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- Posted By: Andrew Johnson <mailto:ajo@ceh.ac.uk?subject=Serious Seiran questions!>
Date: Wednesday, 30 May 2001, at 4:07 a.m.
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- I have been inspired by the photo of the restored Seiran on the message board to go out and buy my own Tamiya kit! I wonder if anyone else has? Try as I might I cannot find any photos of completed Tamiya Seirans on the web, surely there must be some out there?
- I am still confused as to whether the Seirans' were due to be catapulted from the I-400 submarines without their floats? The box art appears to show floats magically being run out from their own wells, a bit like an old 'Thunderbirds' episode! If floats were only present on training versions then the decals provided by Tamiya are
inoppropriate?
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- Thanks
- Andrew Johnson
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- Re: Serious Seiran questions!
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- Posted By: Chris Allred <mailto:allredchris@hotmail.com?subject=Re: Serious Seiran questions!>
Date: Wednesday, 30 May 2001, at 10:13 a.m.
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- In Response To: Serious Seiran questions! (Andrew Johnson)
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- Andrew, The Serian didn't need to have floats to be catapulted off the sub(the weight would reduce the bomb load. The floats were stored in seperate "Tubes"(both port and Starboard)and brought out when needed.
- I've built a Serian as it was stored and there is a photo of her on this site, I'm also building a section of the I-400. Both will be at nationals.
- I could go on and on but, if you have any more questions feel free. Banzai Chris Allred
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- Re: More Serious Seiran questions!
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- Posted By: Andrew Johnson <mailto:ajo@ceh.ac.uk?subject=Re: More Serious Seiran questions!>
Date: Wednesday, 30 May 2001, at 10:18 a.m.
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- In Response To: Re: Serious Seiran questions! (Chris
Allred)
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- Dear Chris
- This leaves me a little puzzled. Why take the floats on the submarine if they did not intend to use them? Would I be right in then thinking that the Seiran with floats could not have taken off from the water or be catapulted into the air carrying the 800 kg bomb?
- Is there any chance you could jpeg and post your Seiran to j-aircraft or me? Would love to see it.
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- Thanks
- Andrew
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- Re: More Serious Seiran questions!
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- Posted By: Bill Leyh <mailto:hawk81@pacbell.net?subject=Re: More Serious Seiran questions!>
Date: Wednesday, 30 May 2001, at 4:41 p.m.
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- In Response To: Re: More Serious Seiran questions! (Andrew Johnson)
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- Andrew,
- The floats were carried for training flights. In the actual attack, the Seiran would have been launched without floats.
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- HTH,
- Bill
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- Re: More Serious Seiran questions!
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- Posted By: Hiroyuki Takeuchi
Date: Wednesday, 30 May 2001, at 7:26 p.m.
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- In Response To: Re: More Serious Seiran questions! (Bill
Leyh)
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- The plane/subamrine were designed so that it could carry out conventional missions but the two missions planned for the weapon system were both Kamikaze missions.
- Since the attacks both did not take place, training flights were the only flights they made.
- These training flights were more or less training for the submarine crew so that they could assemble, launch and recover the plane
asap.
- The landplane version M6A1-K was used to train pilots for the attack flights since they would be flying the Seirans in a floatless configuration in the attack.
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- Re: More Serious Seiran question 2s!
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- Posted By: Andrew Johnson <mailto:ajo@ceh.ac.uk?subject=Re: More Serious Seiran question 2s!>
Date: Thursday, 31 May 2001, at 2:00 a.m.
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- In Response To: Re: More Serious Seiran questions! (Hiroyuki Takeuchi)
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- Thanks Chris, Bill, Hiroyki
- I think I'm getting there. When the I-400 boats sailed off on their mission with their Seirans' they had a few training days on the cruise whereby they could launch and recover their aircraft. So the submarines had cranes to recover their planes?
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- More questions:
- The Garber Seiran seems to have a large reflector gunsight for the pilot, but am I right in thinking the aircraft had no forward facing guns? Why the
gunsight?
- The Seiran was powered by a Japanese copy of the DB-605, wasn't this engine a big failure in the 2nd generation Ki-61? Did Aichi succeed where Kawasaki failed, or are we talking about different engines?
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- Thanks for all your help
- Andrew
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- PS Do any interviews survive from any Seiran pilots? Was any allied technical intelligance put together on the
Seiran?
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- Re: More Serious Seiran question 2s!
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- Posted By: Hiroyuki Takeuchi
Date: Monday, 4 June 2001, at 11:07 p.m.
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- In Response To: (Andrew Johnson)
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- Actually many weeks of training took place before they sailed off to attack. It took the sub crew something like half an hour to assemble and launch the aircraft in the beginning. By the time they sailed off, they could do it in a few minutes.
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- Mr. Takahashi, a former Seiran pilot on the I400 is still alive and well in Tokyo. He's writing an serial autobio on Maru Monthly now.
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- I-400 link
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- Posted By: Bill Sanborn <mailto:bsanborn@psemc.com?subject=I-400 link>
Date: Friday, 1 June 2001, at 8:47 p.m.
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- In Response To: (Andrew Johnson)
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- Andrew,
Thought you might find this interesting.
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- Bill
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- Re: More Serious Seiran question 2s!
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- Posted By: Mike Goodwin <mailto:Mike.Goodwin@iname.com?subject=Re: More Serious Seiran question 2s!>
Date: Thursday, 31 May 2001, at 2:56 p.m.
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- In Response To: Re: More Serious Seiran question 2s! (Chris
Allred)
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- The Aichi DB601 copies were generally thought to be less reliable than the Kawasaki ones. Kawasaki's original Ha-40 was actually fairly robust, the later Ha-140 was the one with problems.
