Engineered exclusively for demanding 550 to 700 class 3D and F3C competition helicopters, the KST SV905-12 high-voltage brushless tail servo delivers blistering 0.040s/60° transit speed, an immense 17 kgf.cm of holding torque at 13V, and a dedicated 760μs / 560Hz narrow-band working frequency. Featuring direct 3S LiPo / 12V battery drive capability, a high-efficiency brushless motor, and hardened steel gears housed in a full CNC aluminum casing, the SV905-12 locks in rock-solid tail authority through the most violent pirouetting maneuvers and high-speed backward flight.

Key Features

• Ultra-Fast 760μs / 560Hz Narrow Band: Purpose-built for modern flybarless (FBL) gyro tail channels, delivering instantaneous corrections, ultra-low latency, and pinpoint stopping power without bounce-back.
• Super High-Voltage (SHV) Direct Drive: Native 8.0V–13.0V operating range supports direct 3S LiPo connection — bypassing separate voltage regulators, cutting system weight, and simplifying wiring.
• Blistering 0.040s Transit Speed: Blazing-fast 0.040 sec/60° response at 13V (0.045s at 12V) ensures immediate tail lock under sudden pitch-pump and load changes.
• Brushless DC Motor: Delivers higher sustained torque efficiency, cooler running temperatures, and exceptional lifespan with zero brush degradation under extreme 3D flight loads.
• Hardened Steel Geartrain: Precision-cut steel gears with dual ball bearing support eliminate slop and resist shock loads from aggressive tail stops.
• Full CNC Aluminum Casing: Precision-machined alloy housing provides structural rigidity, exact mount alignment, and rapid thermal dissipation during high-power sessions.
• Programmable: Supports customizable parameters for fine-tuning via KST programming tool (check programming tool manual for voltage compatibility).

Technical Specifications

• Model: SV905-12 Brushless Tail Servo
• Application: 550–700 Class RC Helicopter Tail Rotor
• Rated Voltage: DC 12.0V
• Voltage Range: DC 8.0V – 13.0V (2S–3S LiPo Direct Drive)
• Working Frequency: 760μs / 560Hz (Tail Gyro Dedicated)
• Motor Type: Brushless DC Motor
• Gear Set Material: Hardened Steel
• Case Material: CNC Aluminum Alloy
• Bearings: Dual Ball Bearings (2BB)
• Position Sensor: Potentiometer
• Operating Temperature: -10°C to +65°C
• Programmable: Yes
• Dimensions: 40.5 × 20.0 × 38.0 mm (±0.2mm)
• Weight: 70g (±10%)

Performance Ratings

• Stall Torque:
  • 13 kgf.cm @ 8.4V
  • 16 kgf.cm @ 12.0V
  • 17 kgf.cm @ 13.0V
• Operating Speed (No-Load):
  • 0.060 sec/60° @ 8.4V
  • 0.045 sec/60° @ 12.0V
  • 0.040 sec/60° @ 13.0V

Dimensions & Sizing

Documentation

• Download SV905-12 HV Brushless Servo Technical Specification Sheet (PDF)