Large vertical takeoff and landing aircraft

Abstract

An aircraft is disclosed, comprising: a fuselage (1); a front lifting wing (2) having a first wingspan; a rear lifting wing (4) having a second wingspan, wherein the second wingspan is greater than the first wingspan; a first tiltrotor and a second tiltrotor (3) respectively mounted at the wingtips of the front lifting wing; a third tiltrotor and a fourth tiltrotor (3) respectively mounted at the wingtips of the rear lifting wing; and a fifth tiltrotor and a sixth tiltrotor (5) mounted on the rear lifting wing and respectively located between the fuselage and the third tiltrotor and the fourth tiltrotor.

Description

Technical Field

[0001] This disclosure relates to the field of vertical takeoff and landing (VTOL) aircraft. Background Technology

[0002] Large urban areas are often difficult to navigate due to severe road congestion and insufficient ground public transportation. In this environment, most trips are less than 50 kilometers, but modern batteries have enabled electric aircraft to fly this distance and even further. Vertical takeoff and landing (VTOL) allows passenger transport in congested urban areas without the need for long runways. Combining electric propulsion with VTOL has given rise to a new type of aircraft known as eVTOL. Leading new entrants in this category include Volocopter, Joby, Archer, Supernal, Autoflight, and Vertical Aerospace, among others.

[0003] The concept of urban air mobility relies on the commercialization of eVTOL for these missions. All existing eVTOL aircraft are designed to carry 1-6 passengers, potentially resulting in relatively high operating costs per passenger-kilometer, similar to today's private jets or helicopters. It is anticipated that a significant portion of planned eVTOL aircraft journeys will originate from a limited number of vertical takeoff and landing (VTOL) stations, such as from city centers to airports, while larger aircraft could significantly reduce costs by carrying more passengers at once, similar to the cost advantage of buses over private cars. Furthermore, airspace congestion and operating frequency would be significantly reduced—less disruption in congested urban areas. Simultaneously, energy consumption per passenger and the resulting environmental impact would be reduced.

[0004] Current engineering designs for such aircraft face several challenges and problems, including: how to efficiently provide sufficient lift to carry 20-50 passengers in helicopter mode (when the aircraft is moving vertically), while remaining compact enough to utilize existing ground infrastructure. Furthermore, weight and procurement costs, as well as operating costs, should preferably be minimized. To this end, overall complexity and aerodynamic drag should be minimized, and aerodynamic disturbances of the combined lift / propulsion unit should be properly managed. Summary of the Invention

[0005] The aircraft as described in claim 1 is disclosed. Optional but preferred technical features are described in the dependent claims. A method for controlling the aircraft as described in claim 10 is also provided.

[0006] In a first aspect, an aircraft is provided, comprising: a fuselage; a front lifting wing having a first wingspan; a rear lifting wing having a second wingspan, wherein the second wingspan is greater than the first wingspan; a first tiltrotor and a second tiltrotor respectively mounted at the wingtips of the front lifting wing; a third tiltrotor and a fourth tiltrotor respectively mounted at the wingtips of the rear lifting wing; and a fifth tiltrotor and a sixth tiltrotor mounted on the rear lifting wing and respectively located between the fuselage and the third tiltrotor and the fourth tiltrotor.

[0007] This configuration can provide sufficient lift to transport a large number of passengers in a mechanically simple and compact manner. Additionally, or alternatively, this configuration can provide sufficient stability and redundancy to avoid complex mechanical linkages between the tiltrotors, since, for example, if any one tiltrotor loses power, the other five tiltrotors can be used for a safe landing. This, in turn, simplifies the mechanical design and reduces cost and weight. This contrasts with some existing designs that require complex mechanical linkages to ensure that, in the event of an engine failure on one side of the fuselage, the engine associated with the tiltrotor on the opposite side of the fuselage can drive both tiltrotors.

[0008] The total number of lifting wings can be two. Therefore, an aircraft can include only two lifting wings. An aircraft may not include a tail assembly (tail fin assembly). Typically, the tail assembly includes a vertical tail surface and a horizontal tail surface for stabilizing yaw and pitch.

[0009] The total number of tiltrotors can be six. Therefore, an aircraft can consist of only six tiltrotors.

[0010] It should be understood that in this disclosure, the "wing" extends from the first outer wingtip to the second outer wingtip. Therefore, the wing extends to both sides of the fuselage.

