Aircraft propulsion system for an aircraft, as well as aircraft with a corresponding aircraft propulsion system and method for operating an aircraft propulsion system

Abstract

Aircraft propulsion (3) for an aircraft (1), comprising: - a propeller (4) which is arranged on a drive shaft (5) of the aircraft propulsion system (3) and can be driven about a rotational axis (6) of the propeller (4) by means of the drive shaft (5), - a propeller spinner (8) which is arranged in the direction (9) of the rotation axis (6) of the aircraft propulsion (3) of the front area (10) of the propeller (4), characterized by - a propeller spinner adjustment device (12) for definingly changing the volume of the propeller spinner (8) in a radial direction (13) to the axis of rotation (6), wherein the volume of the propeller spinner (8) can be changed in a radial direction (13) from a basic state to at least an expansion state with the propeller spinner adjustment device (12) such that a propeller front surface (14) of the propeller (4) is covered at least partially by the propeller spinner (8) with its volume changed, more towards the front than in the basic state.

Description

[0001] The invention relates to an aircraft propulsion system, which includes a propeller arranged on a drive shaft of the aircraft propulsion system and which can be driven about a rotational axis of the propeller by means of the drive shaft. Furthermore, the aircraft propulsion system includes a propeller spinner, which is arranged in the forward region of the propeller when viewed in the direction of the rotational axis of the aircraft propulsion system.

[0002] Furthermore, the invention relates to an aircraft with at least one aircraft propulsion system. The invention also relates to a method for operating an aircraft propulsion system, wherein a propeller of the aircraft propulsion system, which is arranged on a drive shaft of the aircraft, is driven by the drive shaft about a rotational axis of the propeller.

[0003] For example, "Personal Air Vehicles" (PAVs) or aircraft capable of vertical takeoff and landing (eVTOLs, "electric Vertical Take-Off and Landing aircraft") are being developed for future mobility solutions. These aircraft concepts can utilize a single propeller for both vertical takeoff and cruise flight. For instance, the "tilt-wing" or "tilt-rotor" concept can be applied. In contrast to "lift-and-cruise" concepts, these designs allow for the use of separate motor-propeller units for both takeoff and cruise flight, thus minimizing the aircraft's mass.

[0004] The efficiency of the propeller has a significant influence on the range, particularly the electric range, of such aircraft. However, propeller design in these concepts often represents a compromise, as it must be optimized for both hovering (or takeoff) and cruising flight. For example, conventional aircraft typically use variable-pitch propellers. With these, the individual propeller blades rotate synchronously around their longitudinal axis, thus adapting to the respective flight situation. This allows for good efficiency both during takeoff (when there is no airspeed due to the aircraft's movement) and during cruising flight (when airspeed is determined by the aircraft's speed).

[0005] The prior art reveals, for example, variable propeller spinners for targeted control of the cooling airflow for combustion engines located behind them, as well as propeller spinners optimized for aircraft with a "tilt rotor concept".

[0006] For example, US patent 2020 / 0223 552 A1 discloses a rotor assembly for use in an aircraft. This assembly comprises a rotor hub, a spindle structure which includes a spinner opening, and a rotor blade. The rotor blade has a rotor root located near the rotor hub. The rotor assembly also features a movable fairing surface that rests, at least partially, along the rotor hub.

[0007] Furthermore, US 2018 / 0 334 240 A1 discloses, as a spinner shroud, a base configured to be fixed relative to a hub system; a movable spinner assembly movable relative to the base; wherein the movable spinner assembly comprises a first movable element and a second movable element. Each first and second movable element is selectively configurable between a closed position and a retracted position, in which the movable spinner assembly has a reduced shape and / or volume.

[0008] One disadvantage is that, since the rotor blade as a whole is rotated, but the airflow situation differs near the hub (small radius) and near the blade tip (large radius), this represents a compromise that does not fully utilize the propeller's efficiency. Similarly, varying the engine speed and angle of attack offers only limited possibilities (degrees of freedom) for increasing efficiency.

[0009] One object of the present invention is therefore to improve the efficiency of an aircraft propulsion system, in particular a propeller.

[0010] This problem is solved by an aircraft propulsion system, an aircraft, and a method according to the independent patent claims. Meaningful further developments arise from the dependent patent claims.

[0011] One aspect of the invention relates to an aircraft propulsion system for an aircraft, comprising: - a propeller which is arranged on a drive shaft of the aircraft engine and can be driven by means of the drive shaft about a rotational axis of the propeller, - a propeller spinner, which is arranged in the direction of the rotation axis of the aircraft propulsion, the front part of the propeller being considered, - a propeller spinner adjustment device for definingly changing the volume of the propeller spinner in a radial direction to the axis of rotation.

[0012] The aircraft propulsion system according to the invention allows, for example, an aircraft or flying machine to be operated more efficiently. By precisely changing the volume of the propeller spinner using the propeller spinner adjustment device, the propeller's efficiency can be increased. For example, an efficiency increase of 10%, in particular 20%, and especially 25% compared to the prior art propeller can be achieved.

[0013] The aircraft propulsion system according to the invention can increase the range of the aircraft during cruise flight. This is achieved through the improved efficiency of the propulsion system. For example, the more efficient propulsion system allows the aircraft to carry more payload. In particular, the aircraft propulsion system according to the invention allows the aircraft's payload to be increased while maintaining the same range.

[0014] In particular, a variable propeller spinner for aircraft can be provided using the propeller spinner adjustment device. For example, in prior art propellers, it can occur that during cruise flight, local downforce occurs near the propeller hub instead of lift (propeller thrust). Near the hub, propeller blades tend to slow the aircraft instead of propelling it. While a positive propeller thrust (lift) is still generated when averaged over the propeller radius, this comes at the cost of reduced efficiency. These disadvantages can be mitigated, for example, by the defined adjustment of the propeller spinner volume according to the invention, allowing such negative areas near the hub to be sealed off or covered. This increases the efficiency of the propeller and, in particular, the aircraft's propulsion system.In particular, the propeller spinner can be a dynamically adjustable propeller spinner, whose size or volume can be adjusted using the propeller spinner adjustment device, so that, for example, efficiency-reducing areas of the propeller can be covered or sealed off. This can increase the overall efficiency of a flight.

[0015] In particular, the propeller spinner adjustment device allows for a defined change or adjustment of the volume or diameter of the propeller spinner, thereby increasing the efficiency of the aircraft propulsion and the aircraft during cruise flight.

[0016] For example, the aircraft could be a convertible aircraft, which can be described as capable of vertical takeoff and landing. Convertible aircraft are particularly capable of changing flight modes (flight states) during flight. Flight states relevant to a convertible aircraft include, for example, hovering in helicopter mode, the subsequent transition from vertical to horizontal flight, and horizontal flight as a fixed-wing aircraft.

