| 22KG·CM STALL | 0.10S/60° NO-LOAD | 8.4V RATED |
| 36.5G WEIGHT | StainlessGEARTRAIN | 360°TRAVELCustomizable |
Overview
The S2221D is the 22 kg·cm member of the slim-wing family: 36.5 g in a 12 mm case, 0.10 s/60° at 8.4 V. It exists because 11 kg·cm is often just short — a bigger flap, a heavier linkage, a surface with more chord — and the alternative, dropping back to a full-size 20 mm servo, means cutting structure to make room.
The 25T spline and twin ball bearings are shared with the rest of the range, so horns interchange across models. The geartrain is stainless steel, which at 22 kg·cm is not a luxury: it is the difference between a servo that lasts a season and one that develops backlash in a month.
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 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-S2221D 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 3.5 kg surface whose centre of pressure sits 30 mm from the spline centre needs 3.5 × 9.81 × 0.030 × 1.5 ≈ 1.55 N·m. The S2221D delivers 2.16 N·m at 8.4 V — about 40% headroom. That margin matters more than it looks: a servo held near stall for a long glide is dissipating heat continuously, and heat is what kills an otherwise correctly sized servo.
FAQ
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 one the 22 kg·cm figure is measured at.
Why are there three torque figures?
They are the same servo at three supply rails: 15 kg·cm at 6.0 V, 18 at 7.4 V, 22 at 8.4 V. Compare against other servos at the same rail or the comparison means nothing.
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.
Is it waterproof?
Splash water resistance, customizable, per the inspection sheet. No IP rating is published, so do not treat it as submersible.
How much is 22 kg·cm in oz·in?
About 306 oz·in, or 2.16 N·m.
Downloads
- XQ-S2221D inspection specification (PDF, 302 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.
