NL1040979B1 - Air vehicle. - Google Patents

Abstract

An air vehicle is provided comprising duct fans with two counter rotating propellers. The duct fans are rotatable along an axis substantially perpendicular to the longitudinal axis of the fuselage. A control unit is arranged for controlling the position of the duct fans and the rotation speed of the propellers. Also a model-based method is provided for auto-piloting the air vehicle.

Description

AIR VEHICLE

TECHNICAL FIELD

The invention relates generally to aircraft comprising multiple duct fans, which enable vertical takeoff and landing (VTOL) aircrafts and/or support the aircraft in maneuverability. More particularly, the present invention pertains to aircraft having tilting propulsion systems for vertical takeoff. The present invention is particularly, but not exclusively, useful as a VTOL aircraft design for relatively small unmanned aerial vehicles (UAV), remote control (RC) aircraft and larger passenger aircraft.

BACKGROUND

Vertical Takeoff and Landing (VTOL) aircraft are generally any of numerous unconventional designs for aircraft including rotary wing helicopters, having rotatable or divertible propulsion systems that allow for vertical takeoff/landing and horizontal flight.

Some VTOL designs are modifications of fixed wing aircraft to include vertical propulsion while maintaining stability in vertical lift mode.

Additional designs of VTOL aircraft are known in the art each having certain advantages and drawbacks. One such design is a tilt-rotor type that is also referred to a "convertible" type, having rotors, which are capable of being tilted with respect to the aircraft structure. For example, during takeoff, the rotors are orientated almost vertically so as to operate like a rotary wing, in order to allow vertical takeoff in the manner of a helicopter. Next, the aircraft flight is transitioned from vertical to horizontal mode, thus the rotors are tilted horizontally so as to operate like airscrews. VTOL may have, instead of regular open rotors, at least one ducted fan and a propeller engine to drive the propellers. A ducted fan is a propulsion arrangement whereby a propeller, is mounted within a cylindrical shroud or duct. The duct reduces losses in thrust from the tips of the propeller blades, and varying the cross-section of the duct allows the designer to advantageously affect the velocity and pressure of the airflow according to Bernoulli's Principle.

Advantages of employing duct fans are as follows.

By reducing propeller blade tip losses, the ducted fan is more efficient in producing thrust than a conventional propeller, especially at low speed and high static thrust level (airships, hovercraft).

By sizing the ductwork appropriately, the designer can adjust the air velocity through the propeller to allow it to operate more efficiently at higher air speeds than a propeller would.

For the same static thrust, a ducted fan has a smaller diameter than a free propeller, allowing smaller gear.

Ducted fans are quieter than propellers without a duct: they shield the blade noise, and reduce the tip speed and intensity of the tip vortices both of which contribute to noise production.

Duct fans can allow for a limited amount of thrust vectoring, something normal propellers are not well suited for. This allows them to be used instead of tilt rotors in some applications. Furthermore duct fans offer enhanced safety on the ground.

The duct fan produces an airstream that may enable the VTOL to hover or move translationally parallel to the ground.

Also known, are VTOL designs of model aircraft or miniature remote controlled (RC) aircraft. In all designs, weight, stability and power-to-weight ratio of the propulsion system are chief design concerns. A quadcopter, also called a quadrotor helicopter or quadrotor, is a multirotor helicopter that is lifted and propelled by four rotors. The four-rotor design allows quadcopters to be relatively simple in design yet fairly reliable and maneuverable.

Unlike most helicopters, quadcopters currently use two sets of identical fixed pitched propellers; two clockwise (CW) and two counter-clockwise (CCW). Control of vehicle motion is achieved by altering the rotation speed of one or more rotors, thereby changing its torque load and thrust/lift characteristics.

There are several advantages to quadcopters over comparably-scaled helicopters. First, quadcopters do not require mechanical linkages to vary the rotor blade pitch angle as they spin. This simplifies the design and maintenance of the vehicle. Second, the use of four rotors allows each individual rotor to have a smaller diameter than the equivalent helicopter rotor, allowing them to possess less kinetic energy during flight.

This reduces the damage caused should the rotors hit anything. With their small size and agile maneuverability, quadcopters can be flown indoors as well as outdoors.

