DESC:Field of the Invention:
The present invention relates to unmanned aerial vehicles, particularly quadcopter drones. The present invention also relates to a process for design and manufacture of quadcopter drones.
Background:
The following description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
Presently, quadcopter drones have become popular since quadcopter drones are capable of precise aerial manoeuvres, have the ability to hover in place smoothly, and can take off and land vertically. They are crucial for tasks like aerial photography, surveillance, search and rescue missions, mapping, agricultural monitoring, and environmental research. Their ability to access hard-to-reach areas and capture high-resolution data makes them invaluable in various industries.
Quadcopter drone construction involves assembling components like the frame, motors, propellers, flight controller, battery, and electronics. These parts are interconnected, calibrated, and tested for proper function. Pilots control the drone's flight using a remote transmitter. Attention to detail and testing ensure safe and reliable operation.
The frame of a quadcopter drone serves as a structural foundation, supporting and organizing its components. It provides stability, protects the internal electronics, and determines the overall size and shape of the drone. The design of the frame can impact flight performance, aerodynamics, and payload capacity. It is essential for the frame to be lightweight, rigid, and balanced to ensure the drone's stability and manoeuvrability during flight.
The manufacturing methods for quadcopter drone frames can vary based on factors like material choice, complexity of design, and production scale. Some common manufacturing methods include CNC machining, carbon fiber layup, injection molding, and sheet metal fabrication.
In the machining method, carbon fibers are precisely cut and shaped to create intricate frames. In this approach, the frame is produced in multiple parts and then screwed together to achieve the final shape. That increases the weight of the frame. Further, composite materials involve intricate manufacturing processes such as layering and curing. These processes can be time-consuming and require specialized equipment and expertise. Improper curing, impact, or stress concentration points can lead to delamination (separation of layers) or cracking in the composite structure, compromising its integrity. Ensuring consistent quality in composite manufacturing is crucial. Variations in material properties, resin curing, and fiber alignment can lead to structural defects or inconsistencies in the frame. In addition, high-performance composite materials can be expensive, affecting the overall drone cost. Furthermore, composite materials can have limitations in terms of design complexity. Sharp angles, tight radii, or intricate geometries might be challenging to achieve or result in weak points. Repairing composite frames can be more complex than working with traditional materials. Specialized knowledge and tools are often required to fix damages effectively.
The other most common method used for manufacturing quadcopter drone frames is injection molding (IM). This manufacturing process have the following limitations:
1. Inconsistent Material Properties: It involves mixing powders with a binder to create a feedstock that is then molded before sintering. Achieving consistent material properties, such as mechanical strength and density, can be challenging due to variations in powder composition, particle size distribution, and binder content. These inconsistencies could lead to variations in the performance and reliability of the drone frames.
2. Dimensional inaccuracy: It involves the use of intricate molds to create complex shapes. Achieving precise dimensional accuracy across the entire frame, especially in intricate areas, can be difficult. Shrinkage during sintering and the potential for warping can affect the final dimensions of the drone frame, which might impact the overall performance and assembly of the drone.
3. Structural Integrity: The design of a drone frame requires specific structural properties to withstand the stresses and vibrations experienced during flight. Ensuring that the plastic injection molding process produces a frame with the required strength, stiffness, and fatigue resistance is crucial. Inadequate structural integrity could lead to frame failures and potential crashes.
4. Porosity and Density: The injection molding process can result in the formation of internal pores within the material due to incomplete binder removal during sintering. Porosity can negatively impact the properties of the frame, reducing its strength and load-bearing capacity. Controlling and minimizing porosity through careful process optimization is essential.
5. Surface Finish: The surface finish of the injection molding -produced parts may not be as smooth as those manufactured using traditional machining methods. Poor surface finish could impact aerodynamics, affect drag, and potentially lead to uneven stress distribution across the frame. Additional finishing steps might be required to achieve the desired surface quality.
6. Post-Processing Challenges: After sintering, drone frames produced through injection molding might require additional post-processing steps such as heat treatment or surface coatings, to enhance their properties. Coordinating these additional steps while maintaining the desired design and performance can be complex.
7. Cost Considerations: Injection molding can be cost-effective for high-volume production, but it may not be as cost-efficient for lower production quantities due to tooling and setup costs. Balancing the cost-effectiveness of Injection molding with the specific production volume of drone frames is important.
Accordingly, the present invention envisages a new frame design and manufacturing method, in order to overcome the above stated drawbacks.
Object of the Invention:
It is an object of the present invention to provide a quadcopter drone frame which is light weight, sturdy, rigid, durable and modular, provides space and safety for electronics.
It is another object of the present invention to provide a quadcopter drone frame, having an arrangement for a compartment for battery, ensuring safe and balanced weight distribution.

