IJN Yahagi 1944

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by Werner » Sat Jul 28, 2007 6:59 pm

I think if you look closely at the info, the "differential passive" system was probably indigenous. I believe the German homing system relied on doppler effect steering, which would mean "differential passive" was a Japanese development, and one a naturalist (like myself) would think of. The "right" and "left" ears of the torpedo would listen for the sound and when the amplitude was precisely equal, you were properly aimed. Of course, the torpedo would take a curved course to the target, the arc size dependent on target speed. The Japanese were well-suited with the fastest torpedoes and the longest range, so they could discount the cosine costs of this kind of guidance.

by Laurence Batchelor » Sat Jul 28, 2007 6:22 pm

I must have missed your earlier post.
I never said they were, I was making two seperate points about two different types of torpedo development they seemed to be doing.

This same report suggest further down the IJN had a fully working electric 21" torpedo by 1934 they had developed themselves. (p76)

Furthermore after going through page after page the Homing torpedoes are detailed on page290-298:
The experiments appear to have been confined to electrically driven torpedoes, and no information is forthcoming whether any operational success was acheived.
One type of these IJN homing torpedoes were modified Type 92 electric models.

by Werner » Sat Jul 28, 2007 6:16 pm

I posted the German delivery above; It was reported in navweps.com....

I do not believe they were homing torpedoes, simply electric torpedoes.

by Laurence Batchelor » Sat Jul 28, 2007 6:12 pm

I went through this USN report on Japanese weapons systems (I've been through this before, but as its so long I've never been through it all), thanks for reminding me of it!
Click section 0-01-1 and yes authors/researchers seem not to have been looking at these documents properly!:
"Homing Torpedoes": In an effort to develop a "homing" torpedo, the Japanese undertook experiments with hydrophone-equipped torpedoes designed to home on a sound source. Two principles were employed, one depending on the difference in sound intensity at two points, the other on phase difference. Only electric torpedoes (Type 92) were used for experiments.

The research met with only limited success, and the experiments were finally abandoned. p3
The date is not given when their development were abandoned, but at least this is supportive evidence they existed and the Japanese were developing them themselves.
Remember this report was compiled by an Allied technical mission to Japan mostly from whatever documentation survived and by talking to co-operative Japanese personnel.
They (the Allies) may not have been told the full story and what Hara is telling us is some actually were 'gambled' and fitted to the last remaining front line cruiser left the 2nd Fleet.

I've also just found something on page 31 which states Germany delivered 10 of their electric torpedoes to the Japanese in 1942.
Right thats it this thing is getting printed! :big_grin:

by Werner » Sat Jul 28, 2007 5:47 pm

Laurence Batchelor wrote:My mistake sorry correction December 1944 was the month Hara joined Yahagi and it would seem the new weaponry and equipment was fitted Jan/Feb 1945.
And the Final Sortie was after 1 April 45 while the invasion of Okinawa was underway.

I'm sure that the fact that Okinawa was technically part of the Tokyo Prefecture was a great morale reason for this one-way trip.

by Laurence Batchelor » Sat Jul 28, 2007 5:44 pm

My mistake sorry correction December 1944 was the month Hara joined Yahagi and it would seem the new weaponry and equipment was fitted Jan/Feb 1945.

by chuck » Sat Jul 28, 2007 5:36 pm

Laurence Batchelor wrote:
Werner wrote: How would you define Japanese "production" by April, 1945?
This was mid-1944 Werner!

Which was when Kaiten human torpedo became approved.

by Werner » Sat Jul 28, 2007 5:32 pm

Sorry, when you put Yahagi with Yamato, I thought "final sortie".

by Laurence Batchelor » Sat Jul 28, 2007 5:26 pm

Werner wrote: How would you define Japanese "production" by April, 1945?
This was mid-1944 Werner!

Gentlemen, I can only ask of you to read Hara's recently released book and make up your own mind.
I for one see him strikingly as a very thoughtful and methodical officer and commander.

