Vertical takeoff and landing aircraft

Abstract

The invention relates to a vertical takeoff and landing aircraft (1), comprising - a fuselage (2), - two wings (3, 4) which engage the fuselage (2) and extend laterally away from the fuselage (2) in the transverse direction, wherein in the region of each of the two wings (3, 4) at least one electrically driven wing lift unit (5a-5c, 6a-6c) is arranged, wherein the wing lift units (5a-5c, 6a-6c) are designed to enable vertical takeoff and landing as well as hovering of the aircraft (1), and - at least one electrically driven thrust unit (7a, 7b) which is designed to provide thrust for forward flight of the aircraft (1) after takeoff, wherein the aircraft (1) has a pitch trim flap (10) at a rear end of the fuselage (2) with respect to a forward flight direction,which is designed to be pivotable about an axis of rotation (11) extending in the transverse direction of the aircraft (1).

Description

[0001] The present invention relates to an aircraft capable of vertical takeoff and landing, comprising a fuselage, two wings which engage the fuselage and extend laterally away from the fuselage in the transverse direction, wherein in the region of each of the two wings at least one electrically driven wing lift unit is arranged, wherein the wing lift units are designed to enable vertical takeoff and landing as well as hovering of the aircraft, and at least one electrically driven thrust unit which is designed to provide thrust for forward flight of the aircraft after takeoff.

[0002] Vertical takeoff and landing aircraft are already known in various designs from the state of the art. These are often referred to as VTOL aircraft, where "VTOL" is the acronym for "vertical takeoff and landing." A vertical takeoff and landing aircraft is characterized by the fact that it takes off vertically from the ground during takeoff and lands vertically on the ground during landing.

[0003] To enable vertical takeoff and landing, as well as hovering, the aircraft is equipped with at least one wing lift unit (WLU) in the area of each wing. To provide thrust that enables forward flight after vertical takeoff, the aircraft is equipped with one or more thrust drive units, which can be integrated, for example, into the rear of the fuselage and are designed to generate the necessary thrust for the aircraft's forward flight movement during cruise flight.

[0004] An aircraft capable of vertical takeoff and landing is known, for example, from DE 10 2020 127 041 B3.

[0005] Vertical takeoff and landing aircraft can have different loading conditions, which vary, for example, due to the number of occupants and / or the cargo to be carried. Depending on the loading condition, the center of gravity position can vary—particularly in the longitudinal direction of the aircraft. It has been shown that changes in the center of gravity positions resulting from different loading conditions of the aircraft can have a particular impact on the longitudinal stability of the aircraft. In conventional aircraft, whose propulsion units are powered by fuel combustion, the fuel is pumped into specific areas of the fuel tanks during flight to influence the center of gravity position.In the case of a vertical take-off and landing aircraft of this type, which is purely electrically powered, there is no such possibility of influencing the position of the centre of gravity.

[0006] The object of the present invention is to further develop a vertical take-off and landing aircraft of the type mentioned at the outset in such a way that the longitudinal stability of the aircraft can be improved at different load-dependent center of gravity positions.

[0007] The solution to this problem is provided by a generic vertical take-off and landing aircraft having the features of the characterizing part of claim 1. The subclaims relate to advantageous developments of the invention.

[0008] A vertical takeoff and landing aircraft according to the invention is characterized in that the aircraft has a pitch trim tab at a rear end of the fuselage with respect to a forward flight direction, which is designed to pivot about a rotation axis extending in the transverse direction of the aircraft. In the technical world, "pitch" is understood to be the angle of inclination of the aircraft relative to the horizontal. The pitch trim tab is shaped to have an aerodynamically effective outer surface against which an airflow acts.The pitch trim tab can be pivoted vertically upwards or downwards from a neutral position, in which it has no appreciable aerodynamic effect, around the pivot axis extending in the transverse direction of the aircraft, in order to influence the lift or downforce in the rear of the aircraft and thus in particular the longitudinal stability of the aircraft. If the pitch trim tab is pivoted vertically downwards from the neutral position during flight, the oncoming airflow creates an additional upward lift force in the rear of the aircraft. Conversely, if the pitch trim tab is pivoted vertically upwards from the neutral position, the oncoming airflow creates a downward downforce.By adjusting the pitch trim tab, a sufficient torque can be provided around a transversely extending pitch axis of the aircraft to trim the aircraft horizontally depending on the current center of gravity position. Pitch trim can be performed using the pitch trim tab without significantly increasing the complexity and weight of the aircraft.

