aircraft

Abstract

The invention relates to an aircraft (1), in particular an unmanned aircraft, and to a method for producing an aircraft of this type, comprising: • a fuselage (2), • a support structure (3) which supports at least four rotor drives (4) and comprises two supports (6, 7), wherein • a front support (6) is arranged in front of the geometric center point (10) and / or center of gravity (S) of the fuselage (2), and • a rear support (7) is arranged behind the geometric center point (10) and / or center of gravity (S) of the fuselage (2), characterized in that the fuselage (2) is formed from a foamed plastic, preferably expanded polypropylene (EPP), wherein the front support (6) and the rear support (7) are embedded at least in the foamed plastic and form a fixed connection to the fuselage (2) by thermal fusion, without additional securing means being required.

Description

[0001] VON WITZLEBEN, Dietrich, Case: LK_01 WO

[0002] aircraft

[0003] Technical field

[0004] The present invention relates to an aircraft and a method for manufacturing such an aircraft.

[0005] State of the art

[0006] Unmanned aerial vehicles, especially multi-copter drones with a quadcopter architecture, have become increasingly important in recent years and are used in numerous civil, military, and industrial sectors. These aircraft typically feature a symmetrical arrangement of four rotors, which are used to generate lift and control flight behavior.

[0007] Traditionally, the fuselages and load-bearing structures of unmanned aerial vehicles are made from materials such as carbon fiber composites (CFRP), aluminum, or other lightweight metallic materials. While these materials offer high structural strength and stiffness, they also have several disadvantages:

[0008] High manufacturing effort and material costs: The production of CFRP or metal components requires complex manufacturing processes such as lamination, autoclave hardening, or CNC machining, which significantly increases production costs. This has a particularly negative impact on series production.

[0009] Drones are frequently subjected to stresses from hard landings or collisions during operation. Conventional materials often exhibit low impact resistance in this context, leading to fractures or structural damage. This can result in high repair costs or even render the aircraft unusable.

[0010] In conventional designs, electronic components such as batteries, control boards, and sensors usually have to be fixed in place using separate fasteners like screws, clips, or adhesives. This increases the overall weight and makes both assembly and component replacement more difficult.

[0011] Furthermore, rigid materials such as aluminum or CFRP transmit vibrations from the rotors to the entire aircraft, which can lead to undesirable effects such as poorer sensor measurements or mechanical wear.

[0012] Furthermore, conventional quadcopter drones are usually designed so that the rotors generate vertical thrust. To generate horizontal thrust, classic quadcopters must tilt the entire aircraft forward to create a thrust component in the direction of flight. This results in suboptimal aerodynamics. BY WITZLEBEN, Dietrich, Case: LK_01 WO

[0013] To overcome the aforementioned aerodynamic disadvantages of conventional quadcopters, alternative concepts exist that are based on swiveling rotor drives or rotor blade angle adjustment (pitch control). These solutions allow for adjustment of the thrust vector, enabling more efficient propulsion generation during cruise flight. However, these technical approaches are mechanically complex.

[0014] Swiveling rotor drives require movable bearings, actuators, and complex control systems to dynamically adjust the thrust direction during flight. This significantly increases the susceptibility to mechanical failures and maintenance requirements.

[0015] The additional mechanics for adjusting the rotors or rotor blade angles result in a higher overall weight of the aircraft. At the same time, the energy required to control the moving components increases, further reducing flight time.

[0016] The production of such systems requires highly precise mechanical components and robust sensors for the exact control of the swivel movements. This leads to significantly higher manufacturing costs, especially for mass-produced items.

[0017] Description of the invention

[0018] Starting from the known state of the art, it is an object of the present invention to provide an improved solution for an aircraft which is improved in terms of weight and manufacturing costs as well as flight control.

[0019] This problem is solved by an aircraft having the features of claim 1 and a method having the features of claim 10. Advantageous further developments are described in the dependent claims, the present description and the figures.

