Designing Folding Wing Mechanisms for Drones

A folding propeller assembly for drones that allows compact storage without requiring manual folding. The propeller blades self-fold when not in use due to centrifugal forces during flight. The blades have connectors that engage with the hub when folded. The hub has matching openings and faces to connect and hold the blades in the folded position. When rotating, centrifugal forces extend the blades to the flight configuration. This eliminates the need for human intervention to fold and unfold the blades, reducing errors and simplifying storage.

Source

Unmanned aerial vehicle (UAV) with compact deployable wings and stabilizers for improved portability and flight capabilities compared to fixed-wing UAVs. The UAV has a telescoping wing system where outer sections slide into an inner fixed section to reduce size. Hinged ailerons on the outer sections allow roll control during wing extension. Deployable stabilizers pivot to fold against the fuselage. The UAV also has a folding propeller and fairings that sweep back during wing extension. This enables compact storage, fast deployment, and transition to flight control without losing wing area or stability.

Source

Abstract Flapping-Wing Aerial Vehicles (FWAVs) have received extensive attention due to their high maneuverability and efficiency in low Reynolds number flow conditions. Among them, FWAVs with foldable wings effectively improves flight performance by imitating the deformation characteristics of during birds .This paper proposes a new type passive mechanism. Through elastic joint installed on wing, automatic folding wing along vertical direction upward flapping process is achieved, thereby reducing effective area outer section lowering air resistance increasing net lift. When motion reaches highest position, can naturally unfold utilizing inertial force. dynamic modeling simulation optimization, this study successfully developed prototype weight 152.72g. Compared similar designs, overall mass was significantly reduced. Verified through bench experiments multiple sets experiments, results show that when frequency 4 Hz amplitude 80, designed FWAV achieve stable flight, maximum Angle 45. rigid its average lift has increased 16%, relative error between predicted model measured less th... Read More

Source

A compact foldable monocopter with a single wing and propulsion unit that allows easy storage and transportation. The monocopter has a foldable wing structure with rigid and flexible segments. When the monocopter rotates during flight, centrifugal forces straighten the foldable wing. The monocopter can fly with just one propulsion unit, using altitude control from thrust regulation and lateral control from pulsing thrust at specific points during rotations. The body houses electronics and a battery. The foldable design reduces footprint by 65-75%.

Source

This study focuses on the design, development, and optimization of retractable Vertical Take-Off Landing (VTOL) rotor arms for unmanned aerial vehicles (UAVs). The goal is to create a VTOL mechanism that enhances aerodynamic efficiency, reduces drag during forward flight, improves portability storage by retracting when not in use. Retractable offer promising applications, especially hybrid drones used long-range high-speed missions, where minimizing maximizing flight time crucial. project combines structural design principles, material selection, dynamic analysis develop lightweight, durable, reliable arm system. We incorporate mechanical electronic control systems allow seamless deployment retraction arms. Structural fatigue analyses ensure mechanism's durability under various conditions. process uses multi-objective approach, focusing reducing drag, enhancing stability, weight. Design parameters, including length, angles, properties, are iteratively refined using machine learning-based algorithms. Testing validation prototypes conducted assess real-world performance, with results i... Read More

Source

Compact aerial vehicle that folds its propulsion units when not in flight to reduce footprint for ground transportation. The vehicle has a passenger cabin and multiple folding propulsion units that deploy vertically for flight and stow horizontally for ground transport. This allows the vehicle to transition between compact mode for ground use and flight mode with non-intersecting thrust tunnels. The folding mechanism uses rotating arms. The compact design enables stowing the vehicle on a dolly for ground transport between vertical takeoff/landing points. This reduces ground footprint compared to full-size vehicles.

