Language
Views: 267 Author: Yuhang Power Publish Time: 2026-09-27 Origin: Site
Content Menu
● What 3115 and 3508 Motor Sizes Mean
● Which Motor Produces More Thrust?
>> Peak Thrust: Usually the 3115 Advantage
>> Endurance Thrust: Often the 3508 Advantage
● Heavy Lift UAV Selection: Start With the Mission
● KV, Voltage, Propeller, and ESC: The Real System Equation
● Thermal Management: The Metric Many Buyers Miss
● The Overlooked Sourcing Risk: Same Size, Different Motor
● How to Test 3115 and 3508 Motors Fairly
>> Recommended Evaluation Process
● FAQ
>> 1. Is a 3115 motor stronger than a 3508 motor?
>> 2. Which motor is better for a 10-inch heavy lift FPV drone?
>> 3. Which motor is better for a 15-inch aerial photography UAV?
>> 4. Can I use the same ESC for a 3115 and a 3508 motor?
>> 5. How much thrust margin should a heavy lift UAV have?
For a heavy lift UAV, the choice between a 3115 drone motor and a 3508 drone motor is not decided by stator diameter alone. A 3115 motor typically prioritizes higher torque density and burst power for 9–10-inch FPV, long-range, and compact heavy-payload builds, while a 3508 motor often prioritizes larger, slower propellers, lower current draw, efficiency, and predictable endurance for aerial photography, VTOL, and mission-focused UAV platforms.
In practical terms, a 3115 drone motor can produce substantially higher peak thrust in aggressive 6S or 8S configurations. A 3508 drone motor can be the more suitable heavy lift UAV motor when the project needs efficient low-KV operation, larger propeller compatibility, longer flight time, lower vibration, and conservative thermal loading.
At Zhongshan Yuhang Power Technology Co., Ltd., we work with FPV drone motors, UAV propulsion motors, RC motors, gimbal motors, aircraft motors, underwater robot motors, high-speed fan motors, and other customized brushless motor systems. From our perspective as a brushless motor manufacturer, the correct comparison is not "Which motor is bigger?" It is:
Which motor, propeller, battery, ESC, and airframe combination delivers the required payload margin, flight time, thermal stability, and production consistency?
The motor-number format describes approximate stator dimensions:
- 3115 drone motor: approximately 31 mm stator diameter × 15 mm stator height.
- 3508 drone motor: approximately 35 mm stator diameter × 8 mm stator height.
The 3115 has a smaller diameter but almost twice the stator height. The 3508 has a wider stator but a shorter stack.
Using a simplified stator-volume index:
Stator Volume Index∝D2×H
- 3115: 312×15=14,415
- 3508: 352×8=9,800
By nominal geometry, the 3115 stator-volume index is about 47% larger than the 3508. This usually gives the 3115 platform more potential for copper volume, torque, burst power, and high-current operation.
However, this does not prove that every 3115 motor produces more thrust than every 3508 motor. KV, winding design, propeller size, voltage, rotor design, magnets, air gap, ESC settings, and thermal limits can completely change the outcome.
| Factor | 3115 Drone Motor | 3508 Drone Motor | Heavy Lift UAV Implication |
|---|---|---|---|
| Nominal stator size | 31 mm × 15 mm | 35 mm × 8 mm | 3115 has a taller stator; 3508 has a wider stator |
| Simplified stator-volume index | 14,415 | 9,800 | 3115 has more nominal electromagnetic volume |
| Typical KV direction | Medium to high KV | Lower KV | 3115 often suits higher RPM; 3508 often suits efficient larger props |
| Typical voltage range | 6S–8S, model dependent | 3S–6S, model dependent | Verify the motor’s actual winding and published limits |
| Typical propeller range | 9–10 inches | 12–15 inches | 3508 commonly supports larger, slower propellers |
| Typical priority | Peak thrust, torque density, compact high-power builds | Endurance, smoothness, lower disk loading | Mission profile determines the better option |
| Motor mass | Often around 105–120 g | Often around 80–105 g | Motor weight affects total aircraft efficiency |
| Heavy lift use | Compact high-power UAVs, long-range FPV, dynamic payload missions | Camera UAVs, VTOL, survey, endurance-focused aircraft | Select according to payload, endurance, and flight style |
A published 3115 example, the Axisflying AE3115 900KV, is specified for 3–6S use, 8–10-inch propellers, 113.5 g motor weight, 1,617 W maximum power, and 4,185 g peak thrust under its stated test conditions. By comparison, a published T-Motor MN3508 Navigator configuration is marketed for multirotor, VTOL, and fixed-wing UAV applications, with up to 1.8 kg thrust and an approximately 1,000-hour MTBF claim.