Working of a regular quadcopter (2 CW and 2 CCW rotors)]

Spinning rotors result in reaction torques on each motor of a quadcopter aircraft.

Each rotor produces both a thrust and torque about its center of rotation, as well as a drag force opposite to the vehicle's direction of flight. If all rotors are spinning at the same angular velocity, with the first two diagonally opposing rotors rotating clockwise and the second two opposing rotors rotating counterclockwise, the net aerodynamic torque, and hence the angular acceleration about the yaw axis, is exactly zero, which implies that the yaw stabilizing rotor of conventional helicopters is not needed. Yaw is induced by mismatching the balance in aerodynamic torques (i.e., by offsetting the cumulative thrust commands between the counter-rotating blade pairs)

Commonly, the main mechanical components applied for construction are the frame, propellers and the electric motors. For best performance and simplest control algorithms, the motors and propellers are usually placed equidistant. Recently, carbon fiber composites have become popular due to their light weight and structural stiffness.

The electrical components usually applied to construct a working quadcopter are an electronic speed control module, on-board computer or controller board, and battery. Additionally, often a hobby transmitter is also used to allow for human input.

Several attempts have been made to improve fault detection and diagnosis and fault-tolerant control strategies for unmanned rotary wing vehicles. Amongst others, a motivation for using a multicopter with six or more propellers, instead of a four propeller quadrocopter, is that the vehicle is able to maintain normal flight if one of the propellers fails.

More recently quadcopter designs have become popular as unmanned aerial vehicle (UAV), commonly known as a drone. A UAV is an aircraft without a human pilot aboard. Its flight is controlled either autonomously by onboard computers or by the remote control of a pilot on the ground or in another vehicle. These vehicles use an electronic control system and electronic sensors to stabilize the aircraft. The typical launch and recovery method of an unmanned aircraft is by the function of an automatic system or an external operator on the ground. Historically, UAVs were simple remotely piloted aircraft, but autonomous control is increasingly being employed.

For providing autonomy to a UAV which is not under continuous and/or direct control of a ground station autonomy technology has been developed.

The Autonomy technology falls under the following categories:

Sensor fusion: Combining information from different sensors for use on board the vehicle including the automatic interpretation of ground imagery.

Communications: Handling communication and coordination between multiple communication sources in the presence of incomplete and imperfect information Path planning: Determining an optimal path for vehicle to follow while meeting certain objectives and mission constraints, such as obstacles or fuel requirements. Many modern flight controllers use software that allows the user to mark "way-points" on a map, to which the quadcopter will fly and perform tasks, such as landing or gaining altitude.

Trajectory Generation (sometimes called Motion planning): Determining an optimal control maneuver to take in order to follow a given path or to go from one location to another.

Trajectory Regulation: The specific control strategies required to constrain a vehicle within some tolerance to a trajectory. UAVs in general are often deployed for military and special operation applications, but are also used in a small but growing number of civil applications. UAVs are often preferred for missions that are too "dull, dirty or dangerous" for manned aircraft, but also because they are very often more cost efficient in use. Examples of application areas comprise transport equipment, policing and firefighting, surveillance of pipelines, aerial surveying of crops, search and rescue operations, counting wildlife and delivering medical supplies to remote or otherwise inaccessible regions. UAVs are increasingly being used in civilian applications. Many services such as the police services and firefighting services now use UAVs for intelligence-gathering operations, such as to provide real-time video images of locations that are difficult or dangerous to attend in person. UAVs are often able to provide such images quickly, conveniently and inexpensively.

For the above mentioned application areas UAVs may need to store equipment such as avionics, controls, payload, and remote sensing equipment. UAV remote sensing functions include electromagnetic spectrum sensors, gamma ray sensors, biological sensors, and chemical sensors. A UAVs electromagnetic sensors typically include visual spectrum, infrared, or near infrared cameras as well as radar systems. Other electromagnetic wave detectors such as microwave and ultraviolet spectrum sensors may also be used but are uncommon. Biological sensors are sensors capable of detecting the airborne presence of various microorganisms and other biological factors. Chemical sensors use laser spectroscopy to analyze the concentrations of each element in the air.

