Fire Control

[phil gollin]

Japan's electronics industry was not sufficiently advanced for them to independently assess the real potential of radar. Considering their electronic industry overall was on a par with that of Italy, the quality and quantity of IJN electronics equipment actually deployed speaks of a very concentrated effort.

There is a lot of truth there.

The Japanese actually deployed a centrimetric naval radar before the USN - but it was relatively unsatisfactory and only deployed in small numbers.

They never really developed an efficient centrimetric cavity magnetron.

What they seemed to have developed is a reasonable microwave detector which the Germans might have found useful.

Why the Germans and Japanese didn't talk electronics together properly is one of the great mysteries of the war.

[Laurence Batchelor]

Not only the cavity magnetron.

The Bailey committee ensured that ALL british radar designs and samples of almost all radar equipment was sent over to the US in late 1940/early 1941.

In addition three US electrical engineers were sent over in late 1940 to examine all British all radars and look around the experimental establishments.

Yep we shared radar and the jet engine research amongst other things as other inducements for them to enter the war.

[Werner]

The notion that Japanese knew of their own gunnery deficiencies prior to WWII was also untrue. The Japanese had in fact planned on engagements out to beyond 38,000 yards and excercised accordingly. When Yamato first joined the combined fleet in 1942, she participated in an fleet exercise where she failed to hit (Definition of "Hit" is unclear) a target at 38,000 yards. This was considered a grave disappointment for the brand new battleship. Apparently at first it was felt that equipment performance expectation was not met and thus the inexperience of green crew was no excuse - Yamato class having the best fire control equipment in the IJN. Nevertheless a range keeper was later blamed for failing to properly use his intrument correctly. The next instance I know of when Yamato engaged in a super range firing exercise was 1944, when she, along with Musashi and Nagato successfully engaged a target at 38,000 yards - Again, definition of success is unknown to me.

The fact the Japanese exercised successfully by their own measure at such extreme range and yet seemly performed in battle mostly below expectation at closer range suggests to me that Japanese fire control is physically capable of very good performance, but lack the robustness to exhibit maximum performance in battle.

Chuck, thank you for this!!!!!! Now why have you been hiding it for years?

Can you post an attribution from English sources?

[Werner]

Fujimoto was fired. He didn't "take the blame" voluntarily.

Incidentally, all of the top heavy Japanese cruiser and destroyer designs were attributable to Fujimoto. The Japanese cruiser got lighter in construction and more questionable in stability the more Fujimoto was promoted. His first completely autonomous cruiser design not subject to the review of Hiraga his mentor and the navy board was the Mogami, whose hull was so flexible and bends so much in heavy sea that it actually deform the main caliber barbettes into ovals so the turrets jammed in train.

Watching that ship work in heavy seas must be like watching the wings of passenger planes flex in rough air.

Incidentally, his thinking was very advanced. His ships flex like modern ships. But he didn't work out all the consequences of having such a flexible hull.

I don't know if I'd go so far. Hiraga was primary designer of the first 4 classes of cruisers and Fujimoto was put in charge only when Mogami came along. His apologists say he was pressured by hotheads on the staff to overarm the ships on treaty tonnage.

I take a slightly different view. It appears to me that the Japanese staff was prepared to lie about overweight to about 30%, partly to gain military features and mostly to cover yard inefficiencies. Fujimoto misunderstood this course of action. Too bad he was not only cashiered, but committed suicide over this.

The staff was also prepared to endorse annual and quadrennial "refits" which amounted to major constructions greatly altering the military features and treaty compliance. Treaty be damned.

As a contrast, under the 1921 treaty, the British objected to the USA increasing the maximum firing angle of her battleships, (the British having more-or-less already completed this modernization on the ships that mattered). By 1930, the US was no longer considered a possible enemy and the change was permitted in the London Treaty. By way of comparison, some Japanese ships were regunned with an entirely new generation of much more effective 8-inch gun with nary a word spoken about it. They hid the changes in their very obscure mechanism for describing guns, mounts and calibers.

[Guest]

Hiraga was on a sabbatical to the UK during much of early 1920s. Although he was nominally the chief constructor, it was Fujimoto who did the real work. Hiraga and the Navy board than reviewed what Fujimoto had designed. Typically Hiraga would reject many of the Navy staff demands that Fujimoto had accepted and incorporated into the designs because Hiraga had the stature to do so.

