Betaflight vs Stirling-PDF

Betaflight runs two lines at once. The 2025.12.x branch is maintenance: UART interrupt handling, MSP race conditions, failsafe clamping and board-target refreshes. The 2026.6 line, released as 2026.6.1 in August, carries an AUTOPILOT mode with flight plans, CLI waypoint commands, geofence return-to-home and LAND loiter, plus a DroneCAN stack and MAVLink ground control. 2026.6.2 in September backported a single I2C guard fix.

The autopilot work is not a single feature but a rebuild of how the firmware handles position: the release notes show position control unified on a velocity primitive and the existing GPS rescue reimplemented as a flight-plan mission rather than a special case. That direction pulls hardware integration along with it — DroneCAN node allocation, GNSS Fix2, ESC telemetry and MAVLink ground-station handshaking are all things a manually flown craft does not need. The SITL harness gained fidelity and per-run session ids in the same releases, which is what you build when autonomous behaviour has to be regression-tested rather than test-flown.

With GPS rescue now running through the mission engine, the next releases on this line should concentrate on hardening that path — the release candidates already added an rx-loss policy, sanity checks and an arming gate for flight plans, and safety scaffolding of that kind usually keeps accumulating after the feature ships.