An aircraft with a tiltable fuselage body

Abstract

An aircraft including: a fuselage body; a front wing having two or more propulsion sources; and a rear wing, having two or more propulsion sources, wherein the front wing is located closer to the head portion of the fuselage body than the rear wing, and the rear wing is located closer to the tail portion of the fuselage body than the front wing, and wherein the aircraft is configured to apply differential thrust between the propulsion sources of the front wing and the propulsion sources of the rear wing to generate a moment imbalance to tilt the fuselage body—and a method including: applying differential thrust between front-wing propulsion sources and rear-wing propulsion sources of an aircraft to generate a moment imbalance to tilt the fuselage body.

Description

AN AIRCRAFT WITH A TILTABLE FUSELAGE BODYTECHNICAL FIELD

[0001] The embodiments described herein broadly relate to an aircraft with a tiltable fuselage body.BACKGROUND

[0002] The traditional solution for vertical take-off and landing aircraft has been the helicopter. Helicopters have limitations based upon their design around range, performance and speed and also suffer from complexity in the rotor mechanisms (the collective / cyclic rotor head is a mechanically complex element).

[0003] More recently, in the small uncrewed air vehicle (UAV) field, multi-rotor "drones" have become prevalent. These are typically quite small (<20kg), enabled by the advances in electric motors, speed controllers and battery technology. Lightweight electric motors allow for the distributed propulsive elements required (where piston or turbine engines either require multiple engines with a significant weight penalty or complex mechanical drive shaft mechanisms); however this means that electric power availability becomes the limiting constraint for range and endurance. This has typically led to these techniques only being used in small aircraft.

[0004] Recent developments sparked by the Urban Air Mobility field (such as lightweight commercial air-taxis for example) have created a hive of activity and innovation in combined vertical take-off / landing (VTOL) and fixed wing concepts with an aligned interest from the UAV field, trying to obtain VTOL with the cruising benefits of a traditional fixed wing aircraft, also exploring greater electric energy availability through both hybrid solutions and potentially hydrogen based solutions.

[0005] Options for VTOL aircraft typically fall into three categories:Separate lift / cruise: Separate propulsion sources are used for vertical lift in take-off and then cruise. Typically they may include some form of multi-copter attached to asemi-conventional fixed wing aircraft. These are simple in implementation, but suffer performance burdens due to the multiple propulsion sources.• Combined lift cruise through tilting wings or rotors: This is a more advanced version of the lift / cruise concept where the same propulsion source is used for both vertical take-off and conventional flight. The thrust line of the propulsion source is normally rotated from a vertical orientation to a horizontal orientation through a tilting wing or rotor design. Examples include the V22 Osprey, the Wisk UAM platform etc. These platforms address the performance issues of the separate lift cruise configurations, but come with significant complexity in the tilting mechanisms.• Tail-sitter: A ‘conventional’ aircraft ‘ sits’ vertically on its tail, and with a large thrust to weight ratio lifts the vehicle off the ground and then rotates the whole body into a conventional aircraft flight attitude. This offers desired aerodynamic performance and efficiency, however this configuration is problematic due to human factors (for example, the pilot is sitting backwards for landing) and offers significant aircraft ground handling issues (e.g. if the tail-sitter has a sufficiently high centre of gravity, the aircraft could be prone to falling over from wind).SUMMARY

[0006] It is desirable to provide an aircraft with a tiltable fuselage body. Additionally or alternatively, it is desirable to provide the industry with a useful choice.

[0007] In one aspect, there is provided an aircraft including: a fuselage body; a front wing having two or more propulsion sources (“front-wing propulsion sources”); and a rear wing, having two or more propulsion sources (“rear-wing propulsion sources”), wherein the front wing is located closer to the head portion of the fuselage body than the rear wing, and the rear wing is located closer to the tail portion of the fuselage body than the front wing, and wherein the aircraft is configured to apply differential thrust between the propulsion sources of the front wing and the propulsion sources of the rear wing to generate a moment imbalance to tilt the fuselage body.

[0008] In some embodiments, each propulsion source and / or each wing is fixed in position relative to the fuselage body.

[0009] In some embodiments, the tilting of the fuselage body of the aircraft tilts the propulsion sources in tandem with the fuselage body.

[0010] In some embodiments, the aircraft is configured to apply the differential thrust by way of the front wing being anhedral and the rear wing being dihedral.

[0011] In some embodiments, at least one propulsion source of the front wing is located on a thrust force axis that is offset from thrust force axes of the propulsion sources of the rear wing (to substantially avoid wake effects between the front and rear propulsion sources).

[0012] In some embodiments, at least one propulsion source of the rear wing is located on a thrust force axis that is offset from thrust force axes of the propulsion sources of the front wing (to substantially avoid wake effects between the front and rear propulsion sources).

[0013] In some embodiments, the propulsion sources of the aircraft are configured to apply differential thrust to generate moment imbalance when:• net forward thrust is applied by the propulsion sources of the front wing (along their thrust force axes to apply an upward force on the head portion of the fuselage), and / or• net reverse thrust is applied by the propulsion sources of the rear wing (along their thrust force axes to apply a downward force on the tail potion of the fuselage).

[0014] In some embodiments, the propulsion sources of the aircraft are configured to apply differential thrust to generate moment imbalance when:• net reverse thrust is applied by the propulsion sources of the front wing (along their thrust force axes to apply a downward force on the head portion of the fuselage), and / or• net forward thrust is applied by the propulsion sources of the rear wing (along their thrust force axes to apply an upward force on the tail portion of the fuselage).

[0015] In some embodiments, the propulsion sources of the aircraft are configured to apply the differential thrust to generate the moment imbalance when:• a first net forward thrust is applied by the propulsion sources of the front wing (along their thrust force axes to apply an upward force on the head portion of the fuselage), and• a second net forward thrust is applied by the propulsion sources of the rear wing (along their thrust force axes to apply an upward force on the tail portion of the fuselage), wherein: the second net forward thrust is less than the first net forward thrust for a first differential thrust (to tilt the fuselage body from a rest configuration to a tail sitting configuration prior to take off, and / or to tilt the fuselage body to provide pitch control during flight); or the second net forward thrust is more than the first net forward thrust for a first differential thrust (to tilt the fuselage body from a tail sitting configuration to a rest configuration after landing, and / or to tilt the fuselage body to provide pitch control during flight).

[0016] In some embodiments, the aircraft includes at least one wheel, preferably two or more wheels (configured to be pivoted upon by the fuselage body of the aircraft when tilting, for example between the rest configuration and the tail sitting configuration).

[0017] In some embodiments, the aircraft includes brakes for braking the wheels (when tilting, for example between the rest configuration and the tail sitting configuration).

[0018] In some embodiments, at least one propulsion source is angled relative from horizontal when the aircraft is in the rest configuration (including to substantially 5 degrees, e.g., the front propulsion source).

[0019] In some embodiments, each propulsion source is configured to provide lift for takeoff and thrust for cruise.

[0020] In some embodiments, the aircraft is configured to apply the differential thrust to tilt the fuselage body to provide pitch control during flight.

[0021] In some embodiments, the aircraft is configured to apply the differential thrust to tilt the fuselage body between a rest configuration and a tail sitting configuration.

[0022] Tilting the fuselage body between a rest configuration and a tail sitting configuration may include:• tilting the fuselage body from a rest configuration to a tail sitting configuration prior to take off; and / or• tilting the fuselage body from a tail sitting configuration to a rest configuration after landing.

