@swissfreek - we posted simultaneously. Tailtune is implemented and works. Here's a quick rundown of how I set things up.
1)I assign the motor and tail servo to individual channel banks. This allows for motors on sync PWM and the servo at 270 Hz refresh. For BrainRE1, use channels 1-3 for the motors, channel 5 for the servo.
2)On the output tab, set the servo limits. I usually set the tail servo limits here, but you can use tailtune also. I have +/-45 degrees of tail rotation, and I set this in the UAV browser window under triflight settings.
3)I enable triflight, and disable the virtual servo. This activates the servo feedback. For BrainRE1, use the RSSI input, which is ADC2.
4)Assign tail tune to a flight mode. Entering tailtune (without arming) will cause a configuration error, and that's okay, as this will prevent arming while doing the servo calibration. Pull the pitch stick back, and it will set the ADC limits and servo speed. You should see the updated adc limits and servo speed under triflight settings, and the servo angle under triflight status should now read correctly.
5)At this point, I would go fly, put the vehicle in a hover, and then enter tailtune mode. It will now compute the rear motor torque.
6)Next, I would replace tailtune with autotune, and get that all setup.
I didn't list all the nitty gritty details, if you have any further questions, let me know.
This latest update has not been pushed to the triflightPR branch yet.