The Ship Model Forum

Steam electric setup includes isolation of boilers, turbo generators and motors in separate lower pressure hull cylinders.
A rapid method of sealing uptakes/downtakes might help would involve some kind of powered mechanical close/open of these openings.
Dive time might still be minutes but 1920 USN subs required a few minutes for diesel subs,
A goal of four minutes might be achievable.
The K class might be the worst but designers might use the K boats as lessons learned.

The Royal Navy built the K-class submarines in WW1. They were steam turbine operated. Didn't work very well.

There is a good writeup on them in The World's Worst Warships, By Anthony Preston ISBN 0-85177-754-6

How might a steam electric sub had looked and what would be it's capabilities and limitations.
Anyone want to do a line drawing or a model?
There are not any kits out there for a 500 foot long sub so it would have to be built from scratch.
Internal arrangement would be something open to some interpretation for any potential drawing or model.
May bey someday.

Not trying to start an argument here but a sub obviously must be capable of being made 100% airtight and withstand extreme pressure... weight is a concern too as you need to be able to surface/dive and maintain trim, limiting the amount/location and thickness of armor while still allowing the boat to be functional.

That's a tall order... and it creates a whole host of problems that a surface warship just doesn't have to face... which is why the Allies pumped out surface cruisers rather than cruiser submarines. There simply is no way to make a sub as sturdy and ultimately as capable as as a surface cruiser while still maintaining it's usefulness as a submersible. Instead of a "jack of all trades", you end up with something that does an inadequate job in both roles.

But I'll never object to using your imagination! I think model building is more art than engineering.

I salivate at the possibility of one modeled.
The size of the 21,000 tonner is Huge but detailed plans for slow (11.75 knots) armored diesel boat available for modeler to work from.
The 18,500 ton or 21,000 tonner would make great looking model.
Unfortunately for me, I don't have modeling skill/finances to do it.
And this is a what if (?) thread so you can use some imagination.

Please note that the 1920 concepts featured protection against torpedoes and gunfire.
Cruiser standard armor protected the conning tower, each turret, armored deck and the layered side protection system for absorbing torpedo hits so I would say a 500 foot ship protected in this manner might also be able to absorb hits and keep on shooting whether by eight inch shell or torpedo.
I wish I knew how to scan and attach diagram from Friedman's book to my posts.
Again, consider vulnerability in light of armor/SPS schemes before calling these monsters fragile.
Steam propulsion, which could achieve 25 knots @ 52,500 shp, the heat from which was isolated from habitable areas via it's installation in two separate 22 foot diameter lower pressure hulls while upper port/starboard hulls contain quarters, with center line hull containing boiler uptakes. Ballast tanks and fuel storage was around the pressure hulls and inside the outer hull. Multiple pressure hulls with multiple internal bulkheads that subdivided the interiors would allow some pressure hull damage to be acceptable for remaining on surface or submerging. Perhaps one or two compartments might be flooded while A steam plant takes several minutes to go from cold iron to pressure for full speed, which is a vulnerability but only way in 1920 to achieve moderate high speed of 25 knots.
Torpedo armament of six forward/2 stern tubes or the concept with two twin 12 inch turrets that featured ten forward/four stern torpedoes. Battery charging by separate charging diesels would have been a possibility. so limited speed on charging diesels feeding the motors, pioneered by WW I U-boats, could have been used.

It's a cool idea on paper, but the problem is the achilles heel of all submarines... provided you can locate it, a sub is easy to sink. Submarines just can't take much damage; a single direct hit with a 5" gun or a single depth charge is often enough to send one to the bottom.

Surface cruisers on the other hand CAN take a few hits and keep on fighting. A cruiser submarine really is the proverbial boxer with a glass jaw... and one very expensive boxer to boot. The US was wise to not waste money on building any.

My $.02 anyway.

That doesn't mean it wouldn't be cool to see one modeled, though!

Hey guys, where the posts? AM I the only enthusiast for for the really big 18,000-21,000 cruiser subs which were way superior to the French, British and USN cruiser subs of the 1920's having several airplanes, full heavy cruiser eight inch/eight gun/armoring/anti torpedo side protection system?
These submarines were never built and if they had been built you would have had a 20 or 25 knot submersible cruiser with all the hassles of steam propulsion on the surface though the charging diesels might have provided effecent propulsion at low speeds.
Steam uses more fuel but weighs less and gives higher speeds.
Very large diesels not available in 1920-22 although a 2200 hbh Busch-Sulzer may be available in that time frame.
Until the GM railroad engines of the 1930's came about, diesel high surface speed submarines were not practical so steam electric was the only way to go.
Anyone out there interested?