Source

Advances in drone technology have significantly improved their applications, but traditional designs often limit flexibility and efficiency different operating conditions [5]. This paper presents the concept of Xtreme reconfigurable drone, an innovative system that can dynamically change its layout flight to adapt mission requirements. The features variable-pitch adjustable-diameter propellers made flexible materials controlled by a sophisticated control module [7]. uses real-time sensor data machine-learning algorithms maintain transition balance stability [6]. Additionally, chassis has standard gearbox allows torque RPM adjustments, optimizing performance on demand Our approach incorporates origami-inspired folding techniques minimize number required actuators, thereby improving systems [10]. Prototyping included computer-aided design (CAD) modeling, 3D printing, integrating advanced electronics. Extensive testing was conducted evaluate drones various configurations environmental [3]. results showed flexibility, stability, maneuverability compared drones [1], [4]. represents ... Read More

Source

The operational ease of fixed-wing vertical take-off landing (VTOL) unmanned aerial vehicle (UAVs) derives from their capability to take off and land vertically. This particular is achieved through the utilization an additional rotor propulsion system that operates during landing. However, system, located externally airframe, contributes increasing drag force, especially cruise phase, reducing efficiency flight time. To overcome issues, this study proposes a design for VTOL UAV with four-retractable propulsion, demonstrating its feasibility performance flow simulation tests. During tests at speed 18 m/s, UAVs (folded UAV) without retractable systems (unfolded can maintain speeds m/s throttle openings 56.3% 72.1%, respectively. energy consumption was reduced by 33.0% followed in endurance 32.0%. It aligns results, which show reduce coefficient 35.9% increase aerodynamic (C L /C D ) 58.3% compared unfolded UAV. Both results confirm significantly reduces drag, increases endurance.

Source

Base station for unmanned aerial vehicles (UAVs) that provides automated servicing, storage, charging, and accommodation for UAVs. The station has features like: 1. Integrated temperature control system with a thermoelectric cooling/heating module to regulate the UAV's power source temperature. 2. Enclosure with a sliding cradle that retracts into the station when not in use. This allows UAVs to dock, charge, and store inside the station to protect them. 3. Base station door that opens and closes to let UAVs enter and exit. 4. Folding propeller mechanism that folds UAV propellers during docking to prevent collision with the station. 5. Visualization system with illumination and imaging to aid docking and precipitation detection. 6. Enclosure with heating elements, fiducials, and actuated door

Source

Foldable protective cage for unmanned aerial vehicles (UAVs) that can be easily detached from the drone for repair or adaptation to different drones. The cage has interconnected ribs that form a circular shape around the drone when deployed. The ribs have strings between them that fill the space between them when deployed. A closing part with rods joins the first and last ribs to keep them deployed. This allows the cage to be folded into a compact shape around the drone by collapsing the ribs. The rods detach to allow separation of the cage from the drone.

Source

Moving device that allows drones to easily take off and land, especially in confined spaces. The device has a main body that travels and a detachable landing pad with an adjustable leveling table. When a drone lands on the pad, sensors detect the tilt and the table adjusts to level the drone. This prevents tilting issues when the drone tries to take off or land on an uneven surface. The leveling table allows stable charging of the drone's power source and fluid filling of onboard tanks. It also enables compact unmanned aerial vehicles (UAVs) with internal components like power receivers and fluid devices since they don't need external connections on landing.

Source

Agricultural machines like tractors with integrated systems to improve work efficiency using unmanned aerial vehicles (UAVs). The machines have features like cable connections and landing stations to quickly deploy and assist UAVs during farming tasks. The UAVs can tether to the machines via cables to receive power and data. This allows the UAVs to stay longer in the air and closely monitor the machines, improving efficiency compared to separate UAVs. The UAVs can also land on the machine's landing stations to dock and recharge. This allows multiple UAVs to be connected and controlled by the machine. The UAVs can then fly in formation to cover larger areas and perform tasks like crop spraying or scouting. The integrated UAV systems avoid the issues of separate UAVs like limited flight time, restricted monitoring range, and collisions.

Source

A restructurable hybrid-wing vertical take-off and landing (VTOL) aircraft with foldable wings and tilting fuselage to enable vertical takeoff and landing in confined spaces without runways. The aircraft has an H configuration with wings and canards on the fuselage sides, and four vertical rotary wings above and below. In flight, the fuselage tilts to transition between vertical and horizontal modes. The rotary wings provide lift for vertical takeoff and landing. The fixed wings form a horizontal configuration for efficient horizontal flight. The tilting fuselage and foldable wings reduce size for transport and landing in confined spaces.

Source

Combat method using large portable drones capable of carrying heavy duty weapons and being stored inside a backpack. The method involves soldiers carrying folded drones in backpacks, unfolding and arming them to launch missiles at enemy targets, then returning the drones for future use. This allows soldiers to destroy enemy targets without exposing themselves, increasing efficiency and reducing casualties compared to ground-based weapons. The drones have folding designs to compactly fit in backpacks. The folded size is much smaller than extended size, allowing soldiers to carry the drones.