I very much doubt the IJN would be sending their best cruiser (that was left) i.e. Yahagi on a one-way suicide mission with Kaiten suicide torpedoes.
Remember the fleet was something like 9 destroyers, Yahagi and Yamato and that was all the IJN had left of the 2nd fleet.
Consider their intended mission, to make it to the USN's landings off Okinawa and sink all they could.
This is why I believe it more likely this cruiser would be loaded with anything the IJN could 'pull out of the woodwork' e.g. the laboratory.
It's no coicidence Hara was pulled from the torpedo school to Captain Japan's best cruiser that was left to them.
They hoped their lucky Captain 'who always brought his destroyer home without a scratch' and their best torpedo Captain would work miracles for them once again.
This was desperation in the extreame and why also they gave him all the best tools the IJN had to offer at this time.

by Werner » Sat Jul 28, 2007 3:59 pm

chuck wrote:
Werner wrote:It appears that the political view of the USA was in agreement with the post-war veterans of the IJN in that it was essential to rehabilitate the institutional reputation of the Japanese Navy.

All documents need to be evaluated with this in mind. Both the Japanese speakers and American listeners had this as part of their mission, whether based on personal, institutional or national policy dictates.

At a stroke he dismisses all first hand accounts and all primary sources, and extorts instead the value of the true "Truth" as can only be accessed via his unique balance, impartiality and clairvoyance.
Have you read Shattered Sword? I am parroting Tully & Parshall's analysis. To my knowledge no professional historian has challenged this view.

by chuck » Sat Jul 28, 2007 3:41 pm

Werner wrote:It appears that the political view of the USA was in agreement with the post-war veterans of the IJN in that it was essential to rehabilitate the institutional reputation of the Japanese Navy.

All documents need to be evaluated with this in mind. Both the Japanese speakers and American listeners had this as part of their mission, whether based on personal, institutional or national policy dictates.

At a stroke he dismisses all first hand accounts and all primary sources, and extorts instead the value of the true "Truth" as can only be accessed via his unique balance, impartiality and clairvoyance.

:wave_1: :wave_1: :wave_1:

by Werner » Sat Jul 28, 2007 3:29 pm

It appears that the political view of the USA was in agreement with the post-war veterans of the IJN in that it was essential to rehabilitate the institutional reputation of the Japanese Navy.

All documents need to be evaluated with this in mind. Both the Japanese speakers and American listeners had this as part of their mission, whether based on personal, institutional or national policy dictates.

by chuck » Sat Jul 28, 2007 3:16 pm

Perhaps �homing torpedo� is an euphemism for suicide midget submarines based on Long-Lance torpedo body. The last survivors of the large class of 5500 ton Japanese light cruisers were converted to launch platforms for suicide human torpedo using a stern launching ramp.

by Dan K » Sat Jul 28, 2007 2:48 pm

For reference, the reports of the US Naval Technical Mission to Japan are posted online at: http://www.fischer-tropsch.org/primary_ ... MJ_toc.htm

I have the original book, and the that particular paragraph remains as you state. However, I should point out that the book was written 13 years after the war, plenty of time for selective memory and hindsight to creep into the picture. Hara also states that much of this equipment was highly experimental.

Immediately prior to his assignment to Yahagi, Hara ran the"Naval Torpedo School" at Yokosuka, where he reluctantly trained suicide torpedo boat crews. It is entirely possible that exposure to developments at the school were mixed up in his recollections. FWIW.

by Werner » Sat Jul 28, 2007 2:32 pm

Laurence Batchelor wrote:My thoughts are all these weapons went straight from the laboratory to the dockside for fitting.
I doubt they were production, more likely early prototypes.
Just enough to fit out the ships in this one-way suicide mission.
How would you define Japanese "production" by April, 1945?

Torpedoes built in a garage using parts machined on tools in someone's living room is Japanese 1945 production.