Smaller UAVs are often battery powered. This has the advantage of reducing complexity and cost. A problem that exists with such smaller UAVs is that their operational duration is limited by their batteries. It is typical for such UAVs to be able to fly for no longer than 15 to 20 minutes before the battery becomes depleted. This is the principal limitation on the use of such devices. A disadvantage of the current art solutions is that they do not or fall short in delivering an inherent safe design. Furthermore the control of existing vehicles is not fault tolerant enough and has limitations in operation, maneuverability and stability.

DISCLOSURE OF INVENTION

It is an object of the present invention to provide a solution for increasing the stability and maneuverability of an air vehicle. It is a further object of the invention to increase fault tolerance in control of the air vehicle. It is yet a further object of the invention to increase safe operation of the air vehicle. It is yet a further object of the invention to increase the energy efficiency and/or range of flight of the air vehicle. It is yet a further object of the invention to increase employability of the air vehicle in multiple situations and for multiple purposes. It is yet a further object of the invention to increase autonomous operatebility of the air vehicle. It is yet a further object of the invention to increase ease of use of the air vehicle.

The objects are realized by providing an air vehicle comprising rotatable duct fans with each duct fan comprising a pair of counter rotating propellers. The objects are further realized by a model-based automatic control method for auto piloting the air vehicle. The objects are yet further realized by the further embodiments of the invention.

The invention is further described by its aspects and embodiments and illustrated by exemplary figures.

BRIEF DESCRIPTION OF THE DRAWINGS

The figures show views of embodiments in accordance with the present invention. FIGURE 1 shows a top view of an exemplary embodiment of the invented air vehicle. FIGURE 2 shows an isometric view of an exemplary embodiment of a duct fan of the plurality of duct fans of the invented air vehicle. FIGURE 3 shows a top view of an exemplary embodiment of the air vehicle comprising four wings attached to the plurality of duct fans of the invented air vehicle where two duct fans are rotated in a horizontal position and two duct fans are rotated in a vertical position, wherein two of the attached wings are positioned in a different orientation than the duct fans to which they are attached. FIGURE 4 shows an isometric view of Figure 3. FIGURE 5 shows a side view of an exemplary embodiment of the invented air vehicle with the fuselage positioned at a free angle of attack while the plurality of duct fans are positioned horizontally, of which the front two duct fans are located at a different height compared to the back two duct fans. FIGURE 6 Shows an isometric view of an exemplary embodiment of the invented air vehicle with two attachable/detachable wings attached to the fuselage directly. FIGURE 7 Shows an isometric view of an exemplary embodiment of the invented air vehicle with two attachable/detachable wings attached to the fuselage directly, wherein the wings are pivotably connected to the fuselage in order to function as landing gear. FIGURE 8 Shows a side view of a duct fan wherein a cross-section of the cylindrical duct is showing an aerodynamic airfoil.

DETAILED DESCRIPTION

The invention is now described by the following aspects and embodiments, with reference to the figures.

Legend 100 air vehicle 200 fuselage 300a,b,c,d duct fans 310a,b counter rotating propellers 320a,b motors 330a,b,c,d cylindrical ducts, with cross-section of airfoil 331 340a,b,c,d connectors for connecting duct fans 300a,b,c,d to fuselage 200 400a,b,c,d,e,f optional attachable/detachable wings 440a,b,c,d connectors for connecting optional wings 400a,b,c,d FIGURE 1 shows a top view of an exemplary embodiment of the invented air vehicle 100.

The air vehicle comprises a fuselage having a longitudinal axis, said longitudinal axis corresponding to a fore and an aft direction. In the figure the downside is the fore direction. A plurality of duct fans 300a,b,c,d is rotatably connected to the fuselage 200. A preferred configuration is wherein the duct fans 300a,b,c,d are connected as much as possible to the outer corners of the fuselage 200. FIGURE 2 shows an isometric view of an exemplary embodiment of a duct fan 300a of the plurality of duct fans 300a,b,c,d of the invented air vehicle 100.

The duct fan 300a is rotatably connected through connector 340a to fuselage 200.

