Japanese submarines and aircraft

[el cid again]

In all forms of WITP Japanese scouting submarines carry scouting floatplanes.

In RHSCVO and RAO you get the I-400 type submarine aircraft carrier (3 bombers) and the I-13 type (2 bombers).

I have modified RHSBBO (from x.695 level) so that you get the original I-400 type (2 bombers) and no I-13 type with bombers - but you get them sooner (because the original design was available sooner). They are not particularly better performing (a knot at top end, a maneuver point), but they are available soon enough to affect the war.

In RHSCVO and RAO you get the I-351 as a transport submarine (as built).

In RHSBBO (and derivitive PPO and RPO) you get the I-351 as a midget sub tender. [EOS was that way until now]

In RHSEOS (from x.695 level) you could have it in its really original form - as a seaplane tender - that is a flying boat tender. If human controlled it should not fly its aircraft except from some island or coast - but it need not be one with any form of base or location in it. Comments?

[Dili]

House rules!
. It is sad that the floatplanes submarines arent used Historicaly. That's a game issue: a recon in an enemy harbour seldom gives good information but they have no problems finding ships in open sea that is a bigger area and everyday!. In reality they were quit good reconising Bases and Harbours (at least enemy ships even if sometimes for the crew a Cruiser is a BB and a DD is a Cruiser) but ineficient to search the open sea.

[m10bob]

Operational history of the I 400 type sub. Note the intended torpedo bombers as well!

http://www.pacerfarm.org/i-400/




Further down on that site are details of the Kaitan carriers also..

[el cid again]

If anyone is interested in such meterials, I have attempted an English language survey of about 8 cubic meters of materials found at Yokosuka Naval Yard (burried in caves) and a book by one of the officers of I-400 (all in Japanese).
It appears there were several variations of the design, and the original plan was to build 18 of them in two flavors (6 of those nuclear powered). In the event none were laid down at all - only the first of that design was funded and it got cancelled. These ships carried two bombers. They were proposed by Warrant Officer Fujida after he bombed the Oregon coast in a scout plane, forwarded by his XO and adopted by Adm Yamamoto.

After Midway the design was recast, only the first 6 were to be built to an expanded design (3 bombers), supplimented by 5 or 6 two plane upgrades of submarines already in the pipeline (A types redesignated SH). In the event only two of each were completed as such, and another as a tanker. Meanwhile, the nuclear project was transferred to the C4 attack program - more or less a C3 with the power plant designed for I-400. This may have been the first SSN design in the world - but maybe not? RN had one about the same time - about which we know a great deal less - as it won't declassify until 2045! Interestingly, that is not quite the end of the SSN story: the Japanese propulsion program was in present day North Korea, was captured substantially in tact by the USSR, and the prototype reactor was run by them until about 1948.
They also captured a completed (but unfueled) reactor for one of the C4s (the second) - and this apparently influenced Soviet design. The HEN program (Hotel Echo November) used reactors of exactly the same size (12,500 hp) - albiet 2 per boat. But the Japanese concept was rather different - and ultimately the Soviets only used it on land. It was based on very expensive heavy water - attractive as it avoids the need for enriched fuel or high pressure components. But it is hard to fit on a submarine - and only France is known to have tried that - and failed.

[DuckofTindalos]

Submarine-based floatplanes are vastly overpowered in WitP...

[el cid again]

Insofar as they can fly under too many conditions of sea, this is correct.

This could be fixed by a die roll (manual type) - you cannot assign a float plane to fly unless
a) you are in a coastal hex
b) you roll a certain number on the die

Sea based float planes are also underrated insofar as you cannot use them for proper recon missions of land bases, as noted above. And in most mods you are not given advanced float planes at all. In 1945 the First Submarine Flotilla was at sea - and two of the subs carried advanced recon planes.

[Dili]

I think all open sea recon is overpowered - in other hand radio intelligence is underpowered. This has diverse resons one of them is the aircraft availability Vs frequency of operations, crew fatigue etc, then for float planes there is also the recover times (for CS and AVs) , sea state, and gasoline. Anyone knows how many missions a Glen could make from a submarine, and if they had an engine replacement?

[ny59giants]

Has anybody ever given the Allied side a few hypothetical floatplane equiped subs in a mod? 
I know it was not historical, but just a handful would be nice to have. 

[DuckofTindalos]

Well, the French had the Surcouf, which Alikchi put into Iron Storm II, and the US experimented with submarine-launched float planes in the twenties, but very quickly gave it up again, seeing it for the bad idea it was...