By this point, apart from the mass production of various suicide craft in anticipation of Operation Olympic, their efforts seem concentrated on producing an interceptor for B-29s that could actually reach them before it was out of fuel or they dropped their bombs.

by Laurence Batchelor » Sat Jul 28, 2007 2:03 pm

My thoughts are all these weapons went straight from the laboratory to the dockside for fitting.
I doubt they were production, more likely early prototypes.
Just enough to fit out the ships in this one-way suicide mission.

by Werner » Sat Jul 28, 2007 1:09 pm

According to NAVWEPS, 10 German G7e torpedoes were delivered to Japan in 1942. The resulting Type 92 mod 2 was supposed to acoustically home based on differential sound, but self noise was a big problem, and the project was killed for want of manpower.

Based on this information alone, I believe it is possible Hara may have had some torpedoes modified with either the 1942 German equipment installed, or the differential sensors removed from the prototype 92 mod 2 torpedoes.

He did not say they were "production" homing torpedoes, nor did he say he knew them to be especially effective first-hand. Although he implies he believed them to be effective, that may simply have been what he was told.

I think we can all agree that with the chaos in the Japanese procurement system, a larger program would have left a paper trail obvious in post-war analysis.

Although the Army and Navy frequently pursued identical goals independently, The Japanese Navy of this era does not seem to pursue different technologies as a backup. The Kaiten was their answer for active torpedo guidance.

by Laurence Batchelor » Sat Jul 28, 2007 12:31 pm

Thats what I saying can anyone point me to 'proper technical IJN stuff'.
I would have thought people in the USA would scrutinise and spot these small things I have, just by reading a �20 USNI book?

Can anyone point to some references? Journals articles, books, Japanese language stuff, anything? I can order alot out of the British Library.

by Werner » Sat Jul 28, 2007 12:25 pm

Pineau also swallowed Fuchida's accounts hook, line & sinker both during the USSBS interviews and later. He wrote glowing things about Fuchida's forthrightness and honesty.

I am not saying they didn't develop a 24" surface launch homing torpedo. It's just that there is as yet no second source for this information, and the very words "homing torpedo" may have meant something very different in the speakers mind and the listener's ears.

We have to leave Hara at his word and look for other references.

by Laurence Batchelor » Sat Jul 28, 2007 12:20 pm

Can somebody please check their older paperback version of Hara's book. The quotes come from the final chapter.
This brand new version I have was supposed to have corrected any mistakes in his text.
If someone can compare what the original translation says to what mine does above that would quash one idea.

I have found nothing out-of-place in the rest of the book.
Surely such a glaring mis-translation from two well respected authors/researchers as the two gentlemen are isn't likely in my opinion.

On the books new duscover it says this about them:
'Fred Saito translated and expanded the original manuscript, after spending more than 800 hours interviewing Captain Hara, to make the book as full and accurate an account as possible. Saito was a journalist with the Tokyo office of the Associated Press from 1948-1960 and later served on the staff of the Japan Broadcasting Company. He also translated Samurai!, the story of one of Japan's greatest fighter pilots by Saburo Sakai and Martin Caidin'.
Roger Pineau served in the U.S. Naval Reserve during WW2. After the war, he became a member of the U.S. Strategic Bombing Survey in Japan and later assisted Rear Adm. Samuel Eliot Morison in preparing the authoritative History of the United States Naval Operations in WW2. Pineau added the footnotes to Captain Hara's memoir, including the names of U.S. ships and commanders that engaged the Captain's forces, and checked the accuracy of the battle accounts. He also assisted with the writing and fact checking of two other books by Japanese authors about war, The Divine Wind and Midway'.
With all of this above in mind I really doubt this is a translation error.
We have an excellent operational guy and someone who spent all those hours interviewing him.
I'm sure the homing torpedoes would have cropped up in the conversation.

I still believe when Yahagi sortied she had them along with the weaponry stated, as I've not come across any clear evidence to the contrary.
Just because there is little information on these late war toys, in print, in my mind, doesn't mean they didn't exist and were not rushed to the front line due to the IJN's desperation.

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