Split type folding wing range extending device for small multi-rotor aircraft

Abstract

The invention relates to a split type folding wing range extending device for a small multi-rotor aircraft. The problems that the small multi-rotor aircraft is short in voyage and endurance time and poor in capability of executing long voyage tasks are solved through modular design. The device is sequentially provided with a front part, a middle part and a rear part in the flight direction, and a two-section type wing folding mechanism is innovatively adopted; the first section of wing realizes upward reverse unfolding / horizontal storage through the synergistic effect of a sliding piece on a sliding shaft and a pull rod for connecting the wing and the middle part; and the second section of wing realizes rotary unfolding / folding through a rotary steering engine fixed at the tail end of the first section of wing. The tail thrust motor drives the propeller to provide forward flying power, so that the host small-sized multi-rotor aircraft can efficiently cruise in a horizontal attitude. When the device is unfolded, the two sections of wings form a large-span lifting surface, and the power consumption of the rotor wings is reduced through cooperation of wing unloading and horizontal incoming flow effects; during storage, the two sections of wings completely coincide and are hidden in the projection contour of the host aircraft body, and pneumatic interference and rotational inertia increment are remarkably reduced.

Description

Technical Field

[0001] This invention relates to the field of range extender devices for multi-rotor aircraft, and more specifically to a split-type folding wing range extender for small multi-rotor aircraft. Background Technology

[0002] Small multirotor aircraft, with their compact size, agile maneuverability, and foldable configurations in some models, have found widespread and in-depth applications in numerous fields such as power line inspection, emergency rescue, logistics transportation, mapping, and aerial photography. These significant advantages enable them to adapt to complex and ever-changing operating environments and improve the efficiency of completing various tasks. However, limited by battery energy density and rotor aerodynamic efficiency, small multirotor aircraft have relatively weak endurance, exhibiting certain shortcomings in long-range missions such as power line inspection and mapping.

[0003] Compared to multirotor aircraft, fixed-wing aircraft offer superior efficiency during the cruise phase. Therefore, to address the challenges of long-range missions, researchers have combined the advantages of both fixed-wing and multirotor aircraft, designing various configurations of vertical takeoff and landing (VTOL) fixed-wing aircraft. These include configurations equipped with two power systems, configurations that switch flight modes via tilt-propulsion units, and tail-seat configurations. However, due to their large fixed wings, these aircraft are prone to limited maneuverability and weak wind resistance during VTOL and multirotor operations. During the fixed-wing cruise phase, when navigating complex environments such as canyons and power grids, their high cruise speed and large turning radius also result in poor maneuverability and limited mission capabilities. Furthermore, compared to the small folding size and ready-to-use unfolding of some small multirotor aircraft, most of these aircraft with large wings cannot be directly folded. They require significant storage space after disassembly, and the assembly process involves multiple steps such as wing-to-fuselage connection and control surface calibration, which also limits their application in practical scenarios. Therefore, in order to improve the cruising efficiency of multi-rotor aircraft in long-range missions and combine the advantages of both multi-rotor and fixed-wing aircraft, it is urgent to design a small multi-rotor range extender device that can automatically switch between fixed-wing and multi-rotor flight modes during operation and can be quickly installed on the host aircraft through simple assembly.

[0004] For example, a patent (application patent number: CN202322324216.0, publication date: 2024.06.07, publication number: CN221091275U) proposes a quick-connect structure for wings and fuselage and a vertical take-off and landing fixed-wing UAV containing the structure. The wings of the vertical take-off and landing fixed-wing UAV are assembled with the fuselage through the designed quick-connect structure, which occupies a small volume during transportation and is convenient to transport. However, the wings cannot be automatically folded during operation, and thus the performance is poor when the UAV needs to operate in multi-rotor mode due to the influence of the wings and other factors.

[0005] The patent (application number: CN202411681760.3, publication date: 2025.02.14, publication number: CN119429099A) proposes a tilt-folding wing and a vertical take-off and landing aircraft. The aircraft relies on a combination of a rotatable and foldable wing and a power unit on the wing and a tiltable power unit to achieve automatic switching between multi-rotor flight and fixed-wing flight. However, when the aircraft is operating in multi-rotor mode, components such as the vertical tail fin designed for fixed-wing flight will affect flight performance. In addition, the complex tilt mechanism also increases the aircraft's weight.

[0006] The patent (application number: CN202411877805.4, publication date: 2025.02.14, publication number: CN119429087A) discloses a portable single-person low-altitude vector jet aircraft with a folding wing structure. The aircraft relies on a linkage mechanism to fold the flexible wing, which improves the storage efficiency. However, the linkage mechanism can only fold the flexible wing in a plane, which limits the application scenarios of the mechanism. At the same time, the flexible wing is prone to damage and deformation.

[0007] The patent (application number: CN202410511494.3, publication date: 2024.07.09, publication number: CN118306593A) discloses a wing with a secondary folding structure. This folding method solves the problem of complex structure and reduced aerodynamic efficiency of existing folding and unfolding methods, thus improving wing performance. However, the wingspan of this folding method is limited by the fuselage length and the wing's mounting position, and can only reach approximately twice the fuselage length, thus restricting further improvement in wing performance.

