Hydrogen-electric hybrid vertical take-off and landing fixed-wing unmanned aerial vehicle

Abstract

This utility model discloses a hydrogen-electric hybrid vertical takeoff and landing fixed-wing unmanned aerial vehicle (UAV), including a fuselage, main wing, tail fin, vertical takeoff and landing system, cruise propulsion system, and a hydrogen fuel cell stack, lithium battery, hydrogen storage device, and flight control electronics installed inside the fuselage. The UAV also includes two powered arms connected to the main wing and extending rearward, with the tail fin connected to the tail ends of the two powered arms. An air intake duct is located under the fuselage, curving upwards from the inlet, with its cross-sectional shape changing to match and connect to the air intake of the hydrogen fuel cell stack. The outlet of the air intake duct is located at the rear of the fuselage, and the outlet section of the air intake duct gradually narrows. This utility model effectively solves the problems of insufficient air intake cooling, significant airframe vibration, and waste heat in existing hydrogen-electric hybrid UAVs by optimizing aerodynamic layout, strengthening structural rigidity, and innovating thermal management design, significantly improving flight stability, endurance efficiency, and multi-mission adaptability.

Description

Technical Field

[0001] This utility model relates to the field of unmanned aerial vehicle (UAV) technology, and in particular to a hydrogen-electric hybrid vertical take-off and landing fixed-wing UAV. Background Technology

[0002] Unmanned aerial vehicles (UAVs) are now widely used in various fields such as logistics and transportation, emergency rescue, geographic surveying and mapping, and environmental monitoring. Based on different aerodynamic layouts and flight modes, the mainstream UAV types mainly include multi-rotor UAVs, fixed-wing UAVs, and vertical takeoff and landing (VTOL) UAVs. Multi-rotor UAVs have vertical takeoff and landing capabilities and hovering capabilities, offering flexible maneuverability, but their aerodynamic efficiency is relatively low, limiting their flight time and range. Fixed-wing UAVs have high cruise efficiency and long endurance, but typically require runways for takeoff and landing, placing high demands on the takeoff and landing environment. VTOL UAVs combine the advantages of both, enabling vertical takeoff and landing while possessing the high-efficiency cruise performance of fixed-wing mode, thus becoming a research hotspot and development direction in recent years.

[0003] In terms of power systems, hydrogen fuel cells are gradually being introduced into the drone field as a clean energy solution due to their advantages such as high energy density, low operating noise, and emissions consisting only of water. In particular, the hybrid power system composed of hydrogen fuel cells and lithium batteries (called "hydrogen-electric hybrid") can give full play to the advantages of both: lithium batteries provide instantaneous high power output to meet the power requirements during vertical take-off and landing; while hydrogen fuel cells provide continuous and stable electrical energy, significantly extending the drone's flight time.

[0004] Despite the promising application prospects of hydrogen-electric hybrid VTOL drones, the following key issues still exist in the specific design and integration of this type of aircraft:

[0005] a) Inefficient Air Intake and Thermal Management: Hydrogen fuel cells require a continuous supply of air for electrochemical reactions and heat dissipation during operation. Existing UAV air intake designs often follow the layout of traditional fixed-wing or multi-rotor aircraft, failing to adequately consider the specific airflow and cooling requirements of the fuel cell stack. A common practice is to place the air intake at the front or sides of the fuselage, using straight or simply curved flow paths. Such designs are susceptible to boundary layer effects and insufficient incoming flow pressure under complex flight attitudes, leading to unstable airflow into the fuel cell stack and excessive flow resistance, thereby reducing the stack's heat dissipation efficiency and power output stability.

[0006] b) Structural Vibration and Aeroelastic Interference: Most vertical takeoff and landing (VTOL) fixed-wing UAVs have multiple vertical lift rotors mounted on their wings or nacelles. During VTOL takeoff and landing and mode transitions, the downwash generated by the rotors violently impacts the wing surface, inducing wing flutter or periodic vortex shedding, resulting in low-frequency vibrations that affect flight stability and the normal operation of onboard equipment. On the other hand, to achieve long endurance, lightweight materials are often used in the airframe structure to reduce weight, but excessive thinning of the structure may lead to insufficient wing stiffness, causing elastic deformation during turbulent or maneuvering flight and exacerbating vibrations.

