Landing Detection Logic Doesn't Work for High Powered Copter with KDE Motors

[rrr6399]

Perhaps related problems:

http://discuss.ardupilot.org/t/copter-3-4-rc5-almost-flip-landing-detection-failure/11520

http://discuss.ardupilot.org/t/fail-to-disarm-after-landing/14140

http://discuss.ardupilot.org/t/post-landing-flip-with-3-4-2-rc2/13001