8- to 10-inch FPV motor
BrotherHobby SE 3115
A 3115 for 6S: 125.2 g with leads, and 3,784 g of pull per motor on a 9-inch tri-blade on BrotherHobby’s bench.
- 8- to 10-inch builds
- 6S
- 9-inch tri-blade props
The spin is an illustration: the model turns at 1/600 of the no-load speed, and it is a generic 3115 motor drawn from BrotherHobby’s published sizes, not its exact design. Thrust, current and power are BrotherHobby’s bench figures for the HQ 9 × 5 × 3 prop at 25.2 V, read straight across between its throttle steps. Its data starts at 30% throttle.
- Max thrust
- 3,784 g
- HQ 9 × 5 × 3 prop, 25.2 V
- Weight
- 125.2 g
- with 300 mm leads
- Peak current
- 64.9 A
- full throttle
- Max power
- 1,597 W
- full throttle
from $25.00a motor at BrotherHobby
A set of four: $100.00
Price seen Oct 19, 2026. Plain links: we earn nothing from them.
What it pulls
BrotherHobby’s own bench test, one line per prop. Drag across the chart to move the throttle; the model above follows.
At 60% with the HQ 9 × 5 × 3: 1,987 g of thrust, 23.9 A, 600 W, 3.31 g per watt.
On your quad
23.3 : 1
Thrust to weight at full throttle: four motors pull 15,136 g with the HQ 9 × 5 × 3 at 25.2 V.
At 60% throttle they pull 7,948 g, 12.2 times the quad’s weight.
All-up weight is the quad ready to fly, with its battery and camera. The thrust is the maker’s static bench figure; in the air it is lower.
What you get for $25.00
3.8 kg on a 9-inch prop
On BrotherHobby’s 6S bench the 900KV pulled 3,784 g at full throttle on an HQ 9 × 5 × 3, drawing 64.9 A.
Source: BrotherHobby test report, BrotherHobby thrust summary
Hard-anodised 7075
Bell cap and base in 7075 aluminium with a hard-anodised finish, on a SUS420 heat-treated steel shaft.
Source: BrotherHobby product page, BrotherHobby infographic and drawing
Balanced to 3 mg
The test report gives a dynamic-balance standard of 3 mg or less, insulation resistance of 0.5 MΩ or more and a passed coil test.
Source: BrotherHobby test report
What to pair it with
Our reading of BrotherHobby’s numbers, so your build matches what the motor was tested with.
- ESC
- BrotherHobby lists a 6S 65 A ESC; the full-throttle peak was 64.9 A. (BrotherHobby test report, BrotherHobby thrust summary)
- Props
- BrotherHobby pairs it with 9-inch props and tested it on an HQ 9 × 5 × 3: 3,784 g at full throttle. (BrotherHobby prop image, BrotherHobby test report)
- Battery
- 6S. (BrotherHobby product page, BrotherHobby test report)
- Frame
- Four M3 holes on a 19 mm circle (19 × 19 mm); four M3 × 8 screws and an M5 flange nut come in the box. (BrotherHobby product page, BrotherHobby infographic and drawing, BrotherHobby packing list)
Where to buy
- BrotherHobbythe maker’s store$25.00seen Oct 19, 2026Visit
Plain links, not affiliate links. Prices change; the store’s page has the current one.
Full specs
Bench data
Redrawn from BrotherHobby’s test reports. Thrust is static pull on a bench, more than you get in flight. Power is volts × amps; efficiency is thrust divided by power.
