propeller and a sixth propeller 316 mounted through the second wing 306 such that the sixth propeller 316 is a tilting propeller.

[0077] FIG. 4 depicts a possible T-tail configuration of a tail 400 that may be used on a variety of aircrafts, including any if the crafts described above with respect to FIGS. 1A-3. The tail 400 may include a base component 402 connecting a body of a craft to the remaining components of the tail 400, such as is shown in the T-tail configuration here. As such, the tail 400 may include a vertical stabilizer 404 and a horizontal stabilizer 406. The vertical stabilizer 404 of the tail 400 may be included to prevent a nose of a craft from swinging from side to side in the yaw direction during flight, and may further include one or more rudder 408 as a movable surface mounted on the trailing edge of the vertical stabilizer 404 for controlling rotation about the vertical axis of the craft. The horizontal stabilizer 406 of the tail 410 may be included to prevent a nose of a craft from undesirably pitching up or down during flight, and it may further include one or more elevators 410 to control the nose of the craft and/or the angle of attack of one or more wings extending from the craft by changing the inclination of the one or more wings to alter the amount of lift which each wing generates, causing the craft to climb or dive accordingly. Other tail configurations for tail 400 are possible.

[0078] FIG. 5 shows the embodiment described in FIGS. 2A-2C except for the inclusion of a V-tail 502 instead of the T-tail configuration of tail 228 in FIGS. 2A-2C. [0079] Other embodiments, configurations, and combinations are also possible. For instance, a craft similar to craft 200 could be a two boom, 4 tiltrotor aircraft, a 4 boom, 8 tiltrotor aircraft, or a 6 boom, 10 tiltrotor aircraft whereby in the latter, the most outboard rear tiltrotors may be eliminated to maximize a wingtip strike angle of the wings. Alternatively, a craft similar to craft 300 could be a two boom, four lift rotor, two tiltrotor aircraft, a four boom, eight lift rotor, two tiltrotor aircraft, or a two boom, four lift rotor, four tiltrotor aircraft. Further, a craft may utilize more or less booms, lift rotors, and tiltrotors on crafts similar to craft 200 or craft 300.

[0080] In still other embodiments, a craft may include any number of rotors (both lift rotors and/or tilt rotors, and any combination) in any location on the craft. For instance, a rotor may be connected to a boom, connected directly to a wing and/or other lift surface, connected at an end of a wing and/or lift surface, connected to a tail, connected beneath or above the body of the craft, or the like. Similarly, any suitable number of rotors (both lift rotors and/or tilt rotors) may be connected to the craft at any position aforementioned. The craft may contain an even number of each type of rotor, an odd number of each type of rotor, a combination of even and odd numbers of rotors, all one type of rotor that may be arranged symmetrically or otherwise on the craft, a number of both types of rotors that may be arranged symmetrically or otherwise on the craft, or the like. Additionally, any of the crafts shown or described may include any of the tail configurations shown or described, or any other known tail configuration.

[0081] FIGS. 6A-6D include a craft 600 having a body 602, a first wing 608 extending from a first side 604 of the body 602 of the craft 600 such that a first boom 612, a third boom 616, and a fifth boom 620 are mounted through the first wing 608, and a second wing 610 extending from a second side 606 of the body 602 of the craft 600 opposite the first side 604 of the body 602 of the craft 600 such that a second boom 614, a fourth boom 618, and a sixth boom 622 are mounted through the second wing 610. The craft 600 also includes a plurality of rotors such that each rotor of the plurality of rotors is a tiltrotor. The plurality of rotors includes a first set of rotors comprising a front rotor 624 and a rear rotor 626 such that the front rotor 624 of the first set of rotors is coupled to a front edge 612a of the first boom 612 and the rear rotor 626 of the first set of rotors is coupled to a rear edge 612b of the first boom 612, a second set of rotors comprising a front rotor 628 and a rear rotor 630 such that the front rotor 628 of the second set of rotors is coupled to a front edge 614a of the second boom 614 and the rear rotor 630 of the second set of rotors is coupled to a rear edge 614b of the second boom 614, a third set of rotors comprising a front rotor 632 and a rear rotor 634 such that the front rotor 632 of the third set of rotors is coupled to a front edge 616a of the third boom 616 and the rear rotor 634 of the third set of rotors is coupled to a rear edge 616b of the third boom 616, a fourth set of rotors comprising a front rotor 636 and a rear rotor 638 such that the front rotor 636 of the fourth set of rotors is coupled to a front edge 618a of the fourth boom 618 and the rear rotor 638 of the fourth set of rotors is coupled to a rear edge 618b of the fourth boom 618, a fifth set of rotors comprising a front rotor 640 and a rear rotor 642 such the front rotor 640 of the fifth set of rotors is coupled to a front edge 620a of the fifth boom 620 and the rear rotor 642 of the fifth set of rotors is coupled to a rear edge 620b of the fifth boom 620, and a sixth set of rotors comprising a front rotor 644 and a rear rotor 646 such that the front rotor 644 of the sixth set of rotors is coupled to a front edge 622a of the sixth boom 622 and the rear rotor 646 of the sixth set of rotors is coupled to a rear edge 622b of the sixth boom 622. The craft also includes a tail 648 aft of the body 602 of the craft 600.