[0008] The patent (application number: CN202311191417.6, publication date: 2023.11.10, publication number: CN117021861A) discloses a vertical take-off and landing flying car. The flying car has wings that can be folded backward in the plane and a propulsion device at the tail. However, its wingspan and the total length of the car affect each other, which limits the improvement of flight performance.

[0009] The first two patents mentioned above describe specific implementations of folding or disassembling designs for the wings of vertical takeoff and landing fixed-wing aircraft. Wings with manually detachable quick-release structures cannot automatically switch during operation, and structures designed for fixed-wing mode flight cannot be removed. This limits the aircraft's performance in multi-rotor mode and affects its application flexibility. The latter three patents describe specific implementations of wing folding. Linkage-mechanism folding flexible wings have poor durability, fixed-axis folding wings have limited wingspan, and all three can only fold wings in a plane, easily affecting the aerodynamic efficiency of rotors and other critical components. Therefore, it is necessary to design a split-type folding wing range extender that can be quickly assembled and disassembled on small multi-rotor aircraft and automatically retract and extend large-span wings within a limited three-dimensional space. This would allow small multi-rotor aircraft to possess the high cruise efficiency of fixed-wing aircraft in long-range missions, maximizing the advantages of both multi-rotor and fixed-wing aircraft. Summary of the Invention

[0010] To address the aforementioned problems, this invention discloses a split-type folding wing range extender for small multi-rotor aircraft. It solves the problems of short flight time and range of small multi-rotor aircraft, poor performance of existing vertical take-off and landing fixed-wing aircraft when flying in multi-rotor mode, and inconvenient transportation and assembly. It provides a range extender that can be quickly disassembled and used as needed with almost no impact on the original maneuverability.

[0011] Technical solution:

[0012] A split-type folding wing range extender for a small multi-rotor aircraft includes a front component, a middle component, and a rear component connected sequentially along the flight direction. A sliding shaft horizontally connects the front component and the middle component. A sliding member is slidably sleeved on the sliding shaft and driven to move back and forth by a linear servo motor located between the middle component and the rear component.

[0013] The first wing section is hinged to a sliding component via a wing pivot and connected to the middle component via a tie rod; a rotary servo is provided at the end of the first wing section and a second wing section connected to the rotary servo; a propulsion system is provided on the rear component;

[0014] When the linear servo drives the sliding component to move, it pulls the first wing section to unfold around the wing pivot or to retract horizontally via a pull rod; the rotary servo drives the second wing section to rotate outward to unfold or rotate inward to retract.

[0015] Preferably, the front component and the middle component are rigidly connected by a sliding shaft, and the middle component and the rear component are rigidly connected by a fixed shaft.

[0016] Preferably, the middle component is provided with a slot, bolt hole or strap interface for establishing a rigid connection with the host aircraft that can be quickly detached.

[0017] As a preferred option, the first wing section is an upturned wing.

[0018] Preferably, the sliding member is provided with an wing pivot to support the rotational motion of the first wing section and is connected to a linear servo.

[0019] Preferably, the front component has a V-shaped design, and the bottom plane can fit against the upper surface of the host aircraft to reduce forward drag.

[0020] Preferably, the middle component has a frame structure for fixation and weight reduction. It provides front-end fixation for the linear servo and fixed axis, and rear-end fixation for the sliding axis.

[0021] Preferably, the first wing section and the second wing section completely overlap when fully retracted, and the whole is confined within the projected outline of the host aircraft fuselage.

[0022] Preferably, the propulsion system's tail thrust motor is fixed to the rear component, and the propeller is driven by the motor. The rear component also provides a linear servo for fixing to the rear end of the fixed shaft.

[0023] This invention also discloses a folding and unfolding control method for a split-type folding wing range extender for small multi-rotor aircraft, based on the aforementioned split-type folding wing range extender, comprising the following steps:

[0024] S1, Deploy the first wing section: Activate the linear servo to drive the slider to move along the sliding axis towards the central component; use the lever to pull the first wing section to rotate around the wing pivot to the preset dihedral position;

[0025] S2, Deploy the second wing section: Activate the rotation servo to drive the second wing section to rotate outward around the axis at the end of the first wing section until it is horizontally deployed;

[0026] S3, retract the second wing section: activate the rotation servo to drive the second wing section to rotate inward until it overlaps with the first wing section;

[0027] S4, retracting the first wing section: activate the linear servo to drive the sliding component to move forward along the sliding axis; pull the first wing section downward around the wing pivot to the horizontal retracted state by the pull rod.

[0028] S5, fully retractable: the two wings overlap completely and are concealed within the projected outline of the host aircraft's fuselage.