[0020] Accordingly, an aircraft is proposed comprising a fuselage and a supporting structure that carries at least four rotor drives and includes two struts, wherein a front strut is arranged forward of the geometric center and / or center of gravity of the fuselage and a rear strut is arranged aft of the geometric center and / or center of gravity of the fuselage. The fuselage is formed from a foamed plastic, preferably expanded polypropylene, wherein the front and rear struts are at least partially embedded in the foamed plastic and form a solid connection with the fuselage by thermal fusion, without the need for additional fasteners.

[0021] This combination of features offers the advantage that the foamed plastic fuselage exhibits high impact resistance and flexibility, enabling the aircraft to withstand mechanical stresses, while simultaneously allowing for a significant weight reduction. This translates to longer flight times or higher payload capacity, particularly for electrically powered aircraft. Furthermore, the expanded polypropylene construction allows for a [VON WITZLEBEN, Dietrich, Case: LK_01 WO]

[0022] Cost-effective manufacturing using a foam molding machine and / or milling allows for efficient production of both individual and series products. The supporting structure is at least partially encased in expanded polypropylene, ensuring improved connection between the fuselage and the supporting structure, as well as enhanced aerodynamic integration.

[0023] In other words, the front and rear struts are at least partially enclosed within the fuselage and pressed in place; that is, the front and rear struts are bonded to the fuselage by the foamed plastic bonding with the struts, forming a solid material connection without the need for additional fasteners. This makes the struts rotationally fixed and firmly connected to the fuselage in the translational direction along the longitudinal axis.

[0024] Preferably, the supports have positive locking elements in a connection area with the fuselage that interlock with the fuselage.

[0025] A foamed plastic is a plastic that has been foamed using gases or blowing agents to create a cellular structure with many small cavities (pores). This makes the plastic lighter, better insulating (thermally and acoustically), and often more shock-absorbing. Besides EPP, other foamed plastics can be used, such as polyetheretherketone (PEEK) foams or polyvinyl chloride (PVC) foams.

[0026] For an aircraft with high requirements for lightweight construction, shock absorption and electromagnetic permeability, it was recognized that expanded polypropylene (EPP) is particularly suitable due to its higher stiffness and dimensional stability.

[0027] According to one embodiment, the hull, made of foamed plastic, preferably expanded polypropylene (EPP), has a molded part density between 60 and 100 kg / m3, preferably 70 kg / m3, and / or a closed-cell structure to reduce water absorption, and / or a tensile strength between 880 and 1410 kPa.

[0028] It was recognized that at least the hull is made of a specific expanded polypropylene (EPP) with a defined molded part density between 60 kg / m3 and 100 kg / m3, thus achieving an optimal balance between weight, mechanical strength and ease of manufacture.

[0029] Another significant advantage of choosing expanded polypropylene lies in the cost-effective manufacturing of the aircraft. The material enables series production through economical processes such as foam molding machines or milling. Compared to conventional aircraft materials such as composites or metal, EPP offers a

[0030] significant reduction in manufacturing costs, as complex mechanical processing steps are eliminated and direct shaping in an aerodynamically optimized structure is possible.

[0031] Another advantage of expanded polypropylene (EPP) is the easy integration of additional components, especially electronic modules, batteries, and sensors. Due to EPP's elastic yet dimensionally stable structure, these components can be securely attached without the need for separate fasteners such as screws or clamps. By precisely fitting the components into recesses within the EPP, a friction-based fixation is achieved, ensuring the components are held securely, even under vibration or dynamic flight loads. This not only reduces the overall weight of the aircraft but also simplifies assembly and maintenance, as components can be integrated into or replaced within the fuselage without additional effort.

[0032] According to a preferred embodiment, the hull is radar-transparent and allows electromagnetic waves in the frequency range between 1 GHz and 10 GHz to pass through.

[0033] The use of EPP makes it possible to integrate electronic components such as antennas or sensors within the fuselage without their function being affected by the housing. This reduces the need for external mounting structures for antennas, thereby minimizing the aircraft's aerodynamic drag and improving efficiency during cruise flight. Additionally, transporting the aircraft is facilitated, as the antennas are not at risk of damage or breakage compared to externally mounted antennas.

[0034] According to another preferred embodiment, the supporting structure comprises only the front and rear supports. The hull, made of foamed plastic, is self-supporting.