[0017] For example, the aircraft propulsion system could be a tilt rotor. For example, the aircraft could be designed as a tilt-wing aircraft.

[0018] Specifically, the aircraft is a "vertical take-off and landing aircraft" (eVTOL). Therefore, an aviation propulsion system can be used for such a specially designed aircraft. For example, the aircraft could be part of an urban air mobility system, such as air taxis.

[0019] In particular, the aircraft is capable of performing a vertical takeoff and a vertical landing.

[0020] The propeller can refer in particular to the air screw of an aircraft. With the help of the propeller, for example, shaft power of an aircraft engine or thrust of a shaft turbine can be generated.

[0021] In particular, the propeller can be designed as a variable-pitch propeller, where the pitch angle of the propeller blades can be adjusted, thus adapting the angle of attack to different operating conditions of the aircraft. The propeller and the axis of rotation can be driven by the drive shaft, allowing the propeller to be brought to a predetermined rotational speed. For example, the drive shaft can be designed parallel to the axis of rotation.

[0022] A propeller spinner can be an aviation-related component, a streamlined fairing located in front of the propeller, either in the center of the engine or, in the case of turbofan engines, in the case of turbofan engines. The propeller spinner serves, for example, to reduce drag and thus improve airflow to the aircraft's engine.

[0023] For example, the aircraft propulsion system can be referred to as the engine or engine unit of the aircraft.

[0024] For example, a propeller spinner can be used to cover at least part of, or even completely cover, the propeller head. For instance, the propeller spinner can extend right up to the cowling of an aircraft engine. Such a cowling can be called, for example, an engine cowling or engine nacelle.

[0025] Specifically, the propeller spinner adjustment device can be an electromechanical or mechanical device. For example, a control and / or regulating device can be used to actuate and / or regulate the propeller spinner adjustment device in order to change the volume of the propeller spinner. In particular, the changing, adjusting, or setting of the propeller spinner volume is done automatically.

[0026] In particular, the volume changes depending on the flight attitude of the aircraft operation or the aircraft itself.

[0027] Optionally, the propeller spinner can be radially expanded using the propeller spinner adjustment device to change its volume. Specifically, this results in a radial expansion or radial widening of the propeller spinner's volume.

[0028] If necessary, the volume of the propeller spinner can be expanded in a defined manner using the propeller spinner adjustment device.

[0029] In particular, changing the volume of the propeller spinner involves a deliberate adjustment or modification of its volume. The volume of the propeller spinner can be changed system-wide. Therefore, the change in the volume of the propeller spinner can be variably controlled.

[0030] The aircraft propulsion system according to the invention minimizes or counteracts disadvantages of using one and the same propeller for vertical take-off or hovering and cruising flight.

[0031] The propeller spinner adjustment device is designed to allow the volume of the propeller spinner to be changed from a basic state to at least one expanded state, such that the frontal area of ​​the propeller is at least partially covered by the modified propeller spinner to a greater extent than in the basic state. Specifically, the propeller spinner, with its side facing the propeller, covers the frontal area at least partially. For example, the propeller spinner adjustment device can automatically change the volume of the propeller spinner from a basic state to at least one expanded state, depending on a control variable. In the expanded state, for instance, the volume of the propeller spinner is larger than its volume in the basic state.In particular, in the expanded state, the volume of the propeller spinner is extended or enlarged compared to the volume of the propeller spinner in the ground state.

[0032] In particular, the volume of the propeller spinner can be variably changed from its ground state. Specifically, the volume can be gradually expanded or enlarged in the expansion state.

[0033] In the initial state, the volume of the propeller spinner has not been changed by the propeller spinner adjustment device. In the initial state, the volume of the propeller spinner is neither changed nor influenced by the propeller spinner adjustment device.

[0034] For example, depending on the position of the aircraft's propulsion system or the aircraft's flight phase, an expansion state adapted to the specific situation and conditions can be selected from a multitude of possible volume expansion states. In particular, a wide variety of expansion states can be set. Thus, the volume of the propeller spinner can be transformed from its initial state into an expansion state adapted to the specific situation.

[0035] In the expanded state, the propeller's leading edge can be at least partially, and preferably completely, covered or obscured by means of the expanded propeller spinner. Due to the increased volume of the propeller spinner in at least one expanded state compared to the ground state, the leading edge of the propeller can be covered more closely or further. This can be done dynamically using the propeller spinner adjustment device.

[0036] For example, in the expanded state, an inner propeller area (relative to the axis of rotation) can be at least partially covered or sealed off, thus minimizing any negative effects on the aircraft's flight operations in this area. In particular, sealing or covering the propeller's leading edge can at least reduce the flow velocity in such a covered area, resulting in no, or only a minimal, braking effect. This can increase the propeller's efficiency, or overall efficiency, during the aircraft's cruise flight.

[0037] In particular, the area or side of the propeller extending towards the propeller spinner can be at least partially covered by the modified volume. The side or area of ​​the propeller spinner facing the propeller can at least partially cover the propeller's frontal area. For example, the frontal area of ​​the propeller can be the side of the propeller that faces forward in the longitudinal direction of the aircraft propulsion system. Specifically, the side of the propeller spinner facing the propeller can be the side that rests against the propeller and extends, in particular, towards the propeller's center point.

[0038] By at least partially covering the propeller's leading edge, unfavorable airflow patterns near the hub during cruise flight can be prevented or reduced. This prevents the generation of only minimal thrust but negative drag. In particular, in many operating situations, thrust at high speeds can even be negative, causing the inner part of the propeller to slow the airflow. This can also be minimized or reduced by at least partially covering the propeller's leading edge. This results in greater efficiency during cruise flight, as energy consumption can be reduced and range increased. Furthermore, it results in lower noise levels during cruise flight, both inside and outside the aircraft.

[0039] In a further embodiment, it is provided that at least one radially inner partial surface of the propeller front surface, extending radially outwards from the axis of rotation, is covered by the propeller spinner in its radially expanded state, and in particular, is covered more radially than in the ground state. Thus, an inner propeller area is at least partially covered by the propeller spinner in the expanded state.

[0040] For example, the radially inner partial area of ​​the propeller frontal area corresponds to 20%, in particular 30%, in particular 40% of the total area of ​​the propeller frontal area.

[0041] In particular, the inner sub-area can, for example, correspond to one-third of the total area of ​​the propeller frontal surface. Specifically, the inner sub-area of ​​the propeller frontal surface is located in the region of a propeller hub or rotor hub of the rotor.

[0042] With the aid of the propeller spinner, at least the portion of the propeller's frontal area located directly in the region of the axis of rotation can be covered in the expanded state. Specifically, the inner portion is the area of ​​the propeller's frontal surface that extends away from the distal end of the propeller. The proportion of the inner area that is covered can vary depending on the selected expansion state. In particular, depending on the expansion state selected by the propeller spinner adjustment mechanism, a specific area can be determined that is covered within the inner portion of the propeller's frontal surface.

