Aircraft with fuel cell propulsion system

Abstract

The invention relates to an aircraft (1) having a fuel cell propulsion system (2), the fuel cell propulsion system (2) having:-a fuel cell (3) for supplying electric power to an electric propulsion device (4) of the aircraft (1); a fuel reservoir (5) for storing fuel for the fuel cell (3); and a cooling device (6) for cooling the fuel cell (3), the main heat exchanger (7) of the cooling device (6) and the fuel reservoir (5) being arranged on the upper side (8) of the fuselage (9) of the aircraft (1), and the main heat exchanger (7) being arranged on the nose side upstream of the fuel reservoir (5).

Description

Field of the Invention

[0001] The present invention relates to an aircraft having a fuel cell propulsion system. The fuel cell propulsion system has a fuel cell, a fuel storage, and a cooling device. Background Art

[0002] New propulsion systems based on fuel cells are significantly different in structure from the traditional turbine drive systems of aircraft. The fuel cell converts the chemical energy in fuel (especially hydrogen) into electrical energy. Here, as a by-product, a large amount of waste heat is generated at a low temperature level, and this waste heat must be dissipated to the environment through a heat exchanger. The integration method of these new propulsion systems (such as fuel cell propulsion systems) is also very different from that of traditional propulsion systems. The above two aspects, namely the storage of fuel and the heat emission on the aircraft, pose the greatest challenges for aircraft integration. Due to the large size of the heat exchanger, its aerodynamic integration is very complex and will generate a large flow resistance (drag). Summary of the Invention

[0003] The object of the present invention is to provide an aircraft having a fuel cell propulsion system, which integrates the components of the fuel cell propulsion system so as to optimize the air flow resistance of the aircraft while ensuring a high usable volume of the aircraft.

[0004] This object is achieved by the technical solutions of the independent patent claims. The advantageous improvement solutions of the present invention are described in the dependent patent claims, the following detailed description, and the drawings.

[0005] The present invention provides an aircraft having a fuel cell propulsion system. The fuel cell propulsion system has: at least one fuel cell for supplying power to the electric drive device of the aircraft; at least one fuel storage for storing the fuel of the fuel cell, and at least one cooling device for cooling the fuel cell. It is proposed here that the main heat exchanger of the cooling device and the fuel storage are arranged on the upper side of the fuselage of the aircraft, and the main heat exchanger is arranged in front of the fuel storage on the nose side.

[0006] The aircraft can particularly be understood as an airplane. In addition, the aircraft can also be designed as a rotary-wing aircraft. In particular, the aircraft is heavier than air and has an electric drive device.

[0007] The fuel cell in the fuel cell propulsion system is designed to convert the chemical energy of the fuel into electrical energy so as to provide energy for the electric drive device, which can particularly have at least one electric machine, such as an electric motor. In addition, the fuel cell can also provide electrical energy for other systems of the aircraft. The electric machine can in turn drive at least one propulsion means, such as a propeller, a fan, a rotor or a similar device, to generate thrust and / or lift.

[0008] Fuel, especially hydrogen, can be stored in a fuel storage device, which may include at least one pressure storage tank, preferably cylindrical. The fuel storage device can be designed to be of a sufficiently large size according to the maximum range required by the aircraft. In addition, the diameter and / or length of the pressure storage tank can be designed accordingly according to the air flow resistance of the aircraft configuration.

[0009] Fuel can be supplied to the fuel cell through corresponding fuel pipelines connecting the fuel storage device and the fuel cell. In addition, the fuel cell requires oxygen, which can be obtained from ambient air through an air supply device. The fuel cell propulsion system, especially the fuel cell itself, in addition to generating electrical energy, also dissipates a large amount of heat at a low temperature level (for example, between 80 °C and 100 °C). This heat must be dissipated to the environment via a cooling device in order to maintain the fuel cell propulsion system at the required operating temperature.

[0010] The cooling device has at least one main heat exchanger. The main heat exchanger is designed and constructed to dissipate the waste heat generated by the fuel cell propulsion system to the environment, especially to the ambient air. For example, the dissipated heat can be introduced into the heat dissipation fins or cooling plates of the main heat exchanger. These heat dissipation fins can then be preferably cooled by forced convection with ambient air.