[0023] In some embodiments, the front wing is attached closer to the underside of the fuselage body than the rear wing, and the rear wing is attached closer to the topside of the fuselage body than the front wing.

[0024] In some embodiments, the front wing and / or the rear wing is cranked: the front wing has a cranked anhedral angle and / or the rear wing has a cranked dihedral angle.

[0025] In some embodiments, the front wing is a front wing pair including a first left wing with at least one propulsion source and a first right wing with at least one propulsion source.

[0026] In some embodiments, the rear wing is a rear wing pair including a second left wing with at least one propulsion source and a second right wing with at least one propulsion source.

[0027] In some embodiments, the wings are foldable.

[0028] In some embodiments, the aircraft includes two or more wheels, preferably four wheels.

[0029] In some embodiments, the aircraft is configured to take off at an inclination from a range of 65 degrees relative to horizontal, to vertical.

[0030] In some embodiments, the aircraft is configured to take off substantially vertically from a tail sitting configuration.

[0031] In some embodiments, the aircraft is configured to take off at an inclination of 65 degrees to 70 degrees relative to horizontal.

[0032] In some embodiments, the aircraft is configured to land substantially vertically into a tail sitting configuration.

[0033] In some embodiments, the aircraft is configured to land at an inclination of 65 degrees to 70 degrees relative to horizontal.

[0034] In some embodiments, the aircraft includes a control system for operating the aircraft remotely and / or autonomously.

[0035] In some embodiments, the aircraft is configured to carry a payload of 150kgs or greater.

[0036] In another aspect, there is provided a method including: applying differential thrust between front- wing propulsion sources and rear- wing propulsion sources of an aircraft to generate a moment imbalance to tilt the fuselage body.

[0037] In some embodiments, each propulsion source and / or each wing of the aircraft are fixed in position relative to the fuselage body.

[0038] In some embodiments, the tilting of the fuselage body of the aircraft tilts the propulsion sources in tandem with the fuselage body.

[0039] In some embodiments, the method includes applying the differential thrust by way of a front wing being anhedral and a rear wing being dihedral.

[0040] In some embodiments, the method further includes applying the differential thrust to tilt the fuselage body between a rest configuration and a tail sitting configuration.

[0041] In some embodiments, the method further includes applying the differential thrust to tilt the fuselage body to provide pitch control during flight.

[0042] In another aspect, there is provided an aircraft including: a fuselage body; an anhderal front wing having two or more propulsion sources; and a dihedral rear wing, having two or more propulsion sources, wherein the front wing is located closer to the head portion of the fuselage body than the rear wing, and the rear wing is located closer to the tail portion of the fuselage body than the front wing, and wherein the aircraft is configured to apply differential thrust between the propulsion sources of the front wing and the propulsion sources of the rear wing to generate a moment imbalance to tilt the fuselage body.

[0043] In some embodiments, the anhedral front wing provides at least one propulsion source of the front wing with a lever arm separation from the propulsion sources of the rear wing to facilitate the moment imbalance to tilt the fuselage body.

[0044] In some embodiments, the dihedral rear wing provides at least one propulsion source of the rear wing with a lever arm separation from the propulsion sources of the front wing to facilitate the moment imbalance to tilt the fuselage body.

[0045] In another aspect, there is provided a method (of aircraft control) including: applying differential thrust between anhedral front-wing propulsion sources and dihedral rear-wing propulsion sources of an aircraft to generate a moment imbalance to tilt the fuselage body.

[0046] In some embodiments, the method includes:• applying the differential thrust to: tilt the fuselage body between a rest configuration and a tail sitting configuration; and / or• applying the differential thrust to: tilt the fuselage body to provide pitch control during flight.

[0047] In this specification, the "wing" may refer to a single wing, or refer to a wing pair depending on context. For example, a "front wing" may refer to a unitary wing that extends under / across a fuselage body in a port direction and a starboard direction. However, "front wing" may be used to refer collectively to a wing pair such that one wing portion extends out from the fuselage body in a port direction and another wing portion extends out from the fuselage body in a starboard direction.BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figures 1A-1E show various views of an exemplary aircraft embodiment.

[0049] Figures 2A-2E show various views of an exemplary aircraft embodiment.

[0050] Figure 3 shows a sequence of an exemplary aircraft embodiment tilting from a rest configuration to a tail sitting configuration.

[0051] Figure 4 shows a sequence of an exemplary aircraft embodiment taking off from the tail sitting configuration and transitioning to cruise.

[0052] Figure 5 shows a sequence of an exemplary aircraft embodiment transitioning from cruise and landing into the tail sitting configuration.

[0053] Figure 6 shows a sequence of an exemplary aircraft embodiment tilting from a tail sitting configuration to a rest configuration.

[0054] Figure 7 is a force diagram of an exemplary aircraft embodiment showing how a moment imbalance is generated.

[0055] Figure 8 shows an exemplary application of how embodiments of the aircraft may be used.DETAILED DESCRIPTION

[0056] The embodiments described herein may be said to relate to an improved aircraft (e.g., Figures 1A-1E and 2A-2E). The aircraft includes a fuselage body. The aircraft also includes a front wing having two or more propulsion sources. The aircraft also includes a rear wing having two or more propulsion sources. The front wing is located closer to the head portion of the fuselage body than the rear wing. The rear wing is located closer to the tail portion of the fuselage body than the front wing. The aircraft is configured to apply differential thrust between the propulsion sources of the front wing and the propulsion sources of the rear wing. The differential thrust applied assists to generate a moment imbalance to tilt the fuselage body. For example, the differential thrust assists to generate a moment imbalance to tilt the fuselage body from a rest configuration to a tail sitting configuration (e.g., as shown in Figure 3). In some embodiments, the differential thrust assists to generate a moment imbalance to tilt the fuselage body to provide pitch control during flight.

[0057] In some embodiments, the aircraft is configured to take off vertically (or near vertically) from the tail sitting configuration (e.g., Figure 4). In some embodiments, the aircraft is configured to transition from a (near) vertical take-off to a (horizontal) cruise (e.g., Figure 4). In some embodiments, the aircraft is configured to transition from the (horizontal) cruise to a (near) vertical landing (e.g., Figure 5). In some embodiments, the aircraft is configured to land vertically (or near vertically) into the tail sitting configuration (e.g., Figure 5). In some embodiments, the aircraft is configured to apply differential thrust between the propulsion sources of the front wing and the propulsion sources of the rear wing, the differential thrust applied assists to generate a moment imbalance to tilt the fuselagebody from the tail sitting configuration to the rest configuration (e.g., as shown in Figure 6), and to tilt the fuselage body to provide pitch control during flight.

[0058] A first exemplary embodiment now first be described with respect to Figures 1A- 1F by way of example. Another exemplary embodiment will then be described after with respect to Figures 2A-E by way of example.

[0059] Figures 1A-E show diagrams of one exemplary embodiment of an aircraft 10. Figures 1A-C show various views of the aircraft 10 in a rest configuration, while Figure ID shows the aircraft 10 in a tail-sitting configuration, while Figure IE shows the aircraft 10 in a horizontal cruise configuration. The aircraft according to this exemplary embodiment is a tandem aircraft. That is, the aircraft has a fuselage body 12, a front wing 14a-b , and a rear wing 16a-b.