[0082] It is envisioned that craft 600 may be used for any purpose known to those skilled in the art, including for example, as a taxi, a delivery vehicle, a personal vehicle, a cargo transport, a short or long-distance hauling aircraft, and/or a video/photography craft. [0083] Body 602 may be any suitable shape, size, or configuration suitable for the purpose of the craft, as will be understood by a person of ordinary skill in the art. For example, body 602 may be oval, square, triangular, or otherwise any appropriate shape sufficient to hold cargo and/or passengers while remaining structurally sound. Moreover, body 602 may include gear for landing on land and/or water, which may or may not be retractable. The gear may be included at both the front and the back of the craft, and may include wheels, treads, pontoons, or other components that may aid the craft in landing in land and/or water. Body 602 may also include a cockpit configured to hold a pilot, passenger(s), and/or cargo. In one example, the pilot may be located at the front of the aircraft and the passengers and/or cargo may be located behind the pilot. However, it is contemplated that the pilot could be located at any location within the body (or that the craft could be maneuvered without a pilot at least some of the time). Body 602 may also include a windshield of any suitable shape and size; one or more doors configured to open and/or close (e.g., by swinging, sliding, and/or raising/lowering) to allow ingress/egress of persons and/or cargo; one or more seats; and controls and/or a computer system configured to communicate and/or control craft systems for the craft, including for example, tiltrotors 624-646, and/or one or more control surfaces (e.g., elevator, rudder, ruddervator, actuator, spoiler, or other known control s/surfaces). Body 602 may include a fuselage configured to provide structure to connect and/or link a lift surface structure of lift surface. In some embodiments, the fuselage may be of truss, monocoque, or semi-monocoque construction. The fuselage may be constructed of aluminum of carbon fiber.

[0084] The first wing 608 and the second wing 610 may act as a lift surface that extends relatively horizontally, when the craft is at rest, from one end to another. Lift surface 602 may include an airfoil configured to generate lift when air flows past it. The first wing 608 and the second wing 610 may each be a single continuous surface, or may include sections of lift surfaces, for example with one or more sections arranged inboard (e.g., towards body 602) of booms 612 and 614 (discussed below) and one or more sections arranged outboard (e.g., away from body 602) of booms 612 and 614, such as between booms 612 and 616 and between booms 614 and 618 respectively, between booms 616 and 620 and between booms 618 and 622 respectively, or outbound of booms 620 and 622. The first wing 608 and the second wing 610 may each incorporate portions of, or include shaped portions of, body 602, booms 612-622, and/or tiltrotors 624-646 to generate lift and/or reduce drag as air flows past.

[0085] Booms 612-622 may efficiently provide structure for tail structure 648, one or more electric motors for one or more batteries to power one or more tiltrotors 624-646. Booms 612-622 may be supported by the first wing 608 or the second wing 610, and the internal structure of each lift surface. Thus, the structure of the first wing 608 or the second wing 610 may efficiently provide lift to craft 600 to carry persons or cargo while incorporating structure to support booms 612-622, and/or additionally to support tiltrotors 624-646 in horizontal thrust and vertical take-off and landing configurations. Additionally, tiltrotors 624-646 can create stress on structure as it rotates, and it is thus advantageous to support tiltrotors 624-646 through each of the lift surface of the first wing 608 or the second wing 610 that comprises internal structural components, such as spars and ribs, that are capable of withstanding the stress from tiltrotors 624-646 as they operate to generate thrust and as they rotate between configurations. Efficient use of the structure in each of the first wing 608 or the second wing 610 can provide for a lighter craft, leading to less use of fuel and travel at greater speeds.