But as confidence in Fujimoto increased, he was allowed progressively increased latitude in unsupervised work.

In general, Hiraga's ships were stable and well balanced because he would tell the Navy staff to eat :censored_2: when they demanded extra guns and other excessive top weight.

[Werner]

I agree that where Japanese ships matter, Engineer Hiraga is "The Man".

Fujimoto could produce excellent designs as his preliminary matter shows; perhaps he was too junior. Anyway, both men's designs became deadly and powerful by WW.II; among the very best in the world in each class and type. (from the prospective of a Jane's reader or one of the many books be Silverstone, Lenton & College...).

They were probably also the most expensive based on the amount of yard time in which different guns, protection, bulges, boilers and turbines were fit to them.

Akagi was reasonably the most expensive ship of the era.

[Laurence Batchelor]

Any idea of the costs expended on these IJN vessels during their respective rebuilds to back up this point of view?

[Werner]

The numbers are in Shattered Sword. I got the impression that the lifetime costs of Akagi in constant dollars could have purchased several Soryus.

Look at the costs of Mogami. If the Japanese are to be believed, they worked at least 6,000 tons of steel into her hull after "completion", and her 5 x 15.5cm triple turrets were replaced by custom-designed (conical steel base) 20.3cm twins....

Only 2 x 15.5cm turrets of the 36 ( + spares)was ever refit to another ship: Oyodo had them.

[Filipe Ramires]

Only 2 x 15.5cm turrets of the 36 ( + spares)was ever refit to another ship: Oyodo had them.

Not much familiar with this given I pay little or no attention to Yamato but aren't the 6.1'' guns of Yamato and Musashi the same as the early Mogamis?

[Werner]

Yes, but by late war the broadside mounts were stripped off in favor of the nearly useless 5-inch /40.

Interesting. I just for the first time came on a Japanese web source which called the 46cm "disappointing in service". Considering the religious status the ships have assumed in Japanese culture, this is "faint praise", indeed.

In reality they must have been considered nightmares.

[Guest]

Only 2 x 15.5cm turrets of the 36 ( + spares)was ever refit to another ship: Oyodo had them.

Not much familiar with this given I pay little or no attention to Yamato but aren't the 6.1'' guns of Yamato and Musashi the same as the early Mogamis?

Yes, those are. But they were modified with a new range finder mount. The original range finder was faired into the tops of the turret, the new ones were built on a budge above the turrets.

[Guest]

Yes, but by late war the broadside mounts were stripped off in favor of the nearly useless 5-inch /40..

The guns were in most ways directly comparable to the US 5"/38.

[Guest]

A total of 28 Mogami type 6"/60 triple turrets were built. 20 went into the 4 Mogamis, and 8 others were originally intended for the 2 ships of the Tone class. The turrets for Mogamis were removed to make way for the 8" type E turrets during their secret "upgrade" in 1940. The turrets for Tone were never installed as these ships were upgraded while still on stock.

Of those 28 turrets thus available, 8 were modified and installed in the Yamato class, 2 made its way into Oyoda. Those were all lost during the war. Several were captured by the US forces after the way in partially disassembled state. I believe a few was not clearly accounted for. I've read of no account of their being put to an obvious use - coastal defense.

These guns were outstanding in terms of ballistics, best of any 6" gun in WWII. The turrets were intended to be dual purpose - capable of AA barrage fire, but their rates of fire and the turret's rate of train was inadaquate. In any case, they were never intended to be the primary source of heavy AA firepower of any ships. But they would have been deadly destroyer killers.

The Japanese 5" guns which replaced them on the Yamatos was a true dual purpose weapon, with properties closely matching the US 5"/38 guns. It had 3 times the rate of fire of the 6" guns. However on the Yamato their role would have been purely AA.

[Werner]

Unlike the US 5-inch/38 the Japanese 5"/40 had no "variable time" mechanism. So, they were limited to barrage against formations of bombers (think B-17s), but at a closer range than before.

If you read the BuOrd circulars, before late 1942 most US captains were calling for the removal of the 5-inch and replacement with a 40mm quad where possible. After that date and the introduction of the VT projectile, it became the most loved AAA and bombardment gun of WW.II. The monthly tabulation of enemy planes destroyed by gun type bears this out.