Source

Forward-swept wing unmanned aerial vehicle (UAV) with a variable body structure that allows compact storage and launch from ships. The UAV has a canard-type layout with full-motion canards up front and foldable forward-swept wings on the sides. The wings can fold inward by up to 180 degrees for compact storage. The vertical tails also fold. This deformable body reduces the wingspan and height when parked, allowing more UAVs to fit on ships.

Source

A folding mechanism for the wings of a fixed-wing drone that allows compact storage and transportation while maintaining aerodynamic efficiency during flight. The mechanism involves a hinge that connects the wing root to the fuselage. The hinge has a latch mechanism that secures the wing in the extended position during flight. When landing, the latch can be released to allow the wing to fold up against the fuselage for storage and transportation. The latch prevents the wing from folding during flight to maintain aerodynamic shape.

Source

Folding drone with variable center of gravity to improve flight performance. The drone has retractable wings that can slide along the fuselage to adjust the wingspan. This allows optimizing the wing area and center of gravity location for different flight conditions. When the wings are retracted, the drone is compact for transportation. The wings slide out during launch to increase wingspan. A mechanism inside the fuselage slides the wings and torsion springs rotate them out. The wings retract back into the fuselage for landing.

Source

A folding unmanned aerial vehicle (UAV) with forward-swept wings that can fold for compact storage and transportation. The UAV has a fuselage, main wings swept forward, and a wing between the main wings and tail. The main wings fold back against the fuselage using reset and limiting mechanisms. The mechanisms have rotation axes, limiters, and reset pieces. When folded, an external force overcomes the reset piece force, allowing rotation. When unfolded, the limiters expand and reset pieces return the wings.

Source

Foldable wings for drones that enable compact storage and transportation without disassembly. The wings have a folding mechanism between the main wing body and a detachable folding section. The folding section telescopes and rotates to fold up against the main wing body. This allows the wings to be quickly and easily folded by just manipulating the telescoping and rotating components. It avoids the need for disassembling and reassembling the wings during storage and transportation.

Source

A collapsible, vertical takeoff and landing unmanned aerial vehicle (UAV) with improved aerodynamics and transportability. The UAV has a fuselage with wings, payload bay, and collapsible winglets. Engines are mounted on the wingtips instead of the tail. This allows the UAV to take off and land vertically like a drone, but also fly efficiently like a traditional aircraft. The collapsible winglets reduce size for transportation and concealment. The payload bay can be detached for portability. This enables quick, inconspicuous assembly and launch from small spaces.

Source

An aerodynamic layout and control method for a long-endurance unmanned aerial vehicle (UAV) that integrates a multi-rotor and fixed-wing aircraft for improved efficiency and versatility compared to separate UAVs. The UAV has a folding wing design that allows the wings to be stowed parallel to the body when launched vertically like a multi-rotor. This prevents roll and vibration issues during vertical takeoff. The wings unfold for forward flight like a fixed-wing UAV. The multi-rotor provides vertical lift and maneuverability, while the fixed wings provide endurance. The UAV can switch between vertical and forward flight modes. Control is achieved by adjusting thrust on the rotors and wing-mounted motors for six-degrees-of-freedom motion in hover and roll/pitch adjustment in forward flight.

Source

Foldable drone wing design that allows compact storage and transportation of foldable drones without sacrificing flight stability or making the folding process overly complicated. The wing has an inner wing attached to the drone body and an outer wing that can fold inwards. The folding mechanism uses locking screws and plates to secure the wings together when closed. When extended, the screws and plates allow the wings to move freely. The inner wing has screws that slide into through-holes on the connecting plate. The outer wing has a screw that engages a recess on the plate. This allows the wings to lock together when closed and detach when extended.

Source

An aircraft design with foldable wings that improve takeoff and landing performance for vertical takeoff and landing (VTOL) aircraft. The wings have a rotating section that can pivot outward from the body. This allows the wings to fold inwards during VTOL operations to reduce the projected area and air resistance. It also allows the wings to rotate during descent to generate lift in the opposite direction to counteract airflow effects. This improves vertical descent stability and control compared to fixed wings. The wings unfold for forward flight to provide lift and maneuverability.