[0007] c) The Coupling Conflict Between Thermal Management and Aerodynamic Performance: Existing aircraft typically handle fuel cell cooling airflow in a rather crude manner, with high-temperature exhaust gases often being directly discharged into the atmosphere or the cabin. This not only wastes energy, but the discharged hot airflow also interferes with the flow field quality around the aircraft—especially in the tail region—increasing flight drag and reducing overall aerodynamic efficiency. This cooling method fails to effectively utilize waste heat, contradicting the design goals of long endurance and high economic efficiency for UAVs.

[0008] Therefore, it is necessary to address the aforementioned technical bottlenecks by conducting a systematic design from three dimensions: aerodynamic layout, structural rigidity, and thermal energy management, and to develop a new type of hydrogen-electric hybrid vertical take-off and landing fixed-wing UAV to significantly improve its flight stability, endurance efficiency, and multi-mission adaptability. Utility Model Content

[0009] To address the aforementioned technical problems, the purpose of this invention is to provide a hydrogen-electric hybrid vertical takeoff and landing fixed-wing unmanned aerial vehicle (UAV). This invention effectively solves the problems of insufficient air intake cooling, significant airframe vibration, and waste heat in existing hydrogen-electric hybrid UAVs by optimizing aerodynamic layout, strengthening structural rigidity, and innovating thermal management design, significantly improving flight stability, endurance, and multi-mission adaptability.

[0010] To achieve the above-mentioned technical objectives and effects, this utility model is implemented through the following technical solution:

[0011] A hydrogen-electric hybrid vertical takeoff and landing fixed-wing unmanned aerial vehicle (UAV) includes a fuselage, a main wing, a tail wing, a vertical takeoff and landing system, a cruise propulsion system, and a hydrogen fuel cell stack, a lithium battery, a hydrogen storage device, and flight control electronics installed inside the fuselage. The main wing is mounted on the fuselage. The UAV is characterized in that it also includes two powered arms connected to the main wing and extending rearward, and the tail wing is connected to the tail ends of the two powered arms.

[0012] A fuselage air intake is located below the fuselage. The air intake curves upward from the inlet, and its cross-sectional shape changes to match and connect to the air inlet of the hydrogen fuel cell stack. It is used to guide the airflow through the hydrogen fuel cell stack for cooling. The outlet of the air intake is located at the rear of the fuselage, and the outlet section of the air intake gradually narrows. It is used to accelerate the discharge of the heated airflow and utilize the reaction force generated by the thermal expansion of the airflow and its acceleration in the gradually narrowing outlet section to generate additional thrust.

[0013] Furthermore, the air intake of the fuselage maintains a gap with the lower surface of the fuselage, and this gap is not less than the thickness of the boundary layer of the lower surface of the fuselage in flight.

[0014] Furthermore, the vertical take-off and landing system includes multiple vertical motors and multiple take-off and landing propellers driven by the vertical motors, with each vertical motor mounted on the power arm via a vertical motor mounting bracket.

[0015] Furthermore, the hydrogen-electric hybrid vertical takeoff and landing fixed-wing UAV also includes at least one stabilizing rod, which is connected between the vertical motor fixing components on both sides, and at least one stabilizing rod passes through the fuselage to enhance the overall structural rigidity and suppress flight vibration.

[0016] Furthermore, the cruise propulsion system includes a horizontal motor and a cruise propeller driven by the horizontal motor, the horizontal motor being mounted to the front end of the fuselage via a horizontal motor mounting bracket.

[0017] Furthermore, the main wings are mounted on both sides of the rear of the fuselage and close to the upper part of the fuselage, and the rear side of the main wing is provided with main wing control surfaces.

