Vertically launchable aircraft with rotor arrangement

Abstract

A vertically launchable aircraft (12) with a rotor assembly (10) comprising a rotor arm assembly (14) movably attached at a first end (16) to a mounting system of the rotor assembly (10), which is attached to the aircraft (12) by means of the mounting system and is movable in at least two positions, namely a folded parking position and an unfolded flight position, wherein the rotor arm assembly (14) further comprises at least two rotor blades (22) mounted on a rotary device (20) at a second end of the rotor arm assembly (14), wherein the at least two rotor blades (22) are each designed to have a shape that, in a force-free rest state, is longitudinally curved in the direction of the aircraft (12), and which essentially follows an outer contour (24) of the aircraft (12).during a rotation from a predetermined rotational speed, the rotor blades (22) are changed into a substantially planar shape in the longitudinal direction due to a predetermined bending stiffness of the respective rotor blades (22), so that the at least two rotor blades (22) in the rest state and in the folded position of the rotor arm device (14) lie substantially flat against a body of the aircraft (12).

Description

[0001] The invention relates to a vertically launchable aircraft with a rotor arrangement.

[0002] The use of aircraft that can operate without dedicated take-off and landing infrastructure, such as an airport, is becoming increasingly common. These aircraft must then be parked on the ground in such a way that they occupy as little space as possible. Many aircraft already meet this requirement by incorporating flight-mode components that can be folded away when parked. For example, existing aircraft propulsion systems with rotor blades can be folded away from a flight position to a parking position. With these latter concepts, a conflict of objectives exists, particularly regarding the rotor blades. On the one hand, the goal is to have the largest possible rotor area while minimizing the disc load during flight.On the other hand, the required parking space should be as small as possible during a parked state, so smaller rotor areas would be advantageous in this respect. The following are some examples from the state of the art that deal, in the broadest sense, with the problem explained above.

[0003] A functional propeller is disclosed as known in US patent 2016 / 0347441A1. This patent discloses a propeller that can be folded and stowed in a compact form and then used for powered flight. The deployable propeller has two or more blades, and each blade consists of several segments that are separated during stowing and interlock during deployment to form an efficient blade. The segmented, extendable propeller maintains its full effective range up to the spinner radius.

[0004] A rotor-powered flying car is also described as known in publication CN 100 513 214 C. In particular, this rotor-powered flying car features a rotor column, a rotor, and a tail assembly that can be easily folded, allowing for lightweight and space-saving storage. Short-term takeoff and landing are possible, achieved through the autonomous and trouble-free folding of the wings.

[0005] Another rotor-type flying car is also known from publication CN 108 437 725 A. The presented technical innovation concerns the field of vehicles, in particular a rotor-type flying car. The rotor-type flying car mainly comprises a car frame and wheel sets installed at the four corners of the car frame, a propeller mechanism installed horizontally on the top of the car frame, and a propeller blade positioned rearward on the top of the car frame. It also includes a tail assembly installed on the rear section of the car frame and a control computer for controlling the propeller mechanism, the propeller blade, and the tail assembly.The rotor-type flying car is designed for short-range take-off and landing schemes and vertical take-off and landing schemes, so that the car does not need to use a special take-off and landing site, thus increasing the area of ​​application.

[0006] Document US 2018 / 0370625A1 describes a rotorcraft capable of switching between airplane and helicopter flight modes during flight. The aircraft comprises at least one tiltable propeller assembly (TPA) that includes a tiltable propeller to change the propeller's axis of rotation between a substantially horizontal airplane mode and a substantially vertical helicopter mode; and a main rotor system for providing lift during helicopter mode, comprising at least one rotor that generates an airflow passing through at least a portion of the propeller blades of the at least one TPA.

[0007] Further relevant examples are shown in documents DE 11 64 834 A and US 2010 / 0 030 403 A1.

[0008] The invention is based on the objective of providing an alternative vertically launchable aircraft with a rotor arrangement that adapts flexibly to different operating conditions.