[0011] It should be understood that each wing is a fixed wing; for example, the position of each wing relative to the fuselage is fixed.

[0012] The term "tilt rotor," as known to those skilled in the art, refers to a combined propeller / rotor. That is, a unit having multiple rotating airfoils (blades) that simultaneously function as a propeller (e.g., on an aircraft) and a rotor (e.g., on a helicopter). The aircraft may include a (electric) motor associated with each tilt rotor (i.e., each tilt rotor has its own dedicated motor). The aircraft may include a (electric) drive associated with each tilt rotor. The aircraft may include a central control system configured to control the operation of each tilt rotor. Thus, each tilt rotor may have one or more electric motors that drive the tilt rotor directly or via a gearbox. The tilt rotors / their motors may be configured to be battery-powered. Therefore, the aircraft may include one or more batteries configured to power the tilt rotors. The aircraft may include a control system configured to manipulate the tilt rotors (e.g., tilt the tilt rotor, adjust blade pitch, and / or adjust the tilt rotor's rotational speed (RPM)) in response to user input.

[0013] At least two (e.g., each) tiltrotors are tiltable (i.e., tiltably attached to the wing). Therefore, the tiltrotors, or each tiltrotor, can be attached to the wing such that the angle of attack of the blade's rotation axis can vary relative to the wing. For example, the tiltrotors, or each tiltrotor, can be attached to switch between a first configuration (helicopter mode) and a second configuration (aircraft mode), wherein in the first configuration, the blade's rotation axis is substantially perpendicular to the aircraft's longitudinal axis (i.e., vertical), and in the second configuration, the blade's rotation axis is substantially parallel to the aircraft's longitudinal axis (i.e., horizontal). It is possible that at least two (e.g., each) tiltrotors are tilted by 90 degrees.

[0014] As used herein, the term “substantially” perpendicular to or parallel to the longitudinal axis of the aircraft means within ±10 degrees of the longitudinal axis of the aircraft.

[0015] The aircraft may be a tiltrotor aircraft. Therefore, each tiltrotor may include a rotor hub with blades, and the aircraft is configured such that the angle of attack of the rotor hub relative to the wing is variable, so that the aircraft can switch between airplane mode and helicopter mode.

[0016] At least two (e.g., each) tiltrotors can be configured to adjust the total pitch or rotational speed (PRM), or both, to control tiltrotor thrust and thus aircraft attitude. At least two (e.g., each) tiltrotors may have adjustable cyclic pitch.

[0017] The aircraft (e.g., each tilt rotor) can be electrically powered.

[0018] The aircraft may include control surfaces on the front and rear lifting wings, respectively. Each control surface may be mounted (e.g., hinged) to move relative to the rest of the wing.

[0019] The first, second, third, fourth, fifth, and sixth tilt rotors can each have multiple blades.

[0020] The first, second, third, fourth, fifth, and sixth tilt rotors can all be equipped with electric motors.

[0021] Each tilt rotor can be configured to operate independently of any other tilt rotor. For example, there may be no mechanical linkage connecting one tilt rotor to the other, allowing power to be transmitted between the tilt rotors.

[0022] The aircraft may be a passenger plane, such as a 20-50 seater aircraft. The fuselage can accommodate 20 to 50 passengers plus crew. For example, the fuselage may be sized to accommodate 30 people. The aircraft may include internal carry-on baggage space. The aircraft may include external retrieval baggage compartments for larger luggage.

[0023] The front lifting wing (canard) and / or rear lifting wing (rear wing) can be mounted on the top of the fuselage. The canard and rear wing can be mounted in the same vertical position (i.e., the vertical distance from the horizontal ground when the landing gear is down). The vertical positions of the canard and rear wing can differ by less than or equal to 0.5m.

[0024] It should be understood that the forewing is located in the forward half of the aircraft. It should be understood that the rear wing is located in the rear half of the aircraft. The aircraft may have a mid-fuselage section located between the foremost and rearmost points of the fuselage. The forewing may be located in front of the mid-fuselage section. The rear wing may be located behind the mid-fuselage section.

[0025] The first and second tilt rotors can be located outside the fifth and sixth tilt rotors.