[0018] Furthermore, the tail fin includes a horizontal tail fin, a left-canted tail fin, and a right-canted tail fin; both the left-canted tail fin and the right-canted tail fin have an inverted V-shaped structure, and the trailing edges of the left-canted tail fin and the right-canted tail fin are respectively integrated with tail fin control surfaces.

[0019] Furthermore, the fuselage interior is divided into multiple independent compartments, with the hydrogen storage device, hydrogen fuel cell stack, lithium battery, and flight control electronics equipment housed in different independent compartments.

[0020] Furthermore, the upper part of the fuselage is provided with a dedicated opening for installing a data transmission module, a receiver, and an RTK antenna.

[0021] Furthermore, the hydrogen-electric hybrid vertical take-off and landing fixed-wing UAV also includes landing gear installed below the vertical motor mounting bracket, below the front of the fuselage, and below the rear of the fuselage for take-off and landing support.

[0022] The beneficial effects of this utility model are as follows:

[0023] 1. This utility model adopts the aforementioned under-fuselage curved air intake design, precisely arranging the inlet below the fuselage. It significantly increases the intake static pressure by utilizing the pre-compressed airflow area on the lower surface of the fuselage during flight. Combined with the upward curved extension from the inlet and the gradually changing cross-section of the flow channel, it effectively reduces flow resistance and precisely guides the airflow to the fuel cell stack inlet, ensuring that the hydrogen fuel cell can obtain a stable and high-pressure cooling airflow under various flight attitudes, effectively improving the heat dissipation efficiency and output power stability of the fuel cell stack.

[0024] 2. This invention employs a twin-boom composite wing layout (comprising two power arms connected to the main wing and extending rearward, and a hybrid tail fin connected to their tail ends) to construct a high-rigidity frame-type airframe structure. This layout significantly enhances the torsional and bending stiffness of the UAV, effectively suppressing the high-frequency flutter and low-frequency vibration induced by the rotor downwash impacting the main wing surface during vertical takeoff and landing in existing technologies. It provides a stable aerodynamic platform for the flight control system, greatly improving flight quality and control reliability.

[0025] 3. This invention achieves directional control of the waste heat flow from the fuel cell stack by precisely arranging the air intake outlet at the tail of the fuselage and employing a gradually narrowing outlet design. This design not only avoids the interference of disorderly high-temperature exhaust gas emissions on the tail fin flow field, but also converts thermal energy into directional kinetic energy through the physical process of airflow expansion upon heating and acceleration in the contraction section, generating considerable additional thrust. This achieves efficient recovery and utilization of waste heat energy, directly reducing flight drag at the aerodynamic level and contributing to extending the flight range.

[0026] In summary, this utility model, through in-depth collaborative innovation in aerodynamic layout, structural design, and thermal management, organically integrates three major features: twin-tail-boom composite wing layout, under-mounted curved air intake, and tail thrust outlet. It systematically solves the core defects of existing technologies and ultimately achieves a comprehensive improvement in flight stability, endurance efficiency, and multi-mission reliability. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall structure of the hydrogen-electric hybrid vertical take-off and landing fixed-wing UAV of this utility model.

[0028] Figure 2 This is a top view of the hydrogen-electric hybrid vertical take-off and landing fixed-wing UAV of this utility model.

[0029] Figure 3 This is a front view of the hydrogen-electric hybrid vertical take-off and landing fixed-wing UAV of this utility model.

[0030] Figure 4 This is a cross-sectional view of the fuselage air intake of the hydrogen-electric hybrid vertical take-off and landing fixed-wing UAV of this utility model.

[0031] In the diagram, 1: fuselage, 101: fuselage air intake, 1011: inlet, 1012: outlet; 2: main wing; 3: tail, 301: horizontal tail, 302: left canted tail, 303: right canted tail; 4: hydrogen fuel cell stack; 5: main wing control surface; 6: tail control surface; 7: vertical motor; 8: takeoff and landing propeller; 9: stabilizer bar; 10: horizontal motor; 11: cruise propeller; 12: landing gear; 13: vertical motor mounting bracket; 14: horizontal motor mounting bracket; 15: power arm. Detailed Implementation

[0032] The technical solutions of this utility model will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0033] like Figures 1 to 4 A preferred embodiment of a hydrogen-electric hybrid vertical takeoff and landing fixed-wing unmanned aerial vehicle (UAV) is shown, which includes a fuselage 1, a main wing 2, a tail wing 3, a vertical takeoff and landing system, a cruise propulsion system, and a hydrogen fuel cell stack 4, a lithium battery, a hydrogen storage device, and flight control electronics installed inside the fuselage 1.