[0009] According to the invention, a vertically launchable aircraft is provided with a rotor assembly. Such a rotor assembly comprises a rotor arm device movably attached at a first end to a fastening system of the rotor assembly, such that the rotor arm device is attached to the aircraft by means of the fastening system and, in a fastened state, is movable in at least two positions, namely a folded-in parking position and an unfolded flight position, wherein the rotor arm device also comprises at least two rotor blades mounted on a rotary device at a second end of the rotor arm device.The at least two rotor blades are each designed to change their shape from a longitudinally convex form towards the aircraft in a force-free rest state, during rotation above a predetermined rotational speed, due to a (particularly user-defined) predetermined bending stiffness of the respective rotor blades, to a substantially longitudinally flat shape, so that the at least two rotor blades lie flat against the aircraft in the rest state and in a folded position of the rotor arm assembly (saving space). In flight, this ensures energy-efficient operation. In this way, it is possible to provide an alternative rotor arrangement that automatically and flexibly adapts to different operating conditions when installed on an aircraft. The rotor blades are designed to be elastically deformable.They are manufactured in such a way that, in a force-free state, they are pre-curved to a degree that allows them to lie flat against the aircraft in a space-saving manner when at rest and when the rotor arm assembly is folded. The rotor blades are designed with a bending stiffness that enables them to assume an almost completely, or even completely, flat shape under load, thus maximizing efficiency. For example, the rotor blades are designed so that this functionality is available when the aircraft is hovering or in cruise flight. Due to gravity, centrifugal force, and especially the lift-generating forces, a force acts on a rotor blade perpendicular to the rotor plane.With sufficient elasticity of the rotor blades, this leads to a perceptible bending of the blades along their longitudinal axis. This latter effect is specifically exploited in the presented rotor arrangement by pre-stressing or pre-curving the rotor blades in a particular way, so that they assume a deliberately curved shape in a force-neutral state. The combination of pre-formed / pre-stressed and elastically deformable blades results in an ideally flat rotor surface when lift-generating forces are applied to the respective rotor blade. Therefore, a deliberately pre-curved shape of the rotor blades is provided in the unloaded state, with an intentionally elastic design of the rotor blades being an additional deliberate feature.Since at least two rotor blades lie flat against the aircraft in a space-saving manner when at rest and in a folded position of the rotor arm assembly, it is advantageously possible to achieve a particularly space-saving parking position or to maintain an ideal positioning of the rotor assembly with the rotor blades in the "parking" operating state, without requiring any additional assembly processes or the like on the rotor blades. The automatically maintained flat shape of the respective rotor blades during the "flight" operating state then enables maximum energy efficiency due to a low disc load, which is achieved despite the special shape in the resting state that ensures the small parking space of the aircraft with such rotor assembly.A small parking footprint is advantageous because it ensures convenient and practical handling even outside of dedicated aircraft ground infrastructure, such as a separate airport. A space-saving standby mode is particularly beneficial when the parking space is a private parking area or even a garage. This makes activities around the aircraft, which has at least one rotor assembly as defined in the invention, especially easy and practical on the landing field and in the parking and / or handling area. An additional advantage is that the rotor tips, which are also in contact with the aircraft, lie close together in the parked position and are thus protected from potential damage.The shaping of the rotor blades refers to an overall shaping, so that the user-defined bending stiffness, in the sense of the technical interpretation of this term, can be advantageously achieved.

[0010] Further preferred embodiments of the invention result from the other features mentioned in the dependent claims.

[0011] It is thus provided that the pre-curved shape of the respective rotor blades is essentially designed according to an outer contour of the aircraft on which the rotor assembly is mounted, so that the at least two rotor blades, in the resting state and in the folded position of the rotor arm assembly, can be arranged or rest essentially flush against the aircraft body. The aforementioned advantages can therefore be achieved even more effectively. The pre-curved shape of the respective rotor blades is thus preferably designed according to a lateral fuselage profile or an outer contour of the aircraft, at least in this area, so that a particularly space-saving fit of the rotor blades of the presented rotor assembly in the "parked" operating state can be ensured.In other words, the curvature of the lateral fuselage profile, or this outer contour of the aircraft, resembles the respective pre-curved dimension of the rotor blades, so that the at least two rotor blades, when at rest and in a folded position of the rotor arm assembly, lie flat against the aircraft in a space-saving manner, or can be arranged essentially flush against the aircraft's body. The term "outer contour of the aircraft" refers specifically to the respective lateral shape of the exterior of the aircraft or its cockpit.