These figures cannot be compared as a direct winner-and-loser test because they are from different products, KVs, propellers, test conditions, and operating priorities. They do illustrate the essential difference: 3115-class motors can target high burst thrust, while 3508-class motors often target dependable, lower-current propulsion for endurance-oriented UAVs.
The four-digit motor name normally identifies the stator geometry:
- The first two digits refer to approximate stator diameter.
- The final two digits refer to approximate stator height.
Therefore:
- 3115 means approximately 31 mm diameter and 15 mm height.
- 3508 means approximately 35 mm diameter and 8 mm height.
The stator is the laminated electrical-steel core containing copper windings. Its volume and shape influence how the motor manages torque, current, heat, RPM response, and propeller load.
A taller stator, such as the 15 mm stack in a 3115, typically allows more winding copper and can support stronger torque under high electrical loading. A wider stator, such as the 35 mm diameter in a 3508, can provide a larger radius for electromagnetic force and can work well with larger propellers at lower RPM when paired with an appropriate low-KV winding.
Neither architecture is universally superior.
The 3115 layout is generally useful when the design target requires:
- High torque density
- Fast throttle response
- Strong burst current
- High thrust from a compact package
- 9-inch or 10-inch FPV propeller compatibility
- 6S or 8S system potential
- Payload capacity with dynamic maneuvering
A 3115 motor is frequently chosen for long-range FPV, X-class, heavier freestyle, and compact heavy-lift drone configurations. For example, one 3115 800KV product is listed for 6S–8S systems, 9–10-inch propellers, up to 1,724.6 W maximum power, and up to 65.9 A maximum current.
The 3508 layout is typically useful when the design target requires:
- Lower RPM and larger propellers
- Longer flight endurance
- Smooth operation for camera platforms
- Lower vibration
- Lower current draw at cruise
- Conservative motor temperatures
- Reliable flight characteristics for VTOL or fixed-wing UAVs
A published MN3508 KV380 example is designed for 3–6S operation, uses 14–15-inch propellers in its test tables, has a 35 mm stator diameter and 8 mm stator height, and lists 82 g motor weight excluding cable.
This makes the 3508 architecture especially relevant to professional aircraft where the motor is expected to generate steady thrust for an extended period rather than extreme punch-out thrust.
The short answer is: a 3115 drone motor can generate more maximum thrust than a 3508 drone motor in a high-power configuration, but a 3508 may generate more useful endurance-oriented thrust per watt when paired with a larger propeller.
A buyer should separate three different performance questions:
1. Maximum static thrust: How much force can the motor-propeller system produce at full throttle on a test stand?
2. Cruise efficiency: How much thrust does the system provide per watt during normal flight?
3. Sustained payload performance: Can the system carry the required load without overheating, draining the battery too quickly, or creating unstable flight behavior?
The 3115's taller stator can support more copper and current. When matched with a suitable medium- or high-KV winding, strong ESC, high-discharge battery, and 9–10-inch propeller, it can produce high burst thrust.
This is valuable for:
- Heavy FPV drone acceleration.
- Fast climbing with a payload.
- Rapid wind recovery.
- Larger battery packs.
- Dynamic filming.
- Long-range drone safety margin.
- Short-duration high-power applications.
However, high peak thrust normally increases:
- Current draw.