[0011] Specifically, the ambient air can have a temperature level between -50 °C and 35 °C. Therefore, the main heat exchanger is preferably designed to still provide sufficient cooling performance even when the ambient air temperature reaches 35 °C. Especially considering the small temperature difference between the fuel cell system and the ambient air, the main heat exchanger may need to be designed relatively large to ensure that the required cooling capacity can be provided.

[0012] It is proposed here that both the main heat exchanger and the fuel storage device are arranged on the upper side of the aircraft fuselage. The upper side can be understood as one side of the fuselage, which is the part located at the top of the fuselage when the aircraft is operating statically or flying smoothly at a horizontal level. For example, the upper side can also be understood as the top cover of the fuselage. In particular, for a fuselage with a circular or elliptical cross-section, the upper side can be designed as an upper arc section, and the opening angle of this arc section ranges from 90° to 180°, preferably 120°.

[0013] In addition, it is proposed that the main heat exchanger is arranged in front of the fuel storage device on the nose side. In other words, relative to the fuel storage device, the main heat exchanger is closer to the nose of the aircraft or the aircraft nose, while the fuel storage device is closer to the tail of the aircraft. The nose specifically refers to the front part of the aircraft in the main flight direction, and the tail refers to the rear part of the aircraft in the main flight direction. That is to say, the main heat exchanger is located more forward relative to the fuel storage device or in front of the fuel storage device. Conceptually, the fuel storage device is in the "air flow" of the main heat exchanger.

[0014] In addition, the advantages obtained by the present invention are that, through the combined integration of the main heat exchanger and the fuel storage on the top of the fuselage, the air flow resistance can be significantly reduced. Therefore, the overall efficiency of the aircraft can be effectively improved.

[0015] In addition, another advantage is that the present invention basically does not occupy the internal space of the fuselage. Since the fuselage space is essentially the effective use area of the aircraft, this enables this space to be maximally utilized without limitation for loading goods or passengers.

[0016] A further advantage of the present invention is that the main heat exchanger and the energy storage device located on the upper side of the fuselage can be flexibly adjusted according to design requirements. Except for considering the aerodynamic and flight mechanics characteristics of the aircraft, their size and configuration are basically not restricted because they are located on the upper side of the fuselage and will not cause spatial conflicts with other systems of the aircraft.

[0017] Compared with arranging the heat exchanger on the wing of the aircraft (especially in the engine nacelle), adopting this design can significantly reduce the size of the engine nacelle. From an aerodynamic perspective, this is beneficial to improving the air flow around the wing.

[0018] In addition, the present invention improves the integration method of the cooling device. Both the fuel storage and the heat exchanger must be connected to the coolant pipeline. By arranging these two components close to each other in space, the total length of the required coolant pipeline can be reduced, thereby reducing the structural weight of the fuel cell propulsion system.

[0019] Another advantage is that the original structure of the aircraft can be largely kept unchanged, making the integration of the fuel cell propulsion system in the aircraft greatly simplified. The integration of the fuel cell propulsion system can be achieved only by modifying the upper side of the fuselage or the wing. Correspondingly, this enables the fuel cell propulsion system to be integrated into the existing aircraft design.

[0020] By arranging the fuel storage on the top of the fuselage, most of the fuel delivery pipelines can also be placed on the upper side of the aircraft. In the case of fuel leakage, especially hydrogen leakage, a safe leakage channel can be ensured because hydrogen can escape upward. This greatly improves the safety of the entire system.

[0021] One embodiment proposes that the main heat exchanger and the fuel reservoir are arranged closely adjacent to each other as an aerodynamic unit, especially in a compact arrangement in the longitudinal direction of the aircraft. The aerodynamic unit can be understood as this arrangement mode, in which the main heat exchanger and the fuel reservoir are as close as possible and coordinated with each other in external dimensions so that they can cooperate with each other. In other words, the total height and / or total width of the main heat exchanger basically correspond to the total height and / or total width of the fuel reservoir. The space between the main heat exchanger and the fuel reservoir is preferably minimized so that the fuel reservoir is actually located in the wake of the main heat exchanger.

[0022] This compact structural design is particularly advantageous for the aerodynamics of the aircraft because the ambient air flowing around can only generate a minimum of eddies between the main heat exchanger and the energy storage device. On the other hand, the frontal projected area and the wetted surface area of the aircraft can also be effectively reduced.