[0012] In a further embodiment of the invention, the pre-curved shape of the respective rotor blades extends along their entire longitudinal length, allowing the at least two rotor blades to be arranged essentially flat against the aircraft body when at rest and in a folded position of the rotor arm assembly. In other words, the entire length along the longitudinal axes of each rotor blade is pre-curved or pre-stressed, so that when at rest and in a folded position of the rotor arm assembly, they ideally conform to an outer contour, in particular a lateral outer contour of the aircraft or its cabin. Ideally, in the arranged resting state, the rotor blades perfectly conform to the outer contour or cabin contour in the respective area.

[0013] Furthermore, in a further embodiment of the invention, the length of each rotor blade is limited to a maximum length equal to the length of the rotor arm assembly from its first end to its second end and / or a maximum length equal to the length of the aircraft on which the rotor assembly is mounted. The aforementioned advantages are thus even more effectively achieved. In particular, advantageous positioning of the individual rotor blades can be ensured with greater ease.

[0014] Furthermore, in a further embodiment of the invention, the respective rotor blades are provided to comprise at least partially or completely at least one or at least two of the following materials: carbon fiber reinforced plastic, glass fiber reinforced plastic, titanium, and aluminum. These materials or material mixes are particularly advantageous for the previously described shaping, as they provide both a certain degree of stability and a certain degree of flexible elasticity. The technical implementation of the prestress / curvature and elasticity is thus particularly easy to achieve. By way of example, separate areas for the material mix to be used or a special arrangement of the materials used can be provided along a respective longitudinal axis of the rotor blades, so that the respective shape change can be achieved even more effectively.

[0015] Furthermore, in a further embodiment of the invention, it is provided that the respective rotor blades are at least partially constructed using a sandwich design. Rotor blades manufactured in this way can thus be specifically influenced with regard to the desired properties in individual areas, for example in the longitudinal direction of the respective rotor blades, during the individual manufacturing steps, so that the respective shape modification can be achieved even more effectively in the application.

[0016] Furthermore, in a further embodiment of the invention, the rotor blade comprises at least a portion or all of at least one or at least two of the following materials: carbon fiber reinforced plastic, glass fiber reinforced plastic, titanium, and aluminum. These materials, or the material mix, are particularly advantageous for the previously described shaping, as they provide both a certain degree of stability and a certain degree of flexible elasticity. The technical implementation of the prestress / curvature and elasticity is thus particularly easy to achieve. For example, separate areas for the material mix to be used or a special arrangement of the materials can be provided along a longitudinal axis of the rotor blade, so that the respective shape changes are even more easily achieved. The technical implementation of the prestress / curvature and elasticity is thus particularly easy to achieve.

[0017] The presented rotor arrangement and rotor blade can be used, for example, in air taxis and / or passenger transport drones. Generally, they can be used in any multicopter as well as in any eVTOL (eVTOL = electric vertical take-off and landing aircraft).

[0018] Unless otherwise stated in individual cases, the various embodiments of the invention mentioned in this application can be advantageously combined with one another.

[0019] The invention is explained below using exemplary embodiments with reference to the accompanying drawings. These show: Fig. 1 A schematic side view of rotor arrangements on an aircraft in a folded position; Fig. 2 a schematic top view of rotor arrangements on an aircraft in a folded position; Fig. 3 a schematic side view of rotor arrangements on an aircraft in an extended position; Fig. 4 a schematic top view of rotor arrangements on an aircraft in an extended position; Fig. 5 a schematic view of a rotor blade in rotation; Fig. 6 a schematic view of another rotor blade in rotation; Fig. 7 a schematic view of another rotor blade in rotation.