[0035] Reducing the supporting structure to just two beams significantly simplifies the aircraft's construction and contributes to material and weight savings. This allows for lower manufacturing costs and an increased payload. The load-bearing function of the foamed plastic, preferably EPP, ensures that the aircraft maintains high mechanical stability despite the reduced supporting structure. This enables a lightweight yet robust design, which is particularly advantageous for unmanned aerial vehicle (UAV) applications.

[0036] A self-supporting fuselage refers to a load-bearing structure made of foamed plastic that absorbs and transmits the mechanical loads acting on the aircraft without additional supporting structures or reinforcements. The fuselage not only fulfills a function (VON WITZLEBEN, Dietrich, Case: LK_01 WO)

[0037] not only does it serve an aerodynamic or protective function, but it also contributes significantly to the structural strength of the entire aircraft.

[0038] The front support is positioned in front of the aircraft's geometric center, while the rear support is positioned behind it. The supports extend outwards on both sides along a transverse axis of the aircraft to support the at least four rotor drives.

[0039] The supports are preferably designed as aluminum tubes, thus achieving a favorable weight-to-mechanical strength ratio. The front and rear supports are each designed as a continuous tube and extend symmetrically to the longitudinal axis of the aircraft in opposite directions.

[0040] According to a preferred embodiment, the fuselage has an aerodynamic airfoil which generates lift during cruise flight, wherein the aerodynamic airfoil of the fuselage is designed as an airfoil and the expanded polypropylene (EPP) is shaped around the supports such that it forms airfoils with an airfoil profile, preferably with an airfoil from the NACA 4-digit series, in particular a NACA 2412 airfoil.

[0041] The use of EPP offers the particular advantage of being able to form aerodynamic shapes quickly and cost-effectively.

[0042] By using the NACA 2412 airfoil as the basic aerodynamic shape of the fuselage, it can generate additional lift during cruise flight. Unlike conventional multicopters, which generate significant drag in forward flight, the streamlined shape increases lift and reduces the energy consumption of the rotor drives. This results in longer flight durations or allows for a higher payload capacity with the same battery power.

[0043] Another advantage lies in the optimization of the wing profiles around the spars, which are also designed as NACA 2412 airfoils. This allows for efficient airflow direction and reduces flow separation, which in turn lowers the aircraft's overall drag. This not only improves aerodynamic efficiency but also contributes to more stable flight, especially during transitions between hovering and forward flight.

[0044] Advantageously, the invention can also be further developed to utilize various modifications of the NACA 2412 airfoil to achieve optimal aerodynamics depending on flight conditions and load requirements. For example, airfoil adjustments can be made at the transition areas between the fuselage and the supporting structure to further improve flow characteristics. VON WITZLEBEN, Dietrich, Case: LK_01 WO

[0045] According to another preferred embodiment, the at least four rotor drives are arranged on the supports.

[0046] The at least four rotor drives are mounted on the pylons, essentially at the ends of the front and rear pylons. This positioning ensures an even load distribution across the supporting structure and enables stable flight in both hovering and forward flight. Furthermore, placing the rotor drives at the outer ends of the pylons achieves an optimal leverage ratio for control movements, thus improving flight control efficiency. In addition, this configuration reduces aerodynamic interactions between the rotors and the fuselage, resulting in a more unobstructed airflow and increasing the overall efficiency of the aircraft.

[0047] According to a further preferred embodiment, the hull is designed such that additional components, in particular batteries and / or sensors, are received in a force-fit manner in recesses or indentations within the hull, with the fixation being effected by elastic clamping forces and the material restoring force of the foamed plastic.

[0048] Another advantage is the easy integration of additional components, especially electronic modules, batteries, and sensors. Due to the elastic yet dimensionally stable structure of the foamed plastic, preferably EPP, these components can be securely attached without the need for separate fasteners such as screws or clamps. By precisely fitting the components into recesses in the EPP, a friction-based fixation is achieved, ensuring the components are held securely, even under vibrations or dynamic flight loads. This not only reduces the overall weight of the aircraft but also simplifies assembly and maintenance, as components can be integrated into or replaced within the fuselage without additional effort.