- ESC requirements.
- Battery stress.
- Motor heat.
- Noise.
- Propeller loading.
- Total propulsion-system cost.
A 3115 motor is not automatically more efficient simply because it is larger by stator volume.
The 3508 motor is frequently configured at lower KV and matched with larger propellers. A larger propeller can produce the same thrust at lower RPM, reducing disk loading and improving efficiency during steady flight.
For a camera drone, mapping UAV, inspection platform, or fixed-wing VTOL aircraft, the aircraft may spend most of its time in cruise or hover rather than at full throttle. In these missions, grams of thrust per watt can be more important than a maximum-thrust number.
For example, T-Motor's published MN3508 KV380 table shows a 14.8 V test with a 14 × 4.8 carbon-fiber propeller producing 350 g thrust at 19.24 W, or 18.19 g/W at 50% throttle. With a 15 × 5 propeller at the same voltage and throttle point, it lists 430 g thrust at 23.68 W, or 18.16 g/W.
These figures demonstrate why a low-KV, larger-propeller system can be attractive for sustained UAV operation. It is not designed to chase an extreme burst-thrust result. It is designed to create usable thrust efficiently.
A common purchasing mistake is to select a motor only by the phrase "heavy lift drone motor." That phrase does not define the payload, flight time, airframe, altitude, propeller size, battery, or safety margin.
Before comparing a 3115 vs 3508 drone motor, define the mission.
| Mission Requirement | More Likely Choice | Why |
|---|---|---|
| 9-inch or 10-inch FPV heavy-lift frame | 3115 | Strong torque density and high burst potential |
| 10-inch long-range FPV with higher payload | 3115 | Useful for higher-power 6S or 8S systems |
| Cinematic multirotor with 13–15-inch props | 3508 | Larger propeller compatibility and smoother cruise operation |
| VTOL fixed-wing UAV | 3508 or project-specific alternative | Efficient hover propulsion and reliable continuous operation |
| Survey or mapping drone | 3508 | Flight time, stability, low vibration, and efficiency are key |
| Fast-response payload delivery platform | 3115 | Higher burst power may improve acceleration and climb |
| Large industrial heavy-lift drone | Neither may be sufficient | Larger motors and propulsion systems may be required |
For a true industrial heavy-lift platform carrying multi-kilogram payloads, both the 3115 and 3508 may be too small. Heavy-lift motor selection should be based on a verified thrust-to-weight ratio, not a product category name.
A common calculation for a quadcopter is:
Thrust-to-Weight Ratio=Maximum Thrust Per Motor×4/All-Up Weight
A basic stable-lift threshold is above 1:1, but professional aircraft require margin for wind, maneuvering, battery-voltage sag, emergency handling, and degraded conditions. The exact target depends on flight mission and airworthiness requirements.
Motor KV is the approximate unloaded RPM per volt. It is useful, but it is not a thrust rating.
A 900KV motor theoretically turns faster than a 380KV motor at the same voltage without a propeller attached. Under load, the propeller's aerodynamic resistance changes the RPM, current, torque demand, heat generation, and thrust result.
| System Variable | 3115 Configuration Direction | 3508 Configuration Direction |
|---|---|---|
| KV | Often medium to high | Often low to medium |
| Battery | 6S or 8S is common in high-power setups | 4S or 6S is common for low-KV large-prop configurations |
| Propeller | 9–10 inches, depending on KV | 12–15 inches, depending on KV |
| Current profile | Higher peak current | Lower current at efficient cruise points |
| ESC | Higher burst-current capability | Stable continuous-current capability |
| Flight style | Dynamic, responsive, high-power | Smooth, efficient, endurance-focused |
A motor, ESC, battery, and propeller must be treated as a matched propulsion system. Industry propulsion guidance emphasizes that motor, ESC, and battery voltage must be compatible, while propeller loading must be appropriate to prevent excess current and heat.
Consider two UAV concepts:
UAV A: 10-Inch Long-Range Payload Drone
- 4 motors.