[0009] In one embodiment, it is proposed that the pitch trim tab be positioned at a distal rear end of the fuselage. This advantageously ensures that the pitch trim tab is always as far away as possible from the current center of gravity position of the aircraft, regardless of the load.

[0010] In one embodiment, it is possible for the pitch trim tab to have an outer contour that tapers outward in sections. For example, the pitch trim tab can have a drop-shaped outer contour, which is particularly advantageous from an aerodynamic perspective.

[0011] In order to provide a further possibility for adjusting the inclination of the aircraft, it is proposed in an advantageous embodiment that the aircraft comprises at least one electrically driven inclination adjustment unit.

[0012] In a preferred embodiment, it is possible for each of the two wings to comprise an electrically driven inclination adjustment unit in a rear region.

[0013] In a particularly preferred embodiment, the pitch trim tab is arranged between the pitch adjustment units. The possibility of adjusting the pitch trim tab at the rear end, preferably at the distal rear end, of the aircraft's fuselage not only enables horizontal trimming, but also advantageously improves the airflow between the two pitch adjustment units and, moreover, the overall airflow around the fuselage. Overall, the pitch trim tab thus increases the aerodynamic efficiency of the aircraft. Furthermore, it has been shown that the pitch adjustment units, in conjunction with the pitch trim tab arranged between them, advantageously ensure effective noise reduction during aircraft flight.The provision of the pitch trim tab also results in increased redundancy when it comes to adjusting the aircraft's pitch about the lateral pitch axis. In addition to the two electrically driven pitch adjustment units, the pitch can also be adjusted, at least within a certain range, using the pitch trim tab.

[0014] In order to enable control of the vertical takeoff and landing aircraft around its longitudinal axis (so-called "rolling"), particularly during forward flight, an advantageous embodiment proposes that each of the two wings has an aileron. These ailerons are preferably designed as movable flaps. To initiate a rolling movement of the aircraft, the ailerons are pivoted simultaneously in opposite directions. The aileron that is pivoted downward increases the lift on the side of the respective wing, whereas the aileron that is pivoted upward reduces the lift on the side of the respective wing, resulting in a corresponding rolling movement of the aircraft around its longitudinal axis.

[0015] Preferably, the electrically driven wing lift units, thrust units, and pitch adjustment units each have a ducted propeller. Ducted propellers comprise a rotor-side propeller and a stator-side shroud that radially surrounds the propeller and defines a flow channel for the air flowing over the propeller.

[0016] Further features and advantages of the present invention will become clear from the following description of a preferred embodiment with reference to the accompanying drawings. Fig. 1 is a schematically simplified plan view of a vertical take-off and landing aircraft according to an embodiment of the invention, Fig. 2 a section through a fuselage of the vertical take-off and landing aircraft along a line II-II in Fig. 1.

[0017] With reference to Fig. 1 and Fig. 2, a vertical takeoff and landing aircraft 1 comprises a fuselage 2, which provides, among other things, a passenger compartment 20 for accommodating occupants 100, 101, 102, 103 and, if appropriate, also a cargo space for accommodating cargo, as well as a first wing 3 and a second wing 4. The two wings 3, 4 are attached to the fuselage 2 and extend outwardly in the transverse direction (y-direction) of the aircraft 1, laterally away from its fuselage 2. The two wings 3, 4 are designed and shaped such that they generate aerodynamic lift for the aircraft 1 during a forward flight phase.

[0018] The aircraft 1 presented here is capable of vertical takeoff and landing. This means that the aircraft 1 lifts off vertically from the ground during takeoff and lands vertically on the ground during landing. To enable such vertical takeoff and landing of the aircraft 1 and, in addition, also hovering, the aircraft 1 has at least one electrically driven wing lift unit 5a-5c, 6a-6c, frequently also referred to as a "wing lift unit" (WLU for short), at least in the area of each of the two wings 3, 4. In the exemplary embodiment shown here, each of the two wings 3, 4 has three electrically driven wing lift units 5a-5c, 6a-6c embedded therein. Preferably, each of the wing lift units 5a-5c, 6a-6c can each have a ducted propeller.Ducted propellers comprise a rotor-side propeller and a stator-side shroud that encloses the propeller radially on the outside and defines a flow channel for the air flowing over the propeller.

