Unstable Y6 on takeoff - over sensitive gyros?

I have a Y6 with APM2.6. Takeoffs are very uneven with motors winding up erratically. If I put in input i.e. react to one side lifting first it settles down and is much easier. I have recalibrated the ESCs several times by both all in one and individual methods but the problem persists. It is much more noticeable when the copter is not on level ground. Somebody suggested that the “gain of the gyros be reduced” but I have looked at all the parameters and cannot find anything that fits this. When trying an auto takeoff the copter always tries to flip, tail over the other 2 arms. Once in flight it flies fine. Any ideas on what could be causing this?

I too have had issues with my Y6 on RC2. I calibrated and wiped everything twice, then recalibrated the air frame only to have it flip backwards violently. After two attempts I rolled firmware back to 3.1.5 and the airframe lifted off fine after recalibrating everything. Not convinced RC2 is stable.

To be blunt, unless you are a developer contributing to the flight code or a sophisticated operator actively testing the flight code we do not recommend flying a release candidate. That said we appreciate users who are foolish enough to sacrifice their aircraft by finding bugs in the flight code provided they provide us with log files for analysis.

RC = Release Candidate
An RC is by definition unstable! That is why you get the warning box when you switch to Beta firmwares in Mission Planner.