[0029] This invention also discloses a small multi-rotor aircraft system, including a host aircraft and the aforementioned split-type folding-wing range extender, which is detachably mounted on the fuselage of the host aircraft. The system has:

[0030] Multi-rotor flight mode: The split-type folding wing range extender is in a retracted state, and the host aircraft provides all lift, thrust and attitude control through its own rotor;

[0031] Fixed-wing range extension mode: The split-type folding wing range extender is in the deployed state. The device's propulsion system provides all forward flight power, the first and second wing sections provide the main lift, and the rotor of the host aircraft operates under horizontal airflow and provides attitude control force and some lift.

[0032] The present invention also provides a method for extending the range of a small multi-rotor aircraft, comprising: detachably installing the above-mentioned split-type folding wing range extender on the small aircraft, and controlling the linear servo and rotary servo of the range extender to unfold the first wing section and the second wing section to the working position.

[0033] The propulsion system is activated to provide the main forward flight power to the aircraft, enabling the aircraft to fly forward in a near-horizontal attitude, thereby placing the aircraft's rotor in a horizontal airflow;

[0034] The first and second wing sections are used to generate lift, which bears most of the weight of the aircraft and aerodynamically unloads the rotor.

[0035] The horizontal airflow state and the aerodynamic unloading work together to reduce the power consumption of the rotor, thereby increasing the flight time and range of the aircraft.

[0036] The advantages of this invention compared to the prior art are:

[0037] (1) Innovative wing folding method: This split-type range extender adopts a two-section sliding-rotating dual-degree-of-freedom folding wing, making full use of the fuselage projection area to double the wingspan. In the folded state, it can be highly integrated with the host aircraft, thus meeting the needs of small volume storage and large span to improve flight performance. In addition, the linear servo drives the first section of the wing to slide back and forth while achieving horizontal storage and upward deployment, which can effectively suppress aerodynamic interference. Moreover, the wing storage position and the fixed position when deployed are different, which not only ensures the need for efficient storage, but also ensures the positional relationship between the aerodynamic center and the center of gravity when the wing is deployed.

[0038] (2) Optimized energy efficiency enhancement mechanism: This split-type range extender uses a tail thruster to provide power for the aircraft's forward flight. On the one hand, it enables the wings to efficiently bear the weight of the fuselage, reducing the rotor load. On the other hand, the horizontal airflow can further increase the rotor thrust, significantly reducing rotor power consumption. Combined with the efficient tail thruster, it can effectively improve the endurance, range, and flight speed of small multi-rotor aircraft. At the same time, the original control law of small multi-rotor aircraft is used for aircraft attitude control, which greatly simplifies the structure of the device.

[0039] (3) Innovative application mode: The small multi-rotor aircraft range extender of this invention is a split-type device. When the small multi-rotor aircraft faces long-range missions, it can be quickly installed on the host aircraft to improve the efficiency of the host aircraft during cruise flight and increase its range and flight time. When the aircraft is performing regular missions, the device can be quickly removed, enhancing the mission adaptability and application flexibility of the small multi-rotor aircraft. In addition, the flexible automatic deployment and folding method of the device allows the host aircraft to have both high cruise efficiency and the flexibility of a multi-rotor aircraft after the device is installed. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a schematic diagram of the extended range device of the present invention in its deployed state;

[0042] Figure 2 This is a side view of the extended range device of the present invention in its unfolded state;

[0043] Figure 3 This is a front view of the extended range device of the present invention in its deployed state;

[0044] Figure 4 This is a schematic diagram of the transition state of the range extender device of the present invention;

[0045] Figure 5 This is a schematic diagram of the range extender device of the present invention in its stored state;

[0046] Figure 6 This is a side view of the extended range device of the present invention in its stored state;

[0047] Figure 7 This is a schematic diagram of the range extender device of the present invention after being combined with the host aircraft and stored in its storage state;

[0048] Figure 8 This is a schematic diagram of the extended range device of the present invention in its deployed state after being combined with the host aircraft;

[0049] Figure 9 This is an embodiment of the invention showing the variation of total power at different forward flight speeds;

[0050] Figure 10 This is an embodiment of the invention showing the power distribution variation at different forward flight speeds;

[0051] Figure 11This is an embodiment of the invention showing the variation of flight time at different forward flight speeds;

[0052] Figure 12 This illustrates the range variation at different forward flight speeds in one embodiment of the present invention.

[0053] Reference numerals: 1 Second wing section, 2 First wing section, 3 Forward component, 4 Sliding shaft, 5 Sliding component, 6 Middle component, 7 Wing pivot, 8 Linear servo, 9 Rear component, 10 Rod, 11 Fixed shaft, 12 Rotary servo, 13 Tail thrust motor, 14 Tail thrust propeller. Detailed Implementation

[0054] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many different ways as described herein, and those skilled in the art can make similar modifications without departing from the spirit of the invention; therefore, the present invention is not limited to the specific embodiments disclosed below. Embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0055] Example 1