[0060] In this particular exemplary embodiment, the front wing 14a-b is cranked (that is, includes a change in angle along its span). The front wing 14 includes a front port wing portion 14a (may be referred to as a "front left wing portion" herein), and a front starboard wing portion 14b (may be referred to as a "front right wing portion" herein). The front wing is anhedral. The front wing has two propulsion sources 18a-b. That is, the front wing 14 has a port propulsion source 18a (may be referred to as a "left propulsion source" herein) located on the front left wing portion 14a, and has a starboard propulsion source 18b (may be referred to as a "right propulsion source" herein) located on the front right wing portion 14b.

[0061] The rear wing 16a-b is located and connected closer to the top portion of the fuselage body 12 than the front wing 14a-b. The rear wing 16a-b includes a rear port wing portion 16a (may be referred to as a "rear left wing portion" herein), and a rear starboard wing portion 16b (may be referred to as a "rear right wing portion" herein). The rear wing 16a-b is dihedral. The rear wing has two propulsion sources 20a-b. That is, the rear wing 16a-b has a port propulsion source 20a (may be referred to as a "left propulsion source" herein) located on the rear left wing portion 16a and a starboard propulsion source 20b located on the rear right wing portion 16b (may be referred to as a "right propulsion source" herein).

[0062] The propulsion sources 18a-b of the front wing 14a-b are fixed in position such that they do not rotate relative to the front wing 14a-b, or relative to the fuselage body 12.Likewise, the propulsion sources 20a-b of the rear wing 16a-b are fixed in position such that they do not rotate relative to the rear wing 16a-b, or relative to the fuselage body 12. That is, if the fuselage body 12 tilts, the propulsion sources of the front and rear wings 18a-b, 20a- b tilt in tandem with the fuselage body 12. The propulsion sources on the aircraft 10 are propellers. The ability to facilitate a vertical-take off without needing to enable relative rotation of the propulsion sources (relative to the wings and fuselage body) makes the aircraft design mechanically simpler, as the design does not require moveable joints that inherently transmit large forces.

[0063] The aircraft 10 according to this particular exemplary embodiment has a plurality of wheels 22a-b. In this exemplary embodiment, the aircraft has four wheels 22a-d, with two front wheels 22a, and two rear wheels 22b. In the rest configuration shown on Figures 1A- 1C, the aircraft 10 sits on all four wheels 22a-b. Having two front wheels 22a and two rear wheels 22b assists in providing stability in the rest configuration. In the tail-sitting configuration shown in Figure ID, the aircraft 10 sits on the rear wheels 22b. The rear wheels 22b provide stability when the aircraft tilts 10 between the rest configuration and the tailsitting configuration by providing a stationary axis to pivot on while the aircraft 10 tilts. Although the non-limiting example shown in Figures 1A-D show two front wheels and two rear wheels, it is possible to have a single front wheel and / or a single rear wheel instead. In alternative design variants, there could be more than two front wheels and / or two rear wheels.

[0064] Figures 2A-2E show diagrams of another exemplary embodiment of an aircraft 10. The embodiment according to Figures 2A-2E largely has the same features and functions as the exemplary embodiment described according to Figures 1A-1E. For example the exemplary embodiment illustrated has a rest configuration (Figures 2A-2E), a tail-sitting configuration (not shown), and a cruise configuration (not shown). That said, there are some differences:• One difference is that as can be seen in Figure IB, the first exemplary embodiment has a ‘crank’ 24a, 24b in the front wing dihedral (a change in angle along the span of each wing 14a, 14b) (and a relatively low dihedral) and the undercarriage attached to the front wings - this reduces the front wing dihedral which can result in improved aircraft lateral stability and providessignificant clearance for fuselage mounted stores. In contrast, each front wing 14a, 14b of the second exemplary embodiment is substantially straight, as can be seen in Figure 2B.• Another difference is that the second exemplary embodiment has a greater front wing dihedral (compared to the first exemplary embodiment) which allows removal of the dihedral crank, whilst still maintaining the required propeller separation between front and rear wings. The undercarriage is also shown mounted to the main fuselage, providing simpler structural design of the wing.• Another difference is that the each propulsion source 18a-b, 20a-b of the first exemplary embodiment is a propeller with two blades, while each propulsion source 18a-b, 20a-b of the second exemplary embodiment is a propeller with three blades.

[0065] The exemplary embodiment of Figures 1A-1E and the exemplary embodiment of Figures 2A-2E both have a tiltable fuselage body 12 that enables the fuselage body 12 to tilt from the rest configuration to the tail-sitting configuration (for example in the manner shown sequentially in Figure 3), and to tilt the fuselage body to provide pitch control during flight. The tilting of the fuselage body 12 is achieved by applying differential thrust between the front wing propulsion sources 18a-b and the rear wing propulsion sources 20a-b. The differential thrust generates a moment imbalance in the fuselage body 12 which forces the fuselage body 12 to tilt from the rest configuration to the tail-sitting configuration, and to tilt the fuselage body to provide pitch control during flight. This is described in further detail hereinafter. The exemplary embodiments can be additionally or alternatively be configured to apply differential thrust between the front wing propulsion sources 18a-b and the rear wing propulsion sources 20a-b to generate a moment imbalance in the fuselage body 12 so that the fuselage body 12 tilts from the tail-sitting configuration to the rest configuration (for example in the manner shown sequentially in Figure 6) , and to tilt the fuselage body to provide pitch control during flight. This too is explained in further detail hereinafter.

[0066] In addition to the exemplary embodiments of Figures 1A-1E and Figures 2A-2E, it is envisioned that additional embodiments can be designed to be capable of applyingdifferential thrust between the front wing propulsion sources 18a-b and the rear wing propulsion sources 20a-b to generate a moment imbalance in the fuselage body 12 so that the fuselage body 12 tilts from the rest configuration to the tail-sitting configuration (and / or the other way round), and to tilt the fuselage body to provide pitch control during flight. Such additional embodiments may vary in terms of aircraft performance, ground handling and / or design complexity. This will be described in more detail hereinafter.

[0067] Referring to Figures 3(A-C) by way of example, some aircraft embodiments 10 are configured to apply differential thrust between the front wing propulsion sources 18a-b and the rear wing propulsion sources 20a-b to generate a moment imbalance in the fuselage body so that the fuselage body 12 tilts from the rest configuration to the tail-sitting configuration, and to tilt the fuselage body to provide pitch control during flight. This is described in more detail hereinafter.

[0068] Referring to Figure 4 by way of example, some aircraft embodiments 10 may be configured to take off vertically (or near vertically) from the tail sitting configuration. The propulsion sources 18a-b, 20a-b used to tilt the fuselage body from the rest configuration to the tail-sitting configuration may also be used to propel the vertical (or near vertical) takeoff. In some embodiments, the aircraft 10 is configured to take off at an inclination from a range of 65 degrees relative to horizontal to vertical. In some embodiments, the aircraft 10 is configured to take off substantially vertically from the tail sitting configuration. In some embodiments, the aircraft 10 is configured to take off at an inclination of 65 degrees to 70 degrees relative to horizontal.

[0069] Referring back to Figure 4 by way of example again, some aircraft embodiments 10 may be configured to transition from vertical flight (similar to a quad-copter for example) to horizontal flight (similar to a conventional fixed wing aircraft with canard). There are multiple ways to transition from vertical flight to horizontal flight with varying degrees of trade-offs between altitude, speed and stability. The propulsion sources 18a-b, 20a-b used to tilt the fuselage body 12 from the rest configuration to the tail-sitting configuration may also be used to provide thrust during cruise and horizontal flight, and to provide pitch and yaw control during vertical flight.

