How to Set Up ExpressLRS on a Fixed Wing with PWM Outputs

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Introduction

If you’re a hobby RC pilot or maker in the UK looking to upgrade your fixed wing aircraft’s radio control system, ExpressLRS (ELRS) is an excellent choice. It offers long range, low latency, and open-source flexibility. This guide will walk you through setting up ExpressLRS on a fixed wing plane using PWM outputs, which is common for many flight controllers and receivers.

What You’ll Need

Before you start, make sure you have the following components:

  • ExpressLRS compatible transmitter module (e.g. ELRS TX module for your radio)
  • ExpressLRS receiver with PWM outputs
  • Fixed wing flight controller or direct servo connections
  • Battery and power supply suitable for your setup
  • USB cable for flashing firmware
  • Computer with ExpressLRS Configurator software installed

Step 1: Flashing Firmware

First, flash the latest ExpressLRS firmware to both your transmitter module and receiver. Use the official ExpressLRS Configurator to select the correct hardware targets and settings. For fixed wing setups, choose the appropriate packet rate (e.g., 500Hz or 1000Hz) based on your control requirements and range.

Once firmware is flashed, bind the receiver to your transmitter module by following the on-screen instructions in the Configurator or the binding procedure outlined in your receiver’s manual.

Step 2: Connecting the Receiver to Your Plane

Most ExpressLRS receivers provide PWM outputs for connecting servos and ESCs. Here’s how to wire it:

  • Power: Connect receiver power input to your plane’s regulated 5V supply or BEC.
  • Ground: Connect receiver ground to the common ground of your electronics.
  • PWM Channels: Connect the PWM output channels from the receiver to the corresponding servo inputs on your flight controller or directly to servos if you’re not using a flight controller.

Note: Make sure to check your receiver’s datasheet for the exact pinout as it varies by model.

Step 3: Configuring Your Flight Controller (Optional)

If your fixed wing uses a flight controller, configure it to accept PWM inputs from the ExpressLRS receiver. In your flight controller’s configuration software (e.g., Betaflight, INAV), set the receiver mode to PWM input and map channels accordingly (aileron, elevator, throttle, rudder).

Step 4: Testing and Calibration

Power up your system and verify that all control surfaces respond correctly to your transmitter inputs. Perform range checks and ensure no signal drops. If using a flight controller, calibrate your servos and ESCs as needed.

Tips for a Smooth Setup

  • Use quality servo cables and connectors for reliable PWM signal transmission.
  • Keep wiring tidy to avoid interference and mechanical wear.
  • Double-check polarity on all connections to prevent damage.
  • Update your firmware regularly to benefit from improvements and bug fixes.

Conclusion

Setting up ExpressLRS on a fixed wing using PWM outputs is straightforward and greatly enhances your control experience with its responsiveness and range. With the right hardware and careful wiring, you’ll enjoy reliable and precise control for your flights. Happy flying!

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