Proof that the 127/40 was not well regarded is that Yamato only got her dose in 1944 and Aoba in 1945 after she was no longer sea-worthy. If it had been a useful weapon, it would have found higher production. As it is, it suffered the fate of most barrage guns. The real AAA work in Japan was done by the 12.7mm. Look at the production of this weapon for proof.

The 155/60 could never be compared to the US 127/38. It compares favorably to post war US artillery.

[Guest]

The primary Japanese Naval close range AA guns were the 25mm hotchkiss weapons in various single, double, triple and one experimental octuple mounts. The guns are fed by box magazines, thus the triple mount's center gun is difficult to load. Most mounts were manually powered. And it takes 9 men to run a triple mount. Most manually powered mounts relied on local optical control, a technique nearly useless against WWII aircraft. Those manual mounts that were bless with central director control relied on the crew manually elevating and training the mount to match a dial that relays the aiming instruction from the director. Only the relatively rare full enclosed triple mounts were power operated and remotely controlled from central director.

In general, the Japanese 25mm gun was somewhat better than 20mm free swinging Orlikons, somewhat less adequate that the discredited US quadruple 25mms, inferior to German 20mm Quad Flak, and vastly inferior to 40mm Bofors.

[Laurence Batchelor]

The numbers are in Shattered Sword. I got the impression that the lifetime costs of Akagi in constant dollars could have purchased several Soryus.
Oyodo had them.

I don't have the book as I don't study battles between the USN and IJN.
Please reproduce some of the figures as I'd like to see how they compare to the expenditure on the Royal Navy's rebuilds in the 1930s.

[Dan K]

The Japanes 127/40 was introoduced in the late 1930s. Upon rebuilding, all the Japanese BBs carried them on an upper deck, Soryu & Hiryu was commissioned with them, as were the Mogami/Suzuya/Tone classes. Yamato and Mususahi were also commissioned with 12 each in dual mounts as a tertiary battery (primarily AA). At the time, it was considered a good large caliber HA AA weapon by the Japanese.

Faster aircraft & lack of a proximity fused shell rendered them substandard by war's end.

[Guest]

The numbers are in Shattered Sword. I got the impression that the lifetime costs of Akagi in constant dollars could have purchased several Soryus.
Oyodo had them.

I don't have the book as I don't study battles between the USN and IJN. Please reproduce some of the figures as I'd like to see how they compare to the expendire on the Royal Navy's rebuilds in the 1930s.

It would be difficult to match cost to cost given that the international currency exchange rates were not free. Japan, being a less developed country, might well show less cost on a nominal exchange rate basis because their currency would tend to trade at below purchasing power parity. Just how much below PPP their currencies were would be hard to pin down for the same reason why there is such huge disagreement between the US and China now over what the real exchange value should be between the $ and the Chinese Yen.

[Laurence Batchelor]

Still it would good some sort of idea of comparison, especially if someone could tell me the cost of the ship as built and then the cost for the rebuild.
I can compare it proportionally to the cost for the first build itself even if not cross Navy.
That would give a fair representation

[Guest]

In any case, I think we may postulate the following as basis for estimating the relative weight constructors might place on cost vs performance:

1. If the Navy didn't build up to their treaty limits right away, that means whatever their political masters said, the money was not available, and money was the dominating restraint on warship design rather than treaty tonnage. Thus the constructor's primary goal would not be to squeeze as much out of treaty tonnage as possible, but to squeeze as much out of available fund as possible. Thus the ships would be economical.

2. If the Navy immediately built up to treaty limits, that means money is available and treaty limitation is the main constraint. In this case the constructors can be expected to treaty money like water in order to go through contortions to squeeze every possible drop out of available treaty tonnage. Thus the ships would be expensive (gold plated may be a better word)

Based on the fact that Japan built up to her treaty limits right away and was chaffing under the treaty terms which she only observed in a nominally way anyway, I would say Japan fell into the latter camp.

Neither Britain nor the US built up to the maximum allowed under the treaty right away, and Britain continued to believe that the treaty terms were too lax and her needs would be better served if the treaty terms were even tighter for everyone. So I would say the UK and US, at least initially, fell into the former camp.