Description:TECHNICAL FIELD
[0001] The present disclosure relates to the field of rotorcraft systems utilized in unmanned aerial vehicles (UAVs), and more particularly to a semi-articulated rotorhead designed to improve flight stability, gust resistance, and payload capacity in medium and large-scale UAVs.
BACKGROUND
[0002] In the rapidly evolving landscape of unmanned aerial vehicles (UAVs), rotorcraft systems play a critical role in enabling efficient flight, precise maneuvering, and reliable payload delivery. As UAV applications expand into fields such as logistics, surveillance, agriculture, and emergency response, the demands on rotor system performance and adaptability have increased significantly.
[0003] Conventional rotorhead designs, particularly rigid rotorheads, are commonly employed in UAVs due to their simplicity and ease of manufacturing. However, these designs suffer from several limitations, including poor responsiveness to aerodynamic disturbances, direct transmission of structural stress and vibration to the airframe, and restricted payload capacity. Traditional fully articulated rotorheads, as used in manned helicopters, are often too heavy, complex, and costly for UAV integration and may require intricate hydraulic or mechanical damping systems that are impractical for medium and large-scale unmanned platforms.
[0004] As a result, there is a need for a system and device that provides a balance between aerodynamic compliance and mechanical simplicity, enabling improved gust resistance, enhanced flight stability, and greater payload capacity, while remaining lightweight, modular, and suitable for integration into medium and large UAVs.

SUMMARY
[0005] In an embodiment, a system for unmanned aerial vehicles (UAVs) is disclosed. In one example, the system comprises a semi-articulated rotorhead specifically configured to enhance gust resistance, flight stability, and payload capacity in medium and large-scale UAVs. The rotorhead includes a bladeholder for each rotor blade, allowing controlled flapping about a hinge axis, a yolk and main trunnion forming the flapping mechanism, a drive shaft for torque transmission, a pillar block serving as the structural base, and a linkage mount with a pitch horn for pitch input transmission and adjustment. An angle restrainer is also integrated to limit the flapping range, ensuring operational safety and structural stability. Further, the system is designed to absorb aerodynamic disturbances, reduce stress on the UAV frame, and support modular assembly and maintenance. Unlike traditional manned helicopter rotorheads that rely on complex multi-axis articulation and heavy damping systems, this system features a simplified single-axis flapping mechanism with integrated pitch control, actuated via electric servos or simplified swashplates. The semi-articulated configuration provides a balanced approach between aerodynamic adaptability and mechanical simplicity, resulting in superior gust tolerance, enhanced payload flexibility, and reduced maintenance demands, making it ideal for deployment in challenging UAV applications.
[0006] In an embodiment, a method for improving the flight stability and payload capacity of an unmanned aerial vehicle (UAV) is disclosed. In one example, the method includes mounting a rotor blade to a bladeholder configured for controlled flapping about a hinge axis, supporting the bladeholder within a yolk using a main trunnion, and transmitting rotational torque to the rotorhead assembly via a drive shaft anchored to a pillar block. Blade pitch is precisely controlled through a linkage mount and pitch horn operatively connected to either an electric servo or a mechanical swashplate. Further, the method involves limiting the flapping range using an angle restrainer to ensure flight safety and structural stability. In certain embodiments, the bladeholder, yolk, and main trunnion are fabricated from lightweight materials to enhance performance. The angle restrainer may be dynamically adjusted based on changing flight conditions, and the entire rotorhead system is designed for modular assembly and rapid maintenance in field conditions, enabling precise aerodynamic control throughout the UAV’s flight envelope.
[0007] In an embodiment, a device for enhancing the flight performance of an unmanned aerial vehicle (UAV) is disclosed. In one example, the device comprises a semi-articulated rotorhead system that includes a bladeholder configured to support a rotor blade and allow controlled flapping motion about a hinge axis, a yolk serving as the main housing, and a main trunnion positioned within the yolk to act as the central pivot for the bladeholder. The device further comprises a shaft for transmitting rotational torque from the UAV’s powertrain, a pillar block providing a stable structural base, a linkage mount for connecting to the pitch control mechanism, and a pitch horn operatively linked to the mount to enable in-flight blade pitch adjustments. An angle restrainer is incorporated to safely limit the flapping range and maintain stability. Further, the device is designed using lightweight materials for key components such as the bladeholder, yolk, and trunnion to reduce overall mass, and supports input from either electric servos or mechanical swashplates for pitch control. The angle restrainer may be adjustable to meet varying operational needs, and the rotorhead is modularly designed for easy assembly, disassembly, and field maintenance, ensuring high adaptability and serviceability in diverse UAV applications.
