WaltBJ wrote:

I have read inan RAF history that some Canadian Halifax squadrons
installed a single flexible 50 cal in a ventral mount - and were
pretty suucessful at countering Schrage Musik attacks.

We talked about this a few months ago - thread was called "Has there
ever been an off-center gun?" As far as I can tell, all ventral
mountings, apart from the Sperry ball turret, suffered from either an
enormous amount of drag (dustbins), or a restricted field of view
(periscopes, little windows etc). Good visibility seems like a
prerequisite for locating night fighters, but the added weight and drag
of the dustbin turrets was deemed a liability by the crews, who were
instrumental in their removal (apparantly).

The Canadian Halifax "Preston Green" mountings were installed in place
of the missing H2S scanner, when radar production was running behind
bomber production. When the radar became available it was fitted in the
place of the gun.