aircraft

Abstract

The present invention relates to a vertical take-off and landing (VTOL) aircraft featuring a central fuselage and at least two power units. Each power unit is connected to at least two separate lifting rotors via transmission lines, ensuring that each power unit is linked to at least two rotors diametrically opposed relative to the centre of gravity of the aircraft. The lifting rotors might be driven by power transmission lines of hydrostatic type. The power units on either side might be housed in separate pods which might be incorporated into the main fuselage or arranged as separate pods. These separate pods might also function as floats / pontoons for the aircraft to land, take-off and manoeuvre on water.

Description

[0001] AIRCRAFT

[0002] Field of the invention

[0003] The present invention relates to a new type of virtual take-off and landing (VTOL) aircraft based on a multi-lift rotor design

[0004] Background to the invention

[0005] Vertical take-off and landing (VTOL) aircraft structures belong to the field of aircraft and relate to aircraft which have lift producing rotors allowing for take-off and landing without the requirement of forward speed thereby eliminating the requirement for a runway.

[0006] Amphibious aircraft are aircraft which are able to take-off and land on water. Amphibious vertical take-off and landing aircraft are well established as fixed wing aircraft or helicopters which have floats in the place of the traditional landing gear. Amphibious VTOL aircraft with multiple lift rotors represent a relatively new and unexplored field. Traditional fixed-wing aircraft have characteristics such as safe flight processes, fast speeds, long ranges, and large carrying capacities. However, they require runways for take-off and landing and cannot hover, limiting their usage in various venues and thus their development and popularity.

[0007] Traditional single variable pitch rotor helicopters are able to land in case of an engine failure by autorotation of the main rotor.

[0008] Traditionally rotorcraft often deploy one main lift rotor which is powered by one or two engines. The two-engine configuration is often chosen to enhance safety, enabling the aircraft to safely descend or stay airborne in case of a single engine failure.

[0009] A further type of rotorcraft exists which is using multiple engines each connected directly to a single lifting rotor. These aircraft are typically not able to stay airborne in case of an engine failure due to the imbalance of lift in case of loss of lift on one side of the aircraft resulting from a single engine failure.

[0010] Today's fixed pitch multirotor aircraft face challenges such as the inability to safely deploy 'autorotation' in case of engine failure.

[0011] Pontoons or floats to allow landing on water have existed for almost a century. These typically add additional air drag and weight to the aircraft, thereby reducing its performance.

[0012] Traditionally rotorcraft use mechanical linkages between the engine and the rotors which are often spinning shafts with flexible joints. More recently rotorcraft architecture linking one or more central power sources in form of batteries or engine power generators to the rotors by means of electrical lines have been presented. While this type of architecture offers flexibility in design it typically suffers from the high weight of such transmission systems.

[0013] It is in this context that the present inventions have been devised.

[0014] Summary of the invention The present invention aims to address the limitations of today's fixed pitch multirotor aircraft (which face challenges such as the inability to safely deploy 'autorotation' in case of engine failure) by means of multiple engines, each being connected to multiple lift rotors, which are located across the centre of gravity of the aircraft.

[0015] In accordance with an aspect of the present invention, there is provided a vertical takeoff and landing aircraft having a central fuselage, at least two power units, each of said power units being connected to at least two separate lifting rotors characterised in that said power units are connected to the lifting rotors by transmission lines which are arranged so that each of the power units is connected to at least one lifting rotor on each side of the aircraft, relative to the location of the centre of gravity.

[0016] Typically, “each side of the aircraft” refers to a first side (which may be the left e.g. port side) and a second side (which may be the right e.g. starboard side) of the aircraft, respectively, particularly where the aircraft has a single longitudinal axis. It will be understood that the left or port side of the aircraft refers to the side on the left of an observer aboard the aircraft and facing towards the front of the aircraft (e.g. in the direction of forward travel, e.g. in use). It will be understood that the right or starboard side of the aircraft refers to the side on the left of a hypothetical observer aboard the aircraft and facing towards the front of the aircraft (e.g. in the direction of forward travel, e.g. in use).

[0017] The aircraft may be powered by two or more power sources located on either side of a main fuselage. These power sources are typically internal combustion engines but could be other types.

[0018] In some embodiments, the aircraft may comprise at least one power unit on each side of the aircraft (optionally the fuselage, optionally the centre of gravity of the aircraft) that is connected to at least one rotor on the same side of the aircraft and to at least one rotor on the other side of the aircraft.

