Hello there, I'm new in the community.
I hope this thread stills active since I am still impressed by the clear information about German aircraft machineguns and cannons and I'd certainly like to ask many things. I must congratulate Charles Bronson for the time and effort spent in this topic.
My first question is if the Luftwaffe or the Kriegsmarine tested on their bombers and submarines/ships/S-boats respectively, the Rheinmetall-Borsig Mk 108 cannon in turret placements (remote controlled).
I must confess that I'm asking this, not because I'm an instructed person in these gun matters, but for the reason of some very interesting information I had read in a World-War-Two-set historical novel called "Operación Hagen" (Operation Hagen in English) written by the British/Spanish Author Felipe Botaya, a bussinessman, teacher, lecturer and historical researcher (this one in his free time).
Just to give a brief account of the novel, I'll say it's about the Nazi atomic program (there were three according to the book) led by Doctor SS General Hans Kammler. The Novel describes using some historical facts and most of the times just non-official ones, the truly first nuclear attack on enemy territory during the war by the Germans, using a modified He 177 V-38 (the enigmatic atomic variant of this superb bomber), at Tunguska, Siberia on February 23, 1945.
The part which drawn my attention the most was that this bomber (always, according to the book) had a very rare and I'd say devastating defensive system consisting in five
Rheinmetall-Borsig Mk 108 cannons installed this way:
• One cannon on the middle upper part of the bomber, behind the gunner's plexiglas canopy, with 360º horizontal rotation moving capability and 180º vertical rotation moving capability (the book doesn't especify the moving capabilities of this cannon, but it seems pretty obvious to me that they were 360º horizontal and 180º vertical. Those who are keen on German aircraft guns in turret installments, please correct me if I could be wrong).
• One cannon on the lower part of the bomber, under the pilot and copilot, with 180º horizontal rotation moving capability and 90º vertical rotation moving capability, pneumatic-pedal-fired from the cockpit. In case of attack, the pilot would use it, defending the front part of the bomber (the book again, doesn't especify the moving capabilities of this cannon, but in my opinion, it's likely to be 180º horizontal and 90º vertical).
• One cannon just behind the previous one described above, defending the lower back part of the bomber, in case of being attacked, this cannon was meant to be used by the radar operator, with 180º horizontal moving capability and 90º vertical moving capability (yes, the book states this).
• Two cannons as twins in the tail of the bomber (replacing the manned MG 131) inside a bulletproof (steel?) dome, with 180º horizontal rotation moving capability and 90º vertical rotation moving capability (again, the books states this) . In case of attack, these cannons (called Mk108Z on the book) were meant to be controlled by the gunner seated under the plexiglas canopy behind the pilot, copilot and radar operator. The book also states that their remote control firing system was a specially-adapted FDL-131/Z, made by the AEG company exclusively for this bomber. It also adds that these cannons (the "twin" Mk 108 called Mk 108Z) were controlled by "servo-engines" (direct translation from the Spanish "servo-motores", not sure if it's 100% correct) from the gunner's plexiglas canopy, behind the pilots, by means of a pedal that the gunner should use.
All five cannons counted with moving sensors so they could follow enemy fighters trajectories and their firing would be activated by compressed air.
As you may see, it's quite an indomitable beast (the defensive system of course), and since I've bought the novel back in 2013, it stills amazes me ...
It'll be great to know if the Germans led experiments in which Mk 108 cannons were used as defensive devices in turrents for bombers. Maybe Charles, you'll be able to throw some light on this point.
As a plus, I'll add to this comment soon, a quick sketch I made of this He 177 atomic variant, detailing the location of each main component (including of course the location of the Mk 108 turrets).
Here's the sketch I made (sorry for it's low quality, I will try to upload another one which will be better than this):
About the Rheinmetall-Borsig Mk 108 being used by the Kriegsmarine, I'll say that in another novel by the same author (Antártida 1947), which tells us about Operation Highjump being really a military operation to destroy the enigmatic Base 211, supposedly the Nazis' last military redouct, I've read that Type XXI submarines used two moving turrets each containing from two to three Mk 108 cannons ... is this an historical fact?
And also, was the Kriegsmarine trying to use the Mk 108 cannon as a possible defensive device on their warships, S-boats or even patrol boats?
Once again, I'd like to thank you for the big amount of information about German aircraft guns, and I hope you can answer my questions. Thanks.