[0020] Fig. Figure 1 shows a schematic side view of rotor assemblies 10 on an aircraft 12 in a folded position. On the left side of the image plane, a rotor assembly 10 is shown, designed to be used as a main rotor, and a rotor assembly 10, designed as a tail rotor, is shown on the right. The two rotor assemblies 10 are similarly constructed, except for the dimensioning of the components, which is tailored to their respective applications. The left rotor assembly 10 is described in more detail below, whereby similar components on the right rotor assembly 10 are designated with the same reference symbols for clarity, despite the size difference.The rotor assembly 10 is shown with a rotor arm device 14, which is movably attached at a first end 16 to a mounting system (not shown) on a flight capsule 18 of the aircraft 12, such that the rotor arm device 14 is attached to the aircraft 12 or the flight capsule 18 of the aircraft by means of the mounting system and is movable in at least two positions in this attached state. As mentioned above, the folded position is shown. Furthermore, the rotor arm device 14 is shown with a rotating device 20 provided at a second end 19, wherein two rotor blades 22 are attached to this rotating device 20 by means of fastening means (not shown).The rotor blades 22 are attached to the rotating device 20 at opposite sides by means of fastening means not shown, so that they rotate with the rotating device 20 when it rotates about its axis of rotation. In an embodiment not shown, it is conceivable that more than two rotor blades 22 are attached to this rotating device 20 in this manner. For example, there could be a total of four. More than four are also conceivable. These rotor blades 22 can also be arranged offset over at least two planes. The two rotor blades 22 shown are each designed to change their shape from a longitudinally convex shape towards the aircraft 12 when at rest, to a substantially flat shape in the longitudinal direction during rotation from a predetermined rotational speed, due to a user-defined bending stiffness of the respective rotor blades 22.In other words, the two rotor blades 22 shown are currently depicted in a resting state and in a folded position of the rotor arm assembly 14, lying flat against the aircraft 12 to save space. In this position, they are arranged in a particularly space-saving manner, so that in this depicted state the aircraft 12 can be parked particularly well, or is shown in the operating state "parked".

[0021] Fig. Figure 2 shows a schematic top view of rotor arrangements 10 on an aircraft 12 in a folded position. Fig. 2 shows the same items as Fig. 1. The same reference numerals therefore apply, and these are not newly introduced here. This top view clearly shows how all rotor blades 22 have a pre-curved shape towards the aircraft 12, so that the rotor blades 22, in their resting state and in a folded position of the rotor arm assembly 14, essentially rest against an outer contour 24 of the aircraft 12 or can be arranged essentially flat against the flight capsule 18, which can also be referred to as the body, of the aircraft 12.

[0022] Fig. Figure 3 shows a schematic side view of rotor arrangements 10 on an aircraft 12 in an unfolded state. Fig. 3 shows the same items as Fig. 1 and Fig. 2. The same reference symbols apply and are not introduced here. The rotor blades 22 are now shown in the operating state of "flying" or "hovering". In other words, the rotor blades 22 are in rotation at a predetermined rotational speed, so that, due to a user-defined bending stiffness of the respective rotor blades 22, they assume a shape that is essentially planar in the longitudinal direction, compared to the previously shown shapes. Fig. 1 and Fig. 2 have changed.

[0023] Fig. Figure 4 shows a schematic top view of rotor arrangements 10 on an aircraft 12 in an unfolded state. Fig. 4 shows the same items as Fig. 1, Fig. 2 and Fig. 3. Therefore, the same reference symbols apply, which are not newly introduced at this point.

[0024] Fig. Figure 5 shows a schematic view of a rotor blade 22 in rotation. The rotor blade 22 is shown attached to a rotating device 20 by means of fasteners (not shown) to a rotor arm device 14 (also not shown) of a rotor assembly 10. The rotor blade 22 is designed to change its shape from a longitudinally convex form at rest to a substantially flat shape, as shown, during rotation above a predetermined rotational speed, due to a user-defined bending stiffness of the rotor blade 22. This allows the rotor blade 22 to be arranged in a space-saving manner at rest on an aircraft 12 (not shown), on which the rotor blade 22 is mounted, and ensures energy-efficient flight during flight.

[0025] Fig. Figure 6 shows a schematic view of another rotor blade 22 in rotation. The rotor blade 22 is shown attached to a rotating device 20 by means of fasteners (not shown) to a rotor arm device 14 (also not shown) of a rotor assembly 10. The rotor blade 22 is designed to change its shape from a longitudinally convex form at rest to a substantially flat shape, as shown, during rotation from a predetermined rotational speed onwards, due to a user-defined bending stiffness of the rotor blade 22. This allows the rotor blade 22 to be arranged in a space-saving manner at rest on an aircraft 12 (not shown), on which the rotor blade 22 is intended, and ensures energy-efficient flight in flight. In contrast to the Fig. 5 different shapes of both the rotating device 20 and the rotor blade 22 in the Fig. Figure 6 is shown as an example. Other forms of these objects are conceivable. Essentially centered along a longitudinal axis of the rotor blade 22, two essentially oval areas 26 are shown.In these respective areas 26, a targeted bending flexibility can be provided by means of a special arrangement of the material or material mix provided there and / or a special shape design of the rotor blade 22, so that the illustrated rotor blade 22 is designed to change its shape from a longitudinally pre-curved shape in the rest state during rotation from a predetermined rotational speed due to a user-defined bending stiffness of the rotor blade 22 into an essentially longitudinally flat shape, as shown, so that the rotor blade 22 can be arranged in a space-saving manner in the rest state on an aircraft 12 (not shown in detail), on which the rotor blade 22 is provided, and ensures energy-efficient flight in the flight state.It is also possible, at least partially, to provide for a change of material in these areas, so that the intended effect described above can be provided in a user-defined manner.

