Tiny whoop motor (2S–3S)
HappyModel EX1102
A 2.8 g motor for 2S–3S whoops of 75–85 mm: an 11 × 2 mm stator on two bearings, made for 40–66 mm props, and the original motor of HappyModel's Mobula7 HD.
- 2S–3S whoops, 75–85 mm
- 66 mm ductless frames
- Mobula7 HD (9000KV) and Sailfly-X (8500KV)
The spin is an illustration: the model turns at 1/600 of the no-load speed, and it is a generic 1102 motor drawn from HappyModel’s published sizes, not its exact design. No-load speed is KV × 11.1 V, a nominal pack for this version. HappyModel publishes no bench data for it.
- Weight
- 2.8 g
Plain links: we earn nothing from them.
What you get
Mobula7 HD motor
HappyModel fits the 9000KV, with a 1 mm shaft, to its Mobula7 HD, and the 8500KV, with a 1.5 mm shaft, to the Sailfly-X.
Source: HappyModel product page
2.8 g
HappyModel lists 2.8 g per motor.
Source: HappyModel product page
Two bearings
A dual-bearing design, which HappyModel says keeps it better balanced.
Source: HappyModel product page
Props and frames
Rated for 40–66 mm props on 2S–3S whoops of 75–85 mm and on 66 mm ductless frames.
Source: HappyModel product page
What to pair it with
Our reading of HappyModel’s numbers, so your build matches what the motor was tested with.
- Props
- 40–66 mm props, per HappyModel. (HappyModel product page)
- Battery
- 2S–3S LiPo. (HappyModel product page)
- Frame
- Three M1.4 screws on a 6.6 mm circle; HappyModel names 75–85 mm whoops and 66 mm ductless frames. (HappyModel product page, HappyModel drawing)
Where to buy
- RaceDayQuads9000KV, 4-pack (listed with a 1.5 mm shaft)price on the store’s pageVisit
- RaceDayQuads13500KV, 4-pack (listed with a 1.5 mm shaft)price on the store’s pageVisit
Plain links, not affiliate links. Prices change; the store’s page has the current one.
Full specs
| Spec | Value | Source |
|---|---|---|
| KV | 9,000 rpm/V (also 8500KV, 10000KV and 13500KV) | HappyModel product page |
| Stator | 11 × 2 mm (1102) | HappyModel product page |
| Configuration | 9N12P (9 stator slots, 12 magnet poles) | HappyModel product page |
| Battery | 2S–3S LiPo | HappyModel product page |
| Weight | 2.8 g | HappyModel product page |
| Dimensions | φ13.5 × 16 mm (with shaft); 9 mm from the base to the top of the bell | HappyModel drawing |
| Shaft | 1 mm (9000KV, for the Mobula7 HD) or 1.5 mm (8500KV, for the Sailfly-X) (the drawing shows the 1 mm shaft protruding 5.8 mm above the bell) | HappyModel product page |
| Mounting | 3 × M1.4 holes on a 6.6 mm circle | HappyModel drawing |
| Bearings | 2 (dual-bearing design) | HappyModel product page |
| Leads | 3 leads, 32 ± 2 mm, with a 3-pin plug | HappyModel drawing |
Inside the motor
A brushless outrunner: the coils stand still in the middle and the magnets spin around them. From the top down:
- Shaft. 1 mm (9000KV, for the Mobula7 HD) or 1.5 mm (8500KV, for the Sailfly-X) (the drawing shows the 1 mm shaft protruding 5.8 mm above the bell). (HappyModel product page)
- Stator. The coils are wound on a stack of thin steel laminations: 11 × 2 mm (1102). (HappyModel product page)
- Bearings. 2 (dual-bearing design). (HappyModel product page)
- Base. 3 × M1.4 holes on a 6.6 mm circle. (HappyModel drawing)
How fast it spins
KV is the motor’s no-load speed per volt. With nothing on the shaft, the 9000KV 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 | 133,200 | 13,320 Hz | 79,920 |
| 4S full | 16.8 | 151,200 | 15,120 Hz | 90,720 |
| 6S nominal | 22.2 | 199,800 | 19,980 Hz | 119,880 |
| 6S full | 25.2 | 226,800 | 22,680 Hz | 136,080 |
A 12-pole rotor has 6 pole pairs, so every turn of the shaft is 6 electrical cycles, and a six-step ESC switches the phases 36 times per turn.
About the 3D model
A generic outrunner drawn from HappyModel’s published sizes: the 11 × 2 mm stator, 13.5 mm bell, 9 mm height, 1 mm shaft, 6.6 mm mounting circle and 9 teeth and 12 magnets. Anything HappyModel 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
- HappyModel: EX1102 2-3S brushless motor for Sailfly-X and Mobula7 HD 8500/9000/10000/13500KV (product page, spec list). Retrieved Oct 19, 2026.
- HappyModel: EX1102 dimension drawing (image on the product page, drawn with the 1 mm shaft). Retrieved Oct 19, 2026.
- HappyModel: EX1102 main product photo, used for finish. Retrieved Oct 19, 2026.