[0026] The wingspan of the rear wing can be up to twice that of the forewing. The wingspan of the rear wing can be 15-20 m (inclusive of endpoints); the wingspan of the forewing can be 8-12 m (inclusive of endpoints). It should be understood that the wingspan will depend on the size of the aircraft (i.e., on the number of passengers it can accommodate). If the aircraft can accommodate 30 people, the wingspan of the rear wing can be 17.5 m, and the wingspan of the forewing can be 10 m.

[0027] Tiltrotors have a diameter and number of blades that will vary depending on the exact size of the aircraft. The diameter (i.e., the radius of the blade multiplied by 2) can be 4-6m (including the endpoint value). In an aircraft that can accommodate 30 people, each tiltrotor has a diameter of 4.5m and 5-7 blades.

[0028] In a second aspect, a method for controlling an aircraft is disclosed, the aircraft comprising: a fuselage; a front lifting wing having a first wingspan; a rear lifting wing having a second wingspan greater than the first wingspan, wherein the rear lifting wing has a leading edge; a first tiltrotor and a second tiltrotor respectively mounted at the wingtips of the front lifting wing; a third tiltrotor and a fourth tiltrotor respectively mounted at the wingtips of the rear lifting wing; and a fifth tiltrotor and a sixth tiltrotor mounted on the rear lifting wing, respectively located between the fuselage and the third tiltrotor and the fourth tiltrotor. The method includes the following steps: The aircraft can take off vertically with at least two (e.g., all) tiltrotors in a first configuration (helicopter mode), in which the rotor blades' axes of rotation are substantially perpendicular to the aircraft's longitudinal axis (e.g., each tiltrotor is rotated to face 90 degrees to the top surfaces of the front and rear lift wings). The at least two (e.g., all) tiltrotors can then be tilted from the first configuration to a second configuration (airplane mode), in which the rotor blades' axes of rotation are substantially parallel to the aircraft's longitudinal axis (e.g., each tiltrotor is rotated to face a direction parallel to the flight direction and the top surfaces of the front and rear lift wings) for forward flight.

[0029] Additionally or alternatively, during forward flight, at least two (e.g., all) tiltrotors may be in a second configuration (aircraft mode), wherein the axes of rotation of the blades are substantially parallel to the longitudinal axis of the aircraft (e.g., each tiltrotor is rotated to face a direction parallel to the flight direction and the top surfaces of the front and rear lift wings for forward flight). The at least two (e.g., all) tiltrotors can then be tilted from the second configuration to a first configuration (helicopter mode), in which the axes of rotation of the blades are substantially perpendicular to the longitudinal axis of the aircraft (e.g., each tiltrotor is rotated to face a 90-degree angle to the top surfaces of the front and rear lift wings), and the aircraft then lands vertically.

[0030] The method may include: (a) Each tilt rotor is rotated so that it faces 90 degrees to the top surfaces of the front and rear lifting wings; (b) The aircraft takes off vertically; (c) Each tilt rotor is rotated to face a direction parallel to the direction of flight and the top surfaces of the front and rear lifting wings for forward flight; (d) Each tilt rotor is rotated to face 90 degrees to the top surfaces of the front and rear lifting wings; and (e) The aircraft lands vertically.

[0031] When switching between the first configuration and the second configuration, the at least two or each tilt rotor can tilt by 90 degrees.

[0032] The method may include adjusting the total pitch or rotational speed (PRM) or both of at least two (e.g., each) tiltrotors to control tiltrotor thrust and thus control aircraft attitude.

[0033] It should be understood, of course, that features described with respect to one aspect of this disclosure may be incorporated into other aspects of this disclosure. For example, the methods of this disclosure may be incorporated into any feature described with respect to the apparatus of this disclosure, and vice versa. Attached Figure Description

[0034] Figure 1 An isometric view of an aircraft in helicopter mode according to an exemplary embodiment is shown; Figure 2 A top view of an aircraft in flight mode according to an exemplary embodiment is shown, wherein the front lift wing and the rear lift wing, along with their wingtips and inward propulsion units, are horizontal to provide forward thrust; Figure 3 A left-side view of an aircraft in airplane mode according to an exemplary embodiment is shown; Figure 4 A front view of an aircraft in flight mode according to an exemplary embodiment is shown; Figure 5 A top view of the aircraft in helicopter mode according to an exemplary embodiment is shown, with the landing gear deployed; the wingtip propulsion units are tilted upwards by approximately 90 degrees, and the leading section of the inner propulsion units is also tilted to provide vertical lift; Figure 6 A left-side view of the aircraft in helicopter mode according to an exemplary embodiment is shown; Figure 7 A front view of the aircraft in helicopter mode according to an exemplary embodiment is shown; Figure 8a A control flowchart of an aircraft according to an exemplary embodiment is shown; and Figure 8b It shows in Figure 8a A schematic diagram of the aircraft for each step of the flowchart. Detailed Implementation

[0035] The exemplary implementation scheme relates to, for example Figure 1 and Figure 2 The large eVTOL aircraft shown.