[0049] According to a further preferred embodiment, the rotary drives are rigidly connected to the supports, so that the planes of rotation of the rotor drives are arranged at an angle between 10° and 40°, preferably 20°-30°, particularly preferably 25°, relative to the longitudinal direction of the aircraft.

[0050] Accordingly, the rotation axes of the rotor drives are fixed relative to the gravitational axis at an angle between 50° and 80°, preferably between 60° and 70°, and particularly preferably at 65°.

[0051] The fixed inclination of the rotor axes of rotation relative to the longitudinal direction of the aircraft, within a range of 10° to 40°, enables improved controllability and stability during hovering and transitions to forward flight. The preferred arrangement is described by Witzleben and Dietrich in Case: LK_01 WO

[0052] In the range between 25° and 30°, an optimized balance between lift generation and thrust direction is achieved, enabling efficient operation of the aircraft in both hovering and cruise flight. This results in reduced power consumption by the propulsion systems and extended flight duration.

[0053] According to a further preferred embodiment, a flight control device is provided which is configured such that the aircraft is set at an angle between 10° and 40°, preferably between 25° and 30°, particularly preferably at 25°, relative to a horizontal perpendicular to the gravitational axis in hovering flight and at an angle between -1° and 1°, preferably at -0.5°, relative to the horizontal in cruise flight.

[0054] The integrated flight control system enables automatic adjustment of the aircraft's attitude depending on the operating mode. In hovering flight, the aircraft is maintained at a predefined angle of attack, which particularly improves stability during takeoff and landing. During cruise flight, the attitude is automatically adjusted to a near-horizontal angle, allowing optimal use of the lift generated by the aerodynamic fuselage. This reduces energy consumption during level flight and increases the overall efficiency of the aircraft.

[0055] The aircraft is controlled without rudders or ailerons, solely through the targeted control of the rotor speeds. By differentially increasing or decreasing the speed of individual rotors, pitch, roll, and yaw movements of the aircraft can be precisely controlled without the need for mechanical control surfaces. This reduces the aircraft's complexity, as no additional actuators or movable aerodynamic control surfaces are required, making the system lighter, more robust, and requiring less maintenance. Particularly during hovering and slow flight, this control strategy ensures efficient and responsive flight control, while during cruise flight, the aerodynamic design of the fuselage contributes to stabilization.

[0056] According to a second aspect, a process for manufacturing an aircraft is defined, comprising the following steps:

[0057] • Providing a closed mold with a cavity defining the outer contour of the hull, wherein the mold has at least two separable mold halves; • Introducing foamed plastic, preferably expanded polypropylene (EPP) granules, into the cavity of the mold;

[0058] • Inserting a support structure comprising at least one front support and one rear support into the cavity of the mold prior to the expansion of the foamed plastic, VON WITZLEBEN, Dietrich, Case: LK_01 WO

[0059] so that the supporting structure is at least partially enclosed by foamed plastic;

[0060] • Heating the granules by introducing hot steam or hot air to cause expansion and fusion of the granules, resulting in a closed wall structure;

[0061] • Control of material distribution to achieve a defined wall thickness of the hull, in particular by targeted temperature control or adjustment of the steam inlet openings;

[0062] • Formation of a cavity within the hull by a) inserting a removable core structure into the cavity before the expansion of the foamed plastic and removing it after curing, or b) leaving the central area unoccupied by controlled partial expansion of the material.

[0063] In a further process step, the aircraft can be shaped into a desired form by milling.

[0064] Brief description of the characters

[0065] Preferred further embodiments of the invention are explained in more detail by the following description of the figures. These show:

[0066] Figure 1 schematic perspective side view of an aircraft according to one embodiment;

[0067] Figure 2 shows another schematic perspective front view according to one embodiment; and

[0068] Figure 3 AB shows a side view of the aircraft in hovering flight and a side view of the aircraft in cruise flight according to a further embodiment, and Figure 4 shows a sectional view through the longitudinal axis of the aircraft according to an embodiment.

[0069] Detailed description of preferred embodiments

[0070] Preferred embodiments are described below with reference to the figures. Identical, similar, or equivalent elements in the different figures are designated with identical reference numerals, and repeated descriptions of these elements are sometimes omitted to avoid redundancy.