[0056] Traditional vertical take-off and landing fixed-wing aircraft or lifting-wing multirotor aircraft often suffer from limited maneuverability and dynamic response speed in multirotor operation due to the significant increase in air resistance and rotational inertia introduced by the large-sized wings. To overcome this limitation, the design of this split-type range extender follows key principles: in the folded state, the wing assembly must be highly compact, as close as possible to the host aircraft's center of gravity, and minimize the increase in the original fuselage projected area, thereby effectively suppressing the resulting additional aerodynamic drag and rotational inertia increase, and minimizing the negative impact on the host aircraft's inherent maneuverability. Simultaneously, when deployed to provide lift, the wing mounting position must also be as close as possible to the center of gravity to reduce the additional torque disturbance it generates on the flight control system. However, the requirements for controlling the increase in projected area and proximity to the center of gravity significantly constrain the geometry of the foldable wing, thus weakening its lift contribution capability. If the wings are required to be deployed close to the center of gravity and not exceed the original fuselage projection outline after folding, a conventional single-segment folding design would limit the wing chord length to approximately 50% of the fuselage width and the wingspan to approximately 50% of the fuselage length. Wings of this size would struggle to generate significant lift at the cruising speeds of typical small multirotor aircraft. Therefore, this device innovatively employs a two-segment folding wing design.

[0057] This embodiment discloses a split-type folding wing range extender for a small multi-rotor aircraft. The extended range extender is deployed as shown in the figure below. Figure 1 As shown, the expanded state side view is as follows Figure 2 As shown, it includes:

[0058] The front component 3, middle component 6, and rear component 9 are rigidly connected sequentially along the flight direction. The front component 3 and middle component 6 are rigidly connected by a sliding shaft 4, while the rear component 9 is rigidly connected to the middle component 6 by a fixed shaft 11. In this embodiment, the front component 3 adopts a V-shaped design, and its bottom plane can completely fit the upper surface of the host aircraft, reducing forward drag. The front fixing hole of the sliding shaft 4 is located on the front component. The middle component 6 has a frame structure for fixation and weight reduction. It has mounting holes for fixing the linear servo 8 and the rear end of the sliding shaft 4. In addition, it has lugs with fixing holes at both ends, and the upper two sides are recessed downward to fix and accommodate the pull rod 10. The sliding member 5 can slide back and forth along the sliding shaft 4. The middle part has a through hole for the sliding shaft to pass through and an interface for connecting with the moving parts of the linear servo 8. The two sides are machined with U-shaped grooves to accommodate the pivot mechanism 7 of the first wing section, thereby realizing the hinge connection with the first wing section 2. The rear part of the middle component is rigidly connected to the rear component 9 by the fixed shaft 11. The rear component 9 has mounting holes to provide rear-end fixation for the linear servo and the fixed axis, and a tail thrust motor 13 is mounted at its end, with the motor axis parallel to the flight direction.

[0059] A sliding shaft 4 horizontally connects the front component 3 and the middle component 6, and a sliding member 5 is slidably mounted on the sliding shaft 4. A linear servo 8 is fixed between the middle component 6 and the rear component 9, and its moving part is connected to the sliding member 5 to drive its movement. The first wing section 2 is hinged to the sliding member 5 via a wing pivot 7 and connected to the middle component 6 via a pull rod 10; the second wing section 1 is connected to the end of the first wing section 2 via a rotary servo 12. The rear component 9 is equipped with a propulsion system consisting of a tail thruster motor 13 and a propeller 14.

[0060] The sliding component 5, driven by a linear servo 8, can move back and forth on the sliding shaft 4 between the front component 3 and the middle component 6, thereby causing the first wing section 2 to rotate around the wing pivot 7 under the traction of the pull rod 10, achieving folding and deployment. A rotary servo 12 is installed at the end of the first wing section 2, which can drive the second wing section 1 to complete folding and deployment. The tail thrust motor 13 can drive the tail thrust propeller 14 to rotate at high speed, providing sufficient power for the aircraft to fly forward.

[0061] By rationally setting the dimensions and rotation axis of each wing, the first wing section 2 and the second wing section 1 are completely overlapped in the fully retracted state, and the whole is confined within the projection outline of the host aircraft fuselage.

[0062] The main view of the range extender in its deployed state is as follows: Figure 3As shown, the first wing segment 2 is an anhedral wing, which increases the distance between the fixed wing and the rotor plane, reducing aerodynamic interference between the fixed wing and the rotor. Furthermore, the anhedral wing increases the roll stability of the aircraft during forward flight. The second wing segment 1 unfolds to a horizontal position under the drive of a rotary servo motor, with both wing segments forming a large-span lifting surface. In the unfolded state, the aerodynamic center of the wing is close to the center of gravity of the host aircraft, minimizing additional torque disturbances.

[0063] Transition state of range extender such as Figure 4 As shown, when the slider 5 is close to the front component 3, the first wing 2 is in a retracted state; when the slider 5 is close to the middle component 6, the first wing 2 is in an extended state; the second wing 1 rotates outward to extend and rotates back to retract.

[0064] Range extender storage status as follows Figure 5 As shown, the two wings overlap completely and can be completely hidden within the projected area of ​​the host aircraft fuselage, thereby reducing aerodynamic drag and rotational inertia and minimizing interference with multi-rotor flight.

