Chapter 07 · Components
Your link to the drone
The radio is your first purchase and the one that will last you the most years: you’ll use it in the simulator and with every drone you own. The receiver, inside the drone, must speak the same language.
Choosing a radio
Form factor
Full size: long sticks and more precision. Gamepad style: compact and easy to carry. Both work fine.
Sticks
Hall-effect gimbals have no physical contact and don’t wear out. Adjust their tension and springs to your liking.
Firmware
EdgeTX, which is open source, is the standard: one model per drone, configurable switches and scripts for ELRS.
Radio module
Internal (tidier) or external in a bay at the back (you can switch protocol). Choose ELRS at 2.4 GHz.
Why ExpressLRS
ELRS is an open-source radio system that has become the standard: very small, cheap receivers, low latency and a range far beyond what you need for freestyle.
| Concept | What it is |
|---|---|
| Binding phrase | A word you set on the radio and the receiver to bind them without pressing any buttons. |
| Packet rate | From 50 to 1000 Hz. Higher means less latency; lower means more range. Between 250 and 500 Hz is a good spot for freestyle. |
| Output power | Up close, a little is enough. Turn on dynamic power so it adjusts itself. |
| Version | The radio and receiver must be on the same major version (for example, 3.x with 3.x). They update over wifi. |
| 900 MHz | The long-range variant. For freestyle, 2.4 GHz is more than enough. |
Want to know what range you’ll get with each mode and power level? Try the ExpressLRS range calculator.
The receiver, inside the drone
- Wiring: receiver TX to RX on one of the flight controller’s UARTs, RX to TX, plus 5 V and ground.
- T or dipole antenna, sticking out of the frame, away from carbon and the props. With two antennas, angle them apart.
- Protect it with heat-shrink and secure it so it doesn’t vibrate.
- In Betaflight: Serial RX on the right port and CRSF protocol.
| Receiver type | What it’s like | Who it’s for |
|---|---|---|
| Single antenna (2.4 GHz) | One radio chip and one antenna | Most 5" and smaller drones |
| Antenna diversity | One chip, two antennas: it picks the one receiving better | More reliability for little weight |
| True diversity | Two chips and two antennas listening at the same time | Long range and Gemini mode |
| 900 MHz (868 in Europe) | Bigger antennas, better at getting through obstacles | Long range with obstacles; needs a compatible radio |
| Dual band | 2.4 GHz and 900 MHz in the same receiver | Maximum compatibility and Gem-X mode |
The receiver’s band must match the radio’s, and so must the ExpressLRS major version.
Recommended switches
Arm
A two-position switch on AUX1 that you can’t flick by accident.
Beeper
To find the drone in the grass after a crash.
Turtle
To flip it back over when it lands upside down.
Flight mode
Acro by default; Angle optional for your first tests.
For the simulator, the radio connects over USB as a game controller. Create a separate model for it with the radio module turned off.