| 22KG·CM STALL | 0.10S/60° NO-LOAD | 8.4V RATED |
| 36.5G WEIGHT | StainlessGEARTRAIN | 360°TRAVELCustomizable |
Overview
The S2221F is the rotated-tab build of the 22 kg·cm slim servo: 36.5 g, a 12 mm case, 0.10 s/60° at 8.4 V, with the mounting tabs turned 90° relative to the S2221D. Electrically the two are the same servo, and the geartrain, spline and lead are identical.
The only dimensional change is height — 35.5 mm here against 35 mm on the D — and it comes from the tab geometry rather than the case. If your bay was cut for a D, check that half millimetre before assuming an F will drop straight in.
Performance at each supply voltage
| Supply | No-load speed | Peak stall torque | Idle current | Stall current |
|---|---|---|---|---|
| 6.0 V | 0.14 s/60° (429 °/s) | 15 kg·cm (1.47 N·m / 208 oz·in) | 190 mA | 3.5 A |
| 7.4 V | 0.12 s/60° (500 °/s) | 18 kg·cm (1.77 N·m / 250 oz·in) | 220 mA | 4 A |
| 8.4 V | 0.10 s/60° (600 °/s) | 22 kg·cm (2.16 N·m / 306 oz·in) | 250 mA | 5 A |
Control specification
| Item | Specification |
|---|---|
| Command signal | PWM |
| Amplifier | Digital controller |
| Pulse width range | 700–2300 µs |
| Neutral position | 1500 µs |
| Dead band | 2 µs |
| Rotating direction | CCW (1000–2000 µs) |
| Travel | 360°, customizable |
Mechanical specification
| Item | Specification | Item | Specification |
|---|---|---|---|
| Dimensions | 12 × 30 × 35.5 mm | Case material | CNC aluminium |
| Weight | 36.5 g | Geartrain | Stainless steel |
| Bearings | 2 × ball bearing | Motor | Coreless |
| Output spline | 25T / 4.96 mm | Horn in box | POM plastic |
| Lead | 300 mm 3P | Travel limit | 360°, customizable |
| Operating temperature | −15 °C to 65 °C | Storage temperature | −20 °C to 70 °C |
| Ingress protection | Splash resistant (customizable) |
What’s in the box
- 1 × XQ-S2221F servo
- 1 × POM horn set
- 1 × mounting screw pack
Optional: metal horn, sold separately.
How to size it
Torque budget = load at the horn × horn length from spline centre × 1.5 safety factor.
Worked example: a 4 kg surface whose centre of pressure sits 28 mm from the spline centre needs 4 × 9.81 × 0.028 × 1.5 ≈ 1.65 N·m. The S2221F delivers 2.16 N·m at 8.4 V — about 30% headroom. If that feels tight, shorten the horn first: going from 28 mm to 24 mm drops the requirement to roughly 1.41 N·m, which is cheaper and lighter than the next model up.
FAQ
What is the difference between the D and F versions?
The mounting tabs are rotated 90° and the overall height goes from 35 mm to 35.5 mm. Torque, speed, current, geartrain and spline are all identical.
Can I run it directly from a 2S LiPo?
Yes. 8.4 V at full charge is the top rail in the sheet and the rail the 22 kg·cm figure is measured at. Do not exceed it.
Why are there three torque figures?
Torque, speed and current scale with supply voltage: 15 kg·cm at 6.0 V, 18 at 7.4 V, 22 at 8.4 V. All three are published so you can size against your actual BEC output.
Does it rotate continuously?
Travel is 360° when commanded over 1000–2000 µs, as a factory customization. Standard units work across the 700–2300 µs window.
How much is 22 kg·cm in oz·in?
About 306 oz·in, or 2.16 N·m. Same torque, three units.
Downloads
- XQ-S2221F inspection specification (PDF, 323 KB)
Full datasheet: torque, speed and current at every supply rail, mechanical data, control specification and mounting dimensions. - 2D dimension drawing (image)
Quick view of mounting hole positions and case depth; the same drawing is inside the datasheet at higher resolution.
