Nagumo with 7 carriers at Midway

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glenn239
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Re: Nagumo with 7 carriers at Midway

#166

Post by glenn239 » 04 Oct 2017, 17:08

alecsandros wrote: My personal opinion so far is that , lacking information on the enemy location, Yamamoto/Nagumo should have produced a scout group with either 1 small carrier and 2 seaplane carriers, or multiple heavy cruisers with 1 small carrier for local fighter support. The scout group should have been spearheading the attack by 1 day (1 day ahead of Nagumo's main fleet), and should have performed only scouting using long-range seaplanes , passing over Midway for photo recon, and covering at least 250nm of water around the atoll, in a 180 deg semicircle to the North, East and South of the atoll.
Perhaps, but Genda said his personal inclination was to attack Midway with the smaller carrier group while Nagumo's larger group remained in reserve. Given the USN plan, had that actually happened, it could have been really bad, as the main USN blow might land on the wrong force while Nagumo hits with a two-decker attack.
In any case, the principal advantage would have been giving advance vision to Nagumo, which, in this case wouldn't have stumbled blindly into an opened trap...
Without information on US carriers Nagumo could have two-stepped his attack. Remain further from Midway in the morning for naval scouting and naval attack and, if nothing was discovered, rearm for land assault and close on Midway for a full strength attack in the afternoon.

alecsandros
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Re: Nagumo with 7 carriers at Midway

#167

Post by alecsandros » 04 Oct 2017, 17:11

glenn239 wrote:1030-11am for the takeoff of the torpedo bombers is the estimate the 2nd Carrier Division itself gave at 0900 during the battle. Hiryu's 9 torpedo bombers were not ready to go at 1030 or else they'd have been launched, but whether after 11am Yamaguchi held them back, or they were delayed, is not clear.
It is improbable that Hiryu could get off a 18 dive bomber + 9 torpedo bomber strike wave, with 6 fighter escorts.

However, the information brought by Soryu's D4Y at 11:45, which identified all 3 USN carriers operating in 2 distinct task forces was a clear indication on the necessity of launching the torpedo bombers as well - which, in what appears to be the logical course of action, would have necessited a launch as fast as possible. That was only possible at 13:30.
Isom was trying to explain the result of the Battle of Midway by way of rearmament delays, so he was in the market for finding rearmament delays. His model was so time-sensitive that he had to adapt a practically nonsense position on the 0745 HQ 'hold' order because admitting the rearmament was stopped at that point eliminated his entire reconstruction. Kusaka estimated it would take 1 hour to convert from torpedoes back to bombs, and he believed it on June 4th 1942, because at 0715 he ordered it knowing full well that the Midway strike would have returned to orbit by 0800.
Isom quotes a Japanese Navy official document dated Fev 1942, when tests were done on board Hiryu to exacly time the amount of time required to switch the B5Ns from torps to bombs or viceversa.
1st Air Fleet HQ differentiated between the rearm time of dive and torpedo bombers. Genda stated that, while he planned on the dive bombers from Midway joining in the attack on the US fleet, the torpedo bombers might not. 2nd Division's actual estimate at 0900 was between 1.5 and 2 hours to launch positions for 9 torpedo armed bombers each, these then in orbit, not yet having landed at that time. Your estimate of 2.5+ hours looks more appropriate for 18 bombers.
That is what they estimated, not what they actualy accomplished. Remember the times at Santa Cruz - it took over 3 hours for Zuikaku to launch his afternoon strike. And that with only a handfull of operational (thus only ones rearmed and refueled) machines.


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Re: Nagumo with 7 carriers at Midway

#168

Post by alecsandros » 04 Oct 2017, 17:24

glenn239 wrote:
Perhaps, but Genda said his personal inclination was to attack Midway with the smaller carrier group while Nagumo's larger group remained in reserve. Given the USN plan, had that actually happened, it could have been really bad, as the main USN blow might land on the wrong force while Nagumo hits with a two-decker attack.
Ah, that's right.
If Spruance would have committed to attack Ryujo/Junyo, along with the ~ 60 Midway-based bombers, Nagumo would have remained free to attack and destroy Spruance's task forces with 108 + 84 machines, probably destroying all 3 carriers while losing no more of 30 machines + 30 damaged, of which 10 repairable in Japan.

HOwever,

the problem was the PBY range, and search plan established by the US commanders. That PBY range coupled with that search plan almost ensured that both Ryujo/Junyo force AND Nagumo's 4-carriers force would both have been found in the morning of June 4th (before 6:00), and thus Spruance could actualy launch a full attack on Nagumo still.

But, Nagumo would also launch his 2-deck strike.

What would change would be the effect of the USN 150-machines spread over 1 hour over Nagumo. My estimate is that Kaga would be badly damaged , but not sunk, while Soryu would be sunk. AKAGI and HIRYU would remain undamaged, while the USN aviators would fly to Midway to land, because their carriers had been sunk.