It is yet another object of the present invention to provide a quadcopter drone frame, which minimizes air resistance and drag, enhancing the drone's overall efficiency.
It is a further object of the present invention to provide a quadcopter drone frame, which maintains stability during flight.
It is still further object of the present invention to provide a quadcopter drone frame, which has protective features to guard against accidental contact with moving parts, like propellers and which allows easy access to components.
It is another object of the present invention to provide an additive manufacturing method for the quadcopter drone frame which result in elimination of drawbacks of existing manufacturing methods.
It is yet another object of the present invention to provide an additive manufacturing process which can produce desired shapes of the quadcopter drone frame with precision and less material waste.
These and other objects, features and advantages will be readily apparent upon consideration of the following detailed description of the invention in conjunction with the accompanying drawings.
Summary of the Invention:
According to this invention, there is provided a quadcopter drone assembly comprising:
- a frame structure consisting of a cover, a middle plate, a center hub, arms, a bottom plate, landing gears,
o said cover, said middle plate, said center hub, and said bottom plate being collinearly aligned,
o said arms extending, transversely, out of external circumference of said center hub, each of said arms configured to host a propeller at its distal free end,
o said landing gears extending from an operative bottom of said center hub in order to provide support to said quadcopter drone assembly,
o said bottom plate and said middle plate being placed inside said center hub which accommodates said battery, said flight controller, said electronic speed controller (ESC), said power distribution board, said communication RF antenna, and said camera antenna,
- a flight controller, motor/s, electronic speed controller/s, a power distribution board, a GPS, a communication RF antenna, a batter, and a camera antenna,
characterised, in that,
- said arms being hollow tapered arms configured to allow air to pass through its hollow structure, thereby reducing drag by minimizing solid surface area exposed to airflow;
- said arms including a tapered horizontal slot within each arm configured to refine airflow over the arm surface, thereby reducing turbulence;
- said arms being designed for cantilever loading;
- said landing gear having a curved profile configured to provide flexibility and absorb shocks;
- said quadcopter having a thrust-to-weight ratio of 2 for adequate lift; and
- distance between two adjacent propellers being 1/4th diameter of propeller to avoid aerodynamic interference.
In at least an embodiment, said arms being selectable in terms of geometric cross-sections from a group of cross-sections consisting of T-section geometric cross-section, I-section geometric cross-section.
In at least an embodiment, said center hub having an octagonal shape with eight sides of which,
- four sides are adapted to fix said arm(s),
- two sides are adapted to place a battery, and
- two sides are adapted to host electronic items cooling air vents.
In at least an embodiment, said bottom plate and said middle plate are placed inside said center hub which accommodates said battery, said flight controller, a speed controller (ESC), a power distribution board, said communication RF antenna, and said camera antenna.

In at least an embodiment, said center hub consisting, essentially, of:
- a plurality of plate fixing flat rest, protruding as stubs from an internal circumference of said center hub,
- a plurality of motor wire connection hole on the frame of said center hub formed through a frame of said center hub,
- a plurality of battery insertion spaces formed through the frame of said center hub,
- a plurality of arm mounting raised base formed as external supports on an external circumference of said center hub,
- a plurality of electronics item cooling air vents formed as through slots through the frame of said center hub,
- a plurality of landing gear fixing holes formed as through holes through the frame of said center hub, and
- a plurality of arm fixing threaded insert holes formed as through holes through said arm mounting raised base,
characterised, in that,
- said flat plate fixing rest being provided to fix said middle plate and said bottom plate, in that, four flat plate fixing rests being provided at 1/4th of height of center hub from its operative top face and four flat plate fixing rests being provided at an operative bottom face of center hub;
- said battery insertion space is half of the center hub height and starts from said operative bottom face of said center hub, spaced apart from said bottom face, on two opposite faces of said center hub;
- said motor wire connection hole being at a centre of said arm mounting raise base, at 1/4th height of said center hub from its operative top face, said arm aligning with hole, on arm fixing flat base and holes;
- said cooling air vents being located at alternative faces of said center hub at 1/4th height of said center hub from its operative bottom face, said cooling air vents aligning with surface of said speed controller (ESC) and with said battery;
- said landing gear fixing holes being located at alternative faces of said center hub at 1/4th height of said center hub from its operative bottom face and being located horizontally at centre of respective face of said center hub;
- a centre of pitch circle diameter (PCD) of said arm fixing threaded insert holes being aligned with centre of motor wire connection hole; and
- said arm mounting raised base being located at alternative faces of said center hub , having thickness equal to center hub thickness.

In at least an embodiment, said center hub including a plurality of electronic items cooling air vents, each of the plurality of electronic items cooling air vents configured to provide cooling to electronics and battery.
In at least an embodiment, said center hub being equipped with a plurality of plate fixing flat rests, protruding as stubs from an internal circumference of said center hub, said plate fixing flat rests being designed to secure said middle plate and said bottom plate to said center hub.
In at least an embodiment, said center hub being equipped with a plurality of motor wire routing holes, specifically designed to facilitate the connection of motor wires.
In at least an embodiment,
- said bottom plate and said middle plate being positioned inside said center hub, and
- said battery, said flight controller, said electronic speed controller (ESC), said power distribution board, said communication RF antenna, and said camera antenna being fixed on said bottom plate and said middle plate.
In at least an embodiment, said arm includes arm fixing flat base and holes, the wire routing slot and hole, a plurality of motor mount holes, a plurality of motor wire passage holes and the tapered section, wires passing through said motor wire connection hole on said center hub.

