Long range wing: ExpressLRS 868MHz setup and binding

Switched from Crossfire 2.4GHz to ExpressLRS 868MHz on this build. The motivation: two sessions where I lost link briefly flying into a narrow section of the Rhine gorge. Crossfire at 2.4GHz is good, but 868MHz has better obstacle penetration and longer theoretical range.

Hardware: BetaFPV ELRS Nano TX module in the handset, a Matek ELRS 868 RX on the wing.

The binding process is straightforward but not forgiving if you’re used to Crossfire:

1. Flash both TX and RX to the same ELRS firmware version (3.3.x). Version mismatches between TX and RX don’t fail gracefully — they just don’t bind, with no useful error.
2. Put the RX in binding mode by holding the bind button on power-up.
3. On the transmitter, enter the ELRS Lua script → Bind. LED on the RX goes solid.
4. Set your packet rate. I use 50Hz with telemetry on — good balance of latency and range. 25Hz gives more range at the cost of stick feel.

# ELRS Lua settings (via EdgeTX)
Packet Rate: 50Hz
Telem Ratio: 1:8
TX Power: 250mW (legal limit CH for 868MHz with this equipment)

Telemetry back in INAV is clean — RSSI, LQ, SNR all visible on the OSD. The LQ metric is more useful than raw RSSI for judging link margin.

First proper flight: full valley pass, about 4km out at 120m AGL. LQ never dropped below 96. The canyon section that caused the Crossfire drop-outs was fine. Switching back is not on the table.