Gear problems

[Dickert]

I am making a glider with manually retracting gear.  There is some kind of weirdness going on with the contact points.  
Tried everything.  If I make all the contact points wheels, then the gear animation works, but the simulation does not know when the main centre wheel contacts the ground, so the aircraft sinks into the ground past the wings and crashes.
If I make the contact points - other than the main centre wheel

[Brett_Henderson]

Sonds like a :  model-origin/static-CoG-height/compression-ration  problem.

I'd have to see a copy of the Contact Points.. and screen shots of the gear at frames: 0, 100, 200