[0036] This is like Figure 1 and Figure 2 The aircraft shown preferably includes a fuselage 1 (see...) Figure 2 The fuselage accommodates 20-50 passengers and is supported by two lifting wings—a smaller canard 2 with a tiltable propulsion unit 3 at each wingtip (see...). Figure 2 ); and a larger rear wing 4, which has a similar wingtip propulsion unit 3, and on the leading edge 9 of the rear wing 4 ( Figure 2 Two additional propulsion units 5 are installed on the fuselage, located between the fuselage and the wingtips. Each propulsion unit 3 includes a combined propeller / rotor (tilt rotor) and its electro-electrode motor, as well as an associated drive and control system.

[0037] The aircraft in Figure 1 The diagram illustrates a helicopter configuration, with the wingtip propulsion unit 3 tilted upwards and the leading edge of the inner propulsion unit 5 tilted upwards as well. In this configuration, the aircraft will take off and climb until it leaves the ground infrastructure, at which point it will tilt some or all of its propulsion units downwards by approximately 90 degrees to provide forward thrust and continue climbing to its cruising altitude (referred to here as the aircraft being in helicopter mode). Upon approaching its destination, it will decelerate and descend, tilting the rotors back upwards to return to helicopter mode for the final approach and landing.

[0038] The aircraft according to the exemplary embodiment is in Figure 2 The diagram is shown in aircraft form, depicting a fuselage 1 accommodating 20-50 passengers plus crew. It features internal carry-on baggage space and external retrieval compartments for larger items. A canard wing 2 is mounted on top of the fuselage and supports a propulsion unit 3 at each wingtip. A rear wing 4 has a larger wingspan and also supports a propulsion unit 3 at each wingtip, in addition to two inward propulsion units 5 mounted on the leading edge of the wing between the fuselage and the wingtip mounting units. Figure 1 As shown, the wingspan of the rear wing 4 is preferably up to twice the wingspan of the forewing wing 2. For example, in an embodiment where the aircraft can accommodate 30 people, the wingtip span of the rear wing 4 is 17.5m, while the span of the forewing wing 2 is 10.0m. These lengths can range from 15-20m for the rear wing 4 to 8-12m for the forewing wing 2, depending on the number of passengers.

[0039] Each propulsion unit comprises a tiltrotor, the diameter of which and the number of blades will vary depending on the exact dimensions of the aircraft. For example, in an implementation where the aircraft can accommodate 30 people, each tiltrotor would have a diameter of 4.5m and 5-7 blades. The diameter could range from 4-6m.

[0040] Each tilt rotor has one or more electric motors that can drive the tilt rotor directly or via a gearbox, and also has the electronics required to drive the motors from battery power.

[0041] The nominal lateral span of the tilt rotor is from Figure 4 The dashed line 6 in the figure shows this.

[0042] The wing tip-to-root ratio, dihedral angle, and leading-edge sweep angle can vary depending on the specific dimensions and application requirements. For example, in an implementation where the aircraft is designed to accommodate 30 people, recommended values ​​for these parameters are: tip-to-root ratio: 0.55 for canard 2 and 0.4 for aft 4; dihedral angle of both wings: 0 degrees; leading-edge sweep angle of both wings: 0 degrees. For example, the ranges for each of these parameters are as follows: tip-to-root ratio: 0.4-0.6 for canard 2 and 0.35-0.55 for aft 4; dihedral angle of both wings: -2 to +3 degrees; leading-edge sweep angle of both wings: -5 to +5 degrees.

[0043] 7 (wing trailing edge) Figure 2 The control surfaces on the plane are shown in their positions in aircraft mode.