[0019] The vertical takeoff and landing aircraft 1 requires a propulsion architecture that meets the requirements for hovering, forward flight (cruise flight), and a transition from hovering to forward flight (and vice versa). To provide propulsion for the aircraft 1 after takeoff, the aircraft 1 has at least one electrically driven propulsion unit 7a, 7b. In the present exemplary embodiment, the aircraft 1 has two electrically driven propulsion units 7a, 7b near a rear region of the fuselage 2, which can be integrated into the fuselage 2, for example. Each of the electrically driven propulsion units 7a, 7b preferably also comprises a ducted propeller, the basic structural design of which has already been explained above.

[0020] In order to enable control of the vertical takeoff and landing aircraft 1 about its longitudinal axis 8 extending in the x-direction (so-called "rolling"), particularly during forward flight, each of the two wings 3, 4 has an aileron 30, 40 on a trailing edge. These ailerons 30, 40 are preferably designed as movable flaps. To initiate a rolling movement of the aircraft 1, the ailerons 30, 40 are pivoted simultaneously in opposite directions. The aileron 30, 40 that is pivoted downward increases the lift on the side of the respective wing 3, 4, whereas the aileron 30, 40 that is pivoted upward reduces the lift on the side of the respective wing 3, 4, resulting in a corresponding rolling movement of the aircraft 1 about its longitudinal axis 8.

[0021] In order to enable tilting movements of the aircraft 1 about a tilt axis extending in the transverse direction and thus orthogonal to the longitudinal axis 8, the aircraft 1 has, in a rear region of the two wings 3, 4, two electrically driven tilt adjustment units 9a, 9b spaced apart from one another in the transverse direction, which preferably also each have a ducted propeller. By means of the two electrically driven tilt adjustment units 9a, 9b, it is possible to generate a tilting moment of the aircraft 1 about the tilt axis (a so-called "pitch"). This tilting moment, generated during operation of the tilt adjustment units 9a, 9b, can, for example, also compensate for other tilting moments of the aircraft 1 in order to stabilize the hovering flight of the aircraft 1. In the specialist world, the tilt angle of the aircraft 1 relative to the horizontal is often also referred to as "pitch".

[0022] In Fig. 1 and Fig. 2 shows a first center of gravity position S1 of the aircraft 1, which represents the position of the center of gravity in the unloaded state, i.e., without the occupants 100, 101, 102, 103 and without any other load. In the exemplary embodiment shown here, the occupants 100, 101, 102, 103 are positioned in pairs in two rows of seats one behind the other within the passenger compartment 20. Due to the additional mass of the occupants 100, 101, 102, 103 and possibly due to a further additional load, depending on the loading state, starting from the first center of gravity position S1, a shift of the center of gravity of the aircraft 1 in the longitudinal direction (x-direction) forwards into a second center of gravity position S2 results. A thrust center T1 of the aircraft 1 is located between the first center of gravity position S1 and the second center of gravity position S2. Furthermore, Fig. 1 and Fig. 2 shows the position of a neutral point N of the aircraft 1. This neutral point N is often referred to as the aerodynamic center.

[0023] It has been shown that the above-explained changes in the longitudinal center of gravity positions S1, S2, resulting from different loading conditions, can influence the longitudinal stability of aircraft 1. In conventional aircraft, whose propulsion units are powered by fuel combustion, the fuel is specifically pumped into specific areas of fuel tanks to influence the center of gravity position. Since the aircraft 1 presented here is purely electrically powered, such a possibility for influencing the center of gravity position does not exist in this case.

[0024] The aircraft 1 has a pivotable pitch trim flap 10 at a distal rear end of the fuselage 2 with respect to the forward flight direction, which, starting from a Fig. 2, can be pivoted upwards or downwards in the vertical direction (vertical direction, z-direction) about a pivot axis 11 extending in the transverse direction of the aircraft 1, in order to thereby generate a lift (a force F1 directed upwards in the z-direction) or a downforce (a force F2 directed downwards in the z-direction) and thus in particular to influence the longitudinal stability of the aircraft 1. As in the Fig. As can be seen from the plan view of the aircraft 1 shown in Figure 1, the pitch trim flap 10 is arranged between the two inclination adjustment units 9a, 9b which are spaced apart from one another in the transverse direction.