[0086] Tiltrotors 624-646 may be positioned above or away from control surfaces and/or portions of body 602 such that a blade strike is unlikely or not possible. For example, tiltrotors 624-646 may be spaced above a tiltrotor mounting point and along the first wing 608 or the second wing 610 substantially above body 602. Tiltrotors 624-646 away from tail 648 (e.g., outboard) to avoid a blade strike on tail 648. For example, each tiltrotor 624-646 may be positioned at more than half the distance of one wing from body 602 or, in some embodiments, more than two-thirds the distance of one wing from body 602. Tiltrotors 624- 646 and/or controls may be operable by an onboard pilot, an onboard computer (e.g., autonomously), or from a control outside of the craft (e.g., remotely), or a mixture of one or more of an onboard pilot, an onboard computer, and/or a control outside of the aircraft. Each tiltrotor 624-646 may be configured to be controlled through a power control (e.g., throttle), a pitch control (e.g., collective) and/or an angle of attack control (e.g., cyclically), or any suitable combination of these controls. Each of these controls may comprise mechanical and electrical actuators, switches, or other controls known to one of ordinary skill in the art, in conjunction with one or more processors (e.g., within controllers, computers) to effect operation and management of each individual control or as a subset of controls or all controls altogether. Further, although each tiltrotor 624-646 comprises a 5-bladed tiltrotor, other configurations of tiltrotors are possible including tiltrotors having more or less blades (i.e., 3, 4, 6, 7, or 8 blades). Each blade on tiltrotors 624-646 could also be any operable shape, for instance to optimize maximum aerodynamic efficiency.

[0087] Tiltrotors 624-646 may be connected to the booms 612-622 through a rotating linkage such as a rotating spar, and/or extending linkages. In other embodiments, fixed linkages may also be used, such as in the case when only (short takeoff and landing) STOL operations are intended to be performed by the craft. Because each tiltrotor 624-646 blows the wing at certain tilt angles, this configuration further allows craft 600 to perform efficient STOL operations. Further, in some embodiments, the rotating spar may be actuated to rotate the tiltrotors 624-646 relative to each lift surface of the first wing 608 and the second wing 610. In other embodiments, tiltrotors 624-646 may be positioned at any suitable location on the craft, including on either the first wing 608 or the second wing 610, on one or more sides of body 602, or any other location. In some embodiments, extending linkages may be actuated to rotate tiltrotors 624-646 relative to each lift surface of the first wing 608 and the second wing 610. Actuators configured to actuate spars and/or rotating linkages may comprise one or more of a rotating actuator or a linear actuator. Because collective pitch of the blades is needed to be efficient in both thrustbome and high-speed wingbome flight on craft 600, a unique feature of this design is the ability to couple variable pitch with the tilt actuator of each tiltrotor 624-646, thus further reducing the weight, complexity, and cost of the aircraft. Therefore, any high bandwidth thrust modulation would be simply achieved via revolutions per minute (rpm) control of the tiltrotors 624-646.

[0088] Tiltrotors 624-646 may be configured in one configuration to rotate around and/or relative to an axis substantially parallel with a ground surface and/or a lift surface, considered when the aircraft is at rest on the ground surface. As will be understood by a person of ordinary skill in the art, the first wing 608 and the second wing 610 may be lift surfaces that have any shape suitable to maximize lift and minimize drag, thereby reducing fuel consumption. For example, the lift surface may be rectangular, circular, triangular, or any combination thereof.

[0089] In some embodiments, such as is shown in FIG. 6A, tiltrotors 624, 628, 632, 636, 640, and 644 may be mounted to an upper side of booms 612, 614, 616, 618, 620, and 622 respectively. Contrarily, tiltrotors 626, 630, 634, 638, 642, and 646 may be mounted to lower side of booms 612, 614, 616, 618, 620, and 622 respectively. By positioning the aft row of tiltrotors 626, 630, 634, 638, 642, and 646 below the booms 612, 614, 616, 618, 620, and 622, the geometry reduces download onto the aircraft, reduces unwanted noise, and reduces the need to include large flaps and/or aileron deflections to be able to bring the rotors as close as possible to the trailing edge of the wing, further reducing the overall weight of the aircraft.