[0034] The main wing 2 is installed on both sides of the rear part of the fuselage 1 and close to the upper part of the fuselage 1. The main wing control surface 5 is provided on its rear side. Specifically, the main wing control surface 5 is located in the middle and outer section of the main wing 2.

[0035] A fuselage air intake 101 is located below the fuselage 1. Specifically, the inlet 1011 of the fuselage air intake 101 is located below the middle of the fuselage 1 and maintains a gap with the lower surface of the fuselage 1. This gap is not less than the thickness of the boundary layer on the lower surface of the fuselage 1 in flight to reduce boundary layer interference. The fuselage air intake 101 extends upward from the inlet 1011, forming an angle with the horizontal plane. Its flow channel cross-sectional shape changes to match and lead to the air inlet of the hydrogen fuel cell stack 4, guiding the airflow through the hydrogen fuel cell stack 4 for cooling. The outlet section of the fuselage air intake 101 gradually narrows, and the angle then gradually returns to normal. The outlet 1012 of the fuselage air intake 101 is located at the tail of the fuselage 1, with a circular cross-section, used to accelerate the exhaust of the airflow heated by the hydrogen fuel cell stack 4. The heat dissipation process of hydrogen fuel cell stack 4 increases the airflow temperature and static pressure, reducing system pressure drop. The gradually narrowing design at outlet 1012 increases airflow velocity, and the Meredith effect is used to generate additional thrust at outlet 1012, reducing heat dissipation resistance and improving propulsion efficiency. The Meredith effect refers to the phenomenon that when airflow is heated by the radiator, under appropriate flow channel contraction and guidance conditions, the kinetic energy of the airflow is increased, which can generate additional thrust upon discharge.

[0036] The UAV adopts a twin-boom compound wing layout, which includes two powered arms 15 (as a twin-boom structure) connected to the main wing 2 and extending rearward. More specifically, the powered arms 15 are fixed below the inner section of the main wing 2. The tail wing 3 is connected to the tail ends of the two powered arms 15. The tail wing 3 includes a horizontal tail wing 301, a left-canted tail wing 302, and a right-canted tail wing 303; both the left-canted tail wing 302 and the right-canted tail wing 303 have an inverted V-shaped structure, and the trailing edges of the left-canted tail wing 302 and the right-canted tail wing 303 are respectively integrated with tail control surfaces 6.

[0037] In this embodiment, the vertical takeoff and landing system includes four vertical motors 7 and four takeoff and landing propellers 8 driven by the vertical motors 7. Each vertical motor 7 is mounted on the power boom 15 via a vertical motor mounting bracket 13. The vertical takeoff and landing system can provide a total lift greater than the takeoff weight of the entire aircraft under rated operating conditions, has power redundancy capability, and effectively improves the safety and reliability of the system.

[0038] In this embodiment, the hydrogen-electric hybrid vertical take-off and landing fixed-wing UAV also includes two stabilizing rods 9, which are connected between the vertical motor fixing parts 13 on both sides, and the stabilizing rod 9 located at the front passes through the fuselage 1.

[0039] The cruise propulsion system includes a horizontal motor 10 and a cruise propeller 11 driven by the horizontal motor 10. The horizontal motor 10 is mounted to the front end of the fuselage 1 via a horizontal motor mounting bracket 14. The cruise propulsion system is used to provide the main thrust required for high-speed forward flight.