[0025] The pitch trim flap 10 is arranged at the distal rear end of the fuselage 2 so that it is always as far away as possible from the current center of gravity position S1, S2 of the aircraft 1. As shown in Fig. As can be seen in Figure 2, the pitch trim flap 10 has a drop-like, outwardly tapered outer contour with a correspondingly large aerodynamically effective surface. By adjusting the pitch trim flap 10, a sufficiently large torque can be provided around the transversely extending pitch axis of the aircraft 1 to trim the aircraft 1 horizontally depending on the current center of gravity position S1, S2.

[0026] If the pitch trim tab 10 is moved from the position shown in Fig. 2 is pivoted clockwise in a vertical direction downwards, the incoming air generates an additional upward lift force F1 in the tail area of the aircraft 1. Conversely, if the pitch trim flap 10 is pivoted from the neutral position shown in Fig. 2 is pivoted counterclockwise in a vertical direction upwards, the incoming air flow generates a downward downforce (downforce F2).

[0027] The possibility of adjusting the pitch trim flap 10 at the distal rear end of the fuselage 2 of the aircraft 1 not only enables trimming in the horizontal plane, but also advantageously improves the air flow between the two inclination adjustment units 9a, 9b and, moreover, also the entire air flow around the fuselage 2. Overall, the pitch trim flap 10 thus increases the aerodynamic efficiency of the aircraft 1. The pitch trim can be performed by means of the pitch trim flap 10 without significantly increasing the complexity and weight of the aircraft 1.

[0028] Furthermore, the inclination adjustment units 9a, 9b, in cooperation with the pitch trim flap 10, advantageously ensure effective noise reduction during flight operation of the aircraft 1.

[0029] The provision of the pitch trim flap 10 also results in increased redundancy when it comes to adjusting the inclination of the aircraft 1 relative to the pitch axis. In addition to the two electrically driven tilt adjustment units 9a, 9b, the inclination can also be adjusted, at least within a certain range, using the pitch trim flap 10. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2020 127 041 B3

[0004]

Claims

[1] Vertical take-off and landing aircraft (1), comprising - a hull (2), - two wings (3, 4) which engage the fuselage (2) and extend laterally away from the fuselage (2) in the transverse direction, wherein in the region of each of the two wings (3, 4) at least one electrically driven wing lift unit (5a-5c, 6a-6c) is arranged, wherein the wing lift units (5a-5c, 6a-6c) are designed to enable vertical take-off and landing as well as hovering of the aircraft (1), and - at least one electrically driven propulsion unit (7a, 7b) which is designed to provide propulsion for forward flight of the aircraft (1) after takeoff, characterized bythat the aircraft (1) has a pitch trim flap (10) at a rear end of the fuselage (2) with respect to a forward flight direction, which is designed to be pivotable about an axis of rotation (11) extending in the transverse direction of the aircraft (1). [2] Vertical take-off and landing aircraft (1) according to claim 1, characterized by that the pitch trim tab (10) is positioned at a distal rear end of the fuselage (2). [3] Vertical take-off and landing aircraft (1) according to one of claims 1 or 2, characterized by that the pitch trim flap (10) has an outer contour that tapers outwards in sections. [4] Vertical take-off and landing aircraft (1) according to one of claims 1 to 3, characterized by that the pitch trim tab (10) has a drop-shaped outer contour. [5] Vertical take-off and landing aircraft (1) according to one of claims 1 to 4, characterized bythat the aircraft (1) comprises at least one electrically driven inclination adjustment unit (9a, 9b). [6] Vertical take-off and landing aircraft (1) according to claim 5, characterized by that each of the two wings (3, 4) comprises an electrically driven inclination adjustment unit (9a, 9b) in a rear region. [7] Vertical take-off and landing aircraft (1) according to claim 6, characterized by that the pitch trim flap (10) is arranged between the inclination adjustment units (9a, 9b). [8] Vertical take-off and landing aircraft (1) according to one of claims 1 to 7, characterized by that each of the two wings (3, 4) has an aileron (30, 40).

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