In at least an embodiment, said bottom plate includes battery placement flat surface, ESC placement slots, air vents, fastening holes, and camera mount hole,
in that,
- said bottom plate being secured to an operative lower surface of said center hub at a plurality of plate fixing flat rest through fastening holes,
- said battery slides onto a battery placement flat surface of said bottom plate, guided through a square slot (battery insertion space) within said center hub, and is secured with a belt (not shown).
In at least an embodiment, a plurality of ESC placement slots are provided to press-fit said electronic speed controllers (ESC) vertically on said bottom plate in order to facilitate easy routing of motor and signal wires to said power distribution board and said flight controller located on an operative top surface of said middle plate within said center hub.
In at least an embodiment, said middle plate includes a plurality of avionics wire connection slots, a top surface, a plurality of wire access cutouts, a plurality of extrusions and air vents,
in that,
- said operative top surface of said middle plate being designed to mount said flight controller with an anti-vibration pad (not shown) at its center,
- said top surface accommodates various electronic components, including a communication RF antenna for telemetry data, a transmitter-receiver module (not shown), a video camera transmitter antenna, and a buzzer (not shown),
- an operative bottom side of said middle plate being equipped with a plurality of extrusions designed for securing said power distribution board.
In at least an embodiment, said cover includes GPS wire connection slots, GPS mounting cavity, communication antenna slots and cover clamping raise,
in that,
- said cover configured to host a GPS mounting cavity for mounting the GPS,
- said cover includes a plurality of communication antenna slots, which allow the antennas to extend outward for effective communication,
- said the cover being equipped with a cover clamping raise designed to securely attach said cover to said center hub.
In at least an embodiment, said landing gear including a flat surface with holes, reduced cross-sectioned curved profile, extended flat leg surface, and a flexi-Damp Slot.
Brief Description of the Accompanying Drawings:
The accompanying drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
Figure 1 illustrates quadcopter assembly, in accordance with an embodiment of the present disclosure;
Figure 2 illustrates quadcopter components, in accordance with an embodiment of the present disclosure;
Figure 3 illustrates frame structure parts in accordance with an embodiment of the present disclosure;
Figure 4 illustrates frame structure assembly, in accordance with an embodiment of the present disclosure;
Figure 5 illustrates center hub, in accordance with an embodiment of the present disclosure;
Figure 6 illustrates quadcopter drone arm, in accordance with an embodiment of the present disclosure;
Figure 7 illustrates bottom plate, in accordance with an embodiment of the present disclosure;
Figure 8 illustrates middle plate, in accordance with an embodiment of the present disclosure;
Figure 9 illustrates cover, in accordance with an embodiment of the present disclosure;
Figure 10 illustrates landing Gear, in accordance with an embodiment of the present disclosure;
Figure 11 illustrates thrust vectors;
Figure 12a illustrates a first method of calculation;
Figure 12b illustrates a second method of calculation;
Figure 13a, show the arm deformation and stress distributions, validating the material and section choice;
Figure 13b shows a table as to how, and why, the current invention’s arm design was chosen;
Figure 14 illustrates dynamic analysis of landing gear; and
Figures 15a and 15b illustrates various stress profiles observed in landing gear loading condition.
Detailed Description of the Invention:
The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of details offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure.
In the present invention the problems of weight, structure integrity, inefficient space, difficulties with assembly, high cost, and manufacturing limitations have been addressed using intensively designed frame structure, FEA analysis, and testing of quadcopter frame.
The present invention also focuses on additive manufacturing to get advantage for designing lightweight structures at low manufacturing costs.
The presently invented quadcopter is a simple design, easy to assemble, modular, light weight and is made from a single material and single manufacturing process.
In one aspect of the present invention there is provided a quadcopter drone assembly.
In embodiment, the Quadcopter drone assembly is illustrated by using figures 1 to 15. The assembly parts are illustrated with the help of names followed by its reference numeral in parenthesis.

List of Parts:

• Frame structure (102)
• Cover (104)
• Middle plate (106)
• Center hub (108)
• Arms (110)
• Bottom plate (112)
• Landing gears (114)
• Flight controller (116)
• Motors (118)
• Electronic speed controller (ESC) /Electronic control unit (120)
• GPS (122)
• Communication RF antenna (124)
• Battery (126)
• Mounting bolts (128)
• Camera antenna (130)
• Propellers (132)
• Plate fixing flat rest (202)
• Motor wire routing hole (204)
• Battery insertion space (206)
• Arm mounting raised base (208)
• Electronic items cooling air vents (210)
• Landing gear fixing holes (212)
• Arm fixing threaded insert holes (214)
• Arm fixing flat base and holes (302)
• Wire routing slot and hole (304) / tapered horizontal slot (304)
• Motor mount holes (306)
• Motor wire passage holes (308)
• Tapered section (310) / hollow tapered arms (310)
• Battery Placement Flat Surface (402)
• ESC placement slots (404)
• Air vents (406)
• Fastening holes (408)
• Camera mount hole (410)
• Avionics wire connection slots (502)
• Top surface (504)
• Wire access cutouts (506)
• Extrusions (508)
• Air vents (510)
• GPS wire connection slots (602)
• GPS mounting cavity (604)
• Communication antenna slots (606)
• Cover clamping raise (608)
• Flat surface with holes (702)
• Reduced cross-sectioned curved profile (704)
• Extended flat leg surface (706)
• Flexi-Damp Slot (708)

