| 23KG·CM STALL | 0.100S/60° NO-LOAD | 8.4V RATED |
| 65G WEIGHT | StainlessGEARTRAIN | 360°TRAVELCustomizable |
Overview
The S8020D is a 23 kg·cm coreless digital servo in a 20 × 40 × 34.9 mm case, 65 g. It is the thinner alternative to the brushless models in the same footprint: 34.9 mm deep instead of 38–40, which is what matters when the servo sits under a narrow fuselage or inside a tight frame.
Coreless motor, stainless steel geartrain on two ball bearings, 25T-φ5.94 mm spline and a POM horn. Mechanical limit 210°, dead band 1 µs, and the pulse window is the standard 800–2200 µs.
This page covers the PWM build: a standard 50–333 Hz pulse input, 1500 µs neutral and a 3–4 µs dead band. It is the version to pick when the servo hangs off a receiver or a flight controller and you want nothing between the two.
Performance at each supply voltage
| Supply | No-load speed | Peak stall torque | Idle current | Stall current |
|---|---|---|---|---|
| 6.0 V | 0.140 s/60° (429 °/s) | 17 kg·cm (1.67 N·m / 236 oz·in) | 300 mA | 2.8 A |
| 7.4 V | 0.120 s/60° (500 °/s) | 20 kg·cm (1.96 N·m / 278 oz·in) | 350 mA | 3.0 A |
| 8.4 V | 0.100 s/60° (600 °/s) | 23 kg·cm (2.26 N·m / 319 oz·in) | 420 mA | 3.5 A |
Control specification
| Item | Specification |
|---|---|
| Command signal | PWM, 50–333 Hz |
| Amplifier | Digital controller |
| Pulse width range | 800–2200 µs |
| Neutral position | 1500 µs |
| Dead band | 1 µs |
| Rotating direction | CCW (1000–2000 µs) |
| Travel | 360°, customizable |
Mechanical specification
| Item | Specification | Item | Specification |
|---|---|---|---|
| Dimensions | 20 × 40 × 34.9 mm | Case material | Aluminium, CNC |
| Weight | 65 g | Geartrain | Stainless steel |
| Bearings | 2 × ball bearing | Motor | Coreless |
| Output spline | 25T-φ5.94 mm | Horn | Plastic, POM |
| Lead / connector | 300 mm, 3-wire | Mechanical limit | 210° |
| Operating temperature | −15 °C to 65 °C | Storage temperature | −20 °C to 70 °C |
| Ingress protection | Splash resistant (customizable) | Travel | 360°, customizable |
What’s in the box
- 1 × XQ-S8020D servo
- 1 × POM horn set
- 1 × mounting screw pack
Optional: metal horn, sold separately.
How to size it
Torque tracks the rail: 17 kg·cm at 6.0 V, 20 at 7.4 V, 23 at 8.4 V, at 0.14, 0.12 and 0.10 s/60°. On a 2S pack under load, plan on 20.
Stall current is only 3.5 A at 8.4 V against 420 mA no-load. A coreless motor has no iron in the rotor, so it accelerates faster and draws less at stall than a cored motor of the same torque — four of these on a 15 A BEC is a comfortable margin.
FAQ
Is it 22 kg·cm or 23?
23 kg·cm is the measured peak at 8.4 V on the inspection sheet. 22 is the nominal figure carried in the product name. The table above lists the measured values for all three rails.
Coreless or brushless?
Coreless. It is lighter and thinner than the brushless models in this footprint (65 g, 34.9 mm) and has lower stall current, but the brushes remain a wear item. For continuous duty at high torque, the brushless BLS8135D is the longer-lived choice.
What pulse range does it accept?
The inspection sheet specifies a 500–2500 µs window (800–2200 µs on the 9130/9150) with 1500 µs neutral, both customizable at order. Feeding it outside that window is out of spec.
Can I drive it from a normal receiver?
Signal-wise yes, but check the supply. This servo wants 8.4–16.8 V, not a 6 V receiver pack, so the power rail has to be separate from the receiver’s.
Other interfaces
Downloads
- XQ-S8020D inspection specification (PDF, 718 KB)
Torque, speed and current at each supply voltage, mechanical data, control specification, mounting dimensions. - 2D dimension drawing (image)
Mounting hole positions, case depth and overall height; the same drawing is inside the datasheet.