- 6S or 8S battery.
- 9–10-inch propellers.
- Payload: compact camera, communication module, or small sensor payload.
- Need: fast climb, wind resistance, strong acceleration.
A 3115 drone motor may be suitable because the aircraft needs high torque density and burst power in a compact frame.
UAV B: 15-Inch Survey and Inspection Drone
- 4 motors.
- 6S battery.
- 14–15-inch carbon-fiber propellers.
- Payload: stabilized camera, mapping equipment, or inspection sensor.
- Need: steady hover, low vibration, long flight duration, lower noise.
A 3508 low-KV motor may be more suitable because the platform benefits from larger propellers, efficient thrust, and smooth sustained operation.
The two aircraft are both "heavy lift UAVs," but their power-system requirements are fundamentally different.
The most expensive motor failure often happens after the first successful flight.
A prototype may lift the aircraft successfully on a cool day and short test. Then, in real operations, the motor runs hot because of:
- Higher ambient temperature.
- Repeated climbs.
- Heavier payload.
- Lower-quality production propeller.
- Battery voltage sag.
- Incorrect ESC timing.
- Insufficient airflow.
- Poor motor-bell balance.
- Inconsistent winding resistance.
For this reason, ask suppliers for sustained thermal data, not only a maximum-thrust claim.
A proper motor comparison should include:
- Thrust at 25%, 50%, 75%, and 100% throttle.
- Current and wattage at each throttle point.
- RPM.
- Motor temperature after 30 seconds, 60 seconds, 180 seconds, or mission-relevant duration.
- ESC temperature.
- Ambient temperature.
- Propeller model.
- Battery voltage under load.
- Vibration or dynamic-balance result.
The best heavy lift UAV motor is not the one that reaches the highest temperature before failure. It is the one that delivers the needed thrust with a stable thermal margin.
A 3115 motor from one supplier is not identical to a 3115 motor from another supplier. The same is true for 3508 motors.
The external dimensions can look similar while internal construction differs significantly.
Key variables include:
- Electrical-steel lamination grade and thickness.
- Copper-wire purity and insulation class.
- Winding turns and fill factor.
- Magnet grade and temperature rating.
- Rotor-bell material and rigidity.
- Air-gap consistency.
- Bearing brand and tolerance.
- Shaft hardness.
- Adhesive temperature resistance.
- Dynamic balancing process.
- Final inspection standards.
This is the internal procurement rule experienced UAV buyers use:
Approve the exact technical baseline, not only the sample appearance or motor-size code.
A supplier should not change bearings, magnet grade, winding wire, stator laminations, shaft material, or balance process without written approval.
For OEM projects, the approved specification should lock:
| Control Point | Requirement to Define |
|---|---|
| Motor structure | Stator size, rotor dimensions, mounting pattern, shaft diameter |
| Electrical design | KV, phase resistance, winding turns, wire type |
| Magnetic system | Magnet grade, maximum temperature, retention method |
| Mechanical system | Bearing model, shaft material, shaft hardness, runout limit |
| Performance | No-load current, KV tolerance, thrust test setup, efficiency target |
| Thermal validation | Maximum motor temperature at stated load and duration |
| Quality control | Balance standard, inspection frequency, traceability rules |
| Change control | Buyer approval before material or process changes |
At Zhongshan Yuhang Power Technology Co., Ltd., our technical team has more than ten years of brushless-motor manufacturing and design experience. We maintain control from R&D and design through production and testing, with a focus on demand-tailored power solutions rather than a one-size-fits-all configuration.
For OEM and ODM buyers, this approach supports more productive discussions around motor size, winding, KV, voltage, propeller, ESC, cable length, mounting, labeling, packaging, and production planning.
A meaningful test must avoid comparing unrelated conditions.
1. Define the aircraft's all-up weight.
Include airframe, battery, payload, landing gear, camera, radio, wiring, and expected accessories.
2. Set the required thrust reserve.
Define hover thrust, climb thrust, emergency reserve, and wind-handling requirements.