Fig. 1 shows the complete assembly of the quadcopter, including the 3D-printed frame structure parts.
Fig. 2 shows an exploded view of the quadcopter drone assembly. It is an X configuration.
In one embodiment, the quadcopter drone assembly (100) comprises a frame structure (102), said frame structure (102) comprises a cover (104), a middle plate (106), a center hub (108), arms (110), a bottom plate (112) and landing gears (114). The cover (104), the middle plate (106), the center hub (108), and the bottom plate (112) are collinearly aligned.
The quadcopter drone assembly (100) additionally comprises a flight controller (116), motor/s (118), electronic speed controller/s (120), a GPS (122), a communication RF antenna (124), a battery (126) and a camera antenna (130)
. The frame structure parts are designed and manufactured considering its functionality, weight, rigidity, ease of assembly and modularity.
In one embodiment, all frame structure parts are made of polymer material which include but is not limited to polylactic acid or polylactide (PLA) by 3D printing process.
Fig. 3 illustrate the frame structure parts such as center hub (108), arms (110), bottom plate (112), middle plate (106), cover (104) and landing gears (114).
Fig. 4 illustrate the assembly of quadcopter frame structure without any avionics components.
Fig. 5 illustrates the center hub (108) in accordance with an embodiment of the present disclosure. The center hub (108) includes several key features. The center hub (108) includes a plurality of plate fixing flat rest (202), a plurality of motor wire routing hole (204), a plurality of battery insertion space (206), a plurality of arm mounting raised base (208), a plurality of electronics item cooling air vents (210), a plurality of landing gear fixing holes (212) and a plurality of arm fixing threaded insert holes (214).
In an embodiment, the flat plate fixing rest (202) utilised to fix middle plate (106) and bottom plate (112). Four numbers of fixing rest at 1/4th of height of center hub from operative top face and another four numbers at operative bottom face of center hub.
In an embodiment, the cooling air vents (210) is located at alternative faces of center hub (108) at 1/4th height of center hub from operative bottom face. As cooling air vents at this location aligned with the ESC surface and battery surface, it helps in ventilation.
In an embodiment, the landing gear fixing holes (212) is located at alternative faces of center hub (108) at 1/4th height of center hub from operative bottom face. Horizontally, it is at centre of respective face of center hub (108).
In an aspect, the centre of pitch circle diameter (PCD) of arm fixing threaded insert holes (214) is aligned with centre of motor wire routing hole (204).
In one embodiment, the center hub (108) is equipped with a plurality of plate fixing flat rest (202), designed to secure the middle plate (106) and the bottom plate (112) to the center hub (108).
In one embodiment, the center hub (108) is equipped with a plurality of motor wire routing holes (204), specifically designed to facilitate the connection of motor wires.
In an embodiment, the motor wire routing hole (204) is at centre of arm mounting raise base (208). It is at 1/4th height of the center hub from operative top face. Once arm (110) is assembled with the center hub (108) it aligns with hole, on arm fixing flat base and holes (302).
In one embodiment, the center hub (108) includes a plurality of the battery insertion space (206), ensuring the battery (126) is securely and easily replaceable.
In an embodiment, battery insertion space (206) is half of the center hub height, and it starts from operative bottom face of center hub keeping some distance at bottom, on two opposite faces of center hub. Width of the battery insertion space is equal to battery width considering clearance for easy insertion.
In an embodiment, a plurality of arm mounting raised base (208) and a plurality of arm fixing threaded insert holes (214) are configured to securely mount the arms (110) to the center hub (108).
In an embodiment, the arm mounting raised base (208) is located at alternative faces of center hub (108). It is having thickness equal to center hub thickness.
In an embodiment, the center hub (108) includes a plurality of electronic items cooling air vents (210), each of the plurality of electronic items cooling air vents (210) configured to provide proper cooling to the electronics and battery (126).
In an embodiment, a plurality of landing gear fixing holes (212) is configured to securely mount the landing gears (114) to the center hub (108).
In accordance with the present invention, the center hub (108) is an octagonal shape that gives integrity and structural strength with minimum wall thickness.
In an embodiment, an octagonal design offers a balance between structural stability and minimized drag while keeping the drone lightweight. Compared to a hexagonal or decagonal frame, an octagonal design optimizes spatial arrangement for component placement while maintaining better aerodynamic properties. While a square or rectangular shape is bulkier and more prone to drag, the octagonal form minimizes these issues, providing an ideal compromise between stability and aerodynamics.
In an embodiment, four sides of the center hub (108) are utilized to mount the arms (110) and landing gears (114), two sides are utilized to place a battery (126) and the remaining two sides provide the electronic items cooling air vents (210). The arm (110) is mounted on the center hub (108) at arm fixing threaded insert holes (214) by bolts or fasteners.
In an aspect, the landing gears (114) is fixed by nut bolts at landing gear fixing holes (212).
In an embodiment, the arms (110), cover (104), and landing gears (114) are attached to the center hub (108).
In an embodiment, the bottom plate (112) and the middle plate (106) are positioned inside the center hub (108). The battery (126), flight controller (116), electronic speed controller (ESC) (120), power distribution board, communication RF antenna (124), and camera antenna (130) are fixed on these plates.
In an embodiment, this design and arrangement offer the following benefits:
1. The octagonal shape, in combination with plates (i.e. the bottom plate (112) and middle plate (106)), provides structural integrity. With this arrangement a smaller thickness can be used for the center hub (108) which offers optimal weight with sufficient strength for the frame structure to handle loading and vibration.
2. The design serves as an enclosure, securing all safety-critical components.
3. Heat dissipation is effectively addressed through the incorporation of air vents at specific locations.
4. The modular design of the wire harnessing system simplifies the replacement of drone arms.
In an embodiment, the arm (110) includes arm fixing flat base and holes (302), wire routing slot and hole (304), a plurality of motor mount holes (306), a plurality of motor wire passage holes (308) and a tapered section (310). Wires passes through motor wire routing hole (204) on the center hub (108).
In an embodiment, GPS wires are routed through circular GPS wire connection slots (602), enabling connection to the flight controller (116) mounted on the top surface (504) of the middle plate (106).
In an embodiment, the middle plate (106) is an octagonal plate featuring a plurality of curved wire access cutouts (506) on its sides. These cutouts facilitate the routing of wires from the power distribution board (PDB) to the motors (118) and control cables to the flight controller (116).
In an embodiment, the arm (110) function is to mount motors (118) and maintain safe distance between rotating propellers (132), which are mounted at each arm’s distal free end. The arm (110) is designed to take dynamic loading, cantilever loads, and vibration loads. The arm (110) is sturdy enough to take designed loads with optimum weight.
In an aspect, this arm (110) design supports the motors (118), optimizes weight, facilitates easy assembly and replacement, improves stability, reduces deflection, and offers flat surfaces for good contact.
The FEA analysis of arm (110) was completed and result shows stress and deflection within limit. The analysis of Results:
• Deformation: The structure exhibited a total deformation of approximately 1.26 mm under an applied load of 12 Newton. This deformation is within an acceptable operational threshold for polylactic acid (PLA), taking into account typical engineering tolerances and application-specific requirements.
• Stress Analysis: The equivalent stress observed in the structure was determined to be 9.1823 MPa, which is substantially below the tensile strength of PLA, rated at 65 MPa. This indicates that the material operates within a safe stress range under the specified load conditions, minimizing the likelihood of tensile stress-induced failure.
Fig. 6 illustrates Quadcopter drone arm (110) in accordance with an embodiment of the present disclosure. The arm (110) includes arm fixing flat base and holes (302), wire routing slot and hole (304), a plurality of motor mount holes (306), a plurality of motor wire passage holes (308) and a tapered section (310).
In accordance with the present invention, the arms (110) are designed for cantilever loading.
In an embodiment, the arm fixing flat base and holes (302) are designed to securely attach the arms (110) to the center hub (108) at the arm mounting raised base (208).
In an embodiment, to securely and efficiently mount the motors (118) on the arm (110), a plurality of motor mount holes (306), motor wire passage holes (308) and mounting bolts (128) are provided.
In an embodiment, to reduce weight and provide access to wires without affecting strength, a tapered section (310) is incorporated and wire routing slot and hole (304) are provided.