[m10bob]

ORIGINAL: Terminus

Well, the French had the Surcouf, which Alikchi put into Iron Storm II, and the US experimented with submarine-launched float planes in the twenties, but very quickly gave it up again, seeing it for the bad idea it was...

Weren't you ever told not to pee in the pool?[:D]

[DuckofTindalos]

Erm, no... I figured that out myself...[:'(]

I took all submarine float planes out of my personal mod...

[Dili]

Well that's an exageration! They made nice recons of Sidney, Brisbane and other bases...

[DuckofTindalos]

And hey, guess what, they can't do it in the game! What they CAN do is fly several times a day, with little to no risk of being damaged or destroyed in accidents, which is completely unrealistic. The code handles them in a way that leaves them much too powerful.

I took them out because I wanted to, along with the majority of the IJN fleet boats, aircraft-carrying and otherwise...

[ChezDaJez]

They also captured a completed (but unfueled) reactor for one of the C4s (the second) - and this apparently influenced Soviet design. The HEN program (Hotel Echo November) used reactors of exactly the same size (12,500 hp) - albiet 2 per boat.

This is incorrect. Early Soviet nuclear reactor design was heavily influenced by US reactor development, not some hypothetical Japanese reactor. Indeed, Early Soviet submarine reactor design closely followed US developments and experimentations (albeit 2-3 years behind) including developing and installing a liquid-metal reactor in a single submarine (USS Seawolf SSN-575 [1957] and Soviet K-27 [1959]).

During the cold war, it was thought that the general design closely resembled that of the Nautilus, since confirmed by post-cold war inspections. The major difference being in reactor cooling design and the Soviet method of attaching the control rods to the reactor tank lid (which made it possible to lift the lid too far causing reactor criticality- at least 2 nuclear submarine accidents occurred this way). These reactors used 20% enriched uranium 235 as their fuel.

The VM-A PWR reactors installed onboard Soviet Hotel, Echo, Echo-II and November class submarines were capable of producing 70MWt. These classes used turbine gear reduction, turbine electric or a combination called split plant for propulsion. The turbines (not the reactor) were capable of approx 17,500 shp each for a combined total of 35,000 shp.

BTW, this is all open-source info. I have to be careful that I not divulge info not contained in open source references.

Chez

[el cid again]

ORIGINAL: Dili

I think all open sea recon is overpowered - in other hand radio intelligence is underpowered. This has diverse resons one of them is the aircraft availability Vs frequency of operations, crew fatigue etc, then for float planes there is also the recover times (for CS and AVs) , sea state, and gasoline. Anyone knows how many missions a Glen could make from a submarine, and if they had an engine replacement?

It appears that the Japanese fitted their true submarine aircraft carriers (not scout vessels) so that a number of missions could be flown in different profiles: with torpedoes, heavy bombs or lighter bombs. These vessels carried an entire disassembled aircraft as spare parts - so any required assembly was available. They could typically fly two missions as torpedo bombers, four with heavier bombs and six or more with lighter bombs (depending on loading). At least a dozen missions per aircraft. The flying boat tender was fitted with sufficient fuel and bombs for 15 missions.

But the scout submarines were a different kettle of fish entirely. In many cases you got just one mission - because the plane could not find the submarine again. Indeed, that experience led to innovations in the design of the true sub carriers - things like air search and surface search radar were added to help the ship guide her planes home. It is less easy to say how many missions were possible from bombs - because no bombs were normally carried. The single exception had enough for two missions on board. Fuel is a better indicator - but not entierly adequate: there were two different planes carried, with different fuel capacities; nothing said you had to embark 100% of the fuel; nothing said you must use 100% of the fuel on a mission - and in reality you don't do that. But it is reasonable to say that not less than 6 missions could be flown if maintenance was not a problem. And these submarines had an aircraft compliment of three: pilot, observer and mechanic. So some maintenance was possible. There are cases where these aircraft were used like the game code allows - search from a moving submarine at sea - and such cases did result in contact. But it was not possible in many sea states.