[0065] Side view of the range extender in its stored state as shown in the image. Figure 6 As shown, the two wing sections are completely horizontal, reducing the storage volume.

[0066] The range extender can be quickly connected to the host small multirotor aircraft via slots, bolt holes, or strap interfaces at the bottom of the mid-component, enabling modular assembly and disassembly. Figure 7 and Figure 8 As shown. When the aircraft is performing a long-range mission, the device can automatically deploy in flight: a linear servo drives a sliding component to move backward, pulling the first wing section upward to a preset dihedral position via a lever; then a rotary servo drives the second wing section to deploy horizontally outward. Retraction is performed in reverse; the two wing sections completely overlap and are then concealed within the projected outline of the host aircraft's fuselage.

[0067] In summary, this split-type range extender for a small multirotor aircraft utilizes a sliding-rotation dual-degree-of-freedom folding wing to double the wingspan with almost no increase in the system's projected area. This maintains high compactness in the folded state, effectively suppressing negative interference with the host aircraft's aerodynamic characteristics and rotational inertia, while ensuring efficient lift generation in the deployed state. Combined with a modular quick-release design, it allows for rapid mission configuration switching, significantly expanding the mission profile adaptability of the small multirotor platform.

[0068] Example 2

[0069] Based on the split-type folding wing range extender in Embodiment 1, this embodiment discloses a control method for the deployment and retraction of a split-type folding wing range extender for a small multi-rotor aircraft, including the following steps:

[0070] S1, Deploy the first wing section: Activate the linear servo 8 to drive the slider 5 to move along the sliding axis 4 toward the central component 6; use the pull rod 10 to pull the first wing section 2 to rotate around the wing pivot 7 to the preset dihedral position;

[0071] S2, Deploy the second wing section: Activate the rotation servo 12 to drive the second wing section 1 to rotate outward around the axis at the end of the first wing section 2 until it is horizontally deployed;

[0072] S3, retract the second wing section: activate the rotation servo 12 to drive the second wing section 1 to rotate inward until it coincides with the first wing section 2;

[0073] S4, retracting the first wing section: activate the linear servo 8 to drive the sliding component to move forward along the sliding axis 4 towards the forward component 3; pull the first wing section 2 downward around the wing pivot 6 to the horizontal retracted state via the pull rod 10;

[0074] S5, fully retractable: the two wings overlap completely and are concealed within the projected outline of the host aircraft's fuselage.

[0075] Example 3

[0076] Based on the control methods for the split-type range extender in Embodiment 1 and the folding and unfolding of the range extender in Embodiment 2, this embodiment discloses a control method for dynamic wing retraction based on mission phases:

[0077] During the mission preparation phase, when a small aircraft needs to perform a complex mission involving long-range cruise, the folded, separate range extender unit can be quickly assembled with the host aircraft via a lightweight quick-release mechanism, and the electrical and communication interfaces can be integrated to form a compact folded modular system. This configuration significantly improves the system's transport convenience and field deployment efficiency.

[0078] During the takeoff and landing phase, the integrated system fully inherits the vertical takeoff and landing capabilities of the multi-rotor platform. Leveraging the inherent redundant power layout of the multi-rotor configuration and the suppression of airflow disturbances by the distributed rotor blades, the system exhibits excellent low-altitude wind resistance stability, enhancing the aircraft's adaptability in complex environments. Subsequently, through the multi-degree-of-freedom attitude adjustment and high-precision trajectory control capabilities of the multi-rotor aircraft, the system flexibly maneuvers to the designated mission airspace.

[0079] Before entering the long-range cruise phase, the system uses actuators to achieve a one-click, sequential deployment of the folding wings, completing the configuration switch. In this configuration, the tail thruster drives the propeller to provide forward thrust, enabling the system to maintain a horizontal cruise attitude. The aerodynamic lift generated by the fixed wing bears most of the airframe weight, effectively unloading the rotor load. At the same time, the multi-rotor system works in concert to provide precise attitude control. In addition, the horizontal airflow further increases rotor thrust and reduces power consumption. This synergy allows both the fixed wing and the rotor to operate at their optimal aerodynamic and energy efficiency levels, thereby significantly reducing overall energy consumption during the cruise phase and significantly extending the range and endurance of the small multi-rotor aircraft.

[0080] When missions require close-range, detailed observation of critical infrastructure targets, such as power transmission towers and bridge structural nodes, the system can quickly retract its folding wings via actuators, seamlessly switching back to pure multi-rotor mode. In this mode, the system fully leverages the inherent hovering stability, maneuverability, and precise position-keeping capabilities of multi-rotor aircraft to efficiently complete detailed tasks such as close-range inspections, detection, or data acquisition. After the close-range mission is completed, the system can command the wings to unfold again and continue performing subsequent long-distance mission segments in efficient cruise mode.

[0081] In summary, the rapid loading and unloading characteristics and flexible, reliable operating mode switching mechanism achieved by this split-type range extender combine the maneuverability of an aircraft with the high efficiency of long-range cruise in a fixed-wing configuration. This multi-state fusion design effectively expands the overall mission profile adaptability of small multi-rotor flight platforms in complex and diverse mission scenarios.