[0070] Referring to Figure 5 by way of example, some aircraft embodiments 10 may be configured to transition from horizontal flight (where it behaves like a conventional fixedwing aircraft with canard) to vertical flight (where it is behaving like a quad-copter). There are multiple ways to perform this manoeuvre, with varying degrees of trade-offs between altitude, speed and stability. The propulsion sources 18a-b, 20a-b may be used to tilt the fuselage body 12 from the horizontal flight configuration (where it behaves like a conventional fixed wing aircraft with canard, e.g., in Figures 5(A-C) to the vertical flight configuration (where it is behaving like a quad-copter, e.g., in Figures 5(D-E) in preparation for landing in the tail-sitting configuration (e.g., in Figure 5(F)).

[0071] Referring back to Figure 5 by way of example again, some aircraft embodiments may be configured to land vertically (or near vertically) into the tail sitting configuration. The propulsion sources 18a-b, 20a-b used to tilt the fuselage body 12 from the rest configuration to the tail-sitting configuration may also be used to assist with vertical (or near vertical) landing. In some embodiments, the aircraft 10 is configured to land at an inclination from a range of 65 degrees relative to horizontal to vertical. In some embodiments, the aircraft 10 is configured to land substantially vertically into the tail sitting configuration. In some embodiments, the aircraft 10 is configured to land at an inclination of 65 degrees to 70 degrees relative to horizontal.

[0072] Referring to Figure 6 by way of example, some aircraft embodiments 10 may be configured to apply differential thrust between the front wing propulsion sources 18a-b and the rear wing propulsion sources 20a-b to generate a moment imbalance in the fuselage body so that the fuselage body 14 tilts from the tail-sitting configuration to the rest configuration. This is described in greater detail hereinafter.

[0073] Description now turns to implementation and relevant design considerations. In particular, an explanation is given to how the aircraft 10 can be configured to apply differential thrust between the propulsion sources of the front wing 18a-b and the propulsion sources of the rear wing 20a-b to generate a moment imbalance to tilt the fuselage body 12.

[0074] As mentioned, the tilting of the fuselage body 12 is caused by generating a moment imbalance in the fuselage body 12. The moment imbalance is generated as a result of differential thrust being applied by the propulsion sources. That is, the thrust applied by the front wing propulsion sources is different to the thrust applied by the rear wing propulsion sources. The thrust difference may be a difference in magnitude and / or direction.

[0075] The relative positioning in angle and location of the propulsion sources also assists with generating a moment imbalance when differential thrust is applied. That is, it is the suitable relative positioning of the propulsion sources in combination with the applied differential thrust that results in the moment imbalance for tilting the fuselage body. For clarity the angle of the propulsion source refers to the direction of the thrust force axis of the propulsion source (with the thrust axis being perpendicular to disc plane of the propulsion source). Aircraft features relevant to the positioning of the propulsion sources may include for example but not limited to:• Angle of the propulsion sources relative to horizontal plane (e.g., ground) at rest configuration (to be able to tilt to the tail sitting configuration).• Relative offset in angle between the front wing propulsion sources and the rear wing propulsion sources.• Relative displacement offset of front wing propulsion sources relative to rear wing propulsion sources (longitudinally along the fuselage body longitudinal axis and / or transversely along the z-axis of the fuselage body).

[0076] The wing design may also assist with the relative positioning of the propulsion sources. Referring back to the exemplary embodiments of Figures 1A-1E and 2A-2E for example, both embodiments have an anhedral front wing and dihedral rear wing combination. In addition, the anhedral front wing is attached closer to the underside of the fuselage body compared to the dihedral rear wing, and the dihedral rear wing is attached closer to the topside of the fuselage body compared to the anhedral front wing. The anhedral- dihedral wing configuration places the propulsion sources such that the front wing propulsion sources are located lower compared to the rear wing propulsion sources (along the fuselage body height axis - that is along the z-axis of the fuselage body), and the rear wing propulsion sources are located higher compared to the front wing propulsion sources (along the fuselage body height axis - that is along the z-axis of the fuselage body). In this particular example, the exemplary wing design assists with placing the propulsion sources in a suitable location to generate a moment imbalance with differential thrust is applied.

[0077] The use of a stable pivotal axis (along the width of the fuselage body) may also assist with the tilting of the fuselage body when the moment imbalance is generated. Oneway of achieving this is to use rear wheels 22b as a stable pivot axis (along the width of the fuselage body) for the fuselage body to pivot on when tilting. Optionally, rear wheel brakes can be added on to provide a stationary pivot axis (along the width of the fuselage body) for the fuselage body to pivot on when tilting. That is, having a stable or stationary pivot axis reduces the likelihood of the pivot axis from moving longitudinally along with the fuselage body when the fuselage body tilts. Although two rear wheels are preferred for enabling the fuselage body to pivot, any number of rear wheels may alternatively be selected for the fuselage body to pivot on.

[0078] Some example features for generating the moment imbalance to tilt the fuselage body may include, but not limited to, the following:• Offsetting the thrust force axes of the front wing propulsion sources from the thrust force axes of the rear wing propulsion sources. The offsetting may refer to a displacement offset and / or direction offset.• Using an anhedral front wing and / or a dihedral rear wing so that there is an offset in displacement and / or direction between the thrust force axes of the front wing propulsion sources and the rear force axes of the rear wing propulsion sources.• Attaching the front wing closer to the underside of the fuselage body compared to the rear wing so that there is an offset in displacement and / or direction between the thrust force axes of the front wing propulsion sources and the rear force axes of the rear wing propulsion sources.• Attaching the rear wing closer to the topside of the fuselage body compared to the front wing so that there is an offset in displacement and / or direction between the thrust force axes of the front wing propulsion sources and the rear force axes of the rear wing propulsion sources.• Having the front wing propulsion sources apply a net forward thrust (along their thrust force axes) relative to the rear wing propulsion sources to apply a net upward force on the head portion of the fuselage body to tilt the fuselage body, e.g., from the rest configuration to the tail sitting configuration.• Having the rear wing propulsion sources apply a net reverse thrust (along their thrust force axes) relative to the front wing propulsion sources to apply a net downward force on the tail portion of the fuselage body to tilt the fuselage body, e.g., from the rest configuration to the tail sitting configuration.• Having the front wing propulsion sources apply a net reverse thrust (along their thrust force axes) relative to the rear wing propulsion sources to apply a net downward force on the head portion of the fuselage body to tilt the fuselage body, e.g., from the tail sitting configuration to the rest configuration.• Having the rear wing propulsion sources apply a net forward thrust (along their thrust force axes) relative to the front wing propulsion sources to apply a net upward force on the tail portion of the fuselage body to tilt the fuselage body, e.g., from the tail sitting configuration to the rest configuration.• Having a first net forward thrust applied by the propulsion sources of the front wing (along their thrust force axes to apply an upward force on the head portion of the fuselage), and having a second net forward thrust is applied by the propulsion sources of the rear wing (along their thrust force axes to apply an upward force on the tail portion of the fuselage), such that (in order to tilt the fuselage): i. the second net forward thrust is less than the first net forward thrust for a first differential thrust (to tilt the fuselage body from a rest configuration to a tail sitting configuration prior to take off, and / or to tilt the fuselage body to provide pitch control during flight), or ii. the second net forward thrust is more than the first net forward thrust for a first differential thrust (to tilt the fuselage body from a tail sitting configuration to a rest configuration after landing, and / or to tilt the fuselage body to provide pitch control during flight).• Using rear wheels to provide a stable axis for the fuselage body to pivot on the ground when the moment imbalance is generated and the fuselage bodytilts. Preferably the rear wheels are also braked to reduce movement in the axis for the fuselage body to pivot on. More preferably, braking the rear wheels produces a pivoting axis that is stationary or near stationary.• Offsetting the angle of the propulsion sources from horizontal when the aircraft is in rest configuration.One or more of the example features described may be combined to achieve a desired effect of generating a moment imbalance to tilt the fuselage body.