[0043] In one embodiment, it is further provided that a rear end of the propeller spinner facing the propeller is radially expanded in the expanded state compared to the ground state. Consequently, the area or side of the propeller spinner extending towards the propeller can be radially expanded. This allows the propeller's front surface, particularly the inner section, to be efficiently covered or concealed, at least partially.

[0044] For example, the axis of rotation of the propeller spinner corresponds to the axis of rotation of the propeller.

[0045] In one embodiment, the propeller further comprises at least two propeller blades, each connected to the drive shaft at a mounting point. A portion of each of the at least two propeller blades, extending towards the mounting point and towards a radial end region, is at least partially covered by the propeller spinner, the volume of which is adjusted by the propeller spinner adjustment device. In particular, the respective portion of each propeller blade can be located within the radial inner portion of the propeller's front surface.In other words, the respective surface area of ​​the at least two propeller blades, which extends within the radially inner part of the propeller front surface, can be at least partially, and in particular completely, covered or sealed off by means of its propeller spinner, which has a modified volume, in the expanded state.

[0046] In particular, the propeller can have at least two propeller blades, and especially multiple propeller blades. For example, the propeller blades can be referred to as blades or rotor blades.

[0047] The at least two propeller blades are each arranged at the propeller's mounting point and thus connected to the drive shaft, so that a rotational movement of the propeller moves or rotates the propeller blades around the axis of rotation at a predetermined speed. The mounting point of the propeller is, in particular, the center of the propeller. The axis of rotation runs through the mounting point. For example, the mounting point can be referred to as the rotor hub, propeller hub, or hub. The mounting point serves, firstly, to hold or fix the rotor blades and, secondly, to mechanically connect the rotor to the drive shaft, so that a force generated by the drive shaft can be transmitted to the rotor, in particular to the rotor blades. This serves, in particular, to propel the aircraft.

[0048] The radial end region of each rotor blade can be a distal end of that blade. Specifically, the radial end region of each rotor blade is located away from the attachment point.

[0049] In a further embodiment of the invention, the respective surface area of ​​the at least two propeller blades corresponds to at least 20%, in particular 30%, in particular 40%, of the respective propeller frontal area of ​​the at least two propeller blades. In other words, the respective surface area is the radially inner portion of the propeller frontal area, which is covered proportionally according to the set expansion state of the propeller spinner. For example, one-third of the respective propeller frontal area of ​​the at least two propeller blades can be covered by the expanded propeller spinner. Thus, an inner propeller area extending in the region of the propeller hub is at least partially, and in particular completely, covered by the expanded volume of the propeller spinner.For example, the respective area of ​​at least one propeller surface can correspond to any value between 15% and 45% of the respective propeller frontal area of ​​at least two propeller blades. This percentage value is set depending on a stage or category of the propeller spinner's expansion state.

[0050] In one embodiment, the propeller spinner is at least partially, and in particular entirely, made of a material exhibiting anisotropic elasticity, and in particular, the propeller spinner has at least one stiffening element on its outer surface in the circumferential direction. Specifically, the material of the propeller spinner exhibits anisotropic elastic behavior, at least partially, and in particular entirely. Anisotropic elastic behavior means that a property, especially a material property, is direction-dependent. Thus, for example, the material that forms part of the propeller spinner can exhibit different elastic behavior in different directions. For example, the propeller spinner can therefore have high elasticity in the circumferential direction and lower bending elasticity in the axial or radial direction.Due to its high elasticity in the circumferential direction, the propeller spinner's volume can expand radially. Consequently, its diameter can increase in the circumferential direction. Due to its lower bending elasticity in the axial and radial directions, the propeller spinner exhibits a defined shape stability. This is particularly important during flight, as high, and especially extreme, forces act on the propeller and, in particular, on the propeller spinner located in front of the propeller.

[0051] Additionally or instead, the propeller spinner can have at least one or more stiffening elements on its outer surface in the circumferential direction. These additional stiffening elements ensure that the propeller spinner maintains a stable shape in both its inert and expanded states, enabling efficient flight of the aircraft. For example, the at least one stiffening element can consist of several sub-elements. This stiffening element is located on the outer surface or outer shell of the propeller spinner, particularly when viewed in the circumferential direction. The propeller spinner material can be, for example, glass fiber-reinforced polypropylene. This material exhibits, in particular, different moduli of elasticity in two spatial directions, up to a factor of approximately 3.

[0052] Furthermore, the material could be polyurethane (TPU). This exhibits high elasticity and can be reinforced with carbon fibers (CF), for example.

[0053] For example, the propeller spinner can have a honeycomb structure, at least in some areas, which exhibits different elastic behavior in different spatial directions. Such a structure can be realized, for example, using an anisotropic TPU-CF material.

[0054] In a further embodiment, it is provided that a shell of the propeller spinner is designed as a paraboloid, and in particular, that the shell of the propeller spinner is rotationally symmetrical and radially expandable about the axis of rotation. The shell of the propeller spinner is, in particular, the outer casing or outer surface of the propeller spinner.

[0055] A paraboloid is a geometric shape of a second-order surface. In particular, the shell of the propeller spinner can be designed as an elliptical paraboloid. The shell of the propeller spinner is radially expandable to change or increase its volume. The shell is rotationally symmetrical about the axis of rotation and can be radially expanded. This allows the volume of the propeller spinner to be changed or increased to cover at least a portion of the propeller's leading edge.

[0056] In particular, the casing may be a housing, a cover, or a fairing for the propeller spinner.

[0057] In particular, the propeller spinner can be designed to be elastic.

[0058] In one embodiment, the propeller spinner is provided to have several adjustable lamellae as an outer covering by means of the propeller spinner adjustment device, wherein the several lamellae are arranged overlapping each other in a basic state of the volume of the propeller spinner in the direction of rotation around the axis of rotation, and for changing the volume of the propeller spinner, the several lamellae are adjusted by means of the propeller spinner adjustment device such that the several lamellae have a predetermined distance from each other.

[0059] Specifically, the multiple louvers can be automatically controlled and thus varied to change the volume using the propeller spinner adjustment mechanism. In one possible example, the propeller spinner, as a shell or outer casing, can have several movable elements, such as the multiple louvers. Their position relative to each other can be changed to alter the volume of the propeller spinner.

[0060] To expand the volume of the propeller spinner, the position and arrangement of the multiple lamellae are changed so that they are spaced further apart. This occurs particularly in the expanded state of the propeller spinner. In the initial state, the lamellae are arranged overlapping each other. To change the volume of the propeller spinner to an expanded state, the lamellae are moved from their overlapping arrangement to a spaced-apart arrangement, thus increasing the volume of the propeller spinner. Depending on the type and status of the expanded state, the arrangement of the lamellae can be varied. This can be achieved, in particular, via a mechanical connection between the lamellae and the propeller spinner adjustment mechanism.In particular, the adjustment of the louvers is carried out automatically or automatically with the help of the propeller spinner adjustment device.

