While reading up on the Tupolev Tu-2 I came across
a post Shortround made in 2018 saying that the British estimated that a powered mount was three times more effective then an unpowered mount. This got me curious about the relative effectiveness of the various weapons mounts employed on WWII bombers. Not only the effectiveness of the different types of guns themselves, but also of the types of mountings used and the locations of those mountings (chin, tail, dorsal, ventral, waist, etc).
My interest in this subject is partly out of personal curiosity though one of the people working on a strategy game mod I am doing research for has expressed interest in studies on the topic if any are available. I also figured there might be other people on this board with an interest in the general topic.
Its an interesting question, for sure.
I guess the brutal Darwinism of war and the consequent evolution of bomber armament tells its own story. The lesson seems to have clearly been that no amount of armament would ultimately make a bomber an equal to a contemporary attacking fighter in terms of loss rate. And given that a fighter is always going to be cheaper in terms of crew, manufacture and material cost, even a 'one for one' would be unsustainable for the attacking force - especially if its a heavy bomber (all other considerations being equal).
History seems to have shown that the performance penalty of carrying turrets / crew manned guns was something of a balance - and as others pointed out, a lighter aircraft unburdened by their weight and drag can theoretically carry more bombs, likely higher, faster and further. At some point, the advantages of those aspects and reduction in likelihood of interception or having to make repeated raids onto the same target to ensure its destruction, will overtake the advantage/liklihood of the bomber being able to dissuade/disable/shoot down an interceptor. However, during WW2, with the exception of the Mosquito - and perhaps the B29 at the end of the war, the general trend was to try and add more defensive positions and heavier calibre defensive guns (even if the RAF were late to that aspect!)
There are lots of variables - the relative performance difference between bomber and interceptor, mission environment, whether its by day or night etc etc... But given that both the USA and USSR continued to design and field aircraft with tail turrets post war, I suspect the clear implication there is that the tail turret would qualify as the most effective and worthwhile position from their perspective at least. An intercepting aircraft is by necessity most likely to be coming from the rear, its the quarter which pilots and other crew members in the cockpit can least see, and it also affords the gunner with one of the widest fields of fire. It may also (and shooters here can correct me), provide the gunner with the least complex firing solution, making the chance of hitting an attacking aircraft higher. Aerodynamically, it may also be less compromising I'd guess than other turret positions.
Some aircraft without the ability to outrun or outmanoeuvre an interceptor were pretty much reliant on their gunners. But again, there' a difference in practicality and approach between a box formation of bombers using massed ranks of guns with interlocking arcs of mutual covering fire like the B17s and B24s - or something like a Lancaster operating in a stream in darkness. There's also scenarios for aircraft like Il2s, operating relatively slowly and as a 'gaggle' rather than a strict formation.
Anyway, I'm now asking myself nearly as many questions
You might find the following of interest:
Wallace McIntosh - Wikipedia