BRIEF DESCRIPTION OF DRAWINGS
[0008] The accompanying drawings illustrate the various embodiments of systems, methods, and other aspects of the disclosure. Any person with ordinary skills in the art will appreciate that the illustrated element boundaries (e.g., boxes, groups of boxes, or other shapes) in the figures represent one example of the boundaries. In some examples, one element may be designed as multiple elements, or multiple elements may be designed as one element. In some examples, an element shown as an internal component of one element may be implemented as an external component in another, and vice versa. Further, the elements may not be drawn to scale.
[0009] Various embodiments will hereinafter be described in accordance with the appended drawings, which are provided to illustrate and not to limit the scope in any manner, wherein similar designations denote similar elements, and in which:
[0010] FIG. 1 is an illustration of a semi-articulated rotorhead assembly (100) for unmanned aerial vehicles (UAVs), in accordance with an embodiment of the present invention.
[0011] FIG. 2 is a diagram highlighting the blade flapping axis (120) and its range of motion, in accordance with an embodiment of the present invention.
[0012] FIG. 3 is an exploded view (300) of the rotorhead assembly showing individual components and their arrangement, in accordance with an embodiment of the present invention.
DETAILED DESCRIPTION
[0013] The present disclosure may be best understood with reference to the detailed figures and description set forth herein. Various embodiments are discussed below with reference to the figures. However, those skilled in the art will readily appreciate that the detailed descriptions given herein with respect to the figures are simply for explanatory purposes as the methods and systems may extend beyond the described embodiments. For example, the teachings presented and the needs of a particular application may yield multiple alternative and suitable approaches to implement the functionality of any detail described herein. Therefore, any approach may extend beyond the particular implementation choices in the following embodiments described and shown.
[0014] The present disclosure addresses the limitations of conventional rigid and fully articulated rotorhead systems commonly used in UAVs, which suffer from poor gust response, high structural stress transmission, and limited payload capability. The device introduces a semi-articulated rotorhead specifically designed for medium and large-scale unmanned aerial vehicles, providing each rotor blade with a controlled degree of flapping motion about a hinge axis. The device incorporates a modular assembly including a bladeholder, yolk, main trunnion, drive shaft, pillar block, linkage mount, pitch horn, and angle restrainer, all engineered for lightweight construction and ease of field maintenance. The device enables the absorption of aerodynamic loads and vibration, reduces stress on the UAV airframe, and allows for increased payload handling without sacrificing flight stability. The device is further optimized for quick assembly and integration with electric servo-based or simplified pitch control mechanisms, ensuring operational reliability and improved performance in demanding flight conditions.
[0015] The primary objective of the present disclosure is to provide a semi-articulated rotorhead system that overcomes the drawbacks of conventional rotor systems used in medium and large-scale UAVs, particularly with respect to flight stability, gust resistance, and payload capacity. To achieve this, the present disclosure aims to introduce a rotorhead assembly that allows controlled flapping motion of the rotor blades, thereby enabling absorption of aerodynamic disturbances and reducing structural stress on the UAV airframe. The system’s objective is to combine mechanical simplicity with enhanced aerodynamic compliance, resulting in improved maneuverability, reduced vibration, and greater operational reliability. Additionally, the present disclosure seeks to offer a modular, lightweight, and easily maintainable design that facilitates rapid assembly and field servicing, as well as compatibility with various pitch control mechanisms. These advancements collectively support the deployment of UAVs in more demanding environments and broader operational roles.
[0016] The present invention provides a semi-articulated rotorhead specifically designed for medium and large-scale unmanned aerial vehicles (UAVs), enabling each rotor blade to flap about a controlled hinge axis while maintaining mechanical simplicity and lightweight construction. Further, the said invention introduces a uniquely modular architecture comprising a bladeholder, yolk, main trunnion, drive shaft, pillar block, linkage mount, pitch horn, and angle restrainer that allows precise flapping motion and simplified pitch control through electric servos or swashplate mechanisms. The integration of the single-axis flapping capability with UAV-optimized components, resulting in significant improvements in gust resistance, flight stability, payload handling, and ease of assembly or maintenance, all without the weight, complexity, or cost of traditional helicopter rotorheads. Such a balance of aerodynamic compliance, structural efficiency, and operational practicality distinguishes the invention, making it ideally suited for advanced UAV applications in real-world environments.