THe afternoon "final strike" from AKAGI/HIRYU / JUNYO / RYUJO would destroy Midway air force, mostly being still not refueled from the morning strikes.

glenn239
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Re: Nagumo with 7 carriers at Midway

#169

Post by glenn239 » 04 Oct 2017, 18:08

alecsandros wrote:
Exactly, Kaga had 26 torp bombers, and they would have to be ready for the strike as well. The Japanese requirement to coordonate the entire strike wave implied that the attack couldn't be vectored until all the machines were launched in the air. That was contrary to USN contemporary practice, which implied squadron-sized or 2-squadron sized piecemeal attacks, instead of waiting for the entire wave to form, and then for the several waves of the multiple carriers to concentrate all their machines.
IJN doctrine required simultaneous arrival on target of the strike force, not its simultaneous launch. At Midway a simultaneous launch was out because Kaga fell behind, so the launch would have been staggered more than was normal when Kido Butai wasn't under air attack.
Thus actual launching and forming of the attack group couldn't have happened before 11:30-12:00
Launch between 1030 and 11am, with Akagi going first and Kaga last, (ie, up to 30 minutes difference in the start of launch between the two ships), departure of the assembled group around 1115-1130.
(Hiryu had dive-bombers to spot at 10:54, and not torpedo bombers. Remember the torpedo bombers (9+1 of them) were only launched at 13:30.)
Hiryu's spot was obviously already underway by 1025. That's why she launched at 1054 even while evading torpedo attack at full speed.

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Re: Nagumo with 7 carriers at Midway

#170

Post by alecsandros » 04 Oct 2017, 18:27

Hiryu's spot was obviously already underway by 1025. That's why she launched at 1054 even while evading torpedo attack at full speed.
Agreed - with the important notice that that was a dive bomber spot, and not a torpedo-bomber spot.

glenn239
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Re: Nagumo with 7 carriers at Midway

#171

Post by glenn239 » 04 Oct 2017, 18:35

alecsandros wrote: It is improbable that Hiryu could get off a 18 dive bomber + 9 torpedo bomber strike wave, with 6 fighter escorts.
Had they been ready, something like 18 dive bombers in the first deck load, 9 torpedo bombers in the second, then depart to target. (This method was first done in battle during the Darwin Raid).
However, the information brought by Soryu's D4Y at 11:45, which identified all 3 USN carriers operating in 2 distinct task forces was a clear indication on the necessity of launching the torpedo bombers as well - which, in what appears to be the logical course of action, would have necessited a launch as fast as possible. That was only possible at 13:30.
Something other than time to arm 9 bombers will have caused the delay. Perhaps damage repair.
Isom quotes a Japanese Navy official document dated Fev 1942, when tests were done on board Hiryu to exacly time the amount of time required to switch the B5Ns from torps to bombs or vice versa.
But it was Hiryu itself that reported to Akagi at Midway at 0900 that it's division could launch its 9/9 torpedo bombers returning from Midway between 1030 and 11am.
That is what they estimated, not what they actualy accomplished.
The 0900 estimate was given before the planes had landed and been inspected for damage. When the strike was made, Yamaguchi wanted as many torpedo bombers sent as possible. Tonomonga's lead plane was even sent with a defective fuel tank - they had no time for a proper repair.

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Re: Nagumo with 7 carriers at Midway

#172

Post by alecsandros » 04 Oct 2017, 18:41

glenn239 wrote:

But it was Hiryu itself that reported to Akagi at Midway at 0900 that it's division could launch its 9/9 torpedo bombers returning from Midway between 1030 and 11am.
If it's about the Midway returning planes, probably both numbers are accurate.

Isom gives times for switching and for arming. Switching from land bombs to torps took 90minutes, while directly arming the B5Ns with torps (meaning they were empty of load) took 60 minutes.

It's possible that , with the aid of pilots/navigators/etc, those numbers could actualy be lowered...

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Re: Nagumo with 7 carriers at Midway

#173

Post by glenn239 » 04 Oct 2017, 18:42

alecsandros wrote: Agreed - with the important notice that that was a dive bomber spot, and not a torpedo-bomber spot.
No difference on that AFAIK. The important point is that 2nd Division did not care Kaga had been delayed. Hiryu's 1054 launch while under torpedo attack says to me its spot had already started before Kaga was bombed. Once the spot had been started, launch was automatic. No carrier was sailing around with a flight deck full of strike aircraft waiting for Kaga to catch up.
Last edited by glenn239 on 04 Oct 2017, 18:54, edited 3 times in total.

alecsandros
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Re: Nagumo with 7 carriers at Midway

#174

Post by alecsandros » 04 Oct 2017, 18:47

glenn239 wrote:
alecsandros wrote: Agreed - with the important notice that that was a dive bomber spot, and not a torpedo-bomber spot.
No difference on that AFAIK. The important point is that 2nd Division did not care Kaga had been delayed. Hiryu had already started is spot before Kaga was bombed. Once the spot had been started, launch was automatic. No carrier was sailing around with a flight deck full of strike aircraft waiting for Kaga to catch up.
I wanted to say that preparing (below decks) a dive bomber spot was faster then preparing a torp bomber spot. In other words, if 2 carriers would both start equipping - first 18 Vals, second 18 Kates, the first carrier would be ready faster then the second (all other things being equal)...