[0023] One embodiment proposes that the aircraft includes a streamlined outer casing that encloses the main heat exchanger and the fuel reservoir together. In other words, the outer casing forms the outer shell of the main heat exchanger and the fuel reservoir at the top, front, and rear, so that the main heat exchanger and the fuel reservoir are located in the space enclosed by the upper side of the fuselage and the outer casing. The outer casing is designed in a streamlined shape. This means that the outer casing has a shape that minimizes the aerodynamic drag on the ambient air flowing around. In particular, the outer casing can be installed on the fuselage such that the air flow resistance in the transition area between the fuselage and the outer casing is minimized. In other words, the upper side of the outer casing can basically be convex and follow the fuselage curve. Preferably, the main heat exchanger can be structurally integrated into the front part of the outer casing.

[0024] One of the advantages provided by the outer casing is a significant reduction in the air flow resistance of the main heat exchanger and the fuel reservoir. On the other hand, the outer casing can also protect the main heat exchanger and the fuel reservoir from external factors (such as weather).

[0025] One embodiment proposes that the outer casing has an input opening on the nose side for introducing ambient air into the main heat exchanger. Preferably, the outer casing has an output opening for discharging the ambient air from the outer casing. In particular, the input opening of the outer casing and the air inlet of the main heat exchanger can be designed as a common unit.

[0026] In this context, the "nose side" can be understood as, in particular, the front part of the outer casing in the main flight direction of the aircraft, especially the front end of the outer casing. Accordingly, it is proposed that the front end of the outer casing has an input opening.

[0027] In particular, the ambient air can flow into the main heat exchanger through the input opening and absorb heat. The ambient air then flows out of the main heat exchanger through the outlet of the main heat exchanger and preferably leaves the outer casing through the output opening. Ideally, the outer casing should have multiple output openings.

[0028] During the flight operation of an aircraft, especially in the main flight direction, an input opening on the nose side has significant advantages because, as the ambient air flows around the aircraft, it can naturally flow into the input opening along its main flow direction by means of aerodynamic effects.

[0029] One embodiment proposes that the output opening is located in the discharge area of the ambient air flowing around the outer casing. The discharge area can also be understood as the so-called "dead zone". In the discharge area, the flowing-around ambient air separates or detaches from the surface of the outer casing. Therefore, the ambient air forms a vortex in the discharge area. This can have a negative impact on the aerodynamics of the outer casing, especially by increasing the airflow resistance. In particular, the discharge area may be located in the rear area of the outer casing.

[0030] Preferably, one or more discharge areas on the outer casing are known, for example, determined by wind tunnel tests. The output opening can be arranged in a targeted manner in the known discharge area. By the air flowing out of the output opening, the discharge area can be energized or activated in a targeted manner, thereby counteracting the separation tendency of the ambient air. This can effectively reduce the airflow resistance and improve the aerodynamics of the outer casing.

[0031] One embodiment proposes that the output opening is arranged such that the discharged ambient air promotes the flow around the tail unit of the aircraft.

[0032] In particular, viewed from the main flight direction, the tail unit may be located behind the fuselage or the main heat exchanger and the fuel storage. By optimizing the flow around the tail unit, the stability and maneuverability of the aircraft can be effectively improved.

[0033] One embodiment proposes that the air channels of the cooling device in the aircraft, especially in the outer casing, fluidly connect the outlet of the main heat exchanger to the output opening of the outer casing. Specifically, one or more air channels are configured to direct the ambient air flowing out of the outlet of the main heat exchanger to one or more output openings of the outer casing in a targeted manner, so that the air can bypass the fuel storage in a directed manner. This can prevent the heated air flowing out of the outlet of the main heat exchanger from forming a vortex and / or dissipating heat in the outer casing. Therefore, the air can be discharged from the outer casing in a high-energy state (i.e., with high kinetic energy and thermal energy) through at least one air channel.

[0034] One embodiment proposes that the fuel storage has two cylindrical pressure storage tanks, and the main extension direction of each pressure storage tank is substantially parallel to the longitudinal axis of the aircraft. Preferably, these two cylindrical pressure storage tanks are arranged side by side along the longitudinal axis. The main extension direction can especially extend along the geometric height of the cylindrical pressure storage tank. In other words, these cylindrical pressure storage tanks can be arranged adjacent to each other in a horizontal position.

[0035] The fuel storage uses two cylindrical pressure storage tanks, which can effectively reduce the air flow resistance compared to using only one fuel storage tank with the same total capacity. This can improve the overall efficiency of the aircraft.