[0017] FIG. 1 is an illustration of a semi-articulated rotorhead assembly (100) for unmanned aerial vehicles (UAVs), in accordance with an embodiment of the present invention. The assembly (100) comprises a bladeholder (101) configured to support a rotor blade and enable flapping motion, a yolk (102) forming the main housing, a main trunnion (103) serving as the central hinge, a shaft (104) for transmitting rotational torque, a pillar block (105) providing the base structure for the rotating hinge, a linkage mount (106) for connecting pitch control linkages, a pitch horn (107) for adjusting blade pitch, and an angle restrainer (108) for restricting the flapping angle to ensure safety and stability.
[0018] As according to the present invention, the bladeholder (101) is a component of the semi-articulated rotorhead assembly, specifically designed to support and securely retain the rotor blade while enabling controlled flapping motion about a hinge axis. The bladeholder (101) interfaces directly with the yolk (102) and main trunnion (103), allowing the attached rotor blade to pivot in response to aerodynamic forces encountered during flight. Constructed from lightweight and durable materials, the bladeholder (101) ensures both structural integrity and minimal added mass, thereby optimizing overall rotor efficiency. In addition to providing a secure mounting point for the blade, the bladeholder (101) is precisely engineered to maintain the correct alignment and balance of the rotor system, facilitating smooth flapping movement within the predetermined range set by the angle restrainer (108). The said design enables the absorption of gust loads and reduction of stress transmitted to the UAV airframe, contributing significantly to the improved stability, maneuverability, and payload handling of the UAV, as intended by the present invention.
[0019] As according to the present invention, the yolk (102) acts as the main housing and pivotal structural element of the semi-articulated rotorhead assembly. The yolk (102) is designed to accommodate and support the bladeholder (101) and the main trunnion (103), thereby enabling the controlled flapping motion of each rotor blade about its hinge axis. Engineered for a high strength-to-weight ratio, the yolk (102) is typically manufactured from lightweight, robust materials to ensure minimal added mass while maintaining structural integrity under dynamic flight loads. It provides the mechanical interface through which the rotational drive from the shaft (104) is transmitted to the rotor blades, and it integrates mounting points for the linkage mount (106) and pitch horn (107), facilitating precise pitch adjustments. The unique configuration of the yolk (102) according to the present invention not only ensures reliable and smooth articulation of the rotor blades but also contributes to the modularity and maintainability of the rotorhead, supporting quick assembly and disassembly in UAV operations.
[0020] As according to the present invention, the main trunnion (103) functions as the central hinge axis within the semi-articulated rotorhead assembly, facilitating the controlled flapping movement of each rotor blade supported by the bladeholder (101). The main trunnion (103) is securely mounted within the yolk (102) and serves as the pivotal element around which the bladeholder (101) and attached rotor blade can articulate in response to aerodynamic forces encountered during flight. Precision-engineered for high durability and minimal friction, the main trunnion (103) is typically fabricated from strong, lightweight materials to ensure long-term reliability without adding unnecessary weight to the UAV. Its construction and secure integration within the rotorhead assembly allow for smooth, consistent flapping motion, effectively absorbing gust-induced loads and reducing structural stress on the airframe. By enabling the said degree of freedom, the main trunnion (103) contributes significantly to the enhanced flight stability, gust resistance, and payload handling capabilities of the UAV as intended by the present invention.
[0021] As according to the present invention, the shaft (104) acts as the primary drive element within the semi-articulated rotorhead assembly, responsible for transmitting rotational torque from the UAV’s powertrain to the rotorhead and, consequently, to the rotor blades. The shaft (104) is precisely aligned and mechanically coupled to the yolk (102), ensuring efficient transfer of power while accommodating the flapping motion enabled by the main trunnion (103) and bladeholder (101). Engineered for optimal strength and rigidity, the shaft (104) is typically constructed from high-strength, lightweight materials that can withstand the operational loads and rotational speeds encountered during UAV flight. Its design ensures minimal energy loss and vibration transmission, contributing to the smooth and stable operation of the entire rotor system. The integration of the shaft (104) within the rotorhead assembly supports the objective of combining aerodynamic compliance with mechanical simplicity, thereby enhancing overall flight performance and reliability in accordance with the present invention.
