Patch from Jim Wilson:

Patch from Jim Wilson:

Clear frame buffer and render model after rest of 3D scene. This has a
small frame rate cost (YMV). But who thought 3D cockpit would be cheap?
If anyone has a better idea, have at it!

Just did some more careful testing and I see little or no frame rate loss
with the depth buffer clear.  Also you can change the near plane to 0.1
and get rid of the "sunroof" (so I don't have to make up another set of
patches.