[0036] One embodiment proposes that the cooling device has a secondary heat exchanger, which is located in the downwash area of the aircraft propeller. In particular, the secondary heat exchanger can be much smaller in size and design than the primary heat exchanger. The secondary heat exchanger can be designed to provide the required cooling performance when the aircraft is in a stationary operating state and the fuel cell propulsion system and the drive device are in an active state.

[0037] For example, the primary heat exchanger can only provide limited cooling performance in a stationary operating state because, due to the lack of ambient air flow, the heat dissipation fins or cooling plates of the primary heat exchanger cannot be cooled by forced convection. According to this example, the secondary heat exchanger can provide the cooling performance designed for the stationary operation of the fuel cell propulsion system through the downwash of the propeller unit, especially the downwash of the propeller. This has the advantage that the cooling device can provide sufficient cooling performance under various operating conditions of the aircraft.

[0038] One embodiment proposes that the liquid cooling medium of the cooling device is configured to absorb the waste heat of the fuel cell and dissipate it to the ambient air in the primary heat exchanger. This has the advantage that the fuel cell and the primary heat exchanger can be spatially separated and operated. Therefore, the arrangement of the fuel cell can be selected independently of the arrangement of the primary heat exchanger, and vice versa.

[0039] The present invention also includes various combinations of the features of the described embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The following describes embodiments of the present invention. For this purpose, the illustrations are as follows:

[0041] Figure 1 A perspective view of an aircraft with a fuel cell propulsion system according to a preferred embodiment is shown;

[0042] Figure 2 shows a side view of an aircraft with a fuel cell propulsion system according to a preferred embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0043] The embodiments described below are preferred embodiments of the present invention. In this embodiment, the components of the described embodiments represent features that need to be considered separately and independently in the present invention. These features each independently improve the present invention and can therefore be considered as components of the present invention either individually or in combinations different from those shown. In addition, the described embodiments can also be supplemented with other features already described in the present invention.

[0044] In the drawings, like reference numerals denote like elements in function.

[0045] Figure 1 A perspective view of an aircraft 1 having a fuel cell propulsion system 2 according to a preferred embodiment is shown. In Figure 2 A side view of the aircraft 1 is shown. The following description of the drawings applies to both of these figures.

[0046] The aircraft 1 can be designed, for example, as an airplane 1, in particular as a conventional airplane 1 having a fuselage 9, wings 12, and a tail unit 16 at the tail 11. The aircraft 1 is designed as a twin-engine shoulder-wing airplane only by way of example. Accordingly, the aircraft 1 can also be designed as a mid-wing aircraft, a low-wing aircraft, a flying wing, a rotary-wing aircraft, or a similar design.

[0047] The fuel cell propulsion system 2 of the aircraft 1 can have at least one fuel cell 3 for supplying electrical power to an electric propulsion device 4 of the aircraft 1. For example, the fuel cell 3 can be arranged together with the electric propulsion device 4 (in particular an electric motor that can drive a propeller 22 (see Figure 2 )) or a fan) in a pod below the wing 12.

[0048] The fuel cell propulsion system 2 can also have a fuel reservoir 5 for storing fuel for the fuel cell 3. The fuel is in particular hydrogen, which can be stored in the fuel reservoir 5 in a liquid form especially under high pressure. The fuel reservoir 5 can in particular include at least one pressure storage tank, such as a first pressure storage tank 18 and a second pressure storage tank 19. The pressure storage tanks 18, 19 can be cylindrical and each have a main extension direction 20, where the main extension direction 20 can represent the geometric height of the cylindrical shape of the cylindrical pressure storage tanks 18, 19. In particular, the pressure storage tanks 18, 19 can be arranged parallel to each other in a horizontal plane and substantially parallel to the longitudinal axis X of the aircraft 1.

[0049] The fuel reservoir 5 is particularly provided on the upper side 8 of the fuselage 9 of the aircraft 1. In other words, in this example, the pressure storage tanks 18, 19 of the fuel reservoir 5 are located on the top of the fuselage 9, so that the available space inside the fuselage 9 is not restricted by the fuel reservoir 5.

[0050] The fuel cell propulsion system 2 can also have a cooling device 6 for cooling the fuel cell 3. The cooling device 6 can include, for example, a main heat exchanger 7, at least one secondary heat exchanger 21, a coolant tank 24, a coolant pump 26, and coolant lines.