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- After having tried the Atsuta in the D4Y1, I believe that the IJNAF would rather have forgotten about it. But it was needed in the M6A because the thrustline was then lower, meaning that the propeller could be mounted low enough to fit in the submarine. I believe that the Atsuta engineers for the M6A mission were the cream of those from D4Y1 operations, who were necessary to get the maximum possible number running for the operations.
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- Cheers,
- Mike
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- Re: More Serious Seiran question 2s!
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- Posted By: Bill Leyh <mailto:hawk81@pacbell.net?subject=Re: More Serious Seiran question 2s!>
Date: Thursday, 31 May 2001, at 6:08 a.m.
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- In Response To: (Andrew Johnson)
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- Andrew,
- My only reference for the Atsuta says it was a license-built version of the DB601A. I'd be VERY interested to know the answer to your question about Aichi vs. Kawasaki engines though!
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- As for the reflector sight, it probably was used for bomb aiming.
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- Regards,
- Bill
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- Posted By: Hiroyuki Takeuchi
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Date: Monday, 4 June 2001, at 11:01 p.m.
- In Response To: Re: More Serious Seiran question 2s! (Bill
Leyh)
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- IJN and IJA both bought licences for the DB601 separately and paid Germany twice what would have been necessary in precious foreign currency. Then they separately assigned not Nakajima or Mitsubishi who catered for both services, but Aichi and Kawasaki who catered exclusively for IJN and IJA resectively, to licence build them separately.
- There were no interaction between Aichi and Kawasaki in modifying the design to suit Japanese production. One of the main problems in licence building the DB601 was the fuel injector which Bosch refused to sell. I don't remember which was which but if memory serves me correctly, Aichi went ahead and made a dead copy of the Bosch injector and Kawasaki had Mitsubishi modify the injection device developed for the Ha112II.
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- The Ha140 is not a licence built version of the DB605, but a Japanese development of the Ha40 using similar methodology (increased boost pressure and rpm).
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- Re: Atsuta & Ha40/140
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- Posted By: richard dunn <mailto:rdunn@rhsmith.umd.edu?subject=Re: Atsuta & Ha40/140>
Date: Tuesday, 5 June 2001, at 5:43 p.m.
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- In Response To: Atsuta & Ha40/140 (Hiroyuki Takeuchi)
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- Hiroyuki
- You are right Mitsubishi built the fuel injector for Kawasaki. They had problems with it because of the high pressures involved. Something a post-war US technical report based on knowledgeable Japaneses says "was never really solved."
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- Rick
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- Re: Atsuta & Ha40/140
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- Posted By: Bill Leyh <mailto:hawk81@pacbell.net?subject=Re: Atsuta & Ha40/140>
Date: Monday, 4 June 2001, at 11:38 p.m.
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- In Response To: Atsuta & Ha40/140 (Hiroyuki Takeuchi)
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- Thank you, Hiroyuki! That's very interesting. Price gouging seems to have been a common practice in the international arms markets. Curtiss did the same to the French with the Hawk75.
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- Wasn't the crankshaft the most frequent failure item in the Sanshikisen Ha-40 installation?
- I saw a documentary a while ago in which a mechanic who worked on the Black 6 Bf-109 restoration in England related a conversation with a Rolls-Royce engineer concerning the Daimler Benz engine who said "For heaven's sake, don't damage the crankshaft. We couldn't make another with the tooling we have today." The English mechanic was apparently very impressed with how close the tolerances were in the engine.
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- Do you know any of the specifics of the problems with the cooling system in the
sanshikisen?
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- Regards,
- Bill
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- Re: Atsuta & Ha40/140
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- Posted By: Hiroyuki Takeuchi
Date: Tuesday, 5 June 2001, at 12:04 a.m.
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- In Response To: Re: Atsuta & Ha40/140 (Bill
Leyh)
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- As far as I know the main cause of the problem was in crankshaft material and metallurgy. Japan did not have the nickel needed to make the prper alloy, nor did it have the techniques in metallurgy to mass produce satisfacotry products with nickel-less material.
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- Re: Atsuta & Ha40/140
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- Posted By: Bill Leyh <mailto:hawk81@pacbell.net?subject=Re: Atsuta & Ha40/140>
Date: Tuesday, 5 June 2001, at 12:21 a.m.
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- In Response To: Re: Atsuta & Ha40/140 (Hiroyuki Takeuchi)
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- Interesting! That's the first I've ever heard of a nickel shortage impacting Japan's materials engineering. The Ha-40 is the only engine I know of that suffered from this problem. Do you have any idea why only this engine was so affected?
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- Re: Atsuta & Ha40/140
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- Posted By: Hiroyuki Takeuchi
Date: Tuesday, 5 June 2001, at 12:36 a.m.
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- In Response To: Re: Atsuta & Ha40/140 (Bill
Leyh)
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- The long crankshaft required for the in-line engine demanded more precision and strength than that of radials. The BMW based Ha9 V12 were also never reliable.
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- Re: Atsuta & Ha40/140
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- Posted By: Deniz Karacay <mailto:denizkaracay@yahoo.com?subject=Re: Atsuta & Ha40/140>
Date: Thursday, 7 June 2001, at 7:44 p.m.
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- In Response To: (Hiroyuki Takeuchi)
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- Hello,
- Thank you and others for the information about Japanese engines. I follow the threads with keen interest.
- I beleive it was you who also said Japanese delegation found it Junkers Jumo more suitable for Japanese production methods but rejected for some reason.
- Did they ever show interest in BMW801, DB603 or Jumo213?. They imported Me210 with 410 standards thus having DB603s, a FW190.
- Also is the refusal of Bosch to sell injectors due to production needs of Germany or they just don't want to give the technology (which sounds unlikely to me)
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- Thanks in advance
Deniz
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