Source

A drone with folding wings that can be quickly launched and taken off in confined spaces. The drone has a compact form factor with foldable wings that can be stored and transported easily. The wings fold inward during storage and launch, reducing the drone's size for portability. This allows the drone to be launched in confined spaces where it may not have enough room to fully extend the wings. The drone can then rapidly ascend with the folded wings, minimizing air resistance and reaching optimal launch height. The wings unfold mid-flight, providing full flight capability.

Source

Self-locking mechanism for folding wings of fixed-wing drones that automatically unfold and fold during takeoff and landing. The mechanism uses self-locking components installed on the folding joints between sections of the wings. When the drone accelerates, airflow forces the wings to unfold. The self-locking components convert the forces into horizontal thrust to close the joints. When the drone is airborne, the self-locking components provide stability. During landing, reversing the airflow forces closes the wings. The mechanism allows compact storage, easy launching, and avoids manual wing folding.

Source

Folding component, wing folding structure, folding wing, and wing-body integrated drone with reliable folding mechanism. The folding component is a concave hexagonal honeycomb structure with elastic reset members at the corners. It folds by shrinking angles between the hexagon sides. The wings have this folding structure between sections to fold vertically and horizontally. The wings can also fold by heating the skin to soften and lift the wings. This allows more folding shapes compared to just wingtips. The folding wings are used on a drone body to switch between high and low speed flight by folding the wings for compactness at low speeds. The folding drone can have a vertical takeoff central rotor and tilt rotors on the wings for transition flight.

Source

A vertical takeoff and landing fixed-wing UAV with folding wings to combine the benefits of vertical takeoff and landing with efficient fixed-wing flight. The UAV has a canard layout with a forward-swept main wing and a smaller canard wing at the nose. The main wing folds along its root using a servo mechanism. This allows vertical takeoff and landing using the folded wing configuration, then unfolds for efficient fixed-wing flight. The canard provides pitch control and lift during both modes. A single set of propellers can provide thrust for both vertical and horizontal flight. The folding wings eliminate dead weight during fixed-wing flight while still providing vertical lift capability.

Source

A hybrid unmanned aerial vehicle (UAV) with adjustable wingspan for both high and low speed flight. The UAV has a rotating wing assembly that can pivot relative to the fuselage. The wing assembly consists of inflatable telescoping wings at the ends and a fixed center wing. The telescoping wings have cavities and folding structures that allow them to extend or retract. This adjusts the wingspan length. The inflation/deflation system and telescopic mechanism enable the UAV to have a compact wingspan for low speed flight and a longer wingspan for high speed flight. The rotating wing assembly allows optimized wing sweep angle for both regimes.

Source

A foldable variant unmanned aerial vehicle (UAV) that can transform between a fully extended flight configuration and a compact folded configuration for launching from confined spaces like launch tubes. The UAV has a fuselage with symmetrical wings, vertical fins, and horizontal tails. The wings, vertical fins, and horizontal tails can fold up, forward, and downward respectively using mechanisms. This allows the UAV to reduce its size for launching in tight spaces while still maintaining flight capability. The folding mechanisms are simple and reliable for launching from tubes. The UAV can switch between extended flight mode for normal operation and compact folding mode for launching.

Source

Foldable wing aircraft with a mechanism to variably change wing shape mid-flight. The wings have a modular structure with foldable sections that can extend and retract. The wing sections are connected by actuators, hinges, and linkages. The wings can transition between a folded position for storage and a deployed position for flight. This provides adaptability to optimize wing shape for different missions and environments while minimizing storage space.

Source

A propeller assembly for unmanned aerial vehicles that self-folds and unfolds without human intervention. The propeller blades have connectors that move within the central hub, allowing the blades to fold when at rest and extend when spinning during flight.

Source

Foldable and stowable wing structure for drones that allows compact storage and transportation of the drone without compromising wing stability when deployed. The wing structure has an inner wing connected to the fuselage and an outer wing connected to the inner wing. A folding mechanism allows the outer wing to flip and fold parallel to the inner wing, reducing the overall spread width when stowed. A connecting bracket and drive components enable flipping and folding the outer wing perpendicular to the inner wing. This compact folding configuration avoids the outer wing extending beyond the fuselage when stored.