[0040] Mode switching and flight control are accomplished collaboratively by the power system (vertical takeoff and landing system and cruise propulsion system) and aerodynamic control surfaces. Vertical takeoff and landing and hovering modes primarily rely on adjusting the speed differences of the four vertical motors 7 to achieve attitude stability, altitude, and yaw control. Fixed-wing cruise mode is mainly controlled by the aerodynamic lift generated by the wings and the deflection of the control surfaces. Specifically, the main wing control surfaces 5 located on the trailing edge of the main wing 2 are used for roll control; the tail control surfaces 6 integrated on the trailing edge of the tail 3 function as both elevators and rudders, used for pitch and yaw control, respectively. The flight control electronics system comprehensively adjusts the thrust of the vertical motors 7, the pull of the horizontal motors 10, and the deflection angles of each control surface through the flight control system to achieve a smooth transition between vertical lift and aerodynamic lift, ensuring the smoothness and safety of the flight mode switching process.

[0041] The fuselage 1 is divided into multiple independent compartments. The hydrogen storage device, hydrogen fuel cell stack 4, lithium battery and flight control electronic equipment are housed in different independent compartments to prevent the trace water generated during fuel cell operation from corroding electronic components and to improve safety and reliability.

[0042] The upper part of the fuselage 1 has a dedicated opening for installing the data transmission module, receiver and RTK antenna to ensure that communication and positioning signals are unobstructed.

[0043] The hydrogen-electric hybrid vertical take-off and landing fixed-wing UAV also includes landing gear 12 installed below the vertical motor mounting bracket 13, below the front of the fuselage 1, and below the rear of the fuselage 1, respectively, for take-off and landing support.

[0044] The working principle of this hydrogen-electric hybrid vertical takeoff and landing fixed-wing UAV is as follows, and its working process covers three core stages: vertical takeoff and landing, transition, and fixed-wing cruise:

[0045] During vertical takeoff and landing and hovering, four vertical motors 7 drive large takeoff and landing propellers 8 to rotate at high speed, generating a main lift force greater than the total weight of the UAV. The flight control system precisely and independently adjusts the speed of each vertical motor and differentially controls the lift and torque, thereby achieving vertical takeoff and landing, hovering stability and all-attitude control of the UAV.

[0046] After entering the mode conversion and transition phase, the flight control system initiates an automatic coordinated control program: gradually increasing the power of the horizontal motor 10 to provide incremental forward thrust, thereby continuously increasing airspeed; at the same time, as the aerodynamic lift generated by the main wing 2 continues to increase, the power output of the vertical motor 7 is reduced accordingly; during this process, aerodynamic control surfaces (main wing control surface 5 and tail control surface 6) gradually replace the differential control of the vertical motor 7, becoming the dominant control method, achieving a smooth and safe transition from vertical lift as the main force to aerodynamic lift as the main force.

[0047] Once fully engaged in fixed-wing cruise, the UAV demonstrated high efficiency: the vertical motor 7 stopped to reduce drag, and the hydrogen fuel cell stack 4 served as the primary power source, providing continuous power to the horizontal motor 10 and onboard equipment, while the lithium battery pack provided auxiliary power when high power output was required; for example... Figure 4 As indicated by the arrow, the oncoming airflow enters through the inlet 1011 of the fuselage air intake 101 below the fuselage 1. After passing through the curved and gradually changing flow channel to cool the hydrogen fuel cell stack 4, the heated exhaust gas is discharged through the contraction and acceleration section of the fuselage air intake 101 at the outlet 1012. The Meredith effect is used to generate additional thrust, realize the recovery and utilization of waste heat energy, and significantly reduce flight drag. Flight control is entirely achieved by aerodynamic control surfaces (main wing control surface 5 and tail control surface 6). The main wing control surface 5 on the trailing edge of the main wing 2 controls roll, and the tail control surface 6 on the tail 3 controls pitch and yaw respectively.

[0048] The landing phase is the reverse of the above process. The flight control system restarts the vertical motor 7 and increases its power. As the airspeed decreases, control is gradually handed over to the differential control of the vertical motor 7, ultimately achieving a smooth vertical landing.

