The Ju88 gyrocompass is bugged: you can calibrate it, but it doesn't move when you turn.
Since the autopilot works by comparing the gyrocompass to your desired heading, the fact that the gyro is bugged means the autopilot gets false data.
Let's say for example that you are flying a heading of 90 degrees. You calibrate you gyrocompass, set the desired heading to 90 (actualy, 90+9=99, that's another issue in all gyrocompasses, the alignment between gyro and desired heading is a bit off, don't know if this is a bug or realistic limitation of the system) and engage the autopilot.
So your 88 is now flying straight. You take a look through the bombsight and realize you need to turn 2 degrees left to align your target.
You press the relevant keys and adjust your desired heading 2 degrees less than the heading the gyrocompass reads. The AP starts turning left.
And this is where the problems start. The gyro keeps showing 90 degrees (it's stuck), so the autopilot will never level off because it doesn't know it has reached the desired heading of 88 degrees.
At best, it will do a full 360 degree turn and come to settle on the same initial heading, but due to the slow response of the AP system (that's realistic) it will not: the more offset between gyrocompass and desired heading, the more the airplane banks. The more the airplane banks the slower it comes back to level. That's why even the 111 which has a working gyrocompass tends to S-turn a bit when changing headings via autopilot.
In the 88, it will do a complete circle and overshoot even the initial heading, resulting in the same problem repeating itself. So, it keeps going in circles forever.
This is a bug that has been reported a lot of times, so we're keeping our fingers crossed that it will be among the fixes included in the next patch.
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