[0090] As such, in some embodiments, the tiltrotors connected at the respective front edge of each boom may be configured to rotate downwards when transitioning from thrustborne flight to forward flight whereas the tiltrotors connected at the respective rear edge of each boom may be configured to rotate upwards when transitioning from thrustborne flight to forward flight. For instance, as shown in FIGS. 6A-6D, when transitioning from a first flight mode (i.e. vertical take-off flight mode) to a second flight mode (i.e. forward propulsion flight mode), tiltrotors 624, 628, 632, 636, 640, and 644 may be able to be tilted from a position perpendicular to the mounting position on the upper side of booms 612, 614, 616, 618, 620, and 622 respectively forward and downward such that the tiltrotors 624, 628, 632, 636, 640, and 644 are parallel to booms 612, 614, 616, 618, 620, and 622 and a center of the tiltrotors 624, 628, 632, 636, 640, and 644 are in line with booms 612, 614, 616, 618, 620, and 622. This is demonstrated in FIGS. 6C-6D, as tiltrotors 624, 632, and 640 pivot around axis 650 from a perpendicular position shown in FIG. 6C, through an intermediate position as shown in FIG. 6D, to a position parallel with booms 612, 616, and 620. However, because tiltrotors 626, 630, 634, 638, 642, and 646 are mounted to lower side of booms 612, 614, 616, 618, 620, and 622 respectively, when transitioning from a first flight mode (i.e. vertical takeoff flight mode) to a second flight mode (i.e. forward propulsion flight mode), tiltrotors 626, 630, 634, 638, 642, and 646 may be able to be tilted from a position perpendicular to the mounting position on the lower side of booms 612, 614, 616, 618, 620, and 622 respectively backward and upward such that the tiltrotors 626, 630, 634, 638, 642, and 646 are parallel to booms 612, 614, 616, 618, 620, and 622 and a center of the tiltrotors 626, 630, 634, 638, 642, and 646 are in line with booms 612, 614, 616, 618, 620. This is demonstrated in FIGS. 6C- 6D, as tiltrotors 626, 634, and 642 pivot around axis 652 from a perpendicular position shown in FIG. 6C, through an intermediate position as shown in FIG. 6D, to a position parallel with booms 612, 616, and 620.

[0091] Further, in some embodiments, tail 648 may be linked aft of booms 612-622. In some embodiments, tail 648 may be linked aft of each of the first wing 608 and the second wing 610. Tail 648 may comprise an elevator along the link between innermost booms 612 and 614. Tail structure 648 may be aft of body 602. Tail structure 648 may comprise control surfaces such as rudders and/or ruddervators, where the control surfaces extend upwards and/or downwards from booms 612-622. Tail 648 may be configured to provide control to the craft through control surfaces that are positioned in a freestream (e.g., relatively undisrupted air) when the craft is in a horizontal thrust configuration. A number of tail configurations are contemplated, including a T-tail, cruciform tail, dual tail, triple tail, V-tail, Bronco tail, low boom tail, or high boom tail. A Bronco tail may have relatively perpendicular vertical and horizontal surfaces. Tail 648 may have rounded edges between substantial vertical and horizontal surfaces to provide efficient support of substantially horizontal surfaces by the substantially vertical surfaces, considered when craft 600 is at rest on a ground surface. In some embodiments, a tail may extend from body 602 and any number of the booms 612-622 may be connected above the tail extending from the body, where the connection of any number of the booms 612-622 is separate from the tail 648 extending from the body 602 or connected to the tail 648 extending from the body 602.