[0061] In particular, the lamellae are arranged or positioned around the axis of rotation as the outer covering of the propeller spinner. Specifically, the adjustment of the multiple lamellae in the circumferential direction is achieved so that, viewed circumferentially, they have a predetermined, and in particular increased, distance from one another. For example, in the expanded state, the multiple lamellae can be arranged so that they no longer overlap. In a possible expanded state, the multiple lamellae can be arranged to abut each other, at least partially, at their outer edges.

[0062] In particular, the multiple lamellae can be used to form a cup-shaped outer casing or shell for the propeller spinner. In other words, the multiple lamellae can be fanned out to achieve the expanded state of the propeller spinner.

[0063] In particular, the propeller spinner can consist externally of several lamellae, the volume or size of which is variable by the relative displacement of the lamellae to each other.

[0064] In one embodiment, the propeller spinner adjustment device is arranged in an interior region of the propeller spinner, with a movable adjustment element of the propeller spinner adjustment device being located on the front side of the propeller spinner facing away from the propeller. This movable adjustment element is configured to be moved from the side facing away from the propeller towards the propeller within the interior region by means of the propeller spinner adjustment device, thereby changing the volume of the propeller spinner. In particular, the volume of the propeller spinner can be changed by means of a mechanical mechanism.

[0065] For example, the movable adjustment element could be an adjustment cone. The interior of the propeller spinner could, for example, be a hollow interior space.

[0066] The movable adjustment element is located within the interior of the propeller spinner and can be controlled for movement by means of the propeller spinner adjustment device. In the propeller spinner's initial state, the movable adjustment element is located on the front side of the spinner facing away from the propeller, i.e., in the area of ​​the spinner's tip. For the expanded state of the propeller spinner, the movable adjustment element can be controlled and moved such that it moves, or is pulled, from the front side of the spinner facing away from the propeller towards the propeller. This movement of the adjustment element from the front to the rear of the spinner causes a change in the spinner's volume.Thus, with the help of a mechanical adjustment mechanism, the volume of the propeller spinner can be adjusted to cover at least part of the propeller's front surface.

[0067] In one embodiment, the propeller spinner adjustment device includes a pneumatic adjustment unit. This pneumatic adjustment unit allows for the control of at least one inflatable element, located within the propeller spinner, to change its volume. This enables the volume of the propeller spinner to be adjusted simply by inflating or deflating the inflatable element. Specifically, in the propeller spinner's initial state, the inflatable elements are either uninflated or only partially inflated.

[0068] In the expanded state of the propeller spinner, the inflatable elements are partially, or more specifically, fully inflated. Depending on the desired expansion state and the amount of the propeller frontal area to be covered, the inflatable elements can be inflated to varying degrees. This can be achieved using the propeller spinner adjustment mechanism. Specifically, at least one or more inflatable elements can be located inside the propeller spinner. Thus, the volume of the propeller spinner can be changed by means of a pneumatic mechanism.

[0069] In particular, the volume of the propeller spinner can be changed by pneumatic or hydraulic adjustment.

[0070] For example, the inflatable elements can be designed as inflatable rings, which are arranged circumferentially in the inside of the propeller spinner.

[0071] Another aspect of the invention relates to an aircraft with at least one aircraft propulsion system according to the previous aspect or an advantageous embodiment thereof. According to the invention, in hovering flight of the aircraft, the rotational axis of the propeller is aligned with a longitudinal direction of the aircraft at a predetermined angle to the vertical, and in cruise flight of the aircraft, the rotational axis of the propeller is aligned with the longitudinal direction of the aircraft at a predetermined angle to the horizontal.

[0072] For example, during hovering, the propeller's axis of rotation can be positioned within a range of ±10% of the vertical. During cruise flight, the propeller's axis of rotation can be positioned within a range of ±10% of the horizontal.

[0073] Optionally, during hovering flight, the propeller's axis of rotation can be oriented perpendicular to the aircraft's longitudinal direction. Furthermore, optionally, during cruise flight, the propeller's axis of rotation can be aligned parallel to the aircraft's longitudinal direction.

[0074] In particular, the orientation of the propeller's axis of rotation can vary depending on the flight phase or flight condition of the aircraft.

[0075] For example, the aircraft could be a convertible aircraft capable of vertical takeoff and landing. In particular, the aircraft could be able to change flight modes or flight states during flight. For example, the aircraft could be a vertical takeoff and landing (VTOL) aircraft. Specifically, the aircraft could be designed as an eVTOL (vertical takeoff and landing aircraft). Specifically, the aircraft could be described as an air taxi.

[0076] For example, the aircraft can be part of an aircraft fleet to provide an efficient mobility solution.

[0077] In particular, the aircraft can have at least one aircraft propulsion system, and in particular several aircraft propulsion systems, especially engines. For example, the aircraft can have one aircraft propulsion system according to the invention per wing. For example, two aircraft propulsion systems according to the invention can also be arranged per wing.

[0078] For example, the number of aircraft engines can be based on the specific application area of ​​the aircraft.

[0079] In particular, the aircraft according to the invention, and especially the aircraft propulsion system according to the invention, can eliminate or minimize the compromise between the operating states of "hovering" (i.e., without control input) and forward flight (i.e., with airflow). For example, in hovering flight, the propeller can generate usable lift near the hub. In cruise flight, however, the propeller may generate at least partially detrimental downforce near the hub. This can also occur with a variable-pitch propeller. For example, with a variable-pitch propeller, the entire propeller blade can be angled more sharply to accommodate the higher axial airflow. The angle of attack can be varied. This can be achieved, for example, with the present invention.

[0080] Another aspect of the invention relates to a method for operating an aircraft engine, wherein a propeller of the aircraft engine, which is arranged on a drive shaft of the aircraft engine, is driven by the drive shaft about a rotational axis of the propeller. According to the invention, the volume of a propeller spinner, which is arranged in the forward region of the propeller in the direction of the rotational axis of the aircraft engine, is changed by a propeller spinner adjustment device as a function of the position of the aircraft engine in the radial direction to the rotational axis.

[0081] In particular, the method just described can be adapted using an aircraft engine or an aircraft according to the aforementioned aspects or an advantageous further development thereof. Specifically, the aircraft engine and / or the aircraft can include, in particular technical, means to carry out or execute the method just described.

[0082] In particular, the volume can be changed automatically depending on the position of the aircraft engine or the aircraft itself.