3. Choose suitable propellers for each motor.
Do not force the same propeller onto both motors if the load is outside one motor's intended range.
4. Use compatible battery and ESC systems.
Confirm voltage, continuous current, burst current, firmware, timing, and cooling.
5. Test on a calibrated thrust stand.
Measure thrust, torque, current, voltage, RPM, wattage, efficiency, and temperature.
6. Test multiple production samples.
One excellent prototype does not prove production consistency.
7. Conduct an endurance run.
Use mission-relevant load profiles, not only a 10-second full-throttle test.
Professional test equipment can measure thrust, torque, voltage, current, RPM, and efficiency together. This is the minimum useful data set for comparing heavy lift UAV motors.
For compact, high-power UAVs using 9–10-inch propellers, a 3115 drone motor can provide a strong mix of thrust, torque, and burst performance. For smoother, endurance-focused aircraft using 12–15-inch propellers, a 3508 drone motor may be the better option because it can support efficient, low-KV, larger-propeller operation.
The correct choice depends on the mission. Do not select a motor from a stator-size code alone.
Zhongshan Yuhang Power Technology Co., Ltd. supports customized FPV drone motors, UAV motors, RC motors, aircraft motors, and complete power-system solutions. We can work with OEM and ODM buyers on motor size, KV, propeller matching, ESC selection, mounting configuration, cables, branding, packaging, and sample validation.
A 3115 motor usually has a larger nominal stator-volume index and can be configured for higher torque density and burst power. However, a low-KV 3508 with a larger propeller may provide better endurance-oriented thrust and efficiency. "Stronger" depends on the propeller, KV, voltage, current limit, and mission profile.
A 3115 motor is commonly a strong candidate for a 10-inch heavy lift FPV platform because it can provide high torque and burst thrust in a compact configuration. Confirm the motor KV, 6S or 8S battery, propeller size, ESC current rating, aircraft weight, and required flight time before making a final selection.
A 3508 low-KV motor is often more appropriate for a 15-inch aerial photography platform because it can be paired with larger propellers for smoother and more efficient sustained thrust. The final decision should still be based on payload, all-up weight, desired flight time, and verified test data.
Possibly, but not automatically. The ESC must support the selected battery voltage, continuous current, burst current, motor timing, and cooling requirements. A high-power 3115 configuration may require substantially more burst-current capability than a lower-KV 3508 configuration.
The necessary margin depends on the mission, aircraft type, payload, wind conditions, emergency requirements, and local operating rules. The total available thrust must exceed aircraft weight, but professional UAVs need additional reserve for takeoff, maneuvering, battery-voltage drop, wind, and contingency operation. Calculate the required thrust-to-weight ratio using verified motor-propeller data.
1. [Zhongshan Yuhang Power Technology Co., Ltd. — About Us]
Company background covering brushless motor R&D, manufacturing, testing, power-system solutions, and OEM/ODM services. [yuhangmotor]
2. [Axisflying AE3115 900KV Brushless Motor]
Published 3115 product specifications including input voltage, 8–10-inch propeller range, motor weight, maximum power, and stated peak thrust. [axisflying]
3. [T-Motor MN3508 Navigator Motor]
Published MN3508 specifications, thrust data, efficiency data, propeller tests, cell-count range, dimensions, current limits, and stated MTBF. [store.tmotor]
4. [FT Systems 3115 800KV Brushless Motor]
Published technical information for a 3115 800KV motor, including 6S–8S operation, power, current, resistance, and 9–10-inch propeller suitability. [ft]
5. [T-Motor UAV Propulsion System Motor ESC and Propeller Matching]
Technical guidance on matching motors, ESCs, propellers, and battery voltage in UAV propulsion systems. [shop.tmotor]
6. [Unmanned Systems Technology — How Brushless Motors Work and How to Test Them]
Technical overview of brushless motor operation, KV, and test parameters including thrust, torque, voltage, current, RPM, and efficiency. [unmannedsystemstechnology]