[0092] FIG. 7 includes a craft 700, which may include any component described in FIGS. 1 A-6D. In some embodiments, craft 700 includes a body 702, a first wing 708 extending from a first side 704 of the body 702 of the craft 700, and a second wing 710 extending from a second side 706 of the body 702 of the craft 700 opposite the first side 704 of the body 702 of the craft 700. As such, a first boom 712 and a third boom 716 are mounted through the first wing 708 and a second boom 714 and a fourth boom 718 are mounted through the second wing 710. The craft 700 also includes a tail 720 aft of the body of the craft 700 connecting a rear portion 712b of the first boom 712 and a rear portion 714b of the second boom 714. A front portion 712a of the first boom 712 further includes a first rotor 722 and a front portion 714a of the second boom 714 further includes a second rotor 724 such that the first rotor 722 and the second rotor 724 are each a tiltrotor, and a third rotor 726 extends between the rear portion 712b of the first boom 712 and the rear portion 714b of the second boom 714 in front of the tail 720 such that the third rotor 726 is also a tiltrotor. The craft 700 further includes a fourth rotor 728 and a fifth rotor 730 such that the fourth rotor 728 is coupled to a front edge 716a of the third boom 716 and the fifth rotor 730 is coupled to a rear edge 716b of the third boom 716. The fourth rotor 728 and the fifth rotor 730 are each a tiltrotor. The craft 700 also further includes a sixth rotor 732 and a seventh rotor 734 such that the sixth rotor 732 is coupled to a front edge 718a of the fourth boom 718 and the seventh rotor 734 is coupled to a rear edge 718b of the fourth boom 718. The sixth rotor 732 and the seventh rotor 734 are also each a tiltrotor.

[0093] Other embodiments are also possible. For instance, the craft 700 could be a two boom, 4 tilt rotor aircraft, a 4 boom, 8 tiltrotor aircraft, or a 6 boom, 10 tiltrotor aircraft whereby in the latter, the most outboard rear tiltrotors would be eliminated to maximize a wingtipstrike angle of the wings.

[0094] FIG. 8A-D includes a craft 800, which may include any component described in FIGS. 1 A-7. In some embodiments, craft 800 includes a body 802, a first wing 808 extending from a first side 804 of the body 802 of the craft 800, and a second wing 810 extending from a second side 806 of the body 802 of the craft 800 opposite the first side 804 of the body 802 of the craft 800 such that the first wing 808 includes an inner portion 812 and an outer portion 814 and the second wing 810 includes an inner portion 816 and an outer portion 818. A first boom 820 is mounted through the inner portion 812 of the first wing 808 and a second boom 822 is mounted through the inner portion 816 of the second wing 810. The craft 800 also includes a tail 824 aft of the body 802 of the craft 800 connecting a rear portion 820b of the first boom 820 and a rear portion 822b of the second boom 820. A front portion 820a of the first boom 820 further includes a first rotor 826 and a front portion 822a of the second boom 822 further includes a second rotor 828 such that the first rotor 826 and the second rotor 828 are each a tiltrotor. A third rotor 880 extends between the rear portion 820b of the first boom 820 and the rear portion 822b of the second boom 822 in front of the tail 824 such that the third rotor 830 is also a tiltrotor. A fourth rotor 832 is coupled to the outer portion 814 of the first wing 808 such that the fourth rotor 832 is a tiltrotor. The outer portion 814 of the first wing 808 is configured to rotate with the fourth rotor 832. A fifth rotor 834 is coupled to the outer portion 818 of the second wing 810 such that the fifth rotor 834 is a tiltrotor. The outer portion 818 of the second wing 810 is configured to rotate with the fifth rotor 834.

[0095] As such, the fourth rotor 832 coupled to the outer portion 814 of the first wing 808 and the fifth rotor 834 coupled to the outer portion 818 of the second wing 810 may be configured to move with the outer portion 814 of the first wing 808 and the outer portion 818 of the second wing 810 relative to and/or rotation about an axis 850 extending through the first wing 802, the body 802, and the second wing 810. The fourth rotor 832 coupled to the outer portion 814 of the first wing 808 is configured to rotate with the fourth rotor 882 around axis 850 as shown in FIGS. 8B-8D. The outer portion 814 and the fourth rotor 832 may transition from a perpendicular position, as shown in FIG. 8B, through an intermediate position, as shown in FIG. 8C, to a position parallel with the inner portion 812 of the first wing 808, as shown in FIG. 8D by rotating about axis 850.