[0082] Once the range extender's wings are deployed and the aircraft enters cruise mode, the rotor is in a horizontal inflow environment. Aerodynamic analysis of the advancing rotor blade element reveals that the superposition of the rotor blade element linear velocity and the inflow velocity increases the horizontal airflow velocity, thereby decreasing the airflow inflow angle and increasing the effective angle of attack α of the advancing blade element. The following formula quantifies the increase in the effective angle of attack:

[0083]

[0084] Where r is the rotor blade element position, ψ is the rotor azimuth angle, θ is the installation angle at the blade element position, v is the induced velocity, and V is the incoming flow velocity. Before stall, the lift coefficient is directly proportional to the angle of attack, increasing with the angle of attack. Simultaneously, the increase in airspeed on the advancing side increases the Reynolds number, making the boundary layer more stable and further increasing the lift coefficient. The following formula quantifies the magnitude of the corrected lift coefficient:

[0085]

[0086] Where C l0 k is the lift coefficient in hovering mode. ReThis is the Reynolds number correction factor. Furthermore, increasing airspeed increases dynamic pressure, directly increasing lift; blade element lift can be expressed as:

[0087]

[0088] Where U is the actual airspeed and c is the blade element chord length. On the retreating side of the rotor, lift decreases due to the reverse aerodynamic effect. Based on the momentum-blade element combined theory, the ratio of the difference between the advancing and retreating side lift to the hovering lift is calculated. A dimensionless asymmetric factor is introduced to quantify the asymmetric relationship:

[0089]

[0090] Where β is the forward-side lift gain coefficient, and γ is the backward-side lift loss coefficient. This serves as a basis for determining whether the incoming airflow is high-speed or low-speed, and thus for judging the overall trend of lift. Under a horizontal incoming airflow, the total lift of the rotor can be expressed as:

[0091]

[0092] Where N b This refers to the number of blades. After the wings are deployed, the device provides additional lift, sharing the aircraft's weight with the rotor system, achieving lift reconfiguration, reducing the thrust required by the rotor, and thus reducing rotor power consumption. The wing lift can be expressed as:

[0093]

[0094] Where S is the wing area, C L κ is the wing lift coefficient. L The lift loss coefficient due to structural factors, etc. Based on momentum theory, the induced power of the rotor under horizontal inflow conditions is derived as follows:

[0095] P ind =κTv i

[0096] κ is the loss coefficient. The horizontal inflow alters the magnitude and direction of the induced velocity, which can be corrected as follows:

[0097]

[0098] In addition, rotor power consumption also includes form drag power:

[0099]

[0100] The total power consumed by the rotor is the sum of the drag power and the induced power. Due to the reduction in the required thrust and the improvement in the ability to provide thrust, the induced power can be significantly reduced.

[0101] After the wings are deployed, the tail thruster provides the propulsion for the aircraft to fly forward. At this time, the propeller operates in a vertical inflow state, and its induced power and form drag power together constitute the total power of the tail thruster.

[0102] In summary, theoretical analysis shows that after the range extender is deployed, its aerodynamic characteristics significantly improve the energy consumption efficiency of the host small multirotor aircraft. First, the lift generated by the wings shares some of the aircraft's weight, thus reducing the lift required by the rotors, effectively creating an aerodynamic unloading effect and directly lowering the rotor's power consumption. Second, in horizontal forward flight, the incoming airflow further increases the rotor's thrust, thereby reducing its power demand. Although the tail-mounted propeller consumes some power during propulsion, the overall aerodynamic drag of the aircraft in horizontal forward flight is significantly lower than the large pitch angle required for traditional multirotor forward flight. Therefore, compared to the significant power increase caused by attitude adjustments and increased drag during forward flight of traditional multirotors, the small multirotor aircraft equipped with this split-type range extender has a lower net power consumption at the same forward flight speed, effectively improving overall efficiency.

[0103] Example 4

[0104] This embodiment discloses a small multi-rotor aircraft system, including the split-type folding wing range extender as described in Embodiment 1, which can be quickly detached / installed on the host aircraft fuselage. The device's stowed and deployed states after being combined with the host aircraft are as follows: Figure 7 and Figure 8 As shown, the split-type folding wing range extender is tightly connected to the host aircraft via the central component 6. The system has both multi-rotor flight mode and fixed-wing range extender mode.

[0105] Multi-rotor flight mode: The split-type folding wing range extender is in a retracted state, and the host aircraft provides all lift and attitude control through its own rotors;

[0106] Fixed-wing range extension mode: The split-type folding wing range extender is in the deployed state. The device's propulsion system (tail thruster 13 and propeller 14) provides all forward flight power. The first wing section 2 and the second wing section 1 provide the main lift. The rotor of the host aircraft operates under horizontal airflow and provides attitude control force and part of the lift.