The duct fan 300a comprises two counter rotating propellers 310a,310b. The propellers 310a,b are rotatably mounted in cylindrical duct 330a. The propellers are driven by motors 320a,b. The propellers 310a,b may comprise any number of propeller blades. The figure shows a configuration with two propeller blades, which are positioned at equal angles to the next propeller blades. In a preferred embodiment each of the propellers 310a,b is separately driven by a separate motor 320a,b. Propeller 310a is driven by motor 320a and propeller 310b is driven by motor 320b. Different configuration may be chosen, such as one motor driving both propellers 310a,b through a transmission system which rotates one propeller 310a in one direction and the other propeller 310b in an opposite direction. The motors 320a,b or alternatively (not shown), a single motor may also be positioned outside of the duct propeller 300a, such as in the fuselage 200. The outside positioned motor may drive propellers 310a,b through a similar acting transmission system. The motors 320a,b are preferably electro motors and are supplied with power from a battery (not shown) comprised in the duct fan 300a, or more preferably in the fuselage 200.

The configuration of the counter rotating propellers 310a,b provides stability to the air vehicle 100. The counter rotating propellers 310a,b compensate for rotational forces, which elsewise would inherently be caused by a single rotating propeller. In this way multiple configurations of number of duct fans and their position are made possible. The configuration of the number of duct fans or their position will not, or less cause unwanted forces on the fuselage.

The motors 320a and 320b are preferably positioned opposite to each other, wherein the propellers 310a and 310b are positioned in series between the motors 320a,b. This enables placement of the propellers in the closest possible vicinity of each other. In this way the turbulent energy of the first in series placed propeller 310a may be used as useful energy by the second in series placed propeller 310b. This leads to a further increase in aerodynamic efficiency.

The rotatable connection of the duct fan 300a enables enhanced control of the air vehicle, as well in vertical movement and horizontal movement as in maintaining a steady position while airborne.

The figure shows also an optional wing 400a attached to the duct fan 300a, which is explained in figure 3. FIGURE 3 shows a top view of an exemplary embodiment of the air vehicle 100 comprising four wings 400a,b,c,d attached to the plurality of duct fans 300a,b,c,d of the invented air vehicle 100. Figure 3 comprises the description of Figure 1. The duct fans 300c,d are vertically positioned for horizontal displacement, while the duct fans 300a,b are positioned horizontally for vertical displacement. The wings 400a,b are connected with connectors 440a,b,c,d. to the duct fans 300a,b respectively. The wings 400c,d are rotatably connected to the duct fans 300c,d respectively. The wings 400c,d may be positioned independently of the duct fans 300c,d. The configuration of the wings 400a,b,c,d provides extra stability, extra maneuverability, increase the energy efficiency and/or range of flight for the air vehicle 100. Alternatively the wings 400a,b,c,d may be connected to the fuselage 200. FIGURE 4 shows an isometric view of the exemplary embodiment of the air vehicle 100 depicted in Figure 3. The description of Figure 3 applies to Figure 4. FIGURE 5 shows a side view of an exemplary embodiment of the invented air vehicle 100 with the fuselage 200 positioned at a free angle of attack while the plurality of duct fans 300a,b,c,d are positioned horizontally, of which the front two duct fans 300c,d are located at a different height compared to the back two duct fans 300a,b. This positioning is changeable. This positioning shows how the fuselage 200 has a free angle of attack while the air vehicle 100 displaces vertically through the operation of the duct fans 300a,b,c,d.

Another position may be where the duct fans 300a,b,c,d are positioned vertically while the fuselage 200 is at a free angle of attack. The fuselage 200 may then affect the vertical displacement while the duct fans 300a,b,c,d may provide horizontal displacement.

By varying the thrust of the fore and/or aft propellers, the fuselage may be inclined or declined at will.

The angle of the fuselage may be controlled independently of the rotation angles of the duct fans and thereby increasing or decreasing angle of attack of the fuselage in flight direction is possible.

The maneuverability of said air vehicle 100 is improved by varying these positions. Furthermore the air vehicle is autonomously optimized to gain optimal aerodynamic efficiency. FIGURE 6 shows an isometric view of an exemplary embodiment of the invented air vehicle 100 with two attachable/detachable wings 400e,f attached to the fuselage directly. This provides extra lift, which is especially useful when one or more duct fans 300a,b,c,d are in more or less vertical position in order to provide forward trust. FIGURE 7 shows an isometric view of an exemplary embodiment of the invented air vehicle 100 with two attachable/detachable wings attached to the fuselage directly, wherein the wings are pivotably connected to the fuselage in order to function as landing gear.