[0022] As according to the present invention, the pillar block (105) functions as the foundational support structure within the semi-articulated rotorhead assembly, providing a stable mounting base for the rotating hinge mechanism. The pillar block (105) is precisely engineered to securely anchor the shaft (104), main trunnion (103), and yolk (102), thereby ensuring the proper alignment and structural integrity of the entire rotorhead system during operation. Manufactured from durable, lightweight materials, the pillar block (105) is designed to withstand the dynamic loads and vibrations transmitted through the rotor assembly while minimizing additional weight on the UAV. Its robust construction facilitates easy assembly and disassembly of the rotorhead components, enabling quick maintenance and field servicing. By offering a rigid and reliable foundation for the semi-articulated mechanism, the pillar block (105) plays a crucial role in maintaining the operational stability, safety, and performance of the UAV rotor system as intended by the present invention.
[0023] As according to the present invention, the linkage mount (106) and pitch horn (107) collectively serve as the critical control interface for adjusting the pitch of each rotor blade within the semi-articulated rotorhead assembly. The linkage mount (106) is designed to securely connect the control linkages, such as rods or cables, to the rotorhead, transmitting precise pitch commands from an electric servo or swashplate mechanism. Integrated with the bladeholder (101) or yolk (102), the linkage mount (106) ensures accurate and responsive pitch adjustments, essential for controlling lift, maneuverability, and flight dynamics of the UAV. The pitch horn (107), operatively connected to the linkage mount (106), acts as the actuation lever that translates the linear motion of the control linkages into angular rotation of the rotor blade. Engineered for lightweight strength and minimal friction, the pitch horn (107) enables smooth and reliable pitch changes, enhancing the UAV's ability to respond to flight commands and environmental conditions. Together, the linkage mount (106) and pitch horn (107) enable precise, real-time control of blade pitch, contributing significantly to the overall flight stability, efficiency, and versatility of the rotorhead system as intended by the present invention.
[0024] As according to the present invention, all elements depicted in FIG. 1 including the bladeholder (101), yolk (102), main trunnion (103), shaft (104), pillar block (105), linkage mount (106), pitch horn (107), and angle restrainer (108) collectively operate in a synergistic manner to realize the aspect of the semi-articulated rotorhead system for UAVs. The integration of these components enables each rotor blade to perform controlled flapping motion about a hinge axis while simultaneously permitting precise pitch adjustments, thus absorbing gust loads, minimizing structural stress on the UAV frame, and enhancing overall flight stability and payload capacity. The modular and lightweight construction of each element not only ensures ease of assembly, maintenance, and field replacement but also distinguishes the present invention from conventional rigid or fully articulated rotorheads that are either overly complex or inadequate for UAV-specific requirements. This unified design delivers a balanced combination of aerodynamic compliance, mechanical simplicity, and operational flexibility, addressing the unique challenges faced by medium and large-scale UAVs and thereby constituting the advancement offered by the present disclosure.
[0025] As according to the present invention, FIG. 2 is a diagram illustrating the flapping axis (120) of the rotor blade and depicting the range of motion permitted by the semi-articulated rotorhead assembly, in accordance with an embodiment of the present invention. The diagram highlights the interaction between the bladeholder (101), yolk (102), and main trunnion (103), which collectively enable the rotor blade to pivot about the flapping axis (120) in response to aerodynamic forces. The controlled angular movement defined by the angle restrainer (108) ensures safe and stable operation, while the positions of the linkage mount (106) and pitch horn (107) are shown relative to the flapping mechanism for clarity.
[0026] FIG. 2, as according to the present invention, is a diagrammatic representation that highlights the flapping axis (120) around which each rotor blade pivots within the semi-articulated rotorhead assembly. The figure illustrates the coordinated interaction between the bladeholder (101), which securely retains the rotor blade and provides the physical connection to the flapping mechanism, the yolk (102), which houses and supports the bladeholder, and the main trunnion (103), which acts as the pivotal shaft enabling controlled angular movement. The shaft (104) delivers rotational power, while the pillar block (105) anchors the assembly and maintains alignment during operation. The linkage mount (106) and pitch horn (107) are positioned to transmit pitch control inputs even as the blade moves along the flapping axis, ensuring continuous and precise aerodynamic adjustments. The angle restrainer (108) is shown as a safety feature that restricts the range of flapping motion to within optimal and safe operational limits. Collectively, FIG. 2 visually demonstrates how the mechanical configuration allows the rotor blade to pivot responsively about the flapping axis (120), adapting to aerodynamic disturbances encountered during UAV flight.