[0044] Wings 2 and 4 are located at the top of fuselage 1. Figure 3 It is shown in outline in the middle, while Figure 4 In this diagram, the relationship between fuselage 1, wings 2, and wings 4 is the clearest. The range of each tiltrotor is represented by the dashed circle 6. Note that the actual height of each wing above the fuselage may not be exactly the same, and the effects of aerodynamic interference need to be confirmed. For example, in one embodiment, the heights of wings 2 and 4 can be the same. These values ​​can differ by up to 0.5m.

[0045] The relationship between the six tiltrotors, wings 2 and 4, and fuselage 1 is as follows: Figure 5 As shown, propulsion unit 3 and propulsion unit 5 are illustrated in helicopter mode. Note that the relationship between the wing and rotor will be optimized to minimize the impact of the rotor downwash on the wing, thereby optimizing lift. Specifically, note that... Figure 2 The control surface 7 shown is in Figure 5 They are not visible in the middle because they have been folded down to avoid the downwash of the tilting rotor.

[0046] Side view of the aircraft in helicopter mode Figure 6The diagram illustrates how the four wingtip propulsion units 3 rotate as a whole, while only the leading edge of the inner unit 5 tilts. The view also shows a schematic takeoff and landing configuration 8.

[0047] like Figure 7 As shown, the front view of the aircraft in helicopter mode shows propulsion units 3 and 5 tilted upwards to provide lift and control during hovering. The inward / outward tilt will be optimized to minimize interference between the rotors, but will be within the range of approximately 2-5 degrees.

[0048] Figure 8a A flowchart illustrating the steps of a method for controlling the aircraft.

[0049] Step 1, 81: Before takeoff, at least two tiltrotors, preferably all six, are rotated so that their axes are oriented at 90 degrees or approximately 90 degrees to the ground. In this position, the aircraft is in helicopter mode, where passengers and luggage will be loaded, and the batteries will be charged as needed.

[0050] Step 2.82: Takeoff. The aircraft performs vertical takeoff, retracts its landing gear, and climbs vertically to a safe altitude.

[0051] Step 3, 83: Cruise. At least two tiltrotors, preferably all six, are rotated so that they are oriented parallel or substantially parallel to the direction of flight, while the aircraft accelerates to cruise speed. At this position, the aircraft is in aircraft mode, has reached its cruise altitude, and is moving horizontally toward its destination.

[0052] Step 4, Approach and Landing: At least two tiltrotors, preferably all six, are rotated to face 90 degrees or approximately 90 degrees to the ground, in helicopter mode, while the aircraft decelerates to enter hover and lowers its landing gear.

[0053] Step 5.85: After landing, the aircraft has completed a vertical landing at its destination. The aircraft taxis to the terminal to unload passengers and luggage, and, where appropriate, inserts the batteries for charging.

[0054] Figure 8b It shows that according to Figure 8a The flowchart describes the aircraft's status in steps 81, 82, 83, 84, and 85.

[0055] Therefore, this disclosure proposes a unique configuration of VTOL aircraft, preferably an eVTOL, which addresses at least some of the aforementioned technical engineering challenges, as well as others. This configuration preferably features a wing and tiltrotor sized for efficiency, while minimizing the downwash load on the wing from the tiltrotor's downwash flow, and maintaining a compact footprint, enabling it to access numerous VTOL airfields.

[0056] Control in aircraft mode is provided by one or more articulated control surfaces 7 on each wing. Control in helicopter mode is provided by one or more rotors with adjustable blade cyclic pitch and / or collective pitch and adjustable rotational speed (RPM). The articulated control surfaces 7 can deflect downwards by approximately 90 degrees below the rotor to minimize downwash loads from the wingtip rotor downwash.

[0057] Although the above describes a battery-electric aircraft, other methods can also power the aircraft, such as standard fuel or hydrogen fuel cells.

[0058] In the implementation plan, the disclosed aircraft relates to a battery-electric aircraft capable of vertical takeoff and landing with 20-50 passengers.

Claims

1. An aircraft comprising: body; Forward-lifting wing with first wingspan; A rear lifting wing having a second wingspan greater than the first wingspan, wherein the rear lifting wing has a rear lifting wing leading edge; A first tiltrotor and a second tiltrotor are respectively installed at the wingtips of the front lifting wing; The third and fourth tilt rotors are respectively installed at the tips of the rear lifting wing; as well as The fifth and sixth tiltrotors are mounted on the leading edge of the rear lift wing and are respectively located between the fuselage and the third tiltrotor and between the fuselage and the fourth tiltrotor.