[0083] In particular, the position of the aircraft's propulsion system can characterize a flight phase, flight mode, or flight condition of the aircraft. Specifically, the aircraft can hover, for example, in helicopter mode. This occurs particularly during takeoff and / or climb. Hovering also occurs during descent and / or approach or landing. Hovering can be understood as a flight condition in which an aircraft remains in an unchanged position and at an unchanged altitude. Furthermore, cruise flight can be a flight phase during movement or flight. For example, cruise flight can be defined as the phase of flight between the climb after reaching the planned cruising altitude and the beginning of the descent.In particular, the aircraft and thus the aircraft propulsion system are put into cruise flight mode when, for example, a cruising altitude is reached.

[0084] In one embodiment of the method described above, the propeller spinner adjustment device is designed to change the volume of the propeller spinner from a basic state to at least one expansion state, such that at least part of the propeller's frontal area is covered by the modified propeller spinner to a greater extent than in the basic state. Thus, depending on the position of the aircraft's propulsion system and / or a flight phase of the aircraft, at least one of several expansion states for the propeller spinner can be automatically set, allowing the volume of the propeller spinner to be expanded to cover at least a portion of the propeller's frontal area.

[0085] In a further embodiment of the method described above, the volume of the propeller spinner is automatically adjusted when the aircraft engine changes position between cruise and hovering. Furthermore, the volume of the propeller spinner can be adjusted to its expanded state in cruise flight and to its inert state in hovering. Depending on the position of the aircraft engine and / or an operating condition of the aircraft, a specific time and / or duration for changing the volume of the propeller spinner, and / or a specific volume to which the volume of the propeller spinner is adjusted, can be determined. This can be achieved, for example, using an electronic evaluation unit for the propeller spinner adjustment device.

[0086] For example, the electronic evaluation unit can determine when and for how long the volume of the propeller spinner should be changed. This information can then be transmitted to the propeller spinner adjustment device, particularly a control unit. Furthermore, the volume to which the propeller spinner will be adjusted can be determined. Various factors can be considered in this process. For instance, the aircraft's operating state might be a flight phase. It is particularly important to know whether the aircraft is in a takeoff or cruise phase.

[0087] In particular, advantageous embodiments of one aspect can be considered advantageous embodiments of another aspect and / or all aspects. Specifically, advantageous embodiments of the aircraft propulsion system can be considered advantageous embodiments of the aircraft and the method. Likewise, advantageous embodiments of the method can be considered advantageous embodiments of the aircraft propulsion system. The reverse is also true.

[0088] The invention also includes further developments of the aircraft and the method according to the invention, which have features already described in connection with the further developments of the aircraft propulsion system according to the invention. For this reason, the corresponding further developments of the aircraft and the method according to the invention are not described again here.

[0089] The invention also includes combinations of the features of the described embodiments.

[0090] The following describes exemplary embodiments of the invention. This is illustrated by: Fig. 1 a schematic representation of an aircraft with at least one aviation engine in a cruise flight position; Fig. 2 another schematic representation of the aircraft Fig. 1 in a hovering position; Fig. 3 a schematic representation of the aircraft propulsion system Fig. 1, wherein the volume of a propeller spinner of the aircraft propulsion system is in a ground state; Fig. 4 another schematic representation of the aircraft propulsion system Fig. 1, wherein the volume of the propeller spinner of the aircraft propulsion is in a state of expansion; Fig. 5 in an exemplary side-section view of the propeller spinner, a mechanism to change the volume (shown here in its ground state) of the propeller spinner; Fig. 6 in another exemplary side-section view of the propeller spinner, a mechanism to change the volume (shown here in the expanded state) of the propeller spinner; Fig. 7 another schematic representation of the aircraft propulsion system Fig. 1, wherein a special embodiment of a propeller spinner adjustment device is shown; Fig. 8 in an exemplary side-section view of the propeller spinner, a mechanism to change the volume (shown here in its basic state) of the propeller spinner; Fig. 9 in another exemplary side-section view of the propeller spinner a mechanism to change the volume (shown here in the expanded state) of the propeller spinner; Fig. 10 an exemplary front view of the propeller spinner, which has several adjustable lamellae as its outer fairing (here they are shown overlapping each other); Fig. 11 an exemplary side view of the propeller spinner from Fig. 10; Fig. 12 an exemplary front view of the propeller spinner from Fig. 10, where the lamellae are fanned out; and Fig. 13 an exemplary side view of the propeller spinner from Fig. 12.

[0091] The embodiments described below are preferred embodiments of the invention. In these embodiments, the described components each represent individual features of the invention that can be considered independently of one another. Each of these features further develops the invention independently and can therefore be considered part of the invention individually or in a combination other than that shown. Furthermore, the described embodiments can also be supplemented by other features of the invention already described.

[0092] In the figures, functionally identical elements are each provided with the same reference symbols.

[0093] The Fig. Figure 1 shows, for example, a schematic representation of an aircraft 1. For example, aircraft 1 could be a convertible aircraft or an eVTOL. In particular, aircraft 1 serves as a vehicle for urban air mobility. Specifically, aircraft 1 can take off and land vertically.

[0094] For example, the aircraft 1 can have two wings 2. In order for the aircraft 1 to be operated and, in particular, to be moved, the aircraft 1 can have at least one aircraft propulsion system 3. For example, the aircraft propulsion system 3 can be referred to as the engine or propulsion unit of the aircraft 1. In this embodiment, the aircraft 1 has one aircraft propulsion system 3 for each wing 2.

[0095] The aircraft propulsion system 3 can have a propeller 4. For example, the propeller 4 can be referred to as an air screw. The propeller 4 is, for example, arranged on a drive shaft 5 of the aircraft propulsion system 3. By means of this drive shaft, which can be described in particular as a mechanical drive, the propeller 4 can be driven about a rotational axis 6 of the propeller 4. The rotational axis 6 is the axis about which the propeller 4 rotates. For example, the rotational axis 6 can be aligned parallel to the drive shaft 5.

[0096] In particular, aircraft 1 can enter different flight phases. One flight phase can be, for example, cruise flight or the cruise flight phase of aircraft 1.

[0097] In particular, in the Fig. Figure 1 shows the aircraft 1 in cruise flight. In cruise flight, the rotational axis 6 of the propeller 4 is aligned with a longitudinal direction 7, or longitudinal axis (corresponding to the x-axis) of the aircraft 1, at a predetermined angle to the horizontal. For example, the rotational axis 6 and the longitudinal direction 7 can be described as essentially parallel. For landing or takeoff, the position of the aircraft propulsion 3 can be changed. Mechanical adjusting devices can be provided for this purpose. Such an operation or state of the aircraft 1 is shown in the Fig. Figure 2 shows a hovering flight of aircraft 1. Hovering allows aircraft 1 to take off and land vertically (corresponding to the z-axis). Specifically, during hovering, the rotational axis 6 of propeller 4 is aligned with the longitudinal direction 7 of aircraft 1 at a predetermined angle to the vertical. For example, as shown in the Fig. 2 shows that the axis of rotation 6 is essentially perpendicular to the longitudinal direction 7.

