Quick Answer
RotorFlight is helicopter-specific flight controller firmware that replaces Betaflight for collective-pitch builds. The RadioMaster Nexus-X pairs an F722 processor with an onboard gyro and RF 2.2 radio protocol, making it a strong choice for 450-class and larger helicopters. Setup involves flashing RotorFlight, wiring servos and ESCs, and tuning the gyro for stable hover.
What Is RotorFlight?
RotorFlight is an open-source firmware built specifically for RC helicopters. Unlike Betaflight, which is designed for multirotors, RotorFlight understands swashplate mixing, tail rotor logic, and collective-pitch throttle curves. If you are building a helicopter, RotorFlight is the right firmware. For multirotor firmware comparison, see our Betaflight vs iNav vs ArduPilot guide.
RadioMaster Nexus-X Hardware
The RadioMaster Nexus-X Helicopter Flight Controller is built around an STM32F722 processor with an integrated BMI270 gyro. It runs RotorFlight natively and supports the RF 2.2 radio protocol, which provides low-latency control without a separate receiver. For background on F722 boards, read F4 vs F7 vs H7 Flight Controller: Which Do You Need?
The Nexus-X includes dedicated servo output pads, a BEC, and a barometer. It fits into most 450 to 700-class helicopter frames with a standard 30.5mm mounting pattern. If you need a more general-purpose F722 board, the Betaflight F722 Flight Control System is another option in the Flight Controllers collection.
Wiring Your Helicopter
Helicopter wiring differs from multirotor builds. You have more servos and fewer ESCs, and signal routing matters for clean PWM output.
| Connection | Nexus-X Pad | Notes |
|---|---|---|
| Swashplate servos (3x) | S1, S2, S3 | Standard 3-wire servo leads |
| Tail servo | S4 | High-speed digital recommended |
| Main ESC | M1 | BLHeli_S or BLHeli_32 |
| Tail ESC | M2 | Separate ESC for tail rotor |
| RF receiver | Onboard | RF 2.2 protocol, no external RX needed |
| SBus input (optional) | UART RX | Use if pairing with external ELRS receiver |
Use twisted pairs for longer servo runs to reduce noise. Keep servo signal wires away from ESC power leads.
Servo Selection
Swashplate servos handle the cyclic and collective loads. For a 450-class helicopter, digital servos around 12-15kg of torque with metal gears are the minimum. The Emax ES9256 HV Metal Gear Digital Swashplate Servo is designed for exactly this application. For the tail, a fast, low-latency servo keeps the heading locked. Browse the full range in the Servo collection.
Flashing and Configuring RotorFlight
Connect the Nexus-X to your computer via USB and open the RotorFlight Configurator (a Chrome-based tool similar to Betaflight Configurator). The process is straightforward:
- Flash firmware. Select the Nexus-X target and flash the latest RotorFlight release.
- Configure mixer. Choose your swashplate type (120-degree CCPM is most common).
- Assign servo outputs. Map S1-S4 to the correct channels in the mixer tab.
- Calibrate the gyro. Place the helicopter on a level surface and run gyro calibration.
- Set up throttle curve. Helicopters use a collective-pitch curve, not a flat throttle. Start with a linear 0-100% curve for your first hover test.
- Tune PID. RotorFlight ships with sensible defaults for common airframes. Adjust I-term for drift and D-term for wobble, but make small changes.
Radio Setup
The Nexus-X uses the RF 2.2 protocol, so you need a compatible RadioMaster transmitter or an RF module. If you prefer ELRS, the RadioMaster RP3-H ELRS 2.4GHz Nano Receiver can be wired to the SBus input as an alternative.
Channel mapping for helicopters typically follows the TAER convention: Throttle (ch1), Aileron (ch2), Elevator (ch3), Rudder (ch4). Set up a throttle hold switch and an idle-up flight mode switch on your transmitter before flying.
First Flight Tips
Start with training gear or tied-down testing. Verify that the swashplate moves in the correct direction for each stick input before lifting off. Spool up slowly and check for vibrations. A properly tuned RotorFlight setup should hold a steady hover with minimal stick input. If the nose wanders, increase the heading-hold I-gain slightly. If the tail wags, reduce the tail PID values.