Source

Folding wing design for unmanned aerial vehicles that allows compact storage and transportation while maintaining aerodynamic performance when flying. The wings are divided into a fixed wing on the fuselage sides, a first folding wing connected to the fixed wing, and a second folding wing connected to the first folding wing. The folding wings have parallel knuckle assemblies that allow direction-changing folding. The knuckles insert into slots on the wings when folded. This shortens the wingspan for storage but straightens inside the wings when flying to prevent hinge interference and maintain airflow lift.

Source

A modular, flat-packable drone kit can be assembled in multiple configurations with swappable components. The drone kit is made of flat plates that can be cut from a sheet of material, enabling low-cost manufacturing and compact packaging. The components can be secured using integrated mechanisms and elastic bands without specialized tools. The drone can be built in various configurations using different-sized propellers, above/below propeller placement, and modular accessories like cameras or grabbing arms. Multiple drones can be coupled, with one acting as a master flight controller.

Source

Automatic folding and unfolding of multi-arm unmanned vehicles enable compact storage and long-distance deployment. When released, the arms of a UAV can automatically extend from a contracted position to an expanded position. This allows the UAV to be stored in a highly compact configuration for transport and then deployed by autonomously expanding the arms. The expansion can use actuation, shoulder/rotations, and release mechanisms to save over eight times the storage space.

Source

A tilting and folding wing unmanned aerial vehicle (UAV) with improved vertical takeoff and landing capability and reduced ground storage size. The UAV has a fuselage, tilting and folding wings, landing gear, empennage, main rotor, and tail rotor. The tilting and folding wings are located mid-fuselage, the empennage is rear, and the tail rotor is at the tail. When the wings are vertical, the UAV can hover and VTOL like a multirotor. When horizontal, it flies fixed-wing like a conventional aircraft. The wings fold to reduce storage size. The tail has a protector to prevent ground collisions.

Source

High-altitude unmanned aerial vehicle (UAV) with telescoping wings that can extend and retract in flight to adapt to thin air densities at high altitudes. The wings fold compactly for transportation and launch, then extend to provide lift at high altitudes. The wings have a telescoping mechanism and a retractable mechanism. The telescoping mechanism allows the wings to slide horizontally in and out. The retractable mechanism retracts the wings vertically into the fuselage. Sensors monitor wing position. By controlling the telescoping and retracting simultaneously, the wings unfold and retract smoothly and synchronously. This allows the UAV to adapt to changing altitudes with optimized wingspan.

Source

Foldable wing design for drones that allows convenient folding and unfolding of the wings without affecting flight stability or limiting altitude. The wings have a movable mechanism with a pivot point and folding grooves on the top of the wing. The wings can be manually folded by moving the pivot point and sliding the wings into the grooves. This folds the wings against the body of the drone. The folding mechanism is installed between the wing and the fuselage, so it can be easily accessed and operated. This allows the user to manually fold the wings for storage and transportation without needing to disconnect or disassemble the wings. The folding mechanism also prevents the folded wings from shaking during flight, maintaining stability. The folding mechanism is integrated into the wing structure, rather than adding external folding mechanisms, which expands the folding space length compared to traditional folding wings.

Source

A foldable fixed-wing drone that can be compactly stored and transported by folding its wings and tail. The wings and tail unfold and fold simultaneously using mechanisms with ball screws and servo motors. This allows smooth and reliable folding/unfolding. The wings and tail attach close to the body when folded to reduce size. The drone has a main body, front and rear wings, empennages, and a propeller.

Source

Vertical take-off and landing unmanned aerial vehicle with a foldable fixed wing that improves stability and efficiency compared to existing designs. The VTOL drone has a twin-ducted fan power system, foldable wing, and retractable landing gear. The ducted fans provide vertical lift for takeoff/landing and horizontal thrust for forward flight. The ducts also stabilize the aircraft in crosswinds. The foldable wing reduces drag during vertical operations. The rearward center of gravity and duct position enable self-stabilization in the wind.

Source

Automatic folding mechanism for unmanned aerial vehicle (UAV) wings that allows the wings to fold back 90 degrees for compact storage when not in use. The mechanism uses a hydraulic push-pull rod to actuate folding structures on the wing interiors. The folding structures have fixed and rotation points to pivot the wings back. This allows the wings to fold without requiring external components or modifying the wing structure. The hydraulic actuators provide precise control and compact size for space-constrained UAVs.