[0098] Back to Fig. 1. Furthermore, the aircraft propulsion system 3 may, in particular as an aerodynamic measure, have a propeller spinner 8. The propeller spinner 8 may be arranged in the forward region 10 of the propeller 4 when viewed in the direction 9 of the rotation axis 6 of the aircraft propulsion system 3. In particular, the direction 9 of the rotation axis 6 may be the same as the direction 11 of the longitudinal direction 7 during the cruise flight of the aircraft 1.

[0099] Thus, for example, the propeller spinner 8 can be described as the front cap or tip of the propeller 4. In particular, as shown in the Fig. 1 can be seen, the propeller spinner 8 at the foremost position of the aircraft propulsion 3 with respect to direction 10.

[0100] During the hovering flight of aircraft 1 (compare Fig. 2) in turn, the direction 9 of the rotation axis 6 and the direction 11 of the longitudinal direction 7 can be essentially perpendicular.

[0101] In the Fig. Figure 3 shows a schematic representation of the aircraft propulsion system.

[0102] Since negative characteristics can occur, particularly during cruise flight of the aircraft 1, which can be caused, for example, by the propeller 4, the aircraft propulsion 3 can have a propeller spinner adjustment device 12. This is an automatic, electromechanical adjustment device. In particular, it can be an electromechanical system. For example, each aircraft propulsion 3 can have its own propeller spinner adjustment device 12. It is also conceivable that a central propeller spinner adjustment device is provided with which all aircraft propulsion units 3 of the aircraft 1 can be controlled and / or regulated. In particular, the propeller spinner adjustment device 12 can be referred to as a control unit.

[0103] In particular, the propeller spinner adjustment device 12 allows the volume of the propeller spinner 8 to be changed in a defined manner in the radial direction 13 relative to the axis of rotation 6. Thus, for example, the volume of the propeller spinner 8 can be reduced or increased. Specifically, the propeller spinner adjustment device 12 enables automatic radial expansion or widening of the propeller spinner 8. For example, the volume of the propeller spinner 8 can be changed, adjusted, or modified depending on the position of the aircraft propulsion 3 and / or a flight phase of the aircraft 1.

[0104] For example, the volume of the propeller spinner 8 can be changed from a basic state (this is in the Fig. 3 to be seen) into at least one expanded state (this is in the Fig. 4) are changed. In particular, the volume in the expanded state (compare Fig. 4) expanded or enlarged compared to the ground state. In the Fig. Figure 4, as already mentioned, represents one of several possible expansion states of the volume of the propeller spinner 8. In particular, the volume of the propeller spinner 8 can be modified such that the front of a propeller front surface 14 of the propeller 4 is at least partially covered by the propeller spinner 8, which has been modified in its volume. Specifically, the propeller 8 is covered forward (with respect to the direction 9 of the axis of rotation 6). In other words, the front area 10 of the propeller 4 can be covered, at least partially. In particular, the modified volume 8 in this expansion state can cover areas of the propeller 4 that generate negative thrust or efficiency-reducing downforce. This allows for more efficient flight, resulting in, in particular, an increased range of the aircraft 1.

[0105] Furthermore, the propeller front surface 14 can be the entire surface of the propeller 4 with respect to the front area 10 of the propeller 4.

[0106] In its upgraded state, the propeller spinner 8 can, with a side 15 facing the propeller 4, at least partially, and in particular completely, cover or shade the propeller front surface 14. Specifically, at least a radially inner sub-surface 16 of the propeller front surface 14, extending radially outwards from the axis of rotation 6 of the propeller 4, can be covered by the propeller spinner 8 in its radially expanded state. Specifically, the inner sub-surface 16 extends radially 13 from the axis of rotation 6. In particular, in the expanded state, the inner sub-surface 16 is, compared to the ground state (see Figure 1), Fig. 3) radially further covered. Furthermore, in Fig. Figure 4 shows that the rear end 17 of the propeller spinner 8, facing the propeller 4, is radially expanded in the expanded state compared to the ground state. In particular, it is further expanded or extended with respect to the radial direction 13. Specifically, the rear end 17 is located at the opposite end of the propeller spinner 8 with respect to direction 9.

[0107] For example, propeller 4 has at least two propeller blades 19, 18. Optionally, propeller 4 can have more than two propeller blades 18, 19. The propeller blades 18, 19 are connected or mechanically coupled to the drive shaft 5 at a connection point 20 of propeller 4. The connection point 20 can be, in particular, the center of propeller 4. Specifically, the connection point 20 is a propeller hub or rotor hub. For example, a rotation axis 6 can run centrally through the connection point 20, allowing the connection point 20 to rotate symmetrically about the rotation axis 6. For example, the connection point 20 can be connected to the drive shaft 5 along the rotation axis 6 to cause the propeller 4, and in particular the propeller blades 18, 19, to rotate at a specific rotational speed.

[0108] For example, a respective surface area 21, 22 of the at least two propeller blades 18, 19 can be at least partially covered at the front by the propeller spinner 8, the volume of which is changed by the propeller spinner adjustment device 12, with respect to the front area 10. For example, the two surface areas 21, 22 form the inner sub-area 16.

[0109] In particular, the respective surface area 21, 22 extends towards the connection point 20 and away from a respective radial end area 23, 24 of the at least two propeller blades 18, 19. Thus, the respective surface area 21, 22 can be located near the center of the connection point 20 and, in particular, near the center of the propeller 4.

[0110] In particular, the respective area 21, 22 can correspond to at least 20 percent, in particular 30 percent, in particular 40 percent of a respective propeller frontal area 14 of the at least three propeller blades 18, 19. Thus, for example, the inner propeller area of ​​the propeller 4 can be covered. For example, a respective area 21, 22 can correspond to one third, in particular one quarter, of a respective propeller blade frontal area 18, 19.

[0111] In particular, by means of the propeller spinner 8, which is modified in volume, one third, and in particular one quarter, of the propeller frontal area 14 can be covered in an expanded state.

[0112] For example, the propeller spinner 8 can be made at least partially, and in particular completely, of a material exhibiting anisotropic elasticity. The propeller spinner 8 can, for example, have at least one stiffening element 26 on an outer surface 27 in the circumferential direction 25 (compare Fig. 8) exhibit. In particular, the at least one stiffening element 26 is a stabilizing element to improve the stability of the propeller spinner 8, especially during cruise flight. In particular, the propeller spinner 8 can have several stiffening elements 26.

[0113] For example, the propeller spinner 8 can have a shell 28 (compare Fig. 1) exhibit. This shell 28 can, for example, be referred to as a mantle or outer shell. In particular, the shell 28 can be shaped as a paraboloid. Thus, the shell 28, and especially the propeller spinner 8, has a parabolic shape. In particular, the shell 28 can be radially expanded in a rotationally symmetric manner about the axis of rotation 6, so that the volume of the propeller spinner 8 can be changed.