The air vehicle 100 is able to land vertically. Especially when the landing space is full of high grass and the like, the wings 400e,f provide a safe landing and a stable position on the ground. It also allows for a bigger payload attached to the bottom of the fuselage 200. FIGURE 8 shows a side view of a duct fan 300a wherein a cross-section of the cylindrical duct is showing an aerodynamic airfoil. The flight path of the duct fan is indicated by arrow 10. By providing the cylindrical duct 330a with an airfoil profile, the cylindrical duct acts as a venturi, therefore providing a higher air volumetric flow through the cylindrical duct. Through a decrease in area in flow direction, a venturi effect is created, which increases aerodynamic efficiency. Alternatively the cylindrical duct is provided with one or more segments having an airfoil cross-section, e.g. enabling the duct fan itself to provide lifting capabilities.

In a first aspect of the present invention an air vehicle is provided comprising: a fuselage having a longitudinal axis, said longitudinal axis corresponding to a fore and an aft direction; a plurality of duct fans, each comprising a propeller mounted within a cylindrical duct; a duct fan of the plurality of duct fans connected to the fuselage; a duct fan of the plurality of duct fans arranged for being rotatable along an axis substantially perpendicular to the longitudinal axis of the fuselage; a control unit arranged for controlling the position of the plurality of duct fans; the control unit arranged for controlling the rotation speed of a propeller of the plurality of duct fans, wherein a duct fan of the plurality of duct fans comprises two counter rotating propellers 310a,b.

The counter rotating propellers 310a,b provide stability. Furthermore by employing two counter rotating propellers 310a,b, vibrations are decreased. By employing two propellers per duct reliability increases and safety is enhanced. For example in the case of damage or failure of one of the propellers 310a,b, the other propeller may compensate for this decreased functionality, thus keeping the air vehicle in the air even when taking considerable damage. The possibility of crashing of the air vehicle is therefore decreased.

In a first embodiment of the invention the control unit is arranged for controlling each of the duct fans 300a,b,c,d individually.

By controlling each of the duct fans 300a,b,c,d individually, the air vehicle is highly maneuverable. Rotation speed of the set of duct fans 300a,b,c,d, or the rotation of the duct fans 300a,b,c,d themselves may be varied.

In a second embodiment the control unit is arranged for controlling each of the propellers 310a,b of the two counter rotating propellers 310a,b.

By controlling each propeller 310a,b individually, the air vehicle 100 may be maneuvered without having to rotate the duct fans 300a,b,c,d.

In a third embodiment the duct fan 300a,b,c,d comprises a first motor 320a,b for driving a first propeller 310a,b of the two counter rotating propellers 310a,b and a second motor 320a,b for driving the second propeller 310a,b of the counter rotating propellers 310a,b. This enable individual control of each propeller in a direct manner. It also serves as a back-up system, when either one of the motors should fail.

In a fourth embodiment the first and/or second motor 320a,b comprises an electro motor.

By employing an electro motor rotation speed is easily varied and power supply is relatively simple and reliable.

In a fifth embodiment the first and second propeller 310a,b are arranged for being driven by the first and second motor 320a,b respectively at substantially the same speed.

By synchronizing the two motors, the counter rotation leads to a steady operation and less vibration.

In a sixth embodiment each duct fan 300a,b,c,d is arranged for being rotatable by at least 90 degrees from a substantially vertical to a substantially horizontal position.

By rotating the duct fans, the movement in horizontal and vertical direction is controllable. This also enables for example a steady fixed position when airborne.

In a seventh embodiment each duct fan 300a,b,c,d is arranged for being rotatable independently of the other duct fans 300a,b,c,d.

By rotating each duct fan independently, more complicated maneuvers are possible. Also for example cornering speeds may be increased.

