Collisions not working.

When I start the ge, my tank falls through the floor.
Anyone know why?

Heres a .blend
Hovertank.blend (232 KB)

What’s happening is that the mesh (tank) is colliding with the thing that makes it hover. and as it is a child of the hover-box, it follows it around. In the hover-box’s efforts to get away from the ever present collision of the tank, it ignores the floor. Try making the tank a ghost
I also notice you have turned the gravity off, this is the wrong way to make the tank hover. If you use the force field actuator it gives a much better result. See attachment


Hover demo.blend (213 KB)