Source

Foldable wing design for aircraft like drones and small manned aircraft that reduces weight and complexity compared to traditional wings. The foldable wing has a skeleton framework that encloses an inflatable airbag skin. The wing can fold horizontally by collapsing the framework. This allows compact storage and transportation of the aircraft. The foldable wing provides lift when inflated and reduces the number of wing components compared to a traditional wing.

Source

Foldable double-wing unmanned aerial vehicle (UAV) with reconfigurable aerodynamic layout that allows modular design and rapid assembly. The UAV has foldable wings that can be fully articulated by moving and rotating servo mechanisms mounted on guide rails. This eliminates dispersed controllable surfaces and allows compact storage, easy transportation, and quick assembly. The wings fold into the body when not in use. The wings can also be easily swapped for different configurations.

Source

Retractable wing drone with adjustable wing length and telescoping propellers for compact portability. The drone has a retractable wing mechanism that allows the wings to be shortened for storage and transportation. The wings can be extended when needed for flight. The propellers also retract into the drone body when not in use. This reduces the drone's overall size and makes it easier to carry and place in confined spaces. The wings can be adjusted to match different flight requirements and environments. The telescoping propellers extend to match the wing length for optimal performance. The drone also has folding landing gear and a protective case to further enhance portability.

Source

A folding mechanism for unmanned aerial vehicles that allows the wings to fold in mid-air and maintain any folding angle for flight. The mechanism uses a frame with symmetric deflection parts connected to the fuselage and wings. A folding mechanism rotatably connects the frame to the wings, allowing vertical movement. A wing connection mechanism connects the wings to the frame and keeps them level. This allows the wings to fold up or down while maintaining horizontal airfoils. By changing the fold angle, the wings can reduce span for maneuverability or prevent collisions. The folding mechanism can switch between fully extended, folded, and intermediate positions for ground ops and takeoff.

Source

A foldable wing design for launch-type large aspect ratio unmanned aerial vehicles that can quickly and autonomously deploy the wings after launch. The wing has an inner section and an outer section connected by a rotating shaft outside the lower surface. The outer section folds 180 degrees downwards to halve fold with the inner section. An upper overlapping section connects the inner section and has inner reinforcing ribs, upper limit frame, connecting beams, shaft sleeve, fixed winch, and positioning pulley. The lower overlapping section connects the outer section and has a rotating shaft, outer reinforcing rib, lower limit frame, pulley support, and rotating pulley. The outer section unfolds using a rope driven by a rotating pulley to extend until flush with the inner section.

Source

Folding mechanism for quadcopter wings to reduce storage size. The mechanism allows folding the rotor arms and propellers into the body when not in use. It uses locking rings, threaded sections, and sliding grooves to allow folding and unfolding. The rotor arms have adjustable joints with rings that can separate to fold the arms inward. The propellers have locking rings that can disengage to fold them back. This allows compact storage by collapsing the arms and propellers into the body.

Source

Bionic folding unmanned aerial vehicle with flexible wings that can fold into a compact size for storage and transportation, and then unfold in mid-air during launch. The vehicle mimics the folding and unfolding motion of a sugar glider to provide maneuverability and flexibility. The wings, rudder, and tail all retract into the body for storage. When launched, an ejection mechanism propels the vehicle to altitude, then the wings, rudder, and tail unfold like a sugar glider spreading its limbs to provide lift and control. This allows the vehicle to launch from confined spaces and then unfold mid-air.

Source

Folding wing aircraft with hidden rotors for vertical takeoff and landing capability. The aircraft has a fuselage, fixed wings, and a rotor in each wing section. The rotor sections can fold and close into the wings when not needed for level flight. The folding mechanism uses slide plates, drive motors, and springs to automatically close the rotor compartments. When closed, the rotors are hidden inside the wings, providing a streamlined shape for efficient horizontal flight. The rotors can be extended for vertical takeoff and landing maneuvers by opening the compartments.

Source

Folding rigid wing design for drones that allows compact storage without compromising aerodynamics or interfering with the fuselage. The wing has three sections - fuselage wing, inner wing, and outer wing - that fold bi-axially. The fuselage wing connects directly to the fuselage. The inner wing rotates vertically relative to the fuselage wing. The outer wing rotates vertically relative to the inner wing. This allows folding the wings into a compact shape while maintaining a smooth airfoil profile. The folding mechanism uses hooks, grooves, and springs to lock the wings in place when folded.

Source