[0096] Further, the outer portion 814 of the first wing 808 and the outer portion 818 of the second wing 810 may include one or more control systems which may be operable by the pilot located in a cabin on craft 800. The outer portion 814 of the first wing 808 and the outer portion 818 of the second wing 810 may be operated via actuators, active inceptors, sidesticks, switches, and/or buttons and may be configured to generate lift for vertical takeoff and/or landing craft in a horizontal thrust configuration. The outer portion 814 of the first wing 808 and the outer portion 818 of the second wing 810 may also be configured to generate lift in a vertical thrust configuration. The outer portion 814 of the first wing 808 and the outer portion 818 of the second wing 810 may comprise a wing portion with a similar cross-sectional area and/or airfoil shape to the inner portion 812 of the first wing 808 and the inner portion 816 of the second wing 810.

[0097] FIG. 9 includes a craft 900, which may include any component described in FIGS. 1 A-8D. In some embodiments, craft 900 includes a body 902, a first wing 908 extending from a first side 904 of the body 902 of the craft 900, and a second wing 910 extending from a second side 906 of the body 902 of the craft 900 opposite the first side 904 of the body 902 of the craft 900 such that the first wing 908 includes an inner portion 912 and an outer portion 914 and the second wing 910 includes an inner portion 916 and an outer portion 918. As such, a first boom 920 and a third boom 924 are mounted through the inner portion 912 of the first wing 908 and a second boom 922 and a fourth boom 926 are mounted through the inner portion 916 of the second wing 910. The craft 900 also includes a tail 928 aft of the body of the craft 900 connecting a rear portion 920b of the first boom 920 and a rear portion 922b of the second boom 922. A front portion 920a of the first boom 920 further includes a first rotor 930 and a front portion 922a of the second boom 922 further includes a third rotor 934 such that the first rotor 930 and the third rotor 934 are each a tiltrotor. The rear portion 920b of the first boom 920 and the rear portion 922b of the second boom 922 include a third rotor 932 and a fourth rotor 936, respectively. The third boom 924 mounted through the inner portion 912 of the first wing 908 further includes a fifth rotor 938 mounted at a front portion 924a of the third boom 924 and a sixth rotor 940 mounted at a rear portion 924b of the third boom 924. The fourth boom 926 are mounted through the inner portion 916 of the second wing 910 further includes a seventh rotor 942 mounted at a front portion 926a of the fourth boom 926 and a eighth rotor 944 mounted at a rear portion 926b of the third boom 926. As such, in some embodiments, the tiltrotors connected at the respective front edge of each boom may be configured to rotate downwards when transitioning from thrustborne flight to forward flight whereas the tiltrotors connected at the respective rear edge of each boom may be configured to rotate upwards when transitioning from thrustborne flight to forward flight. A ninth rotor 946 is coupled to the outer portion 914 of the first wing 908 such that the ninth rotor 946 is a tiltrotor. The outer portion 914 of the first wing 908 is configured to rotate with the ninth rotor 946. A tenth rotor 948 is coupled to the outer portion 918 of the second wing 910 such that the tenth rotor 948 is a tiltrotor. The outer portion 918 of the second wing 910 is configured to rotate with the tenth rotor 948.

[0098] FIG. 10 is a block diagram of a method 1000 of flying, such as a method of flying the craft 100. As shown in Figure 10, the method 1000 includes one or more operations, functions, or actions as illustrated by blocks 1002 - 1008. Any additional blocks may be performed in parallel, and/or in a different order than those described herein. Also, the various blocks may be combined into fewer blocks, divided into additional blocks, and/or removed based upon the desired implementation.

[0099] At block 1002, the method 1000 includes providing a craft having a front plurality of tiltrotors mounted to a front side of at least two booms extending through a lift surface of the craft, and a rear plurality of tiltrotors mounted to a rear side of the at least two booms, such as the craft 100. [00100] At block 1004, the method 1000 includes rotating the front plurality of tiltrotors upwards and rotating the rear plurality of tiltrotors downwards for vertical take-off mode. In some embodiments, rotating the front plurality of tiltrotors upwards and rotating the rear plurality of tiltrotors downwards for vertical take-off mode includes progressively changing a substantially-perpendicular to a ground plane of rotation of each tiltrotor to a substantially-parallel to the ground plane of rotation, such as in block 1010.