In an embodiment, the arms are displayed as separate structural elements with various geometric cross-sections (e.g., T-section, I-section). The arms (110), used in this drone, have smooth uniform surfaces, have a good aesthetic look, and have place to enclose motor wires towards power distribution board in the center hub (108). The hollow design of the arms (110) minimizes the drone’s overall mass, while reducing drag by minimizing solid surface area exposed to airflow. Instead of a completely solid structure, the hollowed arms allow air to pass through their structure, effectively reducing wind resistance and surface area, which otherwise would generate more drag. Tapering, of arms, is known to reduce drag. Here, in this invention, the design includes a tapered horizontal slot (304) within each arm, not only to reduce weight but also to refine airflow over the arm surface, thereby reducing turbulence. This added feature offers smoother aerodynamic performance compared to standard tapering.
In an embodiment, this arm design supports the motors (118), optimizes weight, facilitates easy assembly and replacement, improves stability, reduces deflection, and offers flat surfaces for good contact.
Fig. 7 illustrates the bottom plate (112) in accordance with an embodiment of the present disclosure. The bottom plate (112) includes battery placement flat surface (402), ESC placement slots (404), air vents (406), fastening holes (408), and a camera mount hole (410).
In an embodiment, the bottom plate (112) is secured to the lower surface of the center hub (108) at a plurality of plate fixing flat rest (202) through fastening holes (408).
In one embodiment, the battery (116) slides onto the battery placement flat surface (402) of the bottom plate (112), guided through a square slot (the battery insertion space (206)) within the center hub (108), and is secured with a belt (not shown).
In one embodiment, a plurality of ESC placement slots (404) are provided to press-fit the electronic speed controller (ESC) (120) vertically on the bottom plate (112). This arrangement facilitates the easy routing of motor and signal wires to the power distribution board (PDB, not shown in drawing) and flight controller located on the top surface of the middle plate (106) within the center hub (108). Unlike the conventional approach where the ESC (120) is mounted on the arm and secured with a cable tie, exposing it to environmental elements and potential damage during crashes, this design improves both the aesthetic and safety aspects. By housing the ESC (120) within the center hub (108), the risk of damage is significantly reduced, enhancing the overall durability and appearance of the drone.
In one embodiment, a surveillance camera can be mounted to the bottom side of the bottom plate (112) through the camera mount hole (410).
In one embodiment, the octagonal shape of the center hub (108) ensures an unobstructed viewing angle for the camera.
In one embodiment, the air vents (406) are provided for the circulation of air inside the center hub (108).
Fig. 8 illustrates the middle plate (106) in accordance with an embodiment of the present disclosure. The middle plate (106) includes a plurality of avionics wire connection slots (502), a top surface (504), a plurality of wire access cutouts (506), a plurality of extrusions (508) and air vents (510).
In one embodiment, the middle plate (106) is an octagonal plate featuring a plurality of curved wire access cutouts (506) on its sides. These cutouts facilitate the routing of wires from the power distribution board (PDB) to the motors (118) and control cables to the flight controller (116).
In one embodiment, the top surface (504) of the middle plate (106) is designed to mount the flight controller (116) with an anti-vibration pad (not shown) at the center. Additionally, this top surface accommodates various electronic components, including a communication RF antenna (124) for telemetry data, a transmitter-receiver module (not shown), a video camera transmitter antenna (130), and a buzzer (not shown). These components are securely placed and mounted on the top surface (504) of the middle plate (106) and are covered with a protective cover (104) to ensure their safety. This design overcomes the conventional limitation in quadcopter drones, where the availability of flat surfaces for securing electronic items is generally restricted.
In one embodiment, the bottom side of the middle plate (106) is equipped with a plurality of extrusions (508) specifically designed for securing the power distribution board.
In one embodiment, the plurality of avionics wire connection slots (502) are strategically positioned to facilitate routing wires to the flight controller (116) for power and connectivity.
In one embodiment, the air vents (510) are provided for the circulation of air inside the center hub (108).
In an embodiment, this innovative design of the middle plate (106) not only secures critical electronic components but also offers dedicated and ample space for mounting, as well as efficient air circulation to facilitate heat dissipation.
Fig. 9 illustrates the cover (104) in accordance with an embodiment of the present disclosure. The cover (104) includes GPS wire connection slots (602), GPS mounting cavity (604), communication antenna slots (606) and cover clamping raise (608). Traditionally, the cover serves primarily an aesthetic purpose and conceals the central portion containing avionics. However, in this embodiment, the cover (104) is uniquely designed to also provide dedicated space, i.e. the GPS mounting cavity (604) for mounting the GPS (122). This innovative design eliminates the need for the delicate raised vertical stand commonly used in most quadcopters for GPS mounting, thereby enhancing both the durability and integration of the GPS component within the drone's structure.
Enclosed design where avionics items are placed and secured inside well ventilated (210, 406) center hub (108).
In an embodiment, generic shape of octagon utilised considering design and application aspects. Four faces of center hub (108) utilised to fix drone arms (110) and landing gears (114), Two faces utilised to insert battery (206), and remaining two faces utilised for strategic location of air vents (210).
In an embodiment, unique design of cover (104) includes a centrally located circular GPS mounting cavity (604) designed for securely positioning the GPS. GPS wires are routed through circular GPS wire connection slots (602), enabling connection to the flight controller (116) mounted on the top surface (504) of the middle plate (106). The GPS is securely retained during flight and protected in the event of a crash landing, due to the flat surface and raised edges of the GPS mounting cavity (604).
In an embodiment, the tapered and slotted arm (110) provides sufficient strength with optimum weight and provides necessary space for wire routing which provides neat and clean wiring for aesthetic look and safety.
In an embodiment, the middle plate (106) and bottom plate (112) provides sufficient designated space for securing avionics items. It provides additional strength to the center hub (108) after assembly and whole assembly become integrated and safe for different loading conditions.
In one embodiment, the cover (104) functions as a GPS stand in a more protective and rugged manner, without compromising performance. This design eliminates the need for an additional GPS stand assembly.
In one embodiment, the cover (104) includes a plurality of communication antenna slots (606), which allow the antennas to extend outward for effective communication.
In one embodiment, the cover (104) is equipped with a cover clamping raise (608) designed to securely attach the cover (104) to the center hub (108).
In one embodiment, this balanced arrangement not only provides secure mounting and guidance for the GPS and antennas, but also enhances the aesthetic appeal.
Fig. 10 illustrates the landing gears (114) in accordance with an embodiment of the present disclosure. The landing gears (114) includes a flat surface with holes (702), reduced cross-sectioned curved profile (704), extended flat leg surface (706), and Flexi-Damp Slot (708). The primary function of the landing gears (114) is to ensure the safe landing of the drone and to protect its assembly from potential damage. Additionally, the landing gear arrangement protects camera beneath the drone from touching to the ground, thereby enhancing the camera’s field of view. The landing gears (114) is also designed to absorb impact energy during landing, contributing to the overall stability and durability of the drone.
In one embodiment, the landing gears (114) is 3D printed using PLA material. It is specifically designed and analysed to withstand impacts and free falls from considerable heights, ensuring durability and reliability under various operating conditions.
In one embodiment, the reduced cross-sectioned curved profile (704) of the landing gears (114) is designed to provide flexibility and absorb shocks, countering the inherently brittle nature of PLA material. This design incorporates additional material at critical areas of bends and curvature to enhance strength and durability. Furthermore, the inclusion of the Flexi-Damp Slot (708) offers additional flexibility and damping for impact loads.
In another aspect of the present invention, there is provided an additive manufacturing method for producing quadcopter drone assembly.
In one embodiment, the drone, of this invention, was designed with a thrust-to-weight ratio of 2 for adequate lift, considering a total weight of 2 kg, including payload. The motor with a propeller was chosen to achieve the required thrust per motor, resulting in a maximum thrust of 3360 gm and sufficient hover thrust at 50% throttle.
Fig. 11 illustrates thrust vectors for the configuration below:
Configuration Quadcopter
Design Max Weight Capacity 2000 gram
Maximum Thrust generated at 50% throttle (with Selecting motor) 1720 gram