I now have the data from Submarines Through 1945 by Norman Friedman Naval Institute Press
pages 170-172
1920 series of designs:
Type I-10,000 tons displacement,400 by 48 by 33.25 feet-pwer plant 5600 bhp diesel surfaced/5600 shp submerged-14 knots max speed-Battery 480 cells radius 16,000 nmi @ 10 knots-guns 8 x 8 inch, 2 X 4 inch AA, six bow and 2 stern-airplanes 4- no armour or torpedo protection
Type III-13,500 tons-490 by 71 by 26 feet-Max speed 11.75 knots-Battery 240 cells-18,000 nmi@10 knots-six bow/2 stern torpedo tubes-4 x 8 inch-2 x 4 inch AA-6/3 inches armored conning tower-turret 6/3/2 inches-deck 90-120 lbs. plates-layered torpedo defense side protection system-6 airplanes

TypeIV-13,5000 tons-425 by 71 by 26 feet-18 knots-18,000 nmi @ 10 knots-11.75 knots max speed-6/2 torpedo tubes, 240 cell battery-4,400 bhp diesel electric plant

Type V-18,500 tons-500 by 72 by 29 feet-20 knots max speed-26,000 shp @ 20 knots-steam electric-8 airplanes- conning tower 6/3 inches-turret armor 6/3/2 inches-90 or 120 lbs. deck armor-layered side protection system

Concept was for long range scouts that could fight for information using submersible cruiser/battlecruiser
The 1922 London Treaty limited submarines to eight inch guns
Airplanes internally stowed in 16 feet diameter water/pressure proof cylinders with elevators to deck. Steam plants had much higher fuel consumption and lighter weight and more SHP per pound while diesels weighed more per pound and had much better fuel burn.
A figure from this era indicated 105 lbs./BHP for diesels.
Seperate diesel generators for battery charging with ability to drive subs at a slow but greatly more fuel economical speed from German WW I practice.

Type VI-530 by 79 by 31 feet-17 knots-21,100 displacement-diesel electric drive final design.

Cost of the 1920 five hulled scout submarine would have cost $25,000,000 per ship-25 knots-52,250 shp steam-electric

Norman Friedman's Submarines Through 1945: A Design History-Naval Institute Press-1990s book.
I have the book from the library and it has some steam submarine designs and specifications tables.
The multiple hull concept is the only one of the cruiser sub designs illustrated although specifications comparision tables are provided.
I should point out that the diesel and steam submarines were BIG!
Something able to mount four twin eight inch gun turrets, hangar for 4-8 aircraft, armored hull, superstructure and turrets.
Two variants featured side protection systems to counter torpedoes.
Of course, alot of torpedo and gun firepower was availiable to these craft.
With the naval treaties in the future, there was only a question of money and technical problems of making these subs work were the only two issues.
I would also point out that these subs were designed to patrol the Pacific distances without much in the way of basing support with the enemy planned for being Japan.
Someone want to design these?
What would you call these 13,500 tonners.
Steam variants faster than diesel variants which had longer ranges and could dive faster.
At this time, everyone used direct diesel drives with all it's problems.
You might have had the main propulsion plant-geared drive-diesel or steam, electric geared motors and seperate charging diesels which could also be coupled to the main motors via diesel electric operation for long endurances, pioneered in large U boats of WW I.

The Royal Navy built a cruiser submarine as did France. The British cruiser submarine has the distinction of being the only warship built after WW1 by the Royal navy to be scrapped before WW2. Improving torpedo technology killed off the cruiser submarine as the "fleet submarine" concept proved a better idea.

Gee, thanks!
So that's Albatross & Nisshin to finish and then the planned Hermes & Eagle.......
I need to give up work!

Cliffy B wrote:I don't recall cruiser sub designs AFTER the war (please post some sketches if you can as I'm know very interested!!!) but there were multiple ones from BEFORE the war in Spring Styles #1.

Spring Style #1 - Root directory
http://www.history.navy.mil/photos/albums/s584.htm

Spring Style #1 - Subs
http://www.history.navy.mil/photos/albums/s584-ss.htm

Full sketches are included! Have fun resisting the urge now Doog

I don't recall cruiser sub designs AFTER the war (please post some sketches if you can as I'm know very interested!!!) but there were multiple ones from BEFORE the war in Spring Styles #1.

Spring Style #1 - Root directory
http://www.history.navy.mil/photos/albums/s584.htm

Spring Style #1 - Subs
http://www.history.navy.mil/photos/albums/s584-ss.htm

Full sketches are included! Have fun resisting the urge now Doog

Are there drawings of these?




No, no, must resist/ 1/144th scales I-400 was enough of a nightmare!!!

Norman Friedman's book, Submarines through 1945 covers pre Treaty cruiser submarines proposed but not built.
Imagine the proposed cruiser subs as follows:

Five pressure hull cylinders with three parallel cylinders with two cylinders below to overcome limitations in pressure hull diameter. Realized in postwar Dutch sub class with one upper and two lower cylinders. Steam boilers in the lower two pressure hulls to isolate the heat output with center upper pressure hull containing uptakes and port/starboard cylinders for quarters.
Typhoon class also used multiple pressure hulls.
Two twin 8 inch gun hemispherical turrets (to resist sea pressure), armor protected, ten forward torpedo tubes, four stern tubes, 52,250 shp steam plant for 25 kts on the surface, 600 foot length.


Series of cruiser submarine proposals with diesel engines or steam surface plant, charging diesels, electric motors.
The 13,500 ton proposal featured side torpedo protection for diesels or steam plants types.
All five proposals have hangars for 4-8 seaplanes.
All five have armor protection for superstructure and turrets.
Eight guns of eight inch caliber and one featured 12 inch turrets, all twin turrets.

They were monsters to be sure but what if they were built?
Surcouf would have been a toy by comparison