[0079] Figure 7 shows a force diagram of an aircraft embodiment 10 with the following axes, forces and dimensions, wherein the forces and dimensions are selected, e.g., to have the example values in the following table, to provide the example features for generating the moment imbalance:

[0080] In embodiments:• the lever arms Tzf and Tzr may be maximised to increase differential moment to aid rotation to tail- sitter and controllability when in quad-copter mode, which can be brought about by setting the inclination of the wings Wdf and Wdr such that the front wing is anhedral and the rear wing is dihedral;• the propulsion wake (z axis) between forward and rear may be substantially separated to improve efficiency of the propulsion sources - preferably ensuring substantially no overlap between the front and rear propellers when viewed along thrust axis (e.g., as viewed in Figure 2E);• the wings may be substantially separated (along the Z axis) between forward and rear to minimise aerodynamic interaction whilst in cruise flight; the net total height of the vehicle in its rest orientation may be minimized because the higher the vehicle and centre of gravity, the less stable the vehicle is on the ground;• the wheel base may be maximised for ground handling and ground stability;• the net thrust force parallel to the ground plane may be minimized to reduce the likelihood of translation;• the magnitude of reverse thrust may be minimized because thrust sources are more efficient and less likely to fail when producing forward thrust;• the angular inclination of the thrust vectors whilst in the rest orientation may be maximized to reduce the translation force;• the area of the fuselage perpendicular to the cruise flight orientation may be minimized to minimise drag (to increase range, endurance and max speed); and• the wing anhedral and dihedral may be limited to ensure suitable aerodynamic performance and lateral stability when in cruise mode.

[0081] To provide the above, described herein is an aircraft 10 including a fuselage body 12, a front wing 14a-b having two or more propulsion sources 18a-b, and a rear wing 16a-b having two or more propulsion sources 20a-b. The front wing 14a-b is located closer to the head portion of the fuselage body 12 than the rear wing 16a-b, and the rear wing 16a-b is located closer to the tail portion of the fuselage body 12 than the front wing 14a-b. The aircraft 10 is configured to apply differential thrust between the propulsion sources of the front wing 18a-b and the propulsion sources of the rear wing 20a-b to generate a moment imbalance to tilt the fuselage body 12.

[0082] In some embodiments, the aircraft 10 is configured to apply differential thrust between the propulsion sources of the front wing 12a-b and the propulsion sources of the rear wing 20a-b to generate the moment imbalance to tilt the fuselage body 12 from a rest configuration to a tail sitting configuration. Additionally or alternatively, the aircraft 10 is configured to apply differential thrust between the propulsion sources of the front wing 12a- b and the propulsion sources of the rear wing 20a-b to generate the moment imbalance to tilt the fuselage body 12 from a tail sitting configuration to a rest configuration. The ability to tilt the aircraft from a rest configuration to a tail-sitting configuration (so that is it is ready for a (near) vertical take-off) and / or vice versa avoids the ground-handling difficultiesassociated with tail-sitting aircraft when it is at rest, while retaining the ability for the aircraft to take off in a near vertical direction in a similar manner to conventional tail sitting aircraft. The tilt-body mechanism therefore provides a solution of an aircraft that can take-off in tight spaces (e.g., where there is no runway) whilst being easier to logistically handle on the ground in comparison with conventional tail sitting aircrafts. Further, the rest configuration of the aircraft means that the aircraft has a lower centre of gravity in comparison to conventional tail- sitter aircraft at rest. The lower centre of gravity provided by the rest configuration provides improved stability to the aircraft at rest (e.g. such that it is difficult for the aircraft to be blown over by wind).

[0083] In some embodiments, each propulsion source 18a-b, 20a-b and / or each wing 14a- b, 16a-b is fixed in position relative to the fuselage body 12. In some embodiments, the tilting of the fuselage body 12 of the aircraft 10 tilts the propulsion sources 18a-b, 20a-b in tandem with the fuselage body 12. As the differential thrust applied by the propulsion sources 18a-b, 20a-b of the aircraft 10 generate a moment imbalance to tilt the fuselage body 12 (for example, from the rest configuration to the tail sitting configuration), it is not necessary for the aircraft 10 to rotate its propulsion sources 18a-b, 20a-b relative to the wing 14a-b, 16a-b and / or fuselage 12 (for a vertical take off for example). The absence of rotating propulsion sources 18a-b, 20a-b and rotating wings 14a-b, 16a-b consequently simplifies the overall design of the aircraft 10.

[0084] In some embodiments, at least one propulsion source of the front wing 18a-b is located on a thrust force axis that is offset from thrust force axes of the propulsion sources of the rear wing 20a-b. In some embodiments, at least one propulsion source of the rear wing 20a-b is located on a thrust force axis that is offset from thrust force axes of the propulsion sources of the front wing 18a-b.

[0085] That is, the moment imbalance used to tilt the fuselage body 12 is created by the relative positioning of the propulsion sources 18a-b, 20a-b. In particular by offsetting of the rotational axes between the propulsion sources of the first and rear wings 18a-b, 20a-b assist in creating the moment imbalance to tilt the fuselage body 12. In some embodiments, the propulsion sources 12 of the aircraft 10 are configured to apply differential thrust to generate moment imbalance (to tilt from the rest configuration to the tail-sitting configuration, and to tilt the fuselage body to provide pitch control during flight) when: net forward thrust isapplied by the propulsion sources of the front wing 18a-b (along their thrust force axes to apply an upward force on the head portion of the fuselage), and / or net reverse thrust is applied by the propulsion sources of the rear wing 20a-b (along their thrust force axes to apply a downward force on the tail potion of the fuselage). In some embodiments, the propulsion sources 12 of the aircraft 10 are configured to apply differential thrust to generate moment imbalance (along their thrust force axes to tilt from the tail-sitting configuration to the rest configuration, and to tilt the fuselage body to provide pitch control during flight) when: net reverse thrust is applied by the propulsion sources of the front wing 18a-b (along their thrust force axes to apply a downward force on the head portion of the fuselage), and / or net forward thrust is applied by the propulsion sources of the rear wing 20a-b (to apply an upward force on the tail portion of the fuselage). In some embodiments, the propulsion sources 12 of the aircraft 10 are configured to apply differential thrust to generate moment imbalance when: a first net forward thrust is applied by the propulsion sources of the front wing (along their thrust force axes to apply an upward force on the head portion of the fuselage), and a second net forward thrust is applied by the propulsion sources of the rear wing (along their thrust force axes to apply an upward force on the tail portion of the fuselage), wherein the second net forward thrust is less than the first net forward thrust for a first differential thrust (to tilt the fuselage body from a rest configuration to a tail sitting configuration prior to take off, and / or to tilt the fuselage body to provide pitch control during flight), or the second net forward thrust is more than the first net forward thrust for a first differential thrust (to tilt the fuselage body from a tail sitting configuration to a rest configuration after landing, and / or to tilt the fuselage body to provide pitch control during flight).