In an eighth embodiment the control unit is arranged for controlling the position of the fuselage by controlling the position of the plurality of duct fans 300a,b,c,d and/or by controlling the rotation speed of one or more propellers 310a,b of the plurality of duct fans 300a,b,c,d .

By enabling controlling of the fuselage itself in this way, the angle of attack, for example may be varied easily. In some cases it is preferred that the fuselage is set at the right angle for maximum lift or for landing. For example, an on-board camera needs to be positioned more flexible in order to take pictures at the right angle.

In a ninth embodiment the air vehicle further comprises one or more wing connectors 440a,b,c,d arranged for connecting one or more wings 400a,b,c,d in such a position as to assist the duct fans 300a,b,c,d in creation of lift.

By attaching optional wings, the flight range may be extended. Moreover, energy efficiency is increased. The extra wings provide additional safety in the case of one or more of the duct fans or propellers are inoperative. In an extreme case of a dead-stick landing, the air vehicle has bigger chance not to crash.

In a tenth embodiment the one or more wing connectors 440a,b,c,d are arranged for rotatably connecting the one or more wings 400a,b,c,d.

By using connectors, the wings may be attached or detached according to the purpose or situation in which the air vehicle has to be operated.

In an eleventh embodiment a first duct fan 300a,b,c,d comprises a first wing connector 440a,b,c,d of the one or more wing connectors 440a,b,c,d.

In a twelfth embodiment the cylindrical duct 330a,b,c,d of the first duct fan 300a,b,c,d comprises the first wing connector 440a,b,c,d.

In a thirteenth embodiment the first wing connector 440a,b,c,d is arranged for fixedly connecting a first wing 400a,b,c,d of the one or more wings 400a,b,c,d, wherein the first wing 400a,b,c,d is arranged for being rotatable together with the first duct fan 300a,b,c,d.

In a fourteenth embodiment the first wing connector 440a,b,c,d is arranged for rotatably connecting the first wing 400a,b,c,d of the one or more wings 400a,b,c,d, wherein the first wing 400a,b,c,d is arranged for being rotatable independently of the first duct fan 300a,b,c,d.

This provides more maneuverability without losing the lift capabilities of the wing.

In a fifteenth embodiment the fuselage 200 comprises a second wing connector 440a,b,c,d of the one or more wing connectors.

In a sixteenth embodiment each duct fan of the plurality of duct fans and/or each wing 400a,b,c,d of the one or more wings 400a,b,c,d is arranged for being rotatable independently of the other duct fans 300a,b,c,d and wings 400a,b,c,d and without angular limit in respect to the fuselage 200.

In seventeenth embodiment the shape of the fuselage 200 is constructed for creating maximum lift at a limited range of degrees of angle of flight.

The fuselage may be aerodynamically designed to be particular efficient in providing extra lift when in a certain angle of attack. The duct fans and/or wings may be configured and/or controlled to maintain the particular angle in order to provide maximum energy efficiency.

In an eighteenth embodiment the air vehicle 100 comprises attachment means arranged for attaching additional equipment, the additional equipment comprising any one of the group comprising: a video or photo camera; a positioning device, such as a global positioning system (GPS); a transponder-based radio navigation distance measuring equipment (DME); one or more sensors, such as a camera, an electromagnetic sensor, LASER, LIDAR or RADAR; a wireless communication device, such as a WIFI device or a cell phone.

By carrying this additional equipment the air vehicle is suitable to operate in various situations, such as cloudy weather. On the other hand equipment such as a camera is in particular suitable for aerial survey. A first sensor of the one or more sensors is arranged for being directed upwards for providing a first set of sensor data, wherein said first set of sensor data is input for compensation of measured sensor data of a downward directed second sensor of the one or more sensors.

This is especially useful for compensating downward directed sensor measurements with environmental fluctuations (e.g. light conditions) as measured from above.

In a nineteenth embodiment the air vehicle 100 comprises a storage facility arranged for storing a payload, the payload comprising any one of the group comprising: a fire extinguishing agent; plant seeds; a pesticide. an integrated payload, which may include a gimbal, i.e. a device able to stabilize the payload in three axes, furthermore the payload may be folded in the air vehicle and may be deployed outwards during flight by an actuator and thereby securing the safety of the expensive sensor systems when on ground or not used.