In one embodiment, in order to achieve frame design optimisation and structural optimisation, the drone, of this invention, was designed with a lightweight frame (589 gm) optimized to house electronics within a closed enclosure. The initial frame size of 450 mm was calculated using propeller dimensions, with iterations tested in ANSYS for structural integrity and deformation, focusing on material and section choices to enhance strength and reduce weight. Fig. 12a illustrates a first method of calculation,
Fig. 12b illustrates a second method of calculation where distance between two adjacent propellers should be 1/4th diameter of propeller to avoid aerodynamic interference.
For initial design, frame size considered is 450 mm, which can be optimised further after first interaction,
Hover condition 50% throttle thrust generated: 430 gm
Hover total thrust generated: 430*4 = 1720 gm
All electronic component and payload total weight = 970 gm
Target frame weight = 1720 – 970 = 750 gm
TARGET: Designing very light weight frame not more than 750 gm and accommodating all electronics component inside frame enclosure.
Fig.13a illustrate simulated results of the arm (110) deformation and stress distributions, validating the material and section choice. Different arm designs were tested, with deformation and stress results provided in a table, proving the selected arm's suitability.
Fig.13b illustrate a table as to how, and why, the current invention’s arm design was chosen:
For initial trials 5th iteration arm (110) is selected based of following consideration:
• 1st solid arm is not considered because of higher weight.
• 2nd T section arm gives strength and less deflection but no proper place for motor wire harnessing and no smooth surface curves for aerodynamic and aesthetic aspects
• 3rd I section and 4th reduced I sec arm not selected for first trial due to same constrained as mentioned above but can be modified and will be useful for further updated version of drone.
• 5th arm having smooth uniform surfaces, good aesthetic look and place to hide motor wire approach to power distribution board inside center hub (108).
In one embodiment, the landing gears (114) has been designed to absorb impact from a 2-meter height with a weight of 2 kg. Explicit dynamic analysis was conducted to determine deformation and stress on impact, achieving a design with deformation limited to 2.7 mm, enhancing durability.
Fig 14 illustrates the simulation data verified that the landing gear’s deformation under crash conditions remained within allowable limits, confirming durability and impact resistance. Landing gears (114) was analysed for fall of drone from 2m height with drone weight of 2000 gm shared by four landing gears.
Loading conditions were as follows:
- Weight of force on top of face of landing gear was 500 gm i.e. 5N
- Free fall velocity from 2m height was 6m/s
- Fall of drone was on rigid surface
- Fixed support was providing at bolting joint with drone body
- Material was PLA
In one embodiment, it is achieved through engineering design and Finite Element simulations. Optimization is done by ANSYS topology optimization module. Also during manufacturing process (3D printing), process parameters were optimized to provide flexibility in landing gears (114) without affecting strength. It is designed for impact loading (free fall from two meters’ height).
The interpretation of results are:
• Equivalent Stress: The Von Mises stress, calculated as approximately 0.08 MPa, indicates that the material is subjected to relatively low stress under the specified impact conditions. This stress level is significantly below the yield strength of polylactic acid (PLA), typically around 50 MPa. Accordingly, the analysis confirms that the landing gears (114) is capable of withstanding the applied loading conditions without exceeding the material's yield point, thereby maintaining structural reliability
• Total Deformation: The observed deformation of approximately 2.7 mm represents the displacement of the landing gears (114) under the applied load. While this deformation is measurable, it remains within the acceptable operational range for polylactic acid (PLA). PLA is characterized by moderate flexibility, enabling it to withstand typical loading conditions without a significant risk of structural failure.
In one embodiment, this innovative configuration not only imparts flexibility to the shape, making the landing gears (114) capable of bearing loads during landing but also maintains a lightweight structure. The modular nature of this design allows for easy interchangeability, thereby offering a convenient solution for maintenance and replacement. Additionally, it serves as a protective feature, safeguarding the camera and center hub assembly from contacting to the ground.