[00101] At block 1006, the method 1000 includes, after reaching a cruise altitude, rotating the front plurality of tiltrotors forward and rotating the rear plurality of tiltrotors backward for horizontal flight mode. In some embodiments, rotating the front plurality of tiltrotors forward and rotating the rear plurality of tiltrotors backward for horizontal flight mode includes progressively changing a substantially-parallel to a ground plane of rotation of each tiltrotor to a substantially-perpendicular to the ground plane of rotation, such as in block 1012.

[00102] At block 1008, the method 1000 includes, after reaching a desired destination, rotating the front plurality of tiltrotors upwards and the rear plurality of tiltrotors downwards for vertical landing mode. In some embodiments, rotating the front plurality of tiltrotors upwards and the rear plurality of tiltrotors downwards for vertical landing mode includes progressively changing a substantially-perpendicular to a ground plane of rotation of each tiltrotor to a substantially-parallel to the ground plane of rotation, such as in block 1014.

[00103] In some embodiments of the method 1000, rotating the front plurality of tiltrotors upwards and rotating the rear plurality of tiltrotors downwards for horizontal flight mode includes simultaneously rotating the front plurality of tiltrotors upwards and the rear plurality of tiltrotors downwards. In other embodiments of the method 1000, rotating the front plurality of tiltrotors upwards and rotating the rear plurality of tiltrotors downwards for horizontal flight mode includes sequentially rotating the front plurality of tiltrotors upwards and the rear plurality of tiltrotors downwards.

[00104] Similarly, in some embodiments of the method 1000, rotating the front plurality of tiltrotors forward and rotating the rear plurality of tiltrotors backward for horizontal flight mode includes simultaneously rotating the front plurality of tiltrotors forward and the rear plurality of tiltrotors backward. In other embodiments of the method 1000, rotating the front plurality of tiltrotors forward and rotating the rear plurality of tiltrotors backward for horizontal flight mode includes sequentially rotating the front plurality of tiltrotors forward and the rear plurality of tiltrotors backward. [00105] Similarly, in some embodiments of the method 1000, rotating the front plurality of tiltrotors upwards and the rear plurality of tiltrotors downwards for vertical landing mode includes simultaneously rotating the front plurality of tiltrotors forward and the rear plurality of tiltrotors backward. In other embodiments of the method 1000, rotating the front plurality of tiltrotors upwards and the rear plurality of tiltrotors downwards for vertical landing mode includes sequentially rotating the front plurality of tiltrotors upwards and the rear plurality of tiltrotors downwards.

[00106] The above detailed description describes various features and functions of the disclosed systems, devices, and methods with reference to the accompanying figures. In the figures, similar symbols typically identify similar components, unless context dictates otherwise. The example embodiments described herein and in the figures are not meant to be limiting. Other embodiments can be utilized, and other changes can be made, without departing from the scope of the subject matter presented herein. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are explicitly contemplated herein.

Claims

CLAIMS What is claimed is:

1. A craft comprising: a body; a first wing extending from a first side of the body of the craft, wherein the first wing comprises a first boom, and wherein the first boom comprises: a first front rotor coupled to a front edge of the first boom, wherein the first front rotor comprises an upward-tilting tiltrotor; and a first rear rotor coupled to a rear end of the first boom, wherein the first rear rotor comprises a downward-tilting tiltrotor; a second wing extending from a second side of the body of the craft, the second side being opposite the first side, wherein the second wing comprises a second boom, and wherein the second boom comprises: a second front rotor coupled to a front end of the second boom, wherein the second front rotor comprises an upward-tilting tiltrotor; and a second rear rotor coupled to a rear end of the second boom, wherein the second rear rotor comprises a downward-tilting tiltrotor; and a tail aft of the body of the craft.

2. The craft of claim 1, wherein the body comprises: a fuselage having a cockpit; and landing gear, wherein the landing gear comprises a three-pronged point of contact.

3. The craft of claim 1 , wherein the first wing further comprises a third boom, and wherein the second wing further comprises a fourth boom.

4. The craft of claim 3, wherein: the third boom comprises a third front rotor coupled to a front end of the third boom and a third rear rotor coupled to a rear end of the third boom, wherein the third front rotor comprises an upward-tilting tiltrotor and the third rear rotor comprises a downward-tilting tiltrotor, and the fourth boom comprises a fourth front rotor coupled to a front end of the fourth boom and a fourth rear rotor coupled to a rear end of the fourth boom, wherein the fourth front rotor comprises an upward-tilting tiltrotor and the fourth rear rotor comprises a downwardtilting tiltrotor.