[0027] As according to the present invention, all elements depicted in FIG. 2 including the bladeholder (101), yolk (102), main trunnion (103), shaft (104), pillar block (105), linkage mount (106), pitch horn (107), angle restrainer (108), and the defined flapping axis (120) work in unison to realize the semi-articulated rotorhead mechanism for UAVs. This coordinated arrangement enables each rotor blade to perform controlled, limited flapping motion about the flapping axis (120), thereby absorbing aerodynamic gusts and reducing the direct transmission of stress to the UAV frame. Simultaneously, the integration of the linkage mount (106) and pitch horn (107) ensures that precise pitch control is maintained throughout the blade’s range of motion. The presence of the angle restrainer (108) further guarantees operational safety by preventing excessive articulation. Such a collective configuration delivers a lightweight, modular rotorhead system that uniquely balances aerodynamic compliance, structural simplicity, and flight performance attributes that are distinctly advantageous and previously unavailable in conventional UAV rotorhead designs.
[0028] In an exemplary operation, a system to enhance flight stability, gust resistance, and payload handling in medium and large-scale unmanned aerial vehicles (UAVs) is provided using a semi-articulated rotorhead assembly. The device comprises a bladeholder (101) that supports each rotor blade and permits controlled flapping motion about a hinge axis. The device comprises a yolk (102) serving as the main housing, a main trunnion (103) functioning as the central pivot for flapping, a shaft (104) transmitting rotational drive from the UAV’s powertrain, and a pillar block (105) anchoring the assembly for structural stability. In an embodiment, the device further includes a linkage mount (106) and a pitch horn (107) for transmitting and adjusting blade pitch via servo or swashplate input, enabling precise aerodynamic control. In an embodiment, an angle restrainer (108) is provided to limit the flapping range and ensure operational safety. In an embodiment, all components are designed for modular assembly, lightweight construction, and easy field maintenance. In an embodiment, the semi-articulated rotorhead absorbs gust-induced loads and vibration, reduces structural stress on the airframe, and maintains flight performance under challenging environmental conditions, collectively offering a unique combination of mechanical simplicity and advanced aerodynamic compliance as intended by the present invention.
[0029] In an embodiment, the bladeholder (101) is configured to securely retain the rotor blade and allow controlled flapping motion about a hinge axis in response to aerodynamic forces encountered during UAV flight. In an embodiment, the yolk (102) is configured to serve as the main structural housing, supporting both the bladeholder (101) and the main trunnion (103), and ensuring smooth articulation and alignment of the rotorhead assembly. In an embodiment, the main trunnion (103) is configured to act as the central pivot, enabling precise and durable flapping movement while maintaining the integrity of the connection between the bladeholder (101) and yolk (102). In an embodiment, the shaft (104) is configured to transmit rotational torque from the UAV’s powertrain to the rotorhead with minimal energy loss and vibration. In an embodiment, the pillar block (105) is configured to anchor the rotorhead components and maintain the overall stability of the assembly during operation. In an embodiment, the linkage mount (106) and pitch horn (107) are configured to receive and transmit pitch control inputs from an electric servo or swashplate mechanism, enabling real-time adjustment of blade pitch. In an embodiment, the angle restrainer (108) is configured to limit the maximum flapping range of the blade, thereby ensuring operational safety and preventing excessive articulation.
[0030] In another embodiment of the present invention, the semi-articulated rotorhead assembly is further configured with integrated damping elements positioned at the flapping hinge interface to provide additional control over blade articulation and minimize oscillations during rapid maneuvering or in highly turbulent conditions. This embodiment may utilize elastomeric or spring-based dampers in conjunction with the main trunnion (103), allowing the system to automatically absorb and dissipate transient aerodynamic loads without requiring complex hydraulic mechanisms. The inclusion of these damping components further enhances the operational stability and vibration reduction capabilities of the rotorhead while maintaining the lightweight, modular, and easily maintainable characteristics of the original design. This alternative configuration ensures that the UAV can operate safely and efficiently even in adverse weather or during aggressive flight maneuvers, thus expanding the versatility and reliability of the semi-articulated rotorhead system as described in the present invention.