[0086] In some embodiments, the aircraft 10 includes at least one wheel, preferably two or more wheels 22b, configured to be pivoted upon by the fuselage body 12 of the aircraft 10 (when tilting, for example between the rest configuration and the tail sitting configuration). In some embodiments, the aircraft 10 includes brakes for braking the wheels 22b (when tilting, for example between the rest configuration and / or the tail sitting configuration). The use of wheels (e.g., rear wheels) and optionally brakes may assist to facilitate a stable stationary longitudinal pivot point (that is, a pivot point that does not move while the fuselage body tilts) to provide reliable take-off / touchdown particularly in adverseenvironmental conditions (e.g., winds, gusts and ground slope (including a moving ship deck)).

[0087] In some embodiments, at least one propulsion source 18a-b, 20a-b is angled relative from horizontal when the aircraft 10 is in the rest configuration. In some embodiments, the front wing 14a-b is anhedral and the rear wing 16a-b is dihedral.

[0088] In some embodiments, the front wing 14a-b is attached closer to the underside of the fuselage body 12 than the rear wing 16a-b, and the rear wing 16a-b is attached closer to the topside of the fuselage body 12 than the front wing 14a-b. Such relative positioning of the wings 14a-b, 16a-b contributes to the lever arm difference between the front wing 14a-b and the rear wing 16a-b. The lever arm difference helps to separate the aerodynamic interaction between the front wing 14a-b and the rear wing 16a-b. In addition, the lever arm difference means that it is possible to reduce the anhedral extent of the front wing 14a-b and / or reduce the dihedral extent of the rear wing 16a-b.

[0089] Also described herein is method including: applying differential thrust between front-wing propulsion sources 18a-b and rear- wing propulsion sources 20a-b of an aircraft 10 to generate a moment imbalance to tilt the fuselage body 12. In some embodiments, each propulsion source and / or each wing of the aircraft are fixed in position relative to the fuselage body. In some embodiments, the tilting of the fuselage body of the aircraft tilts the propulsion sources in tandem with the fuselage body. In some embodiments, the method includes applying the differential thrust by way of a front wing being anhedral and a rear wing being dihedral. In some embodiments, the method includes applying differential thrust to tilt the fuselage body 12 between a rest configuration and a tail sitting configuration. In some embodiments, the method includes applying the differential thrust to tilt the fuselage body 12 to provide pitch control during flight.

[0090] Also described herein is an aircraft 10 including a fuselage body 12, an anhedral front wing 14a-b having two or more propulsion sources 18a-b, and a dihedral rear wing 16a-b having two or more propulsion sources 20a-b. The front wing 14a-b is located closer to the head portion of the fuselage body 12 than the rear wing 16a-b, and the rear wing 16a- b is located closer to the tail portion of the fuselage body 12 than the front wing 14a-b. The aircraft 10 is configured to apply differential thrust between the propulsion sources of the front wing 18a-b and the propulsion sources of the rear wing 20a-b to generate a momentimbalance to tilt the fuselage body 12. In some embodiments, the anhedral front wing 14a- b provides at least one propulsion source 18a-b of the front wing 14a-b with a lever arm separation from the propulsion sources 20a-b of the rear wing 16a-b to facilitate the moment imbalance to tilt the fuselage body 12. In some embodiments, the dihedral rear wing 16a-b provides at least one propulsion source 20a-b of the rear wing 16a-b with a lever arm separation from the propulsion sources 18a-b of the front wing 14a-b to facilitate the moment imbalance to tilt the fuselage body 12.

[0091] In the context of designing one or more disclosed embodiments of aircraft 10, having a combination of an anhedral front wing 14a-b and a dihedral rear wing 16a-b helps to increase lever arm forces for generating the relevant moment imbalance to tilt the fuselage body, for example between a rest configuration and a tail-sitting configuration. For example, see lever arms Tzf and Tzr in the aircraft force diagram of Figure 7. Having at least two wings, as well as making the front wing anhedral and the rear wing dihedral is considered unusual. This is because in conventional aircraft design, anhedral wing design is often avoided due to lateral stability problems associated with anhedral wings that are well known in the art. Further, tandem (dual) wing combinations are also avoided in conventional aircraft design because such design presents a number of aerodynamic and structural challenges that are well known in the art that often outweigh any benefit that the tandem wing combination could provide.

[0092] Also described herein is method including: applying differential thrust between anhedral front-wing propulsion sources 18a-b and dihedral rear- wing propulsion sources 20a-b of an aircraft 10 to generate a moment imbalance to tilt the fuselage body 12.

[0093] Referring to Figure 8, one exemplary application of the aircraft embodiments as described above may relate to a multi-role tactical un-crewed air vehicle that combines the following attributes:• Vertical take and landing for airfield independence and naval operations• Designed to support multiple payload options with a baseline configuration of two air to ground missiles (such as a Hellfire or Brimstone) (i.e., > 150kg payload)• A > 500 km range (i.e., provide a ranged strike capability from Navy surface vessels and Army Brigades)• Attritable asset with a target system price of less than $20m (three airframes plus control station)• Ability to ‘ground handle’ the vehicle for movement around a land based launch area (heli-pad style area into hangar etc.) or for manoeuvring the vehicle across a ship deck into ship hangar or storage areas• Long term stowage and tactical / strategic transportable with minimum setup times

[0094] In some embodiments, the aircraft 10 is configured to carry a payload under the fuselage body 12. In these embodiments, it is desirable to have sufficient ground clearance of the payload so as to avoid damaging the payload during take-off, landing, or when the aircraft 10 tilts between the rest configuration and the tail- sitting configuration. The pay load may then be deployed during flight.

[0095] In some embodiments, the front undercarriage is centrally mounted to facilitate folding wings, whilst also ensuring clearance for payload carry and release.

[0096] In some embodiments, the rear undercarriage is mounted on inboard wing sections providing lateral stability when the aircraft is on the ground (for example during take-off, landing, or when the aircraft 10 tilts between the rest configuration and the tail- sitting configuration).

[0097] In some embodiments, the fuselage body 12 is configured to provide a connecting method for the wings.

[0098] In some embodiments, the fuselage body 12 is configured to improve the aerodynamics of the aircraft 10. Such feature may be applicable in instances where the aircraft 10 does not carry human pilots or passengers.

[0099] In some embodiments, the fuselage body 12 is configured to support multiple payload configurations. Such feature may be applicable in instances where the aircraft 10 does not carry human pilots or passengers.

[0100] In some embodiments, the aircraft 10 may include vertical wings. For example by having small downwards facing vertical fins to provide a level of stability in both the horizontal and vertical flight modes, whilst also providing a level of protection against wing tip strike in adverse landing conditions.

[0101] In some embodiments, the aircraft 10 may include tail locations for payloads deployed during flight (e.g., hovering). The flight (e.g., hovering) configuration allows some sensor pay load configurations to be deployed from the tail of the aircraft 10, without with the payload space required for payload to be used in forward flight.

[0102] In some embodiments, the center of gravity in the wings 14a-b, 16a-b and fuselage body 12 may be selected based on expected applications / payloads of the aircraft 10. The tandem wing and fuselage 12 configuration allow a wider center of gravity range for the aircraft 10, meaning the aircraft 10 is more robust to changes in center of gravity for different payload combinations or when payload mass / location changes in flight (due to deployment / release etc).