5. The craft of claim 4, wherein each rotor comprises a diameter of about 11ft.

6. The craft of claim 1, wherein each rotor comprises four blades.

7. The craft of claim 6, wherein each blade comprises a variable-pitch blade.

8. The craft of claim 1, wherein the tail comprises a V-tail.

9. A craft comprising: a body; a first wing extending from a first side of the body of the craft, wherein a first inboard boom is mounted through the first wing and a first outboard boom is mounted at a first distal end of the first wing, and wherein: a first front rotor is coupled to a front end of the first inboard boom, wherein the first front rotor comprises an upward-tilting tiltrotor, a first rear rotor is coupled to a rear end of the first inboard boom, wherein the first rear rotor comprises a downward-tilting tiltrotor, a second front rotor is coupled to a front end of the first outboard boom, wherein the second front rotor comprises an upward-tilting tiltrotor, and a second rear rotor is coupled to a rear end of the first outboard boom, wherein the second rear rotor comprises a downward-tilting tiltrotor; a second wing extending from a second side of the body of the craft, the second side being opposite the first side, wherein a second inboard boom is mounted through the second wing and a second outboard boom is mounted at a second distal end of the second wing, and wherein: a third front rotor is coupled to a front end of the second inboard boom, wherein the third front rotor comprises an upward-tilting tiltrotor, a third rear rotor is coupled to a rear end of the second inboard boom, wherein the third rear rotor comprises a downward -tilting tiltrotor, a fourth front rotor is coupled to a front end of the second outboard boom, wherein the fourth front rotor comprises an upward-tilting tiltrotor, and a fourth rear rotor is coupled to a rear end of the second outboard boom, wherein the fourth rear rotor comprises a downward-tilting tiltrotor; and a tail aft of the body of the craft.

10. The craft of claim 9, wherein the first inboard boom is mounted below a plane of the first wing and the first outboard boom is mounted in the plane of the first wing, and wherein the second inboard boom is mounted below a plane of the second wing and the second outboard boom is mounted in the plane of the second wing.

11. The craft of claim 9, wherein the first inboard boom and the second inboard boom each comprise a first length, and wherein the first outboard boom and the second outboard boom each comprise a second length such that the second length is shorter than the first length.

12. The craft of claim 9, wherein each front rotor is an upward-tilting tiltrotor, and wherein each rear rotor is a downward -tilting tiltrotor.

13. The craft of claim 9, wherein each front rotor and each rear comprises a diameter of about l ift.

14. The craft of claim 9, wherein the first outward boom, the second outward boom, the first inward boom, and the second inward boom are parallel to each other.

15. The craft of claim 9, wherein the tail comprises a V-tail.

16. The craft of claim 9, wherein the body comprises: a fuselage having a cockpit; and landing gear, wherein the landing gear comprises a three-pronged point of contact.

17. A method of flying, the method comprising: providing a craft having a front plurality of tiltrotors mounted to a front side of at least two booms extending through a lift surface of the craft, and a rear plurality of tiltrotors mounted to a rear side of the at least two booms; rotating the front plurality of tiltrotors upwards and rotating the rear plurality of tiltrotors downwards for vertical take-off mode; after reaching a cruise altitude, rotating the front plurality of tiltrotors forward and rotating the rear plurality of tiltrotors backward for horizontal flight mode; and after reaching a desired destination, rotating the front plurality of tiltrotors upwards and the rear plurality of tiltrotors downwards for vertical landing mode.

18. The method of claim 17, wherein rotating the front plurality of tiltrotors forward and rotating the rear plurality of tiltrotors backward for horizontal flight mode comprises progressively changing a substantially-parallel to a ground plane of rotation of each tiltrotor to a substantially-perpendicular to the ground plane of rotation.

19. The method of claim 18, further comprising simultaneously rotating the front plurality of tiltrotors backward and the rear plurality of tiltrotors forward for horizontal flight mode.

20. The method of claim 18, further comprising sequentially rotating the front plurality of tiltrotors backward and then the rear plurality of tiltrotors forward for horizontal flight mode.