[0114] In particular, the Fig. 5 a possible embodiment or mechanism for changing the volume of the propeller spinner 8. For this purpose, for example, the propeller spinner adjustment device 12 can be arranged in an inner area 29 or cavity of the propeller spinner 8. A movable adjustment element 30 of the propeller spinner adjustment device can be arranged in a front face 31 facing away from the propeller 4 (with respect to the direction 9 of the axis of rotation 6). In the Fig. Figure 5 shows, in particular, the basic state of the propeller spinner 8 and especially of the movable adjustment element 30. In the Fig. Figure 6 now shows at least one expanded state of the propeller spinner 8. The dashed lines 32 visualize the basic state again. Here, the movable adjustment element 30 is moved from the front 31 towards the propeller 4 by means of the propeller spinner adjustment device 12 to change the volume within the inner area 29. For example, the movable adjustment element 30 can be moved in the direction (opposite direction 9) of the propeller 4 by means of a spindle 33. In particular, the adjustment element 30 is moved towards a counter element 34. This movement within the propeller spinner 8 causes an expansion or change in volume.

[0115] In the Fig. Figure 7 shows another possibility for changing the volume. For example, the propeller spinner adjustment device 12 can be arranged outside the propeller spinner 8. This can be done, for example, on a region of the propeller 4 facing away from direction 9. However, in this case, unlike the embodiment in Fig. 6 The spindle 33, or threaded spindle, is arranged outside, in particular completely outside, the propeller spinner 8. For this purpose, the propeller spinner adjustment device 12 can, for example, include an electric motor 35. The electric motor 35 can, for example, have a housing 36, a stator 37, a rotor 38, and a hollow shaft 39. Furthermore, shaft bearings 40 can be provided. For adjusting the movable adjustment element 30, an adjustment actuator 41 can again be provided. This can be operated by means of the electric motor 35. In particular, the adjustment actuator 41 can be arranged inside the propeller spinner 8. For this purpose, cable guides can, for example, be provided. In particular, the electric motor 35 has a cooling air guide 42.

[0116] In particular, the one in the Fig. The propeller spinner 8 shown in Figure 7 is a rotationally fixed spinner.

[0117] In the Fig. Figure 8 shows another possibility for changing the volume. The propeller spinner adjustment device 12 can have a pneumatic or hydraulic adjustment unit 43. This adjustment unit 43 can be arranged, in particular, in the inner area 29 of the propeller spinner 8. With the aid of the pneumatic adjustment unit 43, which can be controlled and / or regulated by the adjustment spinner adjustment device 12, at least one inflatable element 44, which is arranged in the inner area 29, can be controlled. The inflatable elements can be inflated to change the volume, in particular to expand the volume. In particular, the Fig. Figure 8 again shows the basic state of the propeller spinner 8.

[0118] In the Fig. Figure 9 again represents a state of expansion. In this case, the Fig. 9. At least one inflatable element 44, for example an inflatable ring, is inflated, in particular filled with air or a gas, so that the volume of the propeller spinner 8 expands. In particular, the inflatable element 44 can be controlled by means of the pneumatic adjustment unit 43. This unit can be inflated or deflated, depending on the required volume of the propeller spinner 8.

[0119] In the following Fig. Figures 10 to 13 show another way to change the volume of the propeller spinner 8.

[0120] For example, the Fig. 10 a front view of the propeller spinner 8 viewed from the front area 10.

[0121] For example, the propeller spinner 8 can have several adjustable blades 46 as an outer cover 45 by means of the propeller spinner adjustment device 12. In this case, the Fig. Figure 10 again shows the initial state 32 of the propeller spinner 8. In the basic state or initial state 32, the lamellae 46 are arranged overlapping each other in the circumferential direction 25 or direction of rotation around the axis of rotation 6. For this purpose, for example, in the Fig. 11 shows a side view.

[0122] To change the volume 8, the slats 46 can be adjusted or modified, in particular by fanning out the slats 46. This is now described in the Fig. Figure 12 illustrates this. The lamellae 46 are controlled, in particular by means of the propeller spinner adjustment device 12, so that they are fanned out. This expands the volume radially. This is shown in the Fig. 12 can be seen in comparison to the ground state 32. The multiple slats 46 are controlled or adjusted so that they maintain a predetermined distance 47 from each other. This is, for example, in Fig. 13 can be seen. Thus, the volume of the, in particular elastic, propeller spinner 8 can be expanded or increased by means of the now spaced-apart lamellae 46.

[0123] In one embodiment of the invention, the volume of the propeller spinner 8 can be automatically changed in the radial direction 13 to the axis of rotation 6 by means of the propeller spinner adjustment device 12, depending on the position of the aircraft propulsion 3 and / or a flight phase of the aircraft 1. Thus, the volume of the propeller can be adjusted system-side by electromechanical systems.

[0124] Furthermore, for example, the volume of the propeller spinner 8 can be changed from its basic state 32 to at least one expansion state using the propeller spinner adjustment device 12, such that the propeller front surface 14 of the propeller 4 is covered at least partially by the propeller spinner 8 with its changed volume, extending further forward than in the basic state 32. This can also be achieved by an automated system, in particular a control and / or regulating device.

[0125] Furthermore, the volume of the propeller spinner 8 can, for example, be automatically changed when the aircraft engine 3 changes its position between a cruise flight position (compare Fig. 1) and a hovering position (compare Fig. 2) learns. For example, the propeller spinner adjustment device 12 can be an electronic evaluation unit for this purpose (compare Fig.3) exhibit. In particular, the volume of the propeller spinner 8 can be set to the expanded state in the cruise flight position and to the ground state in the hover flight position. Depending on the respective position of the aircraft propulsion system and / or the operating state of the aircraft 1, a time and / or a duration for changing the volume of the propeller spinner 8 and / or a volume magnitude by which the volume of the propeller spinner 8 is changed can be determined. This can be determined by the electronic evaluation unit or processing unit 48 and transmitted to the respective units.