[0049] In summary, this UAV, through the innovative integration of aerodynamic layout, efficient active thermal management and energy recovery mechanism, and deep collaboration with the flight control system, solves the systemic problems of traditional hybrid-powered UAVs in terms of structural vibration, thermal management efficiency and aerodynamic drag, and successfully achieves the unity of vertical take-off and landing agility and fixed-wing long-endurance performance.

[0050] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention.

[0051] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A hydrogen-electric hybrid vertical takeoff and landing fixed-wing unmanned aerial vehicle (UAV), comprising a fuselage, main wing, tail wing, vertical takeoff and landing system, cruise propulsion system, and a hydrogen fuel cell stack, lithium battery, hydrogen storage device, and flight control electronics disposed inside the fuselage, wherein the main wing is mounted on the fuselage, characterized in that: The drone also includes two powered arms connected to the main wing and extending rearward, with the tail fin connected to the tail end of the two powered arms. A fuselage air intake is located below the fuselage. The air intake curves upward from the inlet, and its cross-sectional shape changes to match and connect to the air inlet of the hydrogen fuel cell stack. It is used to guide the airflow through the hydrogen fuel cell stack for cooling. The outlet of the air intake is located at the rear of the fuselage, and the outlet section of the air intake gradually narrows. It is used to accelerate the discharge of the heated airflow and utilize the reaction force generated by the thermal expansion of the airflow and its acceleration in the gradually narrowing outlet section to generate additional thrust.

2. The hydrogen-electric hybrid vertical takeoff and landing fixed-wing UAV according to claim 1, characterized in that, The air intake of the fuselage maintains a gap with the lower surface of the fuselage, and the gap is not less than the thickness of the boundary layer of the lower surface of the fuselage in flight.

3. The hydrogen-electric hybrid vertical takeoff and landing fixed-wing UAV according to claim 1, characterized in that, The vertical take-off and landing system includes multiple vertical motors and multiple take-off and landing propellers driven by the vertical motors. Each vertical motor is mounted on the power arm via a vertical motor mounting bracket.

4. The hydrogen-electric hybrid vertical takeoff and landing fixed-wing UAV according to claim 3, characterized in that, It also includes at least one stabilizing rod, which is connected between the vertical motor mounting members on both sides and passes through the fuselage to enhance the overall structural rigidity and suppress flight vibrations.

5. The hydrogen-electric hybrid vertical takeoff and landing fixed-wing UAV according to claim 1, characterized in that, The cruise propulsion system includes a horizontal motor and a cruise propeller driven by the horizontal motor. The horizontal motor is mounted to the front end of the fuselage via a horizontal motor mounting bracket.

6. The hydrogen-electric hybrid vertical takeoff and landing fixed-wing UAV according to claim 1, characterized in that, The main wings are mounted on both sides of the rear of the fuselage and close to the upper part of the fuselage, and the rear side of the main wing is provided with main wing control surfaces.

7. The hydrogen-electric hybrid vertical takeoff and landing fixed-wing UAV according to claim 1, characterized in that, The tail fin includes a horizontal tail fin, a left-canted tail fin, and a right-canted tail fin; both the left-canted tail fin and the right-canted tail fin have an inverted V-shaped structure, and the trailing edges of the left-canted tail fin and the right-canted tail fin are respectively integrated with tail fin control surfaces.

8. The hydrogen-electric hybrid vertical takeoff and landing fixed-wing UAV according to claim 1, characterized in that, The fuselage is divided into multiple independent compartments, with the hydrogen storage device, hydrogen fuel cell stack, lithium battery and flight control electronics housed in different independent compartments.

9. The hydrogen-electric hybrid vertical takeoff and landing fixed-wing UAV according to claim 1, characterized in that, The upper part of the fuselage has a dedicated opening for installing a data transmission module, a receiver, and an RTK antenna.

10. The hydrogen-electric hybrid vertical takeoff and landing fixed-wing UAV according to claim 3, characterized in that, It also includes tripods installed below the vertical motor mounting bracket, below the front of the fuselage, and below the rear of the fuselage, respectively, for take-off and landing support.

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