[0019] The invention enhances aircraft safety by positioning at least one power source in two positions of the fuselage, each power unit being connected to lift rotors on both its own and the opposite side. This configuration allows balanced lift across the aircraft's centre of gravity in case of failure on one of the two power units. It thereby provides complete redundancy in case of failure in one of the power units and the associated transmission lines, lift rotors and control elements.

[0020] The power units may be of combustion engine type.

[0021] Power units might be housed in separate pods on either side of the fuselage in order to insulate passengers from vibration and noise of engines or any power source, thereby enhancing passenger comfort.

[0022] A further aspect of the invention is for the power unit to be positioned in pods which also function as flotation devices, allowing water landings without increasing air drag or weight due to additional containment.

[0023] This allows for the design of a new class of Amphibious aircraft addressing the needs in Maritime Air Mobility.

[0024] This invention introduces but isn’t limited to the use of a hydrostatic transmission system to transmit the power from the power units to the individual rotors. This system can be based on a commutation hydraulic piston pump with digital solenoids controlling the output from each cylinder also referred to as Digital Displacement pump technology.

[0025] It is further possible to place all critical transmission elements into the external pods. Isolating the power units and fuel tank from the fuselage further enhances passenger safety, ensuring that potential failures such as fires or explosions do not affect passenger safety for the duration needed for a safe emergency landing.

[0026] Traditional vertical landing and take-off aircraft such as helicopters deploy separate flotation devices in form of pontoons under the aircraft thereby greatly increasing the aircraft weight and air drag. A further aspect of the invention is the idea to further develop the external pods, housing the power units, into pontoons to act as flotation devices, thereby enabling the aircraft to land and take off from water and to operate on water. This concept utilises the required volume in the pontoon to support the aircraft on water for the housing of the power and transmission units thereby greatly reducing the aircraft weight and air drag.

[0027] This configuration of power units in these pods also enables considerable weight reduction in the structure of the fuselage by bringing the heaviest components of the craft such as the power and propulsion system close to the undercarriage that supports it. In this configuration, the moment the wheels touch the ground, or the pontoons get partly submerged for floatation, the weight of the power and propulsion system is directly loading on the frame within the pontoon, and thereby reducing that same weight factor from the fuselage structure or the arms between the fuselage and the pontoon.

[0028] Locating the power units into the external pods below the aircraft reduces the centre of gravity of the entire craft. This improves the roll and pitch stability of the vehicle on land and on water, reducing the risk of the vehicle rolling over.

[0029] The upper and lower rotors can be arranged coaxially, with one rotor above another, rotating in opposing directions but both blowing downwards. Each set of power units connect to either all the upper or all the lower rotors, ensuring lift consistency and control in case of a failure. Each power unit can independently support the aircraft in controlled descent without the other.

[0030] Additionally, the frame of the pontoons and power units might include landing skids or wheels for safe landing on land and on water. The pontoon might further incorporate thrusters or water jet engines for manoeuvrability on water.

[0031] The lifting rotors may be driven by hydraulic motors. The lifting motors may be connected to the power units through hydrostatic transmission lines.

[0032] The power units may be arranged to either side of the main fuselage in separate pods. At least one first power unit may be arranged on each side of the main fuselage (optionally on each side of the aircraft, for example relative to the centre of gravity). At least one power unit (optionally each power unit) may be arranged on a first side of the main fuselage (optionally on a first side of the aircraft, for example relative to the centre of gravity) and connected to at least one rotor on the first side of the main fuselage (optionally on the first side of the aircraft, for example relative to the centre of gravity) and at least one rotor on the a second side of the main fuselage (optionally on a second side of the aircraft, for example relative to the centre of gravity). The first side may be a left (e.g. port) side. The second side may be a right (e.g. starboard) side.

[0033] The separate pods may be able to provide buoyancy allowing the aircraft to take-off, land and manoeuvre on water.

[0034] The aircraft may be able to stay airborne in case of a failure in one of the propulsion systems by the remaining power unit having an overdrive move providing sufficient power to the remaining lifting rotors to control the aircraft. The aircraft may be able to manage a controlled descent in case of a failure in one of the propulsion systems by the remaining power unit having an overdrive mode providing sufficient power to remaining lifting rotors to control the aircraft.

[0035] The aircraft may further comprise coaxial rotors. The coaxial rotors may comprise an upper lifting rotor located above a lower pushing rotor, wherein one of the power units is connected to the lifting rotors, and wherein a second power unit is connected to the lower pushing upper lifting rotors.

