Those are great questions! A great resource is this article in
Schiffbau by Goswin Fl�gge which details the construction of WWI U-boats:
https://babel.hathitrust.org/cgi/pt?id= ... up&seq=833
I would also highly recommend the books Eberhard R�ssler has written on WWI U-boats.
Flood holes/valves
You are right that each main ballast tank must have a flood hole or flood valve (Kingston):
To flood the diving tanks, located at the lowest point...are so-called flooding flaps [Kingstons] with a cross-section of about 20x30 cm which are opened and closed by means of a crank inside the pressure hull (Fl�gge p. 743).
If you decide to modify the kit, here are a few references to guide you:
https://i.imgur.com/Pt3vvlc.jpg Outboard drawing from Eberhard R�ssler's
Die Unterseeboote der Kaiserliche Marine
https://i.imgur.com/7X2qYpz.jpg Inboard drawing from the same book, an original German Navy drawing. The divisions between each main ballast tank are shown in the plan view, and probably every one of them had one Kingston per side.
https://i.imgur.com/IoCNdgv.png Notional section of a double-hull U-boat like the
U-9 showing the Kingstons (Flutklappe) from the aforementioned article by Fl�gge.
As for the trim tanks, the variable ballast system, as on modern submarines, is internal and there are no flood valves except a small suction and discharge for the trim pump. But I have no references for that. There should also be small suctions and discharges for circulating water systems, but you would need a docking plan or other detailed drawing for that, and probably none of those survive today.
Conning tower
Many WWI German U-boats, particularly early ones like the
U-9 class, had conning towers that were not enclosed in any sort of bridge fairwater. They also had sightglasses in the conning tower:
About at eye-level, small oval windows made of 30-mm thick glass are built into the walls of the conning tower, which can be closed with shutters (Fl�gge p. 742).
Conning tower sightglasses were quite common in this era; many American submarines through the S-class had them. Looking at photos of the
U-9 class in service and the wreck of the
U-12, it seems that the conning tower is modeled quite accurately.
Hope this helps!
Jacob
Those are great questions! A great resource is this article in [i]Schiffbau[/i] by Goswin Fl�gge which details the construction of WWI U-boats:
[url]https://babel.hathitrust.org/cgi/pt?id=mdp.39015080253258&view=1up&seq=833[/url]
I would also highly recommend the books Eberhard R�ssler has written on WWI U-boats.
[b]Flood holes/valves[/b]
You are right that each main ballast tank must have a flood hole or flood valve (Kingston):
[quote]To flood the diving tanks, located at the lowest point...are so-called flooding flaps [Kingstons] with a cross-section of about 20x30 cm which are opened and closed by means of a crank inside the pressure hull (Fl�gge p. 743).[/quote]
If you decide to modify the kit, here are a few references to guide you:
[url]https://i.imgur.com/Pt3vvlc.jpg[/url] Outboard drawing from Eberhard R�ssler's [i]Die Unterseeboote der Kaiserliche Marine[/i]
[url]https://i.imgur.com/7X2qYpz.jpg[/url] Inboard drawing from the same book, an original German Navy drawing. The divisions between each main ballast tank are shown in the plan view, and probably every one of them had one Kingston per side.
[url]https://i.imgur.com/IoCNdgv.png[/url] Notional section of a double-hull U-boat like the [i]U-9[/i] showing the Kingstons (Flutklappe) from the aforementioned article by Fl�gge.
As for the trim tanks, the variable ballast system, as on modern submarines, is internal and there are no flood valves except a small suction and discharge for the trim pump. But I have no references for that. There should also be small suctions and discharges for circulating water systems, but you would need a docking plan or other detailed drawing for that, and probably none of those survive today.
[b]Conning tower[/b]
Many WWI German U-boats, particularly early ones like the [i]U-9[/i] class, had conning towers that were not enclosed in any sort of bridge fairwater. They also had sightglasses in the conning tower:
[quote]About at eye-level, small oval windows made of 30-mm thick glass are built into the walls of the conning tower, which can be closed with shutters (Fl�gge p. 742).[/quote]
Conning tower sightglasses were quite common in this era; many American submarines through the S-class had them. Looking at photos of the [i]U-9[/i] class in service and the wreck of the [i]U-12[/i], it seems that the conning tower is modeled quite accurately.
Hope this helps!
Jacob