[0107] It should be noted that this range extender is suitable for a variety of small multi-rotor aircraft. Figure 7-8 The host aircraft shown is only one of the applicable platforms, and this embodiment does not limit the aircraft that the range extender is combined with.

[0108] Example 5

[0109] Flight tests were conducted using a prototype to verify the performance of the range extender. The tests were conducted on a 960g-class quadcopter demonstration platform. This platform integrates an airspeed sensor to measure the airspeed when the range extender is installed and flying forward in a horizontal attitude. It also has a reserved electrical interface for the tail thruster motor and its folding system. Furthermore, it has the capability to accurately monitor the power consumption (voltage and current) of the rotor and tail thruster propeller. Real-time monitoring of all parameters was conducted using the Mission Planner ground station.

[0110] To quantify the performance of the range extender, three sets of comparative experimental configurations were established:

[0111] 1. Baseline configuration: The quadcopter demonstrator platform flies in conventional mode as a performance benchmark;

[0112] 2. Extended-range folding configuration: After installing the extended-range mechanism, the aircraft is propelled forward by the tail-mounted propeller in the folded-wing state, verifying the optimization effect of horizontal airflow on rotor performance.

[0113] 3. Extended-range deployment configuration: After the extended-range mechanism is installed, the aircraft is driven forward by the tail propeller in the wing-deployed state. This characterizes the typical working state of the extended-range system and evaluates the overall performance improvement effect.

[0114] In subsequent experiments, power data was calculated by multiplying the voltage and current supplied by the motor's electronic speed controller in real time. For the tail-thrust propeller configuration, the rotor system power and total power were quantified separately; for other configurations, only the total system power was recorded. The aircraft's endurance was the ratio of the battery capacity to the current consumption, and the range was the product of the endurance and the flight speed. Furthermore, to remove interference factors such as wind speed, data under the same conditions was obtained through multiple sets of post-processing after flying back and forth along the same straight route.

[0115] like Figure 9 As shown, the trend of total power of each configuration with increasing flight speed is illustrated. Figure 10 As shown, the curves of rotor power and tail thruster power variation in extended-range folding and extended-range deployment configurations are displayed, revealing the influence mechanism of horizontal airflow and wing unloading on energy distribution.

[0116] A comparison between the baseline multirotor configuration and the extended-range configuration shows that when the speed increases to 20 m / s, the baseline configuration increases power by 194% due to the surge in aerodynamic drag, while the extended-range configuration, optimized by both the horizontal airflow and the lift unloading of the wing, only increases power by 80%. When the speed reaches about 15 m / s, the power consumption of the two configurations is equal. Subsequently, as the speed increases, the power advantage of the extended-range configuration continues to expand, achieving a 20% power reduction at a speed of 20 m / s, confirming the effectiveness of the device.

[0117] The difference between the extended-range deployable configuration and the extended-range folding configuration quantifies the wing aerodynamic benefits. As the flight speed increases, the wing unloading effect becomes more and more obvious. At 20 m / s, the power of the deployable configuration is 11% lower than that of the folding configuration.

[0118] The comparison of rotor power consumption at different speeds in the extended-range folding configuration with the hovering state verifies the optimization mechanism of the horizontal airflow on rotor power consumption: as the forward speed increases, the rotor thrust increases and the power consumption level decreases. At 20 m / s, the rotor power is about 35% lower than that in the hovering state (180.25 W).

[0119] like Figure 11 and Figure 12 The characteristics of endurance and range of each configuration at different forward flight speeds were demonstrated.

[0120] As airspeed increases, the rotor aerodynamic optimization and wing unloading effects become increasingly significant. At 15 m / s, the extended-range deployed configuration performs comparably to the baseline configuration. By the 20 m / s cruise phase, its endurance and range increase by approximately 25%, highlighting the device's advantages. The extended-range folding configuration, because it only retains the horizontal airflow optimization effect, has its performance inflection point delayed to approximately 18 m / s, and its range increase is limited (approximately 7%). This verifies the crucial contribution of wing deployment to aerodynamic efficiency.

[0121] In summary, after installing this split-type range extender, the power consumption of the host small multirotor aircraft is significantly reduced while maintaining a certain forward speed, resulting in a substantial increase in endurance and range. Combined with its modular quick-release design, it allows for rapid mission configuration switching, significantly improving the mission profile adaptability of the host small multirotor aircraft and providing a solution that combines mobility and long endurance for tasks such as power line inspection and mapping.

[0122] This invention discloses a split-type folding wing range extender for small multirotor aircraft, which solves the problems of short endurance and range of small multirotor aircraft, and poor performance and inconvenient transportation and assembly of existing vertical take-off and landing fixed-wing aircraft when flying in multirotor mode. When small multirotor aircraft face tasks that require both long-range cruising and flexible maneuverability (such as power grid inspection), it can be quickly installed on the small multirotor aircraft and can quickly switch between multirotor and fixed-wing modes during aircraft operation, maximizing the advantages of both small multirotor aircraft and fixed-wing aircraft and reducing mutual interference between the two during operation.

