BGS-4120PRO 500KV 250KV 560KV High-performance fixed-wing motor

Key Features Worth Noting

• One of the most significant advantages of the 4120 outrunner is its torque density. Because the rotating housing has a larger effective radius compared to an inrunner of similar weight, the motor can generate approximately 30 to 40 percent more torque in real-world conditions. This translates into quicker throttle response for multirotors and better climb performance for fixed-wing UAVs.

• Heat dissipation is another area where the 4120 outrunner excels, thanks in large part to its rotating outer shell which acts like an integrated fan blade. As the motor spins at higher RPMs, airflow is continuously drawn across the stator and windings, pulling heat away from the copper windings and magnets. This passive cooling effect allows the motor to sustain heavy loads for extended periods, and when paired with 180°C-rated copper wire and 150°C neodymium magnets, the 4120 can handle demanding agricultural or industrial missions without thermal shutdown.

• Precision dynamic balancing is performed on every rotor before it leaves the factory, with an industry-leading target of 5mg or less. This level of balance is critical for applications where vibration can compromise performance, such as fixed-wing mapping UAVs carrying expensive LiDAR or photogrammetry cameras, or heavy-lift cinematography drones where smooth footage is non-negotiable.

Manufacturing Craftsmanship

The stator of the 4120 motor is built from high-grade silicon steel laminations, each coated with a 180°C-resistant insulation layer to minimize eddy current losses. These laminations are stacked under pressure and then secured to create a rigid magnetic core that maintains its shape even under high thermal stress.

Winding the copper coils is a process that can be executed either by precision CNC machines or by skilled technicians using hand-winding techniques, depending on the customer's requirements for copper fill ratio and specific KV values. Hand-wound versions typically achieve a slightly higher slot fill ratio, which reduces internal resistance and improves overall efficiency by a measurable margin.

The magnet system deserves special attention because it directly influences torque output and efficiency. Our 4120 motors use sintered neodymium arc magnets, which are magnetized and then precisely positioned within the rotor housing using advanced magnetic flux simulation software. This approach ensures that the magnetic field interacting with the stator windings is as uniform as possible, resulting in approximately 5 percent higher efficiency compared to motors that use less optimized magnet layouts.

All aluminum components — including the motor housing, stator mount, and shaft sleeve — are machined on precision CNC lathes in a single clamping operation. This single-step machining process guarantees that the concentricity between the stator and rotor remains within 0.02mm, which translates directly into a uniform air gap and smooth, quiet operation across the entire RPM range.

Before any 4120 motor is approved for shipment, it goes through a 100 percent inspection process that includes a high-voltage insulation test at 500V AC, a no-load current measurement to verify winding integrity, and a thrust validation on randomly sampled units to ensure performance matches the published specifications.

Customization Options 

Because we operate our own manufacturing facility with over thirty years of experience in the electric motor industry, we offer a level of customization that resellers and white-label brands rarely provide. The KV value can be adjusted to match your specific voltage and propeller combination, the shaft diameter can be modified from the standard 6mm to other dimensions upon request, and the shaft length can be extended or shortened depending on your mounting requirements. Connector types, wire gauge, and wire length are also fully customizable, allowing you to integrate the 4120 motor into your drone design without unnecessary adapter cables or soldering work.