This provides people in particular fields of industry and services possibilities to perform operations, which would otherwise be dangerous, tedious or difficult to perform manually. A battery pack may be stored in a storage space of the fuselage.

The battery pack may comprise a displacement device arranged for sensing changes in the center of gravity of the air vehicle and arranged for adjusting the position of the battery pack in order to maintain or establish a controlled center of gravity. The battery pack may be displaced manually in the fuselage and fixed by screws, or shims. Alternatively a battery displacement device may be incorporated in the fuselage. The displacement device may sense changes in center of gravity of the air vehicle due to for example payload change, or due to a general change of the air vehicle configuration. The battery pack may be clickable to or in the fuselage for easy and fast swapping of batteries.

In a twentieth embodiment the control unit is arranged for being automatically configured for controlling the air vehicle 100 in dependence of a configuration of the connected wings 400a,b,c,d.

The air vehicle may be equipped with sensor technology which detects when for example a wing is attached. When a wing is detected the flight control may be adapted automatically to the new configuration. This leads to fail safe operation of the air vehicle, because there is less chance of human error.

In a twenty-first embodiment the control unit is arranged for being automatically configured for controlling the air vehicle 100 in dependence of a configuration of the attached additional equipment and/or the stored payload.

In a twenty-second embodiment the air vehicle 100 comprises an Unmanned Aerial vehicle (UAV).

In a twenty-third embodiment the air vehicle 100 comprises a quadcopter.

In a second aspect of the present invention a method for auto piloting of an air vehicle 100 is provided, the method comprising a model-based automatic control method.

In a first embodiment of the second aspect of the invention the method comprises any one of the group of control methods comprising:

Iterative learning based control;

Fault tolerant control;

Resource aware control.

The term "substantially" herein, such as in "substantially ..." etc., will be understood by the person skilled in the art. In embodiments the adjective substantially may be removed. Where applicable, the term "substantially" may also include embodiments with "entirely", "completely", "all", etc. Where applicable, the term "substantially" may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, including 100%. The term "comprise" includes also embodiments wherein the term "comprises" means "consists of.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "to comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The term "and/or" includes any and all combinations of one or more of the associated listed items. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The article "the" preceding an element does not exclude the presence of a plurality of such elements. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims (35)