[0123] Based on the description of preferred embodiments of the present invention, it should be clear that the present invention as defined by the appended claims is not limited to the specific details set forth in the above description, and many obvious modifications to the present invention without departing from its spirit or scope may also achieve the purpose of the present invention.

Claims

1. A split-type folding wing range extender for small multi-rotor aircraft, characterized in that, It includes a front component (3), a middle component (6) and a rear component (9) connected in sequence along the flight direction. A sliding shaft (4) horizontally connects the front component (3) and the middle component (6). A sliding member (5) is slidably sleeved on the sliding shaft (4) and is driven to move back and forth by a linear servo (8) located between the middle component (6) and the rear component (9). The first wing section (2) is hinged to the sliding member (5) via the wing pivot (7) and connected to the middle component (6) based on the tie rod (10); a rotary servo (12) and a second wing section (1) connected to the rotary servo (12) are provided at the end of the first wing section (2); a propulsion system is provided on the rear component (9); When the linear servo (8) drives the sliding member to move, it pulls the first wing section (2) around the wing pivot (7) to unfold or retract horizontally via the pull rod (10); the rotary servo (12) drives the second wing section (1) to rotate outward to unfold or rotate inward to retract.

2. The split-type folding wing range extender according to claim 1, characterized in that, The front component (3) and the middle component (6) are rigidly connected by a sliding shaft (4), and the middle component (6) and the rear component (9) are rigidly connected by a fixed shaft (11).

3. The split-type folding wing range extender according to claim 1, characterized in that, The middle component (6) is provided with a slot, bolt hole or strap interface for establishing a rigid connection with the host aircraft that can be quickly detached.

4. The split-type folding wing range extender according to claim 1, characterized in that, The first section of the wing (2) is an anti-dipole wing.

5. The split-type folding wing range extender according to claim 1, characterized in that, The front component (3) has a V-shaped design, and its bottom plane can fit with the upper surface of the host aircraft to reduce forward drag; the middle component (5) has a frame structure for fixation and weight reduction, providing front-end fixation of the linear servo (8) and rear-end fixation of the sliding shaft (4).

6. The split-type folding wing range extender according to claim 1, characterized in that, The first wing segment (2) and the second wing segment (1) are completely overlapped in the fully retracted state, and the whole is confined within the projection outline of the host aircraft fuselage.

7. The split-type folding wing range extender according to claim 1, characterized in that, The propulsion system includes a tail thruster (13) fixed to the rear component (9) and a propeller (14) driven by it, and the rear component (9) provides a linear servo (8) and a fixed shaft (11) for rear-end fixation.

8. A method for controlling the folding and unfolding of a split-type folding wing range extender for a small multi-rotor aircraft, characterized in that, The split-type folding wing range extender based on any one of claims 1-7 includes the following steps: S1, deploy the first section of the wing: activate the linear servo (8) to drive the slider to move along the sliding axis (4) toward the central component (6); pull the first section of the wing (2) around the wing pivot (7) to the preset dihedral position via the pull rod (10); S2, deploy the second wing section: activate the rotary servo (12) to drive the second wing section (1) to rotate outward around the axis at the end of the first wing section (2) until it is horizontally deployed; S3, retract the second wing section: activate the rotation servo (12) to drive the second wing section (1) to rotate inward until it coincides with the first wing section (2); S4, retract the first wing section: activate the linear servo (8) to drive the sliding component to move forward along the sliding axis (4) towards the component (3); pull the first wing section (2) around the wing pivot (7) to the horizontal retracted state by the pull rod (10); S5, fully retractable: the two wings overlap completely and are concealed within the projected outline of the host aircraft's fuselage.

9. A small multi-rotor aircraft system, characterized in that, The system includes a host aircraft and a split-type folding-wing range extender as described in any one of claims 1-7, detachably mounted on the fuselage of the host aircraft; the system has: Multi-rotor flight mode: The split-type folding wing range extender is in a retracted state, and the host aircraft provides all lift and attitude control through its own rotor. Fixed-wing range extension mode: The split-type folding wing range extension device is in the unfolded state. The device's propulsion system provides all forward flight power. The first wing segment (2) and the second wing segment (1) provide the main lift. The rotor of the host aircraft operates under horizontal airflow and provides attitude control force and part of the lift.

10. A method for increasing the range of a small multi-rotor aircraft, characterized in that, The method includes: A split-type folding wing range extender as described in any one of claims 1-7 can be detachably mounted on a small aircraft; The linear servo (8) and rotary servo (12) of the range extender are used to deploy the first wing section (2) and the second wing section (1) to the working position. The propulsion system is activated to provide the main forward propulsion for the aircraft, enabling the aircraft to fly forward in a horizontal attitude, thereby placing the aircraft's rotor in a horizontal airflow; The first wing section (2) and the second wing section (1) are used to generate lift, bear most of the weight of the aircraft, and perform aerodynamic unloading of the rotor. The horizontal airflow state and the aerodynamic unloading work together to reduce the power consumption of the rotor, thereby increasing the flight time and range of the aircraft.

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