Lightweight 5-inch FPV motor
Hypetrain Bubby 2205
A light 2205 motor made with pilot Bubby FPV: 2004KV, 28 g with leads, rated for 3S–8S, and matched by Hypetrain to the HQ J37 prop.
- 5-inch builds on the HQ J37 prop
- 3S–8S (8S with an 80% motor output limit)
- 16 × 16 mm M3 motor mounts
The spin is an illustration: the model turns at 1/600 of the no-load speed, and it is a generic 2205 motor drawn from Hypetrain’s published sizes, not its exact design. No-load speed is KV × 29.6 V, a nominal pack for this version. Hypetrain publishes no bench data for it.
- Weight
- 28 g
- with leads
from $27.99a motor at Rotor Riot
A set of four: $111.96
Price seen Oct 19, 2026. Plain links: we earn nothing from them.
What you get for $27.99
28 g with leads
A 2205 stator in a φ27.8 mm motor that weighs 28 g with its 150 mm, 20 AWG leads.
Source: Hypetrain product page
Rated for 3S to 8S
Hypetrain rates the 2004KV for 3S–8S; on 8S it says to set Betaflight’s motor output limit to 80%.
Source: Hypetrain product page
Made for the HQ J37
Hypetrain recommends the HQ J37 prop for this motor.
Source: Hypetrain product page
Solder-free version
The same motor is also sold in a solder-free version.
Source: Hypetrain solder-free page
What to pair it with
Our reading of Hypetrain’s numbers, so your build matches what the motor was tested with.
- Props
- Hypetrain pairs the motor with the HQ J37 prop. (Hypetrain product page)
- Battery
- Anything from 3S to 8S; on 8S, set Betaflight’s motor output limit to 80% as Hypetrain advises. (Hypetrain product page)
- Frame
- Four M3 holes on a 16 mm circle (16 × 16 mm) and an M5 prop shaft. (Hypetrain product page)
Where to buy
- Rotor RiotHypetrain’s own store$27.99seen Oct 19, 2026Visit
- Rotor Riotsolder-free version; listed as sold out$28.99seen Oct 19, 2026Visit
Plain links, not affiliate links. Prices change; the store’s page has the current one.
Full specs
| Spec | Value | Source |
|---|---|---|
| KV | 2,004 rpm/V | Hypetrain product page |
| Stator | 22 × 5 mm (2205) | Hypetrain product page |
| Configuration | 12N14P (12 stator slots, 14 magnet poles) | Hypetrain product page |
| Battery | 3S–8S LiPo (on 8S Hypetrain says to set Betaflight’s motor output limit to 80%) | Hypetrain product page |
| Weight | 28 g (with leads) | Hypetrain product page |
| Dimensions | φ27.8 × 30.1 mm (Hypetrain doesn’t say whether the height includes the shaft) | Hypetrain product page |
| Shaft | M5 | Hypetrain product page |
| Mounting | 4 × M3 holes on a 16 mm circle (16 × 16 mm) | Hypetrain product page |
| Internal resistance | 78–81 mΩ | Hypetrain product page |
| Leads | 20 AWG, 150 mm | Hypetrain product page |
Inside the motor
A brushless outrunner: the coils stand still in the middle and the magnets spin around them. From the top down:
- Shaft. M5. (Hypetrain product page)
- Stator. The coils are wound on a stack of thin steel laminations: 22 × 5 mm (2205). (Hypetrain product page)
- Base. 4 × M3 holes on a 16 mm circle (16 × 16 mm). (Hypetrain product page)
How fast it spins
KV is the motor’s no-load speed per volt. With nothing on the shaft, the 2004KV 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 | 29,659 | 3,460 Hz | 20,761 |
| 4S full | 16.8 | 33,667 | 3,928 Hz | 23,567 |
| 6S nominal | 22.2 | 44,489 | 5,190 Hz | 31,142 |
| 6S full | 25.2 | 50,501 | 5,892 Hz | 35,351 |
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 Hypetrain’s published sizes: the 22 × 5 mm stator, 27.8 mm bell, 5 mm shaft, 16 mm mounting circle and 12 teeth and 14 magnets. Anything Hypetrain 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.