[0126] For example, the propeller spinner 8 can have a shape memory alloy with which the shape of the propeller spinner 8 can be changed. For example, the control(s) for changing the volume of the propeller spinner 8 can be effected by means of piezoelectric controls or centrifugal force-controlled controls. Reference symbol list 1 aircraft 2 Wing 3. Aircraft propulsion 4 propellers 5 Drive shaft 6 Rotation axis 7 Longitudinal direction 8 propeller spinners 9. Direction of the axis of rotation 10 front area of ​​the propeller 11. Direction of the longitudinal direction of the aircraft 12 Propeller spinner adjustment device 13 radial direction 14 Propeller frontal area 15. Side of the propeller spinner facing the propeller 16 inner partial surface of the propeller front surface 17 rear end of the propeller spinner 18, 19 propeller blades 20 Connection point 21, 22 area areas 23, 24 radial end areas 25 Circumferential direction 26 stiffening element 27 Outside 28 case 29 Indoor area 30 Adjustment element 31 Front of the propeller spinner 32 Basic state 33 Spindle 34 Counter-element 35 Electric motor 36 Housing of the electric motor 37 Stator of the electric motor 38 Rotor of the electric motor 39 Hollow shaft 40 shaft bearings 41 Adjustment actuator 42 Cooling air duct 43 pneumatic adjustment unit 44 inflatable elements 45 outer cladding 46 multiple slats 47 Distance between the slats 48 electronic evaluation units

Claims

[1] Aviation propulsion system (3) for an aircraft (1), comprising: - a propeller (4) which is arranged on a drive shaft (5) of the aircraft drive (3) and can be driven by means of the drive shaft (5) about a rotation axis (6) of the propeller (4), - a propeller spinner (8) which is arranged in the direction (9) of the rotation axis (6) of the aircraft drive (3) viewed in the front region (10) of the propeller (4), characterized by - a propeller spinner adjusting device (12) for the defined changing of the volume of the propeller spinner (8) in the radial direction (13) to the rotation axis (6), wherein the volume of the propeller spinner (8) can be changed in the radial direction (13) from a basic state into at least one expanded state with the propeller spinner adjusting device (12) in such a way that a propeller front surface (14) of the propeller (4) is covered at least in some areas towards the front by the propeller spinner (8) whose volume has been changed, more than in the basic state. [2] Aviation engine (3) according to claim 1, characterized by that the propeller spinner (8) covers the propeller front surface (14) at least in part with a side (15) of the propeller spinner (8) facing the propeller (4). [3] Aviation engine (3) according to claim 2, characterized bythat at least one partial surface (16) of the propeller front surface (14) which is radially inner with respect to the rotational axis (6) of the propeller (4) and which extends radially outwards from the rotational axis (6) is covered by the propeller spinner (8) in its radially expanded state, in particular is covered radially more than in the basic state. [4] Aviation engine (3) according to claim 2 or 3, characterized by that a rear end (17) of the propeller spinner (8) facing the propeller (4) is radially expanded in the expanded state compared to the basic state. [5] Aviation engine (3) according to one of the preceding claims, characterized byin that the propeller (4) has at least two propeller blades (18, 19), which are each connected to the drive shaft (5) at a connection point (20) of the propeller (4), wherein a respective surface area (21, 22) of the at least two propeller blades (18, 19), which extends towards the connection point (20) and away from a respective radial end area (23, 24) of the at least two propeller blades (18, 19), is covered at least in part at the front by the propeller spinner (8), the volume of which is changed by the propeller spinner adjustment device (12). [6] Aviation engine (3) according to claim 5, characterized by that the respective surface area (21, 22) of the at least two propeller blades (18, 19) corresponds to at least 20%, in particular 30%, in particular 40%, of a respective propeller front surface (14) of the at least two propeller blades (18, 19). [7] Aviation engine (3) according to one of the preceding claims, characterized bythat the propeller spinner (8) is formed at least partially, in particular completely, from a material which has anisotropic elasticity, in particular the propeller spinner (8) has at least one stiffening element (26) on an outer side (27) in the circumferential direction (25). [8] Aviation engine (3) according to one of the preceding claims, characterized by that a shell (28) of the propeller spinner (8) is designed as a paraboloid, in particular the shell (28) of the propeller spinner (8) is radially expandable in a rotationally symmetrical manner about the rotation axis (6). [9] Aviation engine (3) according to one of the preceding claims, characterized byin that the propeller spinner (8) has, as an outer covering (45), a plurality of slats (46) which can be adjusted by the propeller spinner adjusting device (12), wherein the plurality of slats (46) are arranged overlapping one another in the circumferential direction (25) about the rotation axis (6) in a basic state of the volume of the propeller spinner (8), and in order to change the volume of the propeller spinner (8), the plurality of slats (46) are adjusted by the propeller spinner adjusting device (12) in such a way that the plurality of slats (46) are at a predetermined distance (47) from one another. [10] Aviation engine (3) according to one of the preceding claims, characterized byin that the propeller spinner adjusting device (12) is arranged in an inner region (29) of the propeller spinner (8), wherein a movable adjusting element (30) of the propeller spinner adjusting device (12) is arranged in a front side (31) of the propeller spinner (8) facing away from the propeller (4), wherein the movable adjusting element (30) is designed to be moved by means of the propeller spinner adjusting device (12) in order to change the volume of the propeller spinner (8) within the inner region (29) from the side (31) facing away from the propeller (4) towards the propeller (4). [11] Aviation engine (3) according to one of the preceding claims 1 to 9, characterized byin that the propeller spinner adjusting device (12) has a pneumatic adjusting unit (43), wherein by means of the pneumatic adjusting unit (43) at least one inflatable element (44), which is arranged in an inner region (29) of the propeller spinner (8), can be controlled to change the volume of the propeller spinner (8). [12] Aircraft (1) with at least one aviation propulsion system (3) according to one of the preceding claims 1 to 11, characterized by that in a hovering flight of the aircraft (1) the rotation axis (6) of the propeller (4) is aligned with a longitudinal direction (7) of the aircraft (1) at a predetermined angle to the vertical and in a cruising flight of the aircraft (1) the rotation axis (6) of the propeller (4) is aligned with the longitudinal direction (7) of the aircraft (1) at a predetermined angle to the horizontal. [13] Method for operating an aviation drive (3) of an aircraft (1), wherein a propeller (4) of the aviation drive (3), which is arranged on a drive shaft (5) of the aviation drive (3), is driven by the drive shaft (5) about a rotation axis (6) of the propeller (4), characterized by , that - the volume of a propeller spinner (8), which is arranged in the front region (10) of the propeller (4) viewed in the direction (9) of the axis of rotation (6) of the aircraft drive (3), is changed by means of a propeller spinner adjusting device (12) as a function of a position of the aircraft drive (3) in the radial direction (13) to the axis of rotation (6). [14] Method according to claim 13, characterized in that with the propeller spinner adjusting device (12) the volume of the propeller spinner (8) is changed from a basic state into at least one expanded state in such a way that a propeller front surface (14) of the propeller (4) is covered at least in regions by the propeller spinner (8) whose volume has been changed, more than in the basic state. [15] Method according to claim 14, characterized bythat the volume of the propeller spinner (8) is automatically changed when the aircraft drive (3) experiences a change in its position between a cruising flight position and a hovering flight position, in particular the volume of the propeller spinner (8) is set to the expanded state in the cruising flight position and to the basic state in the hovering flight position, in particular depending on the position of the aircraft drive (3) and / or on an operating state of the aircraft (1) a time and / or a time duration for changing the volume of the propeller spinner (8) and / or a volume size to which the volume of the propeller spinner (8) is changed is determined.

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