When you choose a motor for a fixed-wing UAV, maximum power and maximum thrust are not the only factors you should consider.
A suitable propulsion system needs to balance thrust-to-weight ratio, propeller matching, motor efficiency, and cruise performance. The right combination can give your UAV enough power for takeoff and climbing while also improving flight endurance.
The first step is to understand how much thrust your UAV actually needs.
Consider:
UAV weight
Payload weight
Battery weight
Takeoff requirements
Climbing requirements
Expected wind conditions
You should calculate the required thrust based on the total aircraft weight and application requirements. It is also important to leave a reasonable thrust margin.
Why?
Your UAV may need additional power during:
Takeoff
Climbing
Turning
Flying against wind
Carrying a heavier payload
If the motor only provides enough thrust under ideal conditions, the aircraft may have limited performance in real operation.
However, choosing an unnecessarily large motor is not always better. A larger motor can increase system weight and power consumption. This is why you should select the motor based on the complete propulsion system rather than maximum thrust alone.
The motor and propeller should be treated as one system.
Important parameters include:
Motor KV
Battery voltage
Motor operating speed
Propeller diameter
Propeller pitch
Aircraft weight
Target flight speed
Motor speed is affected by both KV and battery voltage. You should select a propeller that allows the motor to operate in an efficient working range.
A larger propeller is not automatically better.
If the propeller is too large for the motor, the motor may draw excessive current and generate unnecessary heat. If the propeller is too small, the propulsion system may not produce enough thrust efficiently.
Therefore, instead of simply choosing the largest propeller or the highest motor speed, you should match the motor KV, battery voltage, propeller size, and aircraft requirements.
A fixed-wing UAV usually spends much more time cruising than taking off.
This means cruise efficiency can be more important than peak thrust for many applications.
During cruise flight, you need to consider the efficiency of the complete system:
Motor efficiency + propeller efficiency + aircraft weight + aerodynamic drag
A motor with very high peak power may provide strong takeoff performance, but if it operates inefficiently during normal cruise, it can increase battery consumption and reduce flight endurance.
For long-duration UAV applications, you should therefore focus on the motor's operating efficiency at the aircraft's normal cruise point.
The goal is not simply to produce more power. The goal is to produce the required power with as little energy loss as possible.
For a fixed-wing UAV, there is no single motor parameter that determines whether a motor is suitable.
You should evaluate the complete operating condition:
| Requirement | What you should consider |
|---|---|
| Takeoff | Required thrust and thrust margin |
| Climbing | Continuous power and motor temperature |
| Cruise | Motor and propeller efficiency |
| Payload | Additional aircraft weight |
| Battery | Voltage, capacity and discharge capability |
| Propeller | Diameter, pitch and operating speed |
| Installation | Motor size, shaft and mounting requirements |
| Endurance | Energy consumption during normal flight |
This approach helps you avoid selecting a motor simply because it has a higher rated power or maximum thrust.
Different fixed-wing UAVs have different requirements.
For example, a small UAV with a light payload may prioritize low weight and efficient cruise operation. A larger UAV carrying more equipment may need higher torque and greater takeoff thrust.
For this reason, the motor should be selected according to your actual aircraft design, including:
Total weight
Payload
Wing design
Target flight speed
Propeller
Battery platform
Required endurance
Takeoff and climbing requirements
A customized motor solution can help you balance these factors instead of choosing a standard motor based only on its rated power.
BG Motor provides customized brushless DC motor solutions and has experience in motor R&D and production. The company has a 12,000 m² production facility and automated production lines. Its R&D team includes power, structural, and mechanical engineers, with experience in customized motor design.
For fixed-wing UAV applications, BG Motor can evaluate motor selection based on your UAV weight, payload, wing configuration, propeller, battery voltage, target speed, and operating requirements.
For applications using fixed-wing external-rotor motors, models such as 4120, 4125, 5230, and 5330 can be considered according to the specific propulsion requirements.
The objective is to find a suitable balance between:
Takeoff thrust + climbing performance + cruise efficiency + flight endurance
BG Motor also provides customized motor dimensions, shafts, mounting holes, installation methods, and other motor parameters according to application requirements. Its brushless DC motor customization range includes 5 W–20 kW power, DC 6 V–310 V voltage, and rated speeds from 20 to 100,000 RPM.
Choosing a motor for a fixed-wing UAV is not simply about choosing the motor with the highest power or thrust.
You should start with the thrust-to-weight ratio, then match the motor, battery, and propeller, and finally evaluate cruise efficiency and energy consumption.
If you are developing a fixed-wing UAV and need help matching the motor to your aircraft, BG Motor can work with your technical requirements and provide a customized motor solution based on your application.
what's app