[0031] In another embodiment of the present invention, the semi-articulated rotorhead assembly is equipped with quick-release fastening mechanisms for the bladeholder (101) and yolk (102), enabling rapid assembly and disassembly of the rotor blades and key rotorhead components without the need for specialized tools. This design facilitates efficient field maintenance and swift replacement of damaged or worn parts, which is particularly advantageous for UAV operations in remote or time-sensitive environments. The quick-release mechanism may incorporate spring-loaded pins or cam-lock fasteners, ensuring both secure attachment during flight and ease of manual operation by ground crew. The said embodiment further enhances the modularity and maintainability of the rotorhead system while preserving its lightweight structure and operational robustness, thereby extending the practical utility and mission readiness of medium and large-scale UAVs in accordance with the present invention.
[0032] Let us consider a practical scenario to illustrate the working of the present disclosure. Consider a medium-scale UAV deployed for aerial survey operations in a coastal region where unpredictable wind gusts and variable weather conditions are common. As the UAV encounters sudden gusts during flight, the semi-articulated rotorhead assembly of the present invention allows each rotor blade to pivot about its flapping axis in response to the aerodynamic forces, thereby absorbing much of the shock and reducing the amount of stress transmitted to the UAV’s airframe. At the same time, the pitch control mechanism, enabled by the linkage mount and pitch horn, adjusts the blade angles to maintain optimal lift and stability. Further, the UAV can carry a heavier sensor payload without sacrificing flight performance or experiencing excessive vibration. The said practical operation ensures stable, reliable UAV performance even in challenging and dynamic flight environments.
[0033] FIG. 3 is an exploded view (300) of the semi-articulated rotorhead assembly, in accordance with an embodiment of the present invention, illustrating the individual components and their spatial arrangement. As depicted, the assembly comprises the bladeholder (101), which is configured to support the rotor blade and enable flapping motion; the yolk (102), serving as the main housing for the flapping mechanism; and the main trunnion (103), functioning as the pivotal shaft for the bladeholder (101) within the yolk (102). The shaft (104) is shown as the primary drive element, transmitting torque from the UAV’s powertrain to the rotorhead. The pillar block (105) provides a stable base and anchors the assembly components. The linkage mount (106) is depicted as the attachment point for pitch control linkages, while the pitch horn (107) is shown for transmitting pitch adjustment inputs to the rotor blade. The angle restrainer (108) is illustrated as the safety mechanism that limits the flapping range of the bladeholder (101) within the assembly. The exploded view of FIG. 3 clearly demonstrates the each component bladeholder (101), yolk (102), main trunnion (103), shaft (104), pillar block (105), linkage mount (106), pitch horn (107), and angle restrainer (108) is positioned and assembled to collectively form the semi-articulated rotorhead system of the present invention.
[0034] FIG. 3, in accordance with an embodiment of the present invention, presents an exploded view of the semi-articulated rotorhead assembly, showcasing each major component and its intended placement within the overall structure. Central to this assembly is the bladeholder (101), which is designed to secure the rotor blade and provide the controlled flapping motion required for aerodynamic compliance. The bladeholder (101) features precise mounting interfaces to integrate seamlessly with the adjoining yolk (102).
[0035] The yolk (102) acts as the primary housing for the flapping mechanism and accommodates the main trunnion (103), which serves as the pivotal axis around which the bladeholder (101) rotates. The main trunnion (103) is engineered to deliver smooth, durable articulation for the bladeholder and is firmly supported by the yolk (102), ensuring both alignment and structural integrity during operation. The shaft (104), illustrated alongside these elements, is responsible for transferring rotational power from the UAV’s drive system to the rotorhead.
[0036] The pillar block (105) forms the foundational base of the assembly, anchoring the shaft (104), main trunnion (103), and yolk (102) to maintain consistent alignment and stability during high-speed rotation and fluctuating loads. Positioned on the yolk (102), the linkage mount (106) serves as the critical interface for connecting pitch control linkages, enabling precise aerodynamic adjustments in real-time. Adjacent to the linkage mount (106), the pitch horn (107) is depicted, designed to efficiently transmit input from servos or a swashplate to alter the rotor blade pitch as needed for dynamic flight maneuvers.
[0037] Further, the angle restrainer (108) is included in the exploded assembly as a dedicated safety feature that limits the maximum allowable flapping angle of the bladeholder (101). This restraint is crucial for preventing over-articulation and ensuring safe, reliable operation under variable flight conditions. Collectively, FIG. 3 demonstrates how each component, bladeholder (101), yolk (102), main trunnion (103), shaft (104), pillar block (105), linkage mount (106), pitch horn (107), and angle restrainer (108) is designed and arranged to work in concert.