[0071] Figure 1 shows a perspective side view of an aircraft 1 comprising a fuselage 2 and a support structure 3. The support structure 3 carries at least four rotor drives 4 and includes a front support 6 and a rear support 7. The front support 6 is located in front of the [VON WITZLEBEN, Dietrich, Case: LK_01 WO]

[0072] The front and rear supports are arranged at the geometric center 10 and / or center of gravity S of the fuselage 2, while the rear support 7 is positioned behind the geometric center 10 and / or center of gravity S of the fuselage 2. The fuselage 2 is made of foamed plastic, preferably expanded polypropylene (EPP). The front and rear supports are at least partially embedded in the foamed plastic and form a solid bond with the fuselage through thermal fusion, without the need for additional fasteners.

[0073] Figure 1 shows the arrangement of the rotation planes of the rotor drives 4 relative to the longitudinal direction of the aircraft 1. The rotor drives 4 are positioned such that their rotation planes are fixed at an angle α between 10° and 40°, preferably between 20° and 30°, and particularly preferably at 25°, to the longitudinal direction of the aircraft 1. This inclination of the rotation planes contributes to improving the transition from hovering to forward flight, as the generated thrust has a combined vertical and horizontal component. Figure 2 shows that the fuselage 2 has an aerodynamic airfoil that generates lift during cruise flight. The fuselage 2 is designed as an airfoil, so that its shape specifically contributes to lift generation during forward flight. As can be seen in Figure 1, the fuselage is shaped around the supports 6 and 7 such that it forms airfoils with an aerodynamic airfoil profile.This improves the aerodynamic efficiency of the aircraft 1, as the wing profiles are integrated into the fuselage 2 and thus generate an additional lift effect. The wing profiles extend at least partially along the supports 6 and 7. In a preferred embodiment, the airfoil of the fuselage 2 and the wing profile around the supports 6 and 7 are designed as profiles from the NACA 4-digit series, in particular as NACA 2412 profiles. This profile is characterized by moderate camber and optimized pressure distribution, resulting in a favorable lift-to-drag ratio.

[0074] As further shown in Figure 2, at least four rotor drives are arranged on the supports 6, 7, located essentially at the respective ends of the forward support 6 and the rear support 7. This positioning ensures an even load distribution on the support structure 3 and enables stable flight in both hovering and forward flight. The arrangement of the rotor drives 4 at the outer ends of the supports 6, 7 also achieves an optimal leverage ratio for control movements, thereby improving the efficiency of the flight control system. Furthermore, this configuration reduces aerodynamic interactions between the rotors 4 and the fuselage 2, allowing for a more unobstructed airflow and increasing the overall efficiency of the aircraft.

[0075] In another example, the rotor drives 4 are positioned such that the center ZV of the rotor blade planes of the front rotor drives 8 lies above the longitudinal axis LT of the front supports 6, while the center ZH of the rotor blade planes of the rear rotor drives 7 lies below the VON WITZLEBEN, Dietrich, Case: LK_01 WO

[0076] The longitudinal axis of the rear rotor supports 7, or vice versa, is arranged. This configuration helps to ensure that the generated airflows are efficiently discharged and that no disruptive interactions occur between the rotor flows. In particular, it prevents the rear rotor drives 9 from being obscured or having their efficiency impaired by the downwash from the front rotor drives 8. This arrangement ensures optimized thrust generation during cruise flight, as the rear rotors are less affected by the downwash from the front rotors. This improves the overall efficiency of the propulsion system and reduces energy consumption.

[0077] Figures 3A and 3B show the control of the flight attitude by the flight control device 11. The flight control device 11 is configured such that the aircraft 1 is set at an angle β between 10° and 40°, preferably between 25° and 30°, particularly preferably at 25°, relative to a horizontal perpendicular to the gravitational axis in hovering flight (Fig. 3A).

