[bullstrap]

The vertical BF-110G cannon turret worked perfectly! Look at this badly damaged B-29 I shot from under! (but it was still flying ok even after 2 passes...)

I just wish it was possible to control this vertical cannon turret...

If you mean the Shrage Musik Cannons facing upward/forward they were not movable in the real aircraft. These cannon were generally a field modification fitted by ground crew (welded in position)