2. The aircraft according to claim 1, wherein the aircraft has two lifting wings, namely the front lifting wing and the rear lifting wing.

3. The aircraft according to claim 1 or 2, wherein the aircraft has a total of six tilt rotors, namely the first tilt rotor, the second tilt rotor, the third tilt rotor, the fourth tilt rotor, the fifth tilt rotor and the sixth tilt rotor.

4. The aircraft according to any one of the preceding claims, wherein, The front lifting wing and the rear lifting wing are fixed wings.

5. The aircraft according to any one of the preceding claims, wherein, The aircraft in question is a passenger plane, such as a 20-50 seat passenger plane.

6. The aircraft according to any one of the preceding claims, wherein, The aircraft is a tiltrotor aircraft, such as a tiltrotor vertical takeoff and landing (VTOL) aircraft.

7. The aircraft according to any one of the preceding claims, wherein, At least two of the tilt rotors are tiltable, for example, each tilt rotor is tiltable.

8. The aircraft according to claim 7, wherein, At least two of the tilt rotors are tilted 90 degrees, for example, each tilt rotor is tilted 90 degrees.

9. The aircraft according to any one of the preceding claims, wherein, At least two of the tiltrotor controls the total pitch or rotational speed, or both, to control the tiltrotor thrust and thus the aircraft attitude.

10. The aircraft according to any one of the preceding claims, wherein, At least two of the tilt rotors have adjustable blade periodic pitch.

11. The aircraft according to any one of the preceding claims, wherein, The aircraft is electrically powered.

12. The aircraft according to any of the preceding claims further includes movable, for example, articulated control surfaces on the front lift wing and the rear lift wing, respectively.

13. The aircraft according to any one of the preceding claims, wherein, The first, second, third, fourth, fifth, and sixth tilt rotors each have multiple blades.

14. The aircraft according to any one of the preceding claims, wherein, The first, second, third, fourth, fifth, and sixth tilt rotors are all equipped with electric motors.

15. A method for controlling an aircraft, said aircraft comprising: body; Forward-lifting wing with first wingspan; A rear lifting wing having a second wingspan greater than the first wingspan, wherein the rear lifting wing has a rear lifting wing leading edge; A first tiltrotor and a second tiltrotor are respectively installed at the wingtips of the front lifting wing; The third and fourth tilt rotors are respectively installed at the tips of the rear lifting wing; And a fifth tiltrotor and a sixth tiltrotor mounted on the rear lifting wing, respectively located between the fuselage and the third tiltrotor and between the fourth tiltrotor; The method includes: (i) The aircraft takes off vertically with at least two, for example, tiltrotors in a first configuration (helicopter mode), in which the rotor blades' rotation axes are substantially perpendicular to the aircraft's longitudinal axis; then (ii) Tilting the tiltrotor from a first configuration to a second configuration (aircraft mode), in which the axis of rotation of the blades is substantially parallel to the longitudinal axis of the aircraft, for forward flight; and / or The method includes: (i) During forward flight, at least two, for example all, of the tiltrotors are in a second configuration (aircraft mode), in which the axis of rotation of the blades is substantially parallel to the longitudinal axis of the aircraft; then (ii) The tilt rotor is tilted from the second configuration to the first configuration (helicopter mode), in which the axis of rotation of the blades is substantially perpendicular to the longitudinal axis of the aircraft, and then the aircraft lands vertically.

16. A method for controlling an aircraft, the aircraft comprising: body; Forward-lifting wing with first wingspan; A rear lifting wing having a second wingspan greater than the first wingspan, wherein the rear lifting wing has a rear lifting wing leading edge; A first tiltrotor and a second tiltrotor are respectively installed at the wingtips of the front lifting wing; The third and fourth tilt rotors are respectively installed at the tips of the rear lifting wing; And a fifth tiltrotor and a sixth tiltrotor mounted on the rear lifting wing, respectively located between the fuselage and the third tiltrotor and between the fourth tiltrotor; the method includes: (a) Each tilt rotor is rotated to face 90 degrees to the top surface of the front lift wing and the rear lift wing; (b) The aircraft takes off vertically; (c) Each tilt rotor is rotated to face a direction parallel to the direction of flight and the top surfaces of the front and rear lifting wings for forward flight; (d) Each tilt rotor is rotated to face 90 degrees to the top surfaces of the front and rear lifting wings; and (e) The aircraft lands vertically.

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