"suddenly, my 234 is diving 50 feet above the water"
The reason for this is that the auto-takeoff puts you into an automatic climb at 170mph, whereas the default auto-climb tries to make the Ar234 maintain 250mph. If you take off automatically, the aircraft will climb steadily at 170mph, and if you then hit auto-climb the aircraft will try and accelerate to 250mph, which it does by diving towards the ground, thus picking up speed. Disaster ensues. Even if you don't hit the ground you will tend to "porpoise" up and down as the aircraft tries to achieve equilibrium. That will make you airsick, although thankfully the Ar234's cockpit is easy to clean, because it is mostly glass, or perspex, whatever. Just spray some vinegar water on it.
If you want an easy life you can simply take off, wait until you are clear of obstacles, engage auto-level, wait until you are at 250mph, and only then engage auto-climb. The same holds for all the aircraft, particularly the Me262, although that is set to auto-climb at about 270. The Me163 is probably set at a much higher number but I have never used auto-climb in that machine.