900KV on 6S, 25.2 V1 prop
| Prop | Throttle | Voltage (V) | Current (A) | RPM | Thrust (g) | Power (W) | Efficiency (g/W) |
|---|---|---|---|---|---|---|---|
| HQ 9 × 5 × 3 (9-inch, three blades)motor at 81 °C | 30% | 25.2 | 1.8 | 4616 | 265 | 45.36 | 5.84 |
| 40% | 25.2 | 7.5 | 7781 | 835 | 189 | 4.42 | |
| 50% | 25.2 | 13.2 | 9697 | 1,321 | 332.64 | 3.97 | |
| 60% | 25.1 | 23.9 | 11748 | 1,987 | 599.89 | 3.31 | |
| 70% | 25 | 40.5 | 13645 | 2,838 | 1012.5 | 2.8 | |
| 80% | 24.8 | 52 | 14632 | 3,249 | 1289.6 | 2.52 | |
| 90% | 24.8 | 61.7 | 15412 | 3,656 | 1530.16 | 2.39 | |
| 100% | 24.6 | 64.9 | 15569 | 3,784 | 1596.54 | 2.37 |
Source: BrotherHobby test report
Inside the motor
A brushless outrunner: the coils stand still in the middle and the magnets spin around them. From the top down:
- Bell. 7075 aluminium bell cap, φ37.5 mm, hard anodised, with five spokes. (BrotherHobby product page, BrotherHobby infographic and drawing)
- Shaft. SUS420 heat-treated steel with an M5 thread, standing 16 mm above the bell. (BrotherHobby product page, BrotherHobby infographic and drawing)
- Magnets. N52H arc magnets, 14 poles. (BrotherHobby product page, BrotherHobby infographic and drawing)
- Stator. 31 × 15 mm with 12 slots, in 0.2 mm Nippon Steel silicon steel, wound with TU1-grade enamelled wire. (BrotherHobby product page, BrotherHobby infographic and drawing, BrotherHobby test report)
- Bearings. NMB, 12 × 6 × 4 mm. (BrotherHobby product page)
- Base. 7075 aluminium, with four M3 holes on a 19 mm circle and 16 AWG leads 300 mm long. (BrotherHobby product page, BrotherHobby infographic and drawing)
How fast it spins
KV is the motor’s no-load speed per volt. With nothing on the shaft, the 900KV version reaches about these speeds; a prop loads the motor and brings it down, typically to around 70–75% of these figures at full throttle.
| Battery | Volts | No-load rpm (KV × V) | Electrical frequency | ESC steps per second |
|---|---|---|---|---|
| 4S nominal | 14.8 | 13,320 | 1,554 Hz | 9,324 |
| 4S full | 16.8 | 15,120 | 1,764 Hz | 10,584 |
| 6S nominal | 22.2 | 19,980 | 2,331 Hz | 13,986 |
| 6S full | 25.2 | 22,680 | 2,646 Hz | 15,876 |
A 14-pole rotor has 7 pole pairs, so every turn of the shaft is 7 electrical cycles, and a six-step ESC switches the phases 42 times per turn.
About the 3D model
A generic outrunner drawn from BrotherHobby’s published sizes: the 31 × 15 mm stator, 37.5 mm bell, 30.75 mm height, 5 mm shaft, 19 mm mounting circle and 12 teeth and 14 magnets. Anything BrotherHobby doesn’t publish is typical for a motor this size, and the bell’s spoked top, the base and the inside are a generic design, not this motor’s. The colours are read off the maker’s product photos. There are no logos or markings: it is our drawing, not the maker’s.
Sources
- BrotherHobby: SE 3115 900KV Motor (CW) (product page on BrotherHobby’s store, with its spec list, photos and Test Data tab). Retrieved Oct 19, 2026.
- BrotherHobby: SE 3115 weight, maximum thrust and full-throttle summary, with the ESC (image on the product page). Retrieved Oct 19, 2026.
- BrotherHobby: SE 3115 “paired with 9 inch prop” (image on the product page). Retrieved Oct 19, 2026.
- BrotherHobby: SE 3115 exploded view (shaft, caps, magnets, bearings, wire, stator steel) and dimension drawing (image on the product page). Retrieved Oct 19, 2026.
- BrotherHobby: SE 3115 packing list (image on the product page). Retrieved Oct 19, 2026.
- BrotherHobby: SE 3115-900KV test report on 6S with an HQ 9 × 5 × 3, 2022 bench, with drawing and spec table (image on the Test Data tab). The copper temperature is after two minutes at full throttle.. Retrieved Oct 19, 2026.