[0078] A key advantage of aircraft 1 is that it operates at an angle of attack relative to the horizontal during hovering. This enables an aerodynamically efficient transition to cruise flight without requiring rotor drive pivoting or active adjustment of the rotor blade angles. The angle of attack ensures that a horizontal thrust component is generated even during hovering, allowing aircraft 1 to accelerate smoothly during the transition to cruise flight without requiring an abrupt change in attitude. This control strategy reduces the mechanical and electronic complexity of the flight control system, minimizes moving components, and contributes to increased operational reliability and lower maintenance costs. Furthermore, Figure 3B illustrates that aircraft 1 is set at an angle between -1° and 1°, preferably -0.5°, relative to the horizontal during cruise flight.This control strategy ensures that the aircraft maintains a near-horizontal flight attitude during forward flight, allowing the aerodynamic fuselage 2 to optimally utilize its lift characteristics. This minimizes the effort required to maintain altitude and significantly reduces energy consumption during cruise flight.

[0079] Figure 4 shows a sectional view through the longitudinal axis of the aircraft 1, showing the internal components of the aircraft 1.

[0080] The internal components, such as battery 10, telemetry device 12, GNSS module 13, power module 14, and flight control unit 11, are positively bonded within the foamed plastic, preferably expanded polypropylene (EPP), thus eliminating the need for additional fasteners. This simplifies assembly, reduces the overall weight of the aircraft 1, and improves shock absorption. (VON WITZLEBEN, Dietrich, Case: LK_01 WO)

[0081] The battery 10 is preferably located in the rear area or in the side walls and provides the energy supply for the rotor drives 4 and the control electronics. Its placement ensures a balanced weight distribution and a central position of the center of gravity S of the aircraft 1.

[0082] The power module 14 is located in the front area of ​​the fuselage 2 and serves to regulate the voltage and distribute the electrical energy to the various system components.

[0083] GNSS module 12 is located in the upper part of the forward fuselage 2 and serves for position determination and navigation of the aircraft 1. Its elevated position allows for unobstructed signal reception.

[0084] The flight control device 11 is preferably located in the front section of the fuselage 2 and serves to control the aircraft, stabilize and regulate the rotor drives 4.

[0085] The telemetry device 12 is located in the lower part of the fuselage 2 and establishes wireless communication with a ground station. It enables the real-time transmission of flight parameters and sensor data.

[0086] Figure 4 further shows the positioning of the forward support 6 and the aft support 7. Figure 4 also shows a cavity 5 formed within the fuselage 2. This cavity 5 serves to reduce weight without significantly compromising the structural integrity of the fuselage 2. By specifically creating this cavity, the overall weight of the aircraft 1 is reduced, thereby improving energy efficiency and flight duration.

[0087] The cavity 5 is created in the manufacturing process by a removable core structure 17 or by controlled expansion of the foamed plastic, preferably expanded polypropylene EPP. This ensures that sufficient material remains in areas with higher mechanical loads, particularly near the supporting structure 3 and the supports 6 and 7, to guarantee the required strength.

[0088] In addition, the cavity 5 enables efficient heat dissipation for the internal electronic components, especially the battery 10 and the power module 14, as a natural airflow can form within the cavity, which contributes to thermal stabilization.

[0089] The invention is not limited to the embodiments illustrated in the figures. The foregoing description is therefore not to be considered limiting, but rather explanatory. The following claims are to be understood as meaning that a named feature is present in at least one embodiment of the invention. This does not preclude the presence of further features. Provided that the claims and the foregoing description are

[0090] Defining 'first' and 'second' characteristics, this designation serves to distinguish between two similar characteristics without establishing a hierarchy. (VON WITZLEBEN, Dietrich, Case: LK_01 WO)