[0036] The lifting rotors may be mounted at different positions on the top structural member. This provides the advantage of reducing the risk of a rotor being impacted by debris ejected from another rotor in the event of a rotor failure, thereby improving aircraft safety.

[0037] It may be that the mass of the power unit is directly coupled to the landing gear through a structural member. The landing gear may be of skid, wheel, or float type. This provides the advantage of reducing the structural stresses on the fuselage.

[0038] The aircraft may be of pure rotorcraft design for take-off and landing. The aircraft may be designed in a way that some or all of the structural elements of the aircraft produce lift during flight. The aircraft may comprise a wing shaped element. The wing shaped element may be configured to produce between half and all of the required lift during forward flight.

[0039] The aircraft may comprise at least one additional propeller configured to propel the aircraft in a horizontal direction.

[0040] The aircraft may comprise one or more isolation members configured to reduce sound and vibration from the main fuselage. The power units may be isolated from the main fuselage through the one or more isolation members.

[0041] The floats may be configured to be separated from the body. This provides the advantage of the aircraft being easier to transport.

[0042] The power units may be changeable or replaceable. Advantageously, this allows for the use of different types of fuel or power, and for different buoyancies.

[0043] A further aspect of the present invention differs from the prior art in the key characteristic of strategically integrating the power source into the pontoon for numerous advantages as described.

[0044] Accordingly, in a further aspect there is provided a vertical take-off and landing aircraft having a central fuselage, at least two power units located on either side of the fuselage, each of power units being connected to at least two separate lifting rotors characterised in that the external pods containing the power units also acting as floats allowing for the craft to take-off, land and manoeuvre on water.

[0045] It may be that the pods housing the power units comprise thrusters configured to propel the aircraft when it is floating on water by means of a propeller submerged in the water or by means of water jets.

[0046] A further aspect of the invention presented is the use of a hydrostatic transmission system to enable the proposed new system architectures. Description of the Drawings

[0047] An example embodiment of the present invention will now be illustrated with reference to the following Figures in which:

[0048] Figure 1 is a front elevation diagram showing the overall layout of an aircraft according to an example embodiment of the invention.

[0049] Figure 2 is a plan elevation view diagram showing the overall layout of the aircraft of Figure 1.

[0050] Figure 3 is a perspective elevation view diagram of the aircraft of Figures 1 and 2.

[0051] Figure 4 is a side elevation view diagram of the aircraft of Figures 1 to 3.

[0052] Detailed Description of an Example Embodiment

[0053] Figure 1 shows the overall layout of an aircraft according to an example embodiment of the invention. The fuselage (2) forms the centre of the aircraft and might be constructed of metal and composite materials. Power units (1) which could be of combustion engine, electrical or other nature are placed on either side of the main fuselage (2). The power units (1) might be placed in separate pods (5) which are only connected to the main fuselage (2) by means of external structural members (6) or the pods (5) could be incorporated into the main fuselage (2) structure.

[0054] The lifting rotors (4a, 4b) are connected to the main fuselage (2) by means of the structural members (7). Each of the power units (1) is connected to at least one rotor (4a, 4b) , located on either side of the main fuselage (2). The power units (1) are connected to the rotors by means of power transmission lines (3). These power transmission lines might be of electrical, shaft driven or hydraulic transmission nature.

[0055] Figure 2 shows the overall layout of the aircraft of Figure 1 from the top / plan view with the front of the fuselage (2) facing upwards on the Figure, and the separate pontoons (5) either side of the fuselage. Power units (1) which could be of combustion engine, electrical or other nature are placed on either side of the main fuselage (2). These power units (1) are shown placed in separate pods (5) on either side of the fuselage (2) and are only connected to the main fuselage (2) by means of external structural members (6) or, in absence of external structural members (6) the pods (5) could also be directly incorporated into the main fuselage (2) structure. Thrusters (11) are in the pods (5) for propelling the craft when on the water.

[0056] The lifting rotors (4a, 4b) are connected to the main fuselage (2) by means of the structural members (7). Each of the power units (1) is connected to at least one rotor (4a, 4b) , located on either side of the main fuselage (2). The power units (1) are connected to the rotors by means of power transmission lines (3). These power transmission lines might be of electrical, shaft driven or hydraulic transmission nature. On the inside of the pontoons (5), the thrusters (8) are provided for movement while floating on water.