[0026] Fig. Figure 7 shows a schematic view of another rotor blade 22 in rotation. The rotor blade 22 is shown attached to a rotating device 20 by means of fasteners (not shown) to a rotor arm device 14 (also not shown) of a rotor assembly 10. The rotor blade 22 is designed to change its shape from a longitudinally convex form at rest to a substantially flat shape, as shown, during rotation above a predetermined rotational speed, due to a user-defined bending stiffness of the rotor blade 22. This allows the rotor blade 22 to be arranged in a space-saving manner at rest on an aircraft 12 (not shown), on which the rotor blade 22 is mounted, and ensures energy-efficient flight in flight.

[0027] In this case, the following are deviated from the Fig. 5 different shapes of both the rotating device 20 and the rotor blade 22 in the Fig.Figure 6 is shown as an example. Other forms of these objects are conceivable. Essentially centered along a longitudinal axis of the rotor blade 22, two essentially angular areas 28 are shown.In these respective areas 28, a targeted bending flexibility can be provided by means of a special arrangement of the material or material mix provided there and / or a special shape design of the rotor blade 22, so that the illustrated rotor blade 22 is designed to change its shape from a longitudinally pre-curved shape in the rest state during rotation from a predetermined rotational speed due to a user-defined bending stiffness of the rotor blade 22 into an essentially longitudinally flat shape, as shown, so that the rotor blade 22 can be arranged in a space-saving manner in the rest state on an aircraft 12 (not shown in detail), on which the rotor blade 22 is provided, and ensures energy-efficient flight in the flight state.It is also possible, at least partially, to provide for a change of material in these areas, so that the intended effect described above can be provided in a user-defined manner. Reference symbol list 10 Rotor arrangement 12 aircraft 14 Rotor arm device 16 first end 18 Flight capsules 19 second end 20 Rotary device 22 rotor blade 24 Outer contour 26 oval area 28 square area

Claims

[1] A vertically launchable aircraft (12) with a rotor assembly (10) comprising a rotor arm assembly (14) movably attached at a first end (16) to a mounting system of the rotor assembly (10), which is attached to the aircraft (12) by means of the mounting system and is movable in at least two positions, namely a folded parking position and an unfolded flight position, wherein the rotor arm assembly (14) also comprises at least two rotor blades (22) mounted on a rotary device (20) at a second end of the rotor arm assembly (14), wherein the at least two rotor blades (22) are each designed to have a shape that, in a force-free rest state, is longitudinally curved in the direction of the aircraft (12), and which essentially follows an outer contour (24) of the aircraft (12),during a rotation from a predetermined rotational speed, the rotor blades (22) are changed into a substantially planar shape in the longitudinal direction due to a predetermined bending stiffness of the respective rotor blades (22), so that the at least two rotor blades (22) in the rest state and in the folded position of the rotor arm device (14) lie substantially flat against a body of the aircraft (12). [2] Aircraft (12) according to claim 1, wherein the pre-curved shape of the respective rotor blades (22) is provided over the entire longitudinal extent of the respective rotor blades (22) in the longitudinal direction. [3] Aircraft (12) according to one of the preceding claims, wherein the length of each rotor blade (22) is at most a length of the rotor arm device (14) from the first end (16) to the second end (19) and / or at most a length of the aircraft (12) on which the rotor assembly (10) is arranged. [4] Aircraft (12) according to any of the preceding claims, wherein the respective rotor blades (22) comprise at least partially or completely at least one or at least two of the following materials: carbon fiber reinforced plastic, glass fiber reinforced plastic, titanium, aluminum. [5] Aircraft (12) according to claim 4, wherein the respective rotor blades (22) are at least partially constructed in a sandwich design.

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