[0091] Reference symbol list

[0092] 1 aircraft

[0093] 2 Hull

[0094] 3 Supporting structure

[0095] 4 rotor drives

[0096] 5-cavity

[0097] 6 Front Carrier

[0098] 7 Rear Carrier

[0099] 8 Front rotor drive

[0100] 9 Rear rotor drives

[0101] 10 batteries

[0102] 11 Flight control system

[0103] 12 Telemetry

[0104] 13 GNSS

[0105] 14 Power module

[0106] M Geometric center of the hull S Center of gravity

[0107] L Longitudinal axis of the aircraft

[0108] LT Longitudinal axis of the beam

Claims

1. VON WITZLEBEN, Dietrich, Case: LK_01 WO Claims 1. Aircraft (1), in particular unmanned aircraft, comprising: o a hull (2), a supporting structure (3) which supports at least four rotor drives (4) and comprises two supports (6, 7), wherein ■ a front support (6) is arranged in front of the geometric center (10) and / or center of gravity (S) of the hull (2), and ■ a rear support (7) is arranged behind the geometric center (10) and / or center of gravity (S) of the fuselage (2), characterized in that the hull (2) is formed from a foamed plastic, preferably expanded polypropylene (EPP), wherein the front support (6) and the rear support (7) are at least embedded in the foamed plastic and form a fixed connection with the hull (2) by thermal fusion without the need for additional fastening means.

2. Aircraft (1) according to claim 1, characterized in that the foamed plastic, preferably expanded polypropylene (EPP), has a molded part density between 60 and 100 kg / m3, preferably 70 kg / m3, and / or a closed-cell structure to reduce water absorption, and / or a tensile strength between 880 and 1410 kPa.

3. Aircraft (1) according to one of the preceding claims, characterized in that the fuselage (2) is radar-transparent and allows electromagnetic waves in the frequency range between 1 GHz and 10 GHz to pass through.

4. Aircraft (1) according to one of the preceding claims, characterized in that the supporting structure (3) comprises only the front support (6) and the rear support (7) and the fuselage (2) is self-supporting made of foamed plastic.

5. Aircraft (1) according to one of the preceding claims, characterized in that the fuselage (2) has an aerodynamic airfoil which generates lift during cruise flight, wherein the aerodynamic airfoil of the fuselage is designed as an airfoil and the expanded polypropylene (EPP) is shaped around the supports (6, 7) such that it forms airfoils with an airfoil profile, preferably with an airfoil from the NACA 4-digit series, in particular a NACA 2412 airfoil. VON WITZLEBEN, Dietrich, Case: LK_01 WO 6. Aircraft (1) according to one of the preceding claims, characterized in that the at least four rotor drives (4) are arranged on the supports (6, 7).

7. Aircraft (1) according to one of the preceding claims, characterized in that the fuselage (2) is designed such that additional components, in particular batteries or sensors, are received in a force-fit manner in recesses or indentations, wherein the fixation is effected by elastic clamping forces and the material restoring force of the foamed plastic.

8. Aircraft (1) according to one of the preceding claims, characterized in that the rotary drives (4) are rigidly connected to the supports (6.7) such that the planes of rotation of the rotor drives (4) are arranged relative to the longitudinal direction (L) of the aircraft (1) at an angle (a) between 10° and 40°, preferably 20°-30°, particularly preferably 25°.

9. Aircraft (1) according to one of the preceding claims, characterized in that a flight control device (11) is provided which is configured such that the aircraft (1) is controlled with respect to the longitudinal axis o is hovering at an angle between 10° and 40°, preferably 25°-30°, particularly preferably 25°, relative to a horizontal perpendicular to the gravitational axis, and o is set at an angle between -1° and 1°, preferably -0.5°, relative to the horizontal during cruise flight.

10. Method for manufacturing an aircraft (1), comprising the steps: o Providing (Sl) a closed mold with a cavity defining the outer contour of the body, wherein the mold has at least two separable mold halves; o Introducing (S2) foamed plastic, preferably expanded polypropylene (EPP), granules into the cavity of the mold; o Inserting (S3) a support structure comprising at least one front support and one rear support into the cavity of the mold prior to the expansion of the foamed plastic, such that the support structure is at least partially enclosed by foamed plastic; o Heating (S4) the granules by introducing hot steam or hot air to cause expansion and fusion of the granules, resulting in a closed wall structure; VON WITZLEBEN, Dietrich, Case: LK_01 WO o Control (S5) of the material distribution to achieve a defined wall thickness of the hull, in particular by targeted temperature control or adjustment of the steam inlet openings; o Formation (S6) of a cavity within the hull, by a) a removable core structure is inserted into the cavity before the expansion of the foamed plastic and is removed after curing, or b) by controlled partial expansion of the material, the central area remains unused.

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