[0057] Figure 3 shows damper units (15) in the connecting member (6) between the main fuselage (2) and flotation pods (5) providing vibration and noise isolation.

[0058] Figure 4 shows the side view of the craft showing landing gear (16) and the frame (17) that holds the landing gear (16) and the power unit (1) as one integrated unit within the containment of the pontoon (5) with wheels (18) at the bottom.

[0059] In summary, there is provided a vertical take-off and landing aircraft having a central fuselage (2), at least two power units (1), each of said power units being connected to at least two separate lifting rotors (4a or 4b) characterised in that said power units are connected to the lifting rotors (4a, 4b) by transmission lines (3) which are arranged so that each of the power units (1) is connected to at least one lifting rotor on each side of the aircraft, relative to the location of the centre of gravity.

[0060] Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to and do not exclude other components, integers, or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

[0061] Features, integers, characteristics, or groups described in conjunction with a particular aspect, embodiment, or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

Claims1 . A vertical take-off and landing aircraft having a central fuselage (2), at least two power units (1), each of said power units being connected to at least two separate lifting rotors (4a or 4b) characterised in that said power units are connected to the lifting rotors (4a, 4b) by transmission lines (3) which are arranged so that each of the power units (1) is connected to at least one lifting rotor on each side of the aircraft, relative to the location of the centre of gravity.

2. A vertical take-off and landing aircraft according to claim 1 , wherein the power units (1) are of combustion engine type.

3. A vertical take-off and landing aircraft according to claim 1 or claim 2, wherein the lifting rotors (4) are driven by hydraulic motors and are connected to the power units (1) through hydrostatic transmission lines.

4. A vertical take-off and landing aircraft according to any one preceding claim, wherein the power units are arranged to either side of the main fuselage in separate pods (5).

5. A vertical take-off and landing aircraft according to claim 4, wherein the separate pods (5) are able to provide buoyancy allowing the aircraft to take-off, land and manoeuvre on water.

6. A vertical take-off and landing aircraft according to any one preceding claim, wherein the aircraft can stay airborne or manage a controlled descent in case of a failure in one of the propulsion systems by the remaining power unit (1) having an overdrive mode providing sufficient power to remaining lifting rotors to control the aircraft.

7. A vertical take-off and landing aircraft according any one preceding claim, further comprising coaxial rotors made from an upper lifting rotor (4a) placed above a lower pushing rotor (4b) where one of the power units is connected tothe lifting rotors (4a) and a second power unit is connected to the lower pushing upper lifting rotors (4b).

8. A vertical take-off and landing aircraft according to claim 7, wherein the lifting rotors (4a, 4b) are mounted at different positions on the top structural member (7) to reduce the risk of a rotor being impacted by debris ejected from another rotor in the event of a rotor failure, thereby improving aircraft safety.

9. A vertical take-off and landing aircraft according to any one preceding claim, characterised in that mass of the power unit (1) is directly coupled to the landing gear (53) which can be of skid, wheel of float type through a structural member (6) reducing the structural stresses on the fuselage.

10. A vertical take-off and landing aircraft according to any one preceding claim, further comprising the aircraft being of pure rotorcraft design for take-off and landing but being designed in a way that the all or some of structural elements (2, 5, 6, 7) of the aircraft produce lift during forward flight.11 . A vertical take-off and landing aircraft according to claim 9, further comprising a wing shaped element incorporated into the aircraft producing between half and all of the required lift during forward flight.

12. A vertical take-off and landing aircraft according to any one preceding claim, further comprising at least one additional propeller propelling the aircraft in a horizontal direction.

13. A vertical take-off and landing aircraft according to any one preceding claim, wherein the power units are isolated from the main fuselage through isolation members (15) to reduce sound and vibration in the main fuselage.

14. A vertical take-off and landing aircraft according to any one preceding claim, whereby the floats can be separated from the body for transporting the aircraft.

15. A vertical take-off and landing aircraft according to any one preceding claim, whereby the power units can be changed in order to accommodate the requirement for different types of fuel, power and buoyancy.

16. A vertical take-off and landing aircraft having a central fuselage (2), at least two power units (1) located on either side of the fuselage (2), each of power units being connected to at least two separate lifting rotors (4a, 4b) characterised in that the external pods containing the power units also acting as floats allowing for the craft to take-off, land and manoeuvre on water.

17. A vertical take-off and landing aircraft according to claim 16, wherein the pods (5) housing the power units having thrusters to propel the aircraft when it is floating on water by means of a propeller submerged in the water or by means of waterjets.

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