[0103] In some embodiments, air is blown over the control surfaces in the propeller wake. Air may be blown due to the wings having elevator / flap / ailerons. This allows a greater level of aerodynamic control at lower airspeeds and allowing ‘different’ stall characteristics which aid in the transition from (near) horizontal to (near) vertical flight. This provides controllability and redundancy, particularly at low airspeeds, and adds greater control flexibility (which are not found on traditional fixed wing aircraft or on rotor-craft that rely only on propeller / rotor forces).

[0104] In some embodiments, the wings and / or undercarriage may be configured to allow for space for wings to fold and / or rotate. This assists to reduce stored and ground handling footprint, avoiding aircraft disassembly. For example, the aircraft may be able to fold rear wings forward and front wings back, and then be rolled (assisted by the undercarriage) into a container (with a ‘ramp’ for the rear wheels in the container to make the aircraft sit in a fuselage-level orientation in the container, e.g., a 20-ft Intermodal container). In some embodiments, the folding mechanism allows a simple pin to be removed, allowing the wings to rotate around their main spar to nearly 90 degrees (so the wing chord-line is nearly parallel with the aircraft ‘z’ axes) and then fold such that the wing span become parallel to the fuselage (aircraft ‘x’ axes). The aircraft can then be containerised.

[0105] In some embodiments, the propulsion sources 18a-b, 20a-b are propellers. Optionally, the propellers are variable pitch. This facilitates are more precise control of rotation moments from the propellers.

[0106] In some embodiments, each propulsion source 18a-b, 20a-b is configured to provide lift for take-off and thrust for cruise.

[0107] In some embodiments, the aircraft 10 includes a control system for operating the aircraft 10 remotely and / or autonomously according to a method that includes applying the differential thrust between the front-wing propulsion sources and the rear-wing propulsion sources of the aircraft to generate the moment imbalance to tilt the fuselage body. Applying the differential thrust can tilt the fuselage body between a rest configuration and a tail sitting configuration, and / or applying the differential thrust can tilt the fuselage body to provide pitch control during flight.

[0108] Description turns to a specific aircraft embodiment 10 tilting from a rest position to a tail sitting position so that it is ready for take-off. As shown in Figure 3:1. The aircraft 10 sits on all four wheels to begin, as shown in Figure 3(A).2. Brakes are applied to the rear wheels 22b to prevent forward motion (noting that in areas where more space is available, brakes can be released allowing small amounts of forward motion if desired).3. Utilising ‘forward thrust’ on the front two propellers 18a-b and ‘reverse thrust’ on the rear propellers 20a-b, this creates a moment imbalance, resulting in the aircraft 10 generating a pitching acceleration (nose up) and corresponding pitch rate, as shown in Figure 3(B). Note that thrust control may be achieved by variable speed and / or propeller pitch. Optionally, ‘reverse thrust’ can be applied for example if the wheel brakes cannot hold the aircraft 10 stationary (the reverse thrust provides both rearwards force, but also downward force on the rear wheels, resulting in greater traction from the brakes).4. Once a near vertical aircraft pitch attitude is achieved, as shown in Figure 3(C), active control between the front 18a-b and rear propellers 20a-b maintain the desired pitch attitude.5. All propellers 18a-b, 20a-b then provide forward thrust, resulting in the aircraft 10 accelerating vertical (in a similar manner to a quad-copter), utilising variations in propeller thrust, as well as blown air across the aerodynamic control surfaces to provide attitude and acceleration control of the aircraft 10.

[0109] Description turns to a specific aircraft embodiment 10 tilting from a tail sitting position to a rest position so that it is landed. As shown in Figure 6:1. The aircraft 10 arrives in a vertical orientation (in a similar manner to a ‘quadcopter’).2. The aircraft 10 utilises variations in propeller thrust, and blown air across the aerodynamic control surfaces, to provide attitude and acceleration control of the aircraft 10 to position the aircraft 10 above the landing location.3. The aircraft 10 develops and maintains the desired sink rate (utilising the control in step 1.)4. When the rear wheels 22b come in contact with the ground (with brakes on), as shown in Figure 6(A), the aircraft control changes mode to load up the rear wheels 22b to prevent lateral motion.5. The aircraft 10 then utilises differential thrust between front 18a-b and rear propellers 20a-b to allow the pitch attitude to ‘de-rotate’, allowing the aircraft nose to drop at a controlled rate, as shown in Figure 6(B). Once the aircraft front wheels 22a come into contact with the ground, as shown in Figure 6(C), the thrust is reduced and the aircraft 10 is considered ‘landed’

[0110] The various aircraft embodiments 10 described heretofore may provide one or more of the following:• The tiltability of the aircraft fuselage body by having the propulsion sources apply differential thrust to achieve a moment imbalance can provide excellent control precision. Such control precision can provide a robust take- off / landing in adverse conditions. Adverse conditions may include: environmental conditions (such as wind and gusts), launch surface conditions(such as a pitching / heaving / rolling ship deck), and fault conditions (such as degradation or failure of control surfaces or rotors). Such control precision can also provide excellent pitch control during flight.• The tiltability of the aircraft fuselage body by having the propulsion sources apply differential thrust to achieve a moment imbalance provides for an aircraft that can achieve a (near) vertical take-off and optionally a (near) vertical landing similar to a conventional tail-sitting aircraft, whilst being easily manoeuvrable at rest, thus removing the ground handling issues associated with conventional tail-sitting aircraft.• The propulsion sources used to create a differential thrust to achieve a moment imbalance and tilt the fuselage body can also be used to provide lift to the aircraft for a (near) vertical take-off and for cruise. This makes it unnecessary for the aircraft to have separate propulsion sources for take-off and cruise, thus removing redundancy with propulsion source design.• The propulsion sources used to create a differential thrust to achieve a moment imbalance and tilt the fuselage body means that it is unnecessary for the aircraft to have tilt rotors and / or tilt wings (relative to the fuselage body), both of which are inherently complex systems.• It is noted that embodiments of the aircraft described herein have a fuselage body that is tiltable for the purposes of positioning aircraft into a tail-sitting position in order to take off in a vertical or near vertical direction. Such tiltbody mechanism facilitates a transition from (near) vertical take-off to cruise at a significantly high altitude from the launch pad. This provides an advantage of being able to launch the aircraft from a launch pad where space is extremely limited. The embodiments described herein should be distinguished from conventional VTOL aircraft designs where the fuselage body may tilt when taking off, because such conventional design can only transition from (near) vertical take-off to cruise at a lower altitude than what is achievable with the described aircraft embodiments, and in some cases notfar above to the launch pad. Such conventional VTOL aircraft designs lack versatility compared to the embodiments described.

[0111] Many modifications will be apparent to those skilled in the art without departing from the scope of the present invention. For example, the aircraft may have more than one fuselage body. In another example, there may three wings, or additional wings. In another example, any wing may have more than two propulsion sources. In another example, while the disclosed exemplary embodiments use propellers as propulsion sources, the propulsion source may be something else other than a propeller, such as an engine for example. In another example, the aircraft may be configured to have a tilt-body and / or a tilt-wing mechanism. In another example, the aircraft may be manned or unmanned. In another example, the aircraft may be used for civilian and / or military applications.