An aircraft comprising: - a fuselage with a longitudinal axis, said longitudinal axis corresponding to a forward and a rearward direction; - a plurality of tube propellers, each of which is mounted in a cylindrical channel; - a tube propeller from the plurality of tube propellers connected to the hull; - a tube propeller of the plurality of tube propellers adapted to be rotatable along an axis substantially perpendicular to the longitudinal axis of the hull; - a control unit adapted to control the position of the plurality of tube propellers; - the control unit adapted to control the rotational speed of a propeller of the plurality of tube propellers, characterized in that a tube propeller of the plurality of tube propellers comprises two counter-rotating propellers. The aircraft according to claim 1, characterized in that the control unit is adapted to control each of the tube propellers individually. The aircraft according to any one of the preceding claims, characterized in that the control unit is adapted to control each of the propellers of the two propellers rotating in the opposite direction. The aircraft according to any one of the preceding claims, characterized in that the tube propeller comprises a first motor for driving a first propeller of the two counter-rotating propellers and a second motor for driving the second propeller of the rotating propellers in the opposite direction. The aircraft of claim 4, characterized in that the first and second engines are arranged in a position opposite to each other wherein the first and second propellers are positioned in series between the first and second engines. The aircraft according to claim 4 or 5, characterized in that the first and / or second engine comprises an electric motor. The aircraft according to any of claims 4-6, characterized in that the first and second propellers are adapted to be driven by the first and second engines respectively at substantially the same speed. The aircraft according to any of the preceding claims, characterized in that each tube propeller is adapted to be rotatable by at least 90 degrees from a substantially vertical to a substantially horizontal position. The aircraft according to any one of the preceding claims, characterized in that each tube propeller is adapted to be rotatable independently of the other tube propellers. The aircraft according to any one of the preceding claims, characterized in that the control unit is adapted to control the position of the fuselage by controlling the position of the plurality of tube propellers and / or by controlling the rotational speed of one or more propellers of the plurality of tube propellers. The aircraft according to any one of the preceding claims, characterized in that the aircraft further comprises one or more wing attachment points, which are adapted to attach one or more wings in a position to assist the tube of propellers with the creation of thrust. The aircraft according to claim 11, characterized in that the one or more wing attachment points are arranged for rotatably connecting the one or more wings. The aircraft according to any of claims 11-12, characterized in that a first tube propeller comprises a first wing attachment point of the one or more wing attachment points. The aircraft of any one of claims 11-13, characterized in that the cylindrical channel of the first tube propeller comprises the first wing attachment point. The aircraft of any one of claims 11-14, characterized in that the first wing attachment point is adapted to attach a first wing of the one or more wings, the first wing being adapted to be rotatable together with the first tube propeller. The aircraft of any one of claims 11-12, characterized in that the first wing attachment point is adapted to attach a first wing of the one or more wings, the first wing being adapted to be rotatable independently of the first tube propeller. The aircraft of any one of claims 11-16, characterized in that the fuselage comprises a second wing attachment point of the one or more wing attachment points. The aircraft according to any of the preceding claims, characterized in that each tube propeller of the plurality of tube propellers and / or each wing of the one or more wings is arranged to be rotatable independently of the other tube propellers and wings and without limitation on angular displacement relative to the hull The aircraft of any one of the preceding claims, characterized in that the shape of the fuselage is constructed to create maximum propulsion force with a limited range of flight angles. The aircraft according to any one of claims 11-20, characterized in that the one or more wing attachment points are adapted to pivot the one or more wings from a horizontal position to a downward position. The aircraft according to any one of the preceding claims, characterized in that the aircraft comprises mounting means adapted to mount additional equipment, the additional equipment comprising one of the group comprising: - a video or photo camera; - a positioning device, such as a global positioning system (GPS); - a transponder-based radio navigation distance measuring device (DME); - one or more sensors, such as a camera, an electromagnetic sensor, LASER, LIDAR or RADAR; - a wireless communication device, such as a WIFI device or a mobile phone. The aircraft according to claim 21, characterized in that a first sensor of the one or more sensors is adapted to be directed upwards for providing a first set of sensor data, wherein said first set of sensor data is input for compensation of measured sensor data from a downward-facing sensor of the one or more sensors. The aircraft according to any of the preceding claims, characterized in that the aircraft comprises a storage facility adapted to store a load, the load comprising one of the group comprising: - a fire extinguishing means; - plant seeds; - a pesticide. The aircraft according to any one of the preceding claims, characterized in that the load is adapted to be folded into the fuselage by an actuator and furthermore is arranged to be folded outwards by said actuator. The aircraft according to any of the preceding claims, characterized in that the control unit is arranged to be automatically configured to control the aircraft in dependence on the configuration of the attached wings. The aircraft according to any of the preceding claims, characterized in that the control unit is arranged to be automatically configured to control the aircraft in dependence on the attached additional equipment and / or the stored cargo. The aircraft of any one of the preceding claims, characterized in that the aircraft comprises an Unmanned Air Vessel (UAV). The aircraft of any one of the preceding claims, characterized in that the aircraft comprises a quadcopter. The aircraft according to any of the preceding claims, characterized in that a section of the cylindrical channel comprises a wing profile. The aircraft according to any one of the preceding claims, characterized in that substantially all cross sections of the cylindrical channel comprise a substantially equal wing profile. The aircraft according to any of the preceding claims, characterized in that a battery pack is arranged to be carried by the aircraft, said battery pack being arranged to be movable within the fuselage of the aircraft. The aircraft according to any one of the preceding claims, characterized in that the battery pack comprises a displacement device adapted to detect changes in the center of gravity of the aircraft and adapted to adjust the position of the battery pack to maintain or maintain a controlled center of gravity to gain. The aircraft according to any of the preceding claims, characterized in that the battery pack is clickable on or in the fuselage for easily and quickly changing the battery pack. 34. An aircraft autopilot method, the method comprising a model-based automatic control method. The method of claim 34, characterized in that the method comprises one of the group of control methods, comprising: - Iterative learning based control; - Fault tolerant control; - Resource aware control.