[0051] The main heat exchanger 7 is arranged on the upper side 8 of the fuselage 9 of the aircraft 1 and is arranged in front of the fuel reservoir 5 on the nose side. The "nose side" means that the main heat exchanger 7 is closer to the nose 10 of the aircraft 1 than the fuel reservoir 5. In particular, it can be envisaged that the main heat exchanger 7 of the fuel cell propulsion system 2 must be designed with larger specifications compared to the heat exchangers of traditional propulsion systems with heat engines, because the temperature of the fuel cell 3 is significantly lower than that of the heat engine. Due to the size required for the main heat exchanger 7, placing it on the top of the aircraft 1 is particularly aerodynamically advantageous.

[0052] For example, the main heat exchanger 7 and the fuel reservoir 5 are arranged compactly adjacent to each other as an aerodynamic unit, so that the aerodynamic performance of the aircraft can be improved. In particular, the outer casings 13 of the main heat exchanger 7 and the fuel reservoir 5 can thus be designed as a common outer casing 13. This streamlined outer casing 13 forms a space together with the upper side 8 of the fuselage 9, in which the main heat exchanger 7 and the fuel reservoir 5 are arranged. In particular, the outer casing 13 has an aerodynamically advantageous shape. Other components can also be arranged inside the outer casing 13, such as components like the coolant pump 26, coolant pipelines, fuel pipelines, etc.

[0053] Preferably, the outer casing 13 is formed with an inlet opening 14 at its front part (i.e., on the nose side), and this inlet opening can correspond to the air inlet 25 of the main heat exchanger 7. During the flight operation or forward movement of the aircraft 1, ambient air can thus flow into the air inlet 25, and by means of the flow of this ambient air, and in particular through forced convection, heat can be extracted from the heat dissipation fins or cooling plates of the main heat exchanger 7.

[0054] The air flowing into the air inlet 25 can flow out from the outlet 17 of the main heat exchanger 7. In particular, the outflowing air can pass around the pressure storage tanks 18, 19 through the air channels in the outer casing 13 and be guided to one or more outlet openings of the outer casing 13. Preferably, these outlet openings are arranged in the discharge area 15 such that the outflowing air can activate the so-called dead zone of the discharge area 15. Additionally, the outlet openings can also be designed to promote the flow around the tail unit 16.

[0055] Overall, this example shows how the present invention can be used to integrate the main heat exchanger and the fuel reservoir unit into the aircraft in an aerodynamically optimized manner.

[0056] The present invention can provide a solution for combining and integrating the fuel reservoir and the main heat exchanger on the top of the aircraft. Through the combined integration of these two subsystems, the drag of the aircraft can be significantly reduced and the overall efficiency of the aircraft can be improved. Conceptually, the relatively large pressure storage tanks are located in the "wake region of the main heat exchanger".

[0057] Different from traditional integration solutions, the fuel storage is not installed on the fuselage or wings but placed on top of the aircraft. The cylindrical shape of the pressure storage tank can remain unchanged. Depending on the drag characteristics of the configuration, fuel storage tanks of different diameters or lengths can be considered. In addition, it is also possible to consider dividing a large pressure storage tank into two smaller ones. Although the diameters of these smaller pressure storage tanks will be significantly reduced, thereby reducing the storage efficiency. However, from an aerodynamic perspective, this division may bring significant advantages in terms of air flow resistance, thus improving the efficiency of the entire aircraft.

[0058] To further reduce the drag of this configuration, a fairing can be designed for the entire top-mounted structure. The main heat exchanger, cooling device or thermal system is structurally integrated into the front part of this fairing. By installing the main heat exchanger on top, the size of the engine nacelle on the wing can be significantly reduced. From an aerodynamic perspective, this can improve the air flow around the wing. Combining the fuel storage and the main heat exchanger in the fairing can not only reduce the front projection area of the aircraft but also reduce the wetted surface of the aircraft. Therefore, the air flow resistance of the aircraft can be optimized.

[0059] Other advantages of integrating the storage tank and the heat exchanger on top are as follows: First, the integration of the cooling system is improved. Both the storage tank and the heat exchanger must be connected to the coolant pipeline. Due to the spatial proximity of these two components, the total length of the coolant pipeline used can be reduced, thereby reducing the structural weight of the propulsion system. Second, the original structure of the aircraft can largely remain unchanged, which greatly simplifies the integration in the aircraft. The integration of the propulsion system can be achieved only through modifications to the top or wings, and in this case, even existing aircraft models can be retrofitted. Third, by placing the H 2 storage tank on top, most of the pipelines for transporting hydrogen can also be placed on the upper side of the aircraft. In the case of hydrogen leakage, a safe leakage path can be ensured because hydrogen rises. In this way, the safety of the entire system is improved.