[0112] The presence of " / " in a FIG. or text herein is understood to mean "and / or" unless otherwise indicated, i.e., “A / B” is understood to mean “A” or “B” or “A and B”. The recitation of a particular numerical value or value range herein is understood to include or be a recitation of an approximate numerical value or value range, for instance, within + / - 20%, + / - 15%, + / - 10%, + / - 5%, + / - 2.5%, + / - 2%, + / - 1%, + / - 0.5%, or + / - 0%. The term "essentially all" or "substantially" can indicate a percentage greater than or equal to 50%, 60%, 70%, 80%, or 90%, for instance, 92.5%, 95%, 97.5%, 99%, or 100%.

[0113] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that the prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

[0114] Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Claims

CLAIMS:

1. An aircraft including: a fuselage body; a front wing having two or more propulsion sources; and a rear wing, having two or more propulsion sources, wherein the front wing is located closer to the head portion of the fuselage body than the rear wing, and the rear wing is located closer to the tail portion of the fuselage body than the front wing, and wherein the aircraft is configured to apply differential thrust between the propulsion sources of the front wing and the propulsion sources of the rear wing to generate a moment imbalance to tilt the fuselage body.

2. The aircraft according to claim 1, wherein each propulsion source and / or each wing is fixed in position relative to the fuselage body.

3. The aircraft according to claim 1 or 2, wherein the tilting of the fuselage body of the aircraft tilts the propulsion sources in tandem with the fuselage body.

4. The aircraft according to any one of the previous claims, wherein the aircraft is configured to apply the differential thrust by way of the front wing being anhedral and the rear wing being dihedral.

5. The aircraft according to any one of the previous claims, wherein at least one propulsion source of the front wing is located on a thrust force axis that is offset from thrust force axes of the propulsion sources of the rear wing.

6. The aircraft according to any one of the previous claims, wherein at least one propulsion source of the rear wing is located on a thrust force axis that is offset from thrust force axes of the propulsion sources of the front wing.

7. The aircraft according to any one of the previous claims, wherein the propulsion sources of the aircraft are configured to apply the differential thrust to generate the moment imbalance when:• net forward thrust is applied by the propulsion sources of the front wing, and / or• net reverse thrust is applied by the propulsion sources of the rear wing.

8. The aircraft according to any one of the previous claims, wherein the propulsion sources of the aircraft are configured to apply the differential thrust to generate the moment imbalance when:• net reverse thrust is applied by the propulsion sources of the front wing, and / or• net forward thrust is applied by the propulsion sources of the rear wing.

9. The aircraft according to any one of the previous claims, wherein the propulsion sources of the aircraft are configured to apply the differential thrust to generate the moment imbalance when:• a first net forward thrust is applied by the propulsion sources of the front wing, and• a second net forward thrust is applied by the propulsion sources of the rear wing, wherein the second net forward thrust is less than the first net forward thrust for a first differential thrust, or the second net forward thrust is more than the first net forward thrust for a first differential thrust.

10. The aircraft according to any one of the previous claims, wherein the aircraft includes at least one wheel, preferably two or more wheels.

11. The aircraft according to any one of the previous claims, wherein the aircraft includes brakes for braking the wheels.

12. The aircraft according to any one of the previous claims, wherein at least one propulsion source is angled relative from horizontal when the aircraft is in the rest configuration.

13. The aircraft according to any one of the previous claims, wherein each propulsion source is configured to provide lift for take-off and thrust for cruise.

14. The aircraft according to any one of the previous claims, wherein the aircraft is configured to apply the differential thrust to tilt the fuselage body to provide pitch control during flight.

15. The aircraft according to any one of the previous claims, wherein the aircraft is configured to apply the differential thrust to tilt the fuselage body between a rest configuration and a tail sitting configuration.

16. The aircraft according to any one of the previous claims, wherein the front wing is attached closer to the underside of the fuselage body than the rear wing, and the rear wing is attached closer to the topside of the fuselage body than the front wing.

17. The aircraft according to any one of the previous claims, wherein: the front wing has a cranked anhedral angle and / or the rear wing has a cranked dihedral angle.

18. The aircraft according to any one of the previous claims, wherein the front wing is a front wing pair including a first left wing with at least one propulsion source and a first right wing with at least one propulsion source.

19. The aircraft according to any one of the previous claims, wherein the rear wing is a rear wing pair including a second left wing with at least one propulsion source and a second right wing with at least one propulsion source.

20. The aircraft according to any one of the previous claims, wherein the wings are foldable.

21. The aircraft according to any one of the previous claims, wherein the aircraft includes two or more wheels, preferably four wheels.

22. The aircraft according to any one of the previous claims, wherein the aircraft is configured to take off at an inclination from a range of 65 degrees relative to horizontal, to vertical.

23. The aircraft according to any one of the previous claims, wherein the aircraft is configured to take off substantially vertically from a tail sitting configuration.

24. The aircraft according to any one of the previous claims, wherein the aircraft is configured to take off at an inclination of 65 degrees to 70 degrees relative to horizontal.

25. The aircraft according to any one of the previous claims, wherein the aircraft is configured to land substantially vertically into a tail sitting configuration.

26. The aircraft according to any one of the previous claims, wherein the aircraft is configured to land at an inclination of 65 degrees to 70 degrees relative to horizontal.

27. The aircraft according to any one of the previous claims, wherein the aircraft includes a control system for operating the aircraft remotely and / or autonomously.

28. The aircraft according to any one of the previous claims, wherein the aircraft is configured to carry a pay load of 150kgs or greater.

29. A method including: applying differential thrust between front-wing propulsion sources and rear-wing propulsion sources of an aircraft to generate a moment imbalance to tilt the fuselage body.

30. The method according to claim 29, wherein each propulsion source and / or each wing of the aircraft are fixed in position relative to the fuselage body.

31. The method according to claim 29 or 30, including wherein the tilting of the fuselage body of the aircraft tilts the propulsion sources in tandem with the fuselage body.

32. The method according to any one of claims 29 to 31, including applying the differential thrust by way of a front wing being anhedral and a rear wing being dihedral.

33. The method according to any one of claims 29 to 32, wherein the method further includes applying the differential thrust to tilt the fuselage body between a rest configuration and a tail sitting configuration.

34. The method according to any one of claims 29 to 33, wherein the method further includes applying the differential thrust to tilt the fuselage body to provide pitch control during flight.

35. An aircraft including: a fuselage body; an anhderal front wing having two or more propulsion sources; and a dihedral rear wing, having two or more propulsion sources, wherein the front wing is located closer to the head portion of the fuselage body than the rear wing, and the rear wing is located closer to the tail portion of the fuselage body than the front wing, and wherein the aircraft is configured to apply differential thrust between the propulsion sources of the front wing and the propulsion sources of the rear wing to generate a moment imbalance to tilt the fuselage body.

36. The aircraft according to claim 35, wherein the anhedral front wing provides at least one propulsion source of the front wing with a lever arm separation from the propulsion sources of the rear wing to facilitate the moment imbalance to tilt the fuselage body.

37. The aircraft according to claim 35 or 36, wherein the dihedral rear wing provides at least one propulsion source of the rear wing with a lever arm separation from the propulsion sources of the front wing to facilitate the moment imbalance to tilt the fuselage body.

38. A method including: applying differential thrust between anhedral front-wing propulsion sources and dihedral rear-wing propulsion sources of an aircraft to generate a moment imbalance to tilt the fuselage body.

Images