The **R9255-R** is a high-performance, high-voltage digital brushless servo designed primarily for RC helicopters (specifically tail rotor control) and high-end robotic applications. It is manufactured by Futaba. Below is a detailed breakdown of its electronic and mechanical specifications. ### Technical Specifications | Feature | Specification | | :--- | :--- | | **Motor Type** | Brushless (BLDC) | | **Control System** | Digital (PWM) | | **Operating Voltage** | 6.0V - 7.4V (High Voltage Capable) | | **Torque (6.6V)** | 3.2 kgf・cm (44.4 oz-in) | | **Torque (7.4V)** | 3.6 kgf・cm (50.0 oz-in) | | **Speed (6.6V)** | 0.06 sec/60° | | **Speed (7.4V)** | 0.05 sec/60° | | **Dimensions** | 40.0 x 20.0 x 36.6 mm | | **Weight** | 56 g (1.98 oz) | --- ### Key Electronic Components & Features #### 1. Brushless Motor Technology Unlike traditional brushed servos, the R9255-R utilizes a **Brushless Motor**. * **Longevity:** No brushes to wear out, significantly increasing the lifespan. * **Efficiency:** Generates less heat and offers a higher power-to-weight ratio. * **Response:** Provides faster acceleration and more precise stops. #### 2. S.BUS2 Compatibility The "R" designation often refers to its integration with Futaba’s **S.BUS2 system**. * This allows for bi-directional communication. * Telemetry data (such as internal temperature or current draw) can be sent back to the transmitter. * Multiple servos can be linked via a single cable bus, reducing wiring complexity. #### 3. High Voltage (HV) Support The internal circuitry is designed to handle **2S LiPo (7.4V nominal)** power sources directly. This eliminates the need for a voltage regulator (BEC), providing more raw speed and torque to the gears. #### 4. Metal Gear Train To handle the high-speed oscillations required for tail rotor gyro stabilization, the R9255-R uses a combination of reinforced metal gears. This prevents "stripping" under high centrifugal loads. --- ### Application Note This servo is specifically optimized for **Helicopter Tail Rotors**. Its extremely low transit time (0.05s) makes it ideal for use with high-frequency Heading Hold Gyros or Flybarless (FBL) controllers.