Air search is a powerful tool - and the biggest variables were meterological and human. Presumably the game code takes night and storms into consideration - so that is present. It may also be that pilot quality somewhat models the human aspect - as does plane type. [I believe that a scout plane is more likely to spot than, say, a fighter plane - although that isn't fair to the British scout fighters] If you want to get a sense of air search - take a flight in a light plane. Even at 500 feet you have fantastic visibility - if you are not dealing with fog or other meteorlogical issues. Much more so than you intuitively would expect. But if your observers are not trained, you will not do well. Thus, in most of history, most Army aircraft are not worth a lot in naval search, while aircraft with naval observers are worth a lot. Part of this is the observers ability to understand what they see? IJN Haruna was officially attacked by Colen Kelly in 1941 - in spite of not being anywhere in the area of the attack. The WITP model of letting die rolls simulate such things - and giving different national/service weights to algorithms - goes a long way toward creating the flavor of these variable. On balance, the search mechanism works remarkably well. It isn't really that easy to miss a task group of major ships in a daylight air search - although a single low lieing vessel in conditions of fog or darkness probably will almost never be seen. Everything else is in between. If we assume that a search aircraft transits a hex twice in a turn (outbound and inbound) - and that it on the statistical average is on the centerline of the hex - that means it must be within 30 nm or less of any possible target at least once - and statistically will be within 15 nautical miles or less 50% of the time - typically twice during the search period - but at least once. The search results are not very unreasonable in such conditions.

[el cid again]

ORIGINAL: Terminus

Well, the French had the Surcouf, which Alikchi put into Iron Storm II, and the US experimented with submarine-launched float planes in the twenties, but very quickly gave it up again, seeing it for the bad idea it was...

Which then means the research invested in a US version of the I-400s - with 3 jets no less - was entirely stupid?
What killed the idea was the advent of the cruise missile - which replaced the jets - and a number of both conventional and nuclear powered vessels did go to sea with them - before they too were upstaged by ballistic missiles. See Strike From the Sea for a history of this work in various navies. Also see US Submarines Since 1945 for a description and drawings of the "US I-400s". Interesting that major naval authors don't think it was such a bad idea.

[el cid again]

ORIGINAL: Terminus

Erm, no... I figured that out myself...[:'(]

I took all submarine float planes out of my personal mod...

Which, of course, makes it entirely true to history.

[el cid again]

ORIGINAL: ChezDaJez

They also captured a completed (but unfueled) reactor for one of the C4s (the second) - and this apparently influenced Soviet design. The HEN program (Hotel Echo November) used reactors of exactly the same size (12,500 hp) - albiet 2 per boat.

This is incorrect. Early Soviet nuclear reactor design was heavily influenced by US reactor development, not some hypothetical Japanese reactor. Indeed, Early Soviet submarine reactor design closely followed US developments and experimentations (albeit 2-3 years behind) including developing and installing a liquid-metal reactor in a single submarine (USS Seawolf SSN-575 [1957] and Soviet K-27 [1959]).

During the cold war, it was thought that the general design closely resembled that of the Nautilus, since confirmed by post-cold war inspections. The major difference being in reactor cooling design and the Soviet method of attaching the control rods to the reactor tank lid (which made it possible to lift the lid too far causing reactor criticality- at least 2 nuclear submarine accidents occurred this way). These reactors used 20% enriched uranium 235 as their fuel.

The VM-A PWR reactors installed onboard Soviet Hotel, Echo, Echo-II and November class submarines were capable of producing 70MWt. These classes used turbine gear reduction, turbine electric or a combination called split plant for propulsion. The turbines (not the reactor) were capable of approx 17,500 shp each for a combined total of 35,000 shp.

BTW, this is all open-source info. I have to be careful that I not divulge info not contained in open source references.

Chez

We were long very ignorant of Soviet reactor work. For example, we didn't understand the HEN series (the three original nuclear powered sub classes) used dual reactors - and it was thought they used just one - like we did.

Also - in all navies since WWII - submarine reactor fuel is not 20% enriched uranium. Indeed, reactor fuel is higher than the HEU used in nuclear weapons. It is 97% enriched. Indeed, it would not be possible to fuel any nuclear reactor ever built since WWII with 20% uranium - they would need to be much larger than they are. Only the French attempted a natural uranium reactor in this period - and it turned out so big the submarine (which still exists as a test ship for missiles but without a nuclear plant) was unable to carry it. It may be the Japanese natural uranium reactor is the only practical one ever actually completed - although until the British work is declassified we cannot be sure. The Soviets did capture one of these reactors and exported it to the USSR for study. One series of reactors in the USSR might be related to it in some ways - but the submarine reactor program indeed elected not to use the same technology. Nevertheless, the first design studies were based on that reactor - and the specification for plant size never changed. When the Russians learned we planned to build a 15,000 hp plant in Nautilus (it didn't end up quite that size), they took the simple expedient of using two reactors (of 12,500) to give them a total power advantage (at 25,000). Presumably by then the plant design was too far along to change its rating. And also the Soviets no doubt liked the principle of redundancy.