Fig. 15a and Fig 15b illustrates various stress profiles there were observed in loading condition above.
After assembly, the flight test data validated thrust calculations and frame weight efficiency, showing stable and efficient flight performance at the designed thrust-to-weight ratio.
While fundamental aerodynamics principles apply, the specific design here uses rounded, tapered arms combined with strategically placed horizontal slots to balance drag reduction and structural integrity. The enclosed, streamlined frame reduces exposed components, further reducing drag while protecting internal components. This inventive arrangement within a lightweight frame helps it perform better than prior art drones.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher / lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
While considerable emphasis has been placed herein on the specific features of the preferred embodiment, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiment without departing from the principles of the disclosure. These and other changes in the preferred embodiment of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.
,CLAIMS:WE CLAIM,
1. A quadcopter drone assembly (100) comprising:
- a frame structure (102) consisting of a cover (104), a middle plate (106), a center hub (108), arms (110), a bottom plate (112), landing gears (114),
o said cover (104), said middle plate (106), said center hub (108), and said bottom plate (112) being collinearly aligned,
o said arms (110) extending, transversely, out of external circumference of said center hub (108), each of said arms configured to host a propeller (132) at its distal free end,
o said landing gears (114) extending from an operative bottom of said center hub (108) in order to provide support to said quadcopter drone assembly (100), and
o said bottom plate (112) and said middle plate (106) being placed inside said center hub (108) which accommodates said battery (126), said flight controller (116), said electronic speed controller (ESC) (120), said power distribution board, said communication RF antenna (124), and said camera antenna (130),
- a flight controller (116), motor/s (118), electronic speed controller/s (120), a power distribution board, a GPS (122), a communication RF antenna (124), a battery (126), and a camera antenna (130),
characterised, in that,
- said arms (110) being hollow tapered arms (310) configured to allow air to pass through its hollow structure, thereby reducing drag by minimizing solid surface area exposed to airflow;
- said arms (110) including a tapered horizontal slot (304) within each arm (110) configured to refine airflow over the arm surface, thereby reducing turbulence;
- said arms being designed for cantilever loading;
- said landing gear (114) having a curved profile (704) configured to provide flexibility and absorb shocks;
- said quadcopter having a thrust-to-weight ratio of 2 for adequate lift; and
- distance between two adjacent propellers being 1/4th diameter of propeller to avoid aerodynamic interference.