[0038] The present disclosure offers several technical advantages over conventional rotorhead systems used in UAVs. Its integration of a semi-articulated flapping mechanism through the precise arrangement of components such as the bladeholder, yolk, and main trunnion enables each rotor blade to respond dynamically to aerodynamic forces, significantly enhancing gust resistance and overall flight stability. This enhanced responsiveness reduces the transmission of vibration and structural stress to the UAV airframe, thereby extending airframe lifespan and improving operational reliability. Additionally, the use of lightweight, modular components such as the quick-release bladeholder, integrated pitch control via the linkage mount and pitch horn, and a robust angle restrainer collectively provides a system that is not only easy to assemble and maintain in the field but also scalable for UAVs of varying sizes and payload capacities. Such a configuration enables improved payload handling, lower maintenance requirements, and increased operational efficiency.
[0039] The present disclosure provides a concrete and tangible solution to a significant technical problem in the field of unmanned aerial vehicle (UAV) rotorcraft systems, namely, the challenge of achieving flight stability, gust resistance, and payload capacity without excessive weight or mechanical complexity. The present disclosure offers specific technical features and functionalities, such as a semi-articulated rotorhead assembly that incorporates a bladeholder enabling controlled flapping motion, a yolk and main trunnion providing a robust yet lightweight flapping axis, and an angle restrainer to limit and stabilize blade articulation. Further, the integration of a linkage mount and pitch horn facilitates precise, servo-based pitch control, while the modular design of all components, including the shaft and pillar block, ensures straightforward assembly, maintenance, and scalability. These technical solutions collectively allow UAVs to absorb aerodynamic loads, reduce vibration and structural stress on the airframe, and support greater payloads, thus delivering reliable, efficient, and versatile performance in challenging operational environments.
, Claims:CLAIMS
We Claim:
1. A semi-articulated rotorhead system for an unmanned aerial vehicle (UAV), comprising:
a bladeholder configured to support a rotor blade and enable controlled flapping motion about a hinge axis;
a yolk serving as a main housing and supporting the bladeholder;
a main trunnion disposed within the yolk and forming a central pivot for the bladeholder;
a shaft configured to transmit rotational torque from a powertrain to the rotorhead assembly;
a pillar block providing a structural base for the rotorhead assembly;
a linkage mount configured to connect to a pitch control linkage;
a pitch horn operatively connected to the linkage mount for adjusting blade pitch; and
an angle restrainer configured to limit a range of flapping motion of the bladeholder.

2. The system as claimed in claim 1, wherein the bladeholder, yolk, and main trunnion are constructed of lightweight materials to minimize added mass to the UAV.

3. The system as claimed in claim 1, wherein the linkage mount and pitch horn are adapted to receive input from an electric servo or a swashplate mechanism.

4. The system as claimed in claim 1, wherein the angle restrainer is adjustable to vary the permissible flapping angle of the rotor blade according to operational requirements.

5. The system as claimed in claim 1, wherein the rotorhead assembly is configured for modular assembly and rapid disassembly to facilitate maintenance and component replacement in field conditions.

6. A method for improving flight stability and payload capacity of a UAV using a semi-articulated rotorhead system, the method comprising:
mounting a rotor blade to a bladeholder configured to enable controlled flapping motion about a hinge axis;
supporting the bladeholder within a yolk using a main trunnion as a pivot;
transmitting rotational torque to the rotorhead assembly via a shaft;
anchoring the assembly on a pillar block;
controlling blade pitch using a linkage mount and pitch horn operatively connected to a servo or swashplate; and
limiting a range of flapping motion of the rotor blade using an angle restrainer.
7. The method as claimed in claim 6, further comprising constructing the bladeholder, yolk, and main trunnion from lightweight materials to optimize UAV performance.

8. The method as claimed in claim 6, further comprising adjusting the angle restrainer to vary the maximum flapping angle in response to flight conditions.

9. The method as claimed in claim 6, further comprising assembling or disassembling the rotorhead system in a modular manner for rapid maintenance or field replacement.

10. The method as claimed in claim 6, further comprising operating the pitch control mechanism using electric servo-based or mechanical swashplate input to achieve precise aerodynamic adjustments during flight.