We all have to be careful not to divulge things not in open sources. In my case, I always have every source in my collection - and from time to time I am invited to show them to official investigators - who are often amazed at what is open source. At US Senate hearings, Oppenheimer described in open hearings things everyone believed was classified - but when called on it he said he merely had quoted what he read in the Encyclopedia Britannica that morning. Note, however, that just because a source is scholarly and/or official, or classified, does not make it correct. It only means that is what was known or believed at the time it was written. And in matters nuclear, sometimes what is officially written is known to be false, for various reasons. If you want to stir up a firestorm, try to get your hands on the official chemical analysis of the nuclear cargo of U-234 - which a neighbor of mine - a famous Manhattan Project Oak Ridge chemist - did a few years ago. Never mind the theory of automatic declassification - never mind that it hardly matters at this late date - it is still something that can produce remarkable (and contradictory) official statements.

[DuckofTindalos]

ORIGINAL: el cid again

ORIGINAL: Terminus

Erm, no... I figured that out myself...[:'(]

I took all submarine float planes out of my personal mod...

Which, of course, makes it entirely true to history.

Which, of course, isn't what it's supposed to be in the first place.[:-]

[DuckofTindalos]

ORIGINAL: el cid again

ORIGINAL: ChezDaJez

They also captured a completed (but unfueled) reactor for one of the C4s (the second) - and this apparently influenced Soviet design. The HEN program (Hotel Echo November) used reactors of exactly the same size (12,500 hp) - albiet 2 per boat.

This is incorrect. Early Soviet nuclear reactor design was heavily influenced by US reactor development, not some hypothetical Japanese reactor. Indeed, Early Soviet submarine reactor design closely followed US developments and experimentations (albeit 2-3 years behind) including developing and installing a liquid-metal reactor in a single submarine (USS Seawolf SSN-575 [1957] and Soviet K-27 [1959]).

During the cold war, it was thought that the general design closely resembled that of the Nautilus, since confirmed by post-cold war inspections. The major difference being in reactor cooling design and the Soviet method of attaching the control rods to the reactor tank lid (which made it possible to lift the lid too far causing reactor criticality- at least 2 nuclear submarine accidents occurred this way). These reactors used 20% enriched uranium 235 as their fuel.

The VM-A PWR reactors installed onboard Soviet Hotel, Echo, Echo-II and November class submarines were capable of producing 70MWt. These classes used turbine gear reduction, turbine electric or a combination called split plant for propulsion. The turbines (not the reactor) were capable of approx 17,500 shp each for a combined total of 35,000 shp.

BTW, this is all open-source info. I have to be careful that I not divulge info not contained in open source references.

Chez

We were long very ignorant of Soviet reactor work. For example, we didn't understand the HEN series (the three original nuclear powered sub classes) used dual reactors - and it was thought they used just one - like we did.

Also - in all navies since WWII - submarine reactor fuel is not 20% enriched uranium. Indeed, reactor fuel is higher than the HEU used in nuclear weapons. It is 97% enriched. Indeed, it would not be possible to fuel any nuclear reactor ever built since WWII with 20% uranium - they would need to be much larger than they are. Only the French attempted a natural uranium reactor in this period - and it turned out so big the submarine (which still exists as a test ship for missiles but without a nuclear plant) was unable to carry it. It may be the Japanese natural uranium reactor is the only practical one ever actually completed - although until the British work is declassified we cannot be sure. The Soviets did capture one of these reactors and exported it to the USSR for study. One series of reactors in the USSR might be related to it in some ways - but the submarine reactor program indeed elected not to use the same technology. Nevertheless, the first design studies were based on that reactor - and the specification for plant size never changed. When the Russians learned we planned to build a 15,000 hp plant in Nautilus (it didn't end up quite that size), they took the simple expedient of using two reactors (of 12,500) to give them a total power advantage (at 25,000). Presumably by then the plant design was too far along to change its rating. And also the Soviets no doubt liked the principle of redundancy.

We all have to be careful not to divulge things not in open sources. In my case, I always have every source in my collection - and from time to time I am invited to show them to official investigators - who are often amazed at what is open source. At US Senate hearings, Oppenheimer described in open hearings things everyone believed was classified - but when called on it he said he merely had quoted what he read in the Encyclopedia Britannica that morning. Note, however, that just because a source is scholarly and/or official, or classified, does not make it correct. It only means that is what was known or believed at the time it was written.

Ah, classic cid: being caught in an untruth, you try to obfuscate... Bra-vo![8|]