[0060] Due to the FOD risk (Foreign Object Damage, that is, damage caused by foreign objects thrown by the nose landing gear), installing the fuel storage and the main heat exchanger at the lower part of the fuselage may not be as advantageous as the solution of the present invention.

[0061] In addition, air can be guided through a specifically designed air channel through the fairing and around the pressure storage tank, and then selectively discharged at the end of the fairing. This can pursue multiple integration goals, such as optimizing the aerodynamic characteristics of the air flow around the fairing (restoring the "dead zone") or specifically influencing the air flow around the tail unit.

[0062] List of reference numerals

[0063] 1 Aircraft

[0064] 2 Fuel cell propulsion system

[0065] 3 Fuel cell

[0066] 4 Electric drive device

[0067] 5 Fuel storage

[0068] 6 Cooling device

[0069] 7 Main heat exchanger

[0070] 8 Upper side

[0071] 9 Airframe

[0072] 10 Nose

[0073] 11 Tail

[0074] 12 Wing

[0075] 13 Cowling

[0076] 14 Inlet opening of the cowling

[0077] 15 Discharge area

[0078] 16 Tail unit

[0079] 17 Outlet of the main heat exchanger

[0080] 18 Pressure storage tank

[0081] 19 Pressure storage tank

[0082] 20 Main extension direction

[0083] 21 Secondary heat exchanger

[0084] 22 Propeller

[0085] 23 Air supply device

[0086] 24 Coolant tank

[0087] 25 Inlet of the main heat exchanger

[0088] 26 Coolant pump

[0089] X Aircraft longitudinal axis.

Claims

1. An aircraft (1) having a fuel cell propulsion system (2), wherein, the fuel cell propulsion system (2) has: - at least one fuel cell (3) for supplying electric power to an electric propulsion device (4) of the aircraft (1), - at least one fuel reservoir (5) for storing fuel for the fuel cell (3), and - at least one cooling device (6) for cooling the fuel cell (3), characterized in that, - a main heat exchanger (7) of the cooling device (6) and the fuel reservoir (5) are arranged on an upper side (8) of a fuselage (9) of the aircraft (1), and - the main heat exchanger (7) is arranged in front of the fuel reservoir (5) on the nose side.

2. The aircraft (1) according to claim 1, wherein, the main heat exchanger (7) and the fuel reservoir (5) are arranged closely adjacent to each other as an aerodynamic unit.

3. The aircraft (1) according to claim 1 or 2, characterized in that, a streamlined outer casing (13) is provided, which encloses the main heat exchanger (7) and the fuel reservoir (5) together.

4. The aircraft (1) according to claim 3, characterized in that, the outer casing (13) has an input opening (14) on the nose side for introducing ambient air into the main heat exchanger (7) and an output opening for discharging the ambient air from the outer casing (13).

5. The aircraft (1) according to claim 4, characterized in that, the output opening is arranged in a discharge area (15) of the ambient air flowing around the outer casing (13).

6. The aircraft (1) according to claim 4 or 5, characterized in that, the output opening is arranged such that the ambient air discharged from the output opening promotes the flow around a tail unit (16) of the aircraft (1).

7. The aircraft (1) according to any one of claims 4 to 6, characterized in that, an air passage is provided, which fluidly connects an outlet (17) of the main heat exchanger (7) with the output opening of the outer casing (13) within the outer casing (13).

8. The aircraft (1) according to any one of the preceding claims, characterized in that, the fuel reservoir (5) has two cylindrical pressure storage tanks (18, 19), wherein a main extension direction (20) of each of the pressure storage tanks is substantially parallel to a longitudinal axis (X) of the aircraft (1), and wherein the two cylindrical pressure storage tanks (18, 19) are arranged adjacent to each other along the main extension direction (20).

9. The aircraft (1) according to any one of the preceding claims, characterized in that, the cooling device (6) has a secondary heat exchanger (21), which is arranged in a downwash area of a propeller (22) of the aircraft (1).

10. The aircraft (1) according to any one of the preceding claims, characterized in that, The liquid cooling medium of the cooling device (6) is designed to absorb waste heat from the fuel cell (3) and dissipate the waste heat to the ambient air within the main heat exchanger (7).

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