2. The quadcopter drone assembly (100) as claimed in claim 1 wherein, said arms (110) being selectable in terms of geometric cross-sections from a group of cross-sections consisting of T-section geometric cross-section, I-section geometric cross-section.

3. The quadcopter drone assembly (100) as claimed in claim 1 wherein, said center hub (108) having an octagonal shape with eight sides of which,
- four sides are adapted to fix said arm(s) (110),
- two sides are adapted to place a battery (126), and
- two sides are adapted to host electronic items cooling air vents (210).

4. The quadcopter drone assembly (100) as claimed in claim 1 wherein, said bottom plate (112) and said middle plate (106) are placed inside said center hub (108) which accommodates said battery (126), said flight controller (116), a speed controller (ESC) (120), a power distribution board, said communication RF antenna (124), and said camera antenna (130).

5. The quadcopter drone assembly (100) as claimed in claim 1 wherein, said center hub (108) consisting, essentially, of:
- a plurality of plate fixing flat rest (202), protruding as stubs from an internal circumference of said center hub (108),
- a plurality of motor wire connection hole (204) on the frame of said center hub (108) formed through a frame of said center hub (108),
- a plurality of battery insertion spaces (206) formed through the frame of said center hub (108),
- a plurality of arm mounting raised base (208) formed as external supports on an external circumference of said center hub (108),
- a plurality of electronics item cooling air vents (210) formed as through slots through the frame of said center hub (108),
- a plurality of landing gear fixing holes (212) formed as through holes through the frame of said center hub (108), and
- a plurality of arm fixing threaded insert holes (214) formed as through holes through said arm mounting raised base (208),
characterised, in that,
o said flat plate fixing rest (202) being provided to fix said middle plate (106) and said bottom plate (112), in that, four flat plate fixing rests (202) being provided at 1/4th of height of center hub (108) from its operative top face and four flat plate fixing rests (202) being provided at an operative bottom face of center hub (108);
o said battery insertion space (206) is half of the center hub (108) height and starts from said operative bottom face of said center hub (108), spaced apart from said bottom face, on two opposite faces of said center hub (108);
o said motor wire connection hole (204) being at a centre of said arm mounting raise base (208), at 1/4th height of said center hub (108) from its operative top face, said arm (110) aligning with hole, on arm fixing flat base and holes (302);
o said cooling air vents (210) being located at alternative faces of said center hub (108) at 1/4th height of said center hub (108) from its operative bottom face, said cooling air vents (210) aligning with surface of said speed controller (ESC) (120) and with said battery (126);
o said landing gear fixing holes (212) being located at alternative faces of said center hub (108) at 1/4th height of said center hub (108) from its operative bottom face and being located horizontally at centre of respective face of said center hub (108);
o a centre of pitch circle diameter (PCD) of said arm fixing threaded insert holes (214) being aligned with centre of motor wire connection hole (204); and
o said arm mounting raised base (208) being located at alternative faces of said center hub (108), having thickness equal to center hub thickness.

6. The quadcopter drone assembly (100) as claimed in claim 1 wherein, said center hub (108) including a plurality of electronic items cooling air vents (210), each of the plurality of electronic items cooling air vents (210) configured to provide cooling to electronics and battery (126).

7. The quadcopter drone assembly (100) as claimed in claim 1 wherein, said center hub (108) being equipped with a plurality of plate fixing flat rests (202), protruding as stubs from an internal circumference of said center hub (108), said plate fixing flat rests (202) being designed to secure said middle plate (106) and said bottom plate (112) to said center hub (108).

8. The quadcopter drone assembly (100) as claimed in claim 1 wherein, said center hub (108) being equipped with a plurality of motor wire routing holes (204), specifically designed to facilitate the connection of motor wires.

9. The quadcopter drone assembly (100) as claimed in claim 1 wherein,
- said bottom plate (112) and said middle plate (106) being positioned inside said center hub (108), and
- said battery (126), said flight controller (116), said electronic speed controller (ESC) (120), said power distribution board, said communication RF antenna (124), and said camera antenna (130) being fixed on said bottom plate (112) and said middle plate (106).

10. The quadcopter drone assembly (100) as claimed in claim 1 wherein, said arm (110) includes arm fixing flat base and holes (302), the wire routing slot and hole (304), a plurality of motor mount holes (306), a plurality of motor wire passage holes (308) and the tapered section (310), wires passing through said motor wire connection hole (204) on said center hub (108).

11. The quadcopter drone assembly (100) as claimed in claim 1 wherein, said bottom plate (112) includes battery placement flat surface (402), ESC placement slots (404), air vents (406), fastening holes (408), and camera mount hole (410),
in that,
- said bottom plate (112) being secured to an operative lower surface of said center hub (108) at a plurality of plate fixing flat rest (202) through fastening holes (408), and
- said battery (116) slides onto a battery placement flat surface (402) of said bottom plate (112), guided through a square slot (battery insertion space (206)) within said center hub (108), and is secured with a belt (not shown).

12. The quadcopter drone assembly (100) as claimed in claim 1 wherein, a plurality of ESC placement slots (404) are provided to press-fit said electronic speed controllers (ESC) (120) vertically on said bottom plate (112) in order to facilitate easy routing of motor and signal wires to said power distribution board and said flight controller located on an operative top surface of said middle plate (106) within said center hub (108).

13. The quadcopter drone assembly (100) as claimed in claim 1 wherein, said middle plate (106) includes a plurality of avionics wire connection slots (502), a top surface (504), a plurality of wire access cutouts (506), a plurality of extrusions (508) and air vents (510),
in that,
- said operative top surface (504) of said middle plate (106) being designed to mount said flight controller (116) with an anti-vibration pad (not shown) at its center,
- said top surface accommodates various electronic components, including a communication RF antenna (124) for telemetry data, a transmitter-receiver module (not shown), a video camera transmitter antenna (130), and a buzzer (not shown), and
- an operative bottom side of said middle plate (106) being equipped with a plurality of extrusions (508) designed for securing said power distribution board.

14. The quadcopter drone assembly (100) as claimed in claim 1 wherein, said cover (104) includes GPS wire connection slots (602), GPS mounting cavity (604), communication antenna slots (606) and cover clamping raise (608),
in that,
- said cover (104) configured to host a GPS mounting cavity (604) for mounting the GPS (122),
- said cover (104) includes a plurality of communication antenna slots (606), which allow the antennas to extend outward for effective communication, and
- said the cover (104) being equipped with a cover clamping raise (608) designed to securely attach said cover (104) to said center hub (108).

15. The quadcopter drone assembly (100) as claimed in claim 1 wherein, said landing gear (114) including a flat surface with holes (702), reduced cross-sectioned curved profile (704), extended flat leg surface (706), and a flexi-Damp Slot (708).

Dated this 27th day of December, 2024

CHIRAG TANNA
of NOVO IP
Patent Agent for the Applicant
Registration No. IN/PA 1785