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Re: Nagumo with 7 carriers at Midway

#175

Post by glenn239 » 04 Oct 2017, 18:49

alecsandros wrote:
Isom gives times for switching and for arming. Switching from land bombs to torps took 90minutes, while directly arming the B5Ns with torps (meaning they were empty of load) took 60 minutes.
Right, but when Isom is citing a Hiryu exercise and it was Hiryu itself that radioed its estimate at Midway, Hiryu is already aware of what it had done in the Indian Ocean. I believe the specific Isom figures 40 minutes per group of 6 aircraft when going from bombs to torpedoes, 30 minutes per 6 aircraft when going from torpedoes to bombs. Isom assumed 6 carts (not 9) for Akagi. Had he assumed 9 carts then the rearm would take 1 hour, bang on to what Kusaka said. 2nd Division's planes were orbiting empty when the 0900 estimate was made, so there was no requirement to unload and store bombs or torpedoes. Bringing torpedoes up from the magazine could have commenced at 0900. That is, as the planes were landing. I suspect that repairing aircraft was a big part of the delay.
Last edited by glenn239 on 04 Oct 2017, 18:51, edited 1 time in total.

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Re: Nagumo with 7 carriers at Midway

#176

Post by glenn239 » 04 Oct 2017, 18:50

alecsandros wrote: I wanted to say that preparing (below decks) a dive bomber spot was faster then preparing a torp bomber spot. In other words, if 2 carriers would both start equipping - first 18 Vals, second 18 Kates, the first carrier would be ready faster then the second (all other things being equal)...
Right, torpedo bombers took longer to arm, but once the planes were ready to spot, AFAIK there was no difference in the time that took.

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Re: Nagumo with 7 carriers at Midway

#177

Post by alecsandros » 04 Oct 2017, 19:14

I think much the same thing.

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Re: Nagumo with 7 carriers at Midway

#178

Post by Eugen Pinak » 06 Oct 2017, 10:18

alecsandros wrote:It's curious that an Admiral often times mentioned as "overly-cautious" actualy took a terrific gamble at 7:25, by ordering the comittment of his reserve anti-shipping force to be re-equipped with land attack weapons, in effect robbing him of any chance of potential counterattack up until at least 12:00 (earliest time when the 1st strike planes against Midway would have been ready for spotting on the flight decks of the 4 Kido Butai carriers). Hence Nagumo took a big risk by constientiously opting for remaining without an anti-shipping force for at least 4h30m hours (7:25 - 12:00).
There was nothing risky in Nagumo's decision. All he could reasonably expect to encounter, were submarines and some surface ships - nothing too dangerous for his force.
As for Nagumo's "caution", I know about two contemporary sources, claiming him to be over-cautions: Combined Fleet HQ (that liked to put his force in harm's way and than complained, that he could do better - universal complaint :) ) and admiral Yamaguchi (who obviously aimed at Nagumo's place so he never hesitated to voice some slander about his boss).
alecsandros wrote:This is even more curious, IMHO, because Nagumo broke radio silence on June 2nd 10:30 in the morning, to rally his fleet.
He mentions this in his post-action report. He also mentions that that may have been the moment when the enemy "discovered" him.
That's what Narumo really sates on this matter: "We were not discovered until early in the morning of the 5th at the earliest."
glenn239 wrote:Interestingly, Genda answered a question after the war on what he'd have done if Ryujo and Junyo had been assigned to Midway. He said,

...the task force should have been reserved for a decisive battle with the American main force. In order to do so, however, the Aleutians operation should have been called off, so that the 2nd task force might be used to attack Midway."

That seems to imply that Nagumo's main striking force would not have attacked Midway at all, instead Ryujo and Junyo would have while Nagumo lurked in the shadows. That plan might have been trouble...
After the war Genda could tell anything he want - hindsight is always 20/20 ;) Of course, during the battle there was a question of sending Kakuta to support Nagumo after one Japanese force was, in the eyes of Combined Fleet HQ, discovered by US submarine before the battle. Ugaki in his diary laments about not following this idea.
glenn239 wrote:Furuta's (dive bomber squadron leader, Akagi) has his account in Beyond Pearl Harbor. He says that when Kaga was dive bombed his Val was already on the flight deck, (he said taken to the deck' from the hanger after completing rearmament and refuelling). He ran to the head to relieve himself because he figured, at 1022, that he would be taking off within minutes.
The problem with Furuta's account is, that there were no dive-bombers from "Kaga" included in this attack force.

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Re: Nagumo with 7 carriers at Midway

#179

Post by alecsandros » 06 Oct 2017, 11:38

Eugen Pinak wrote: That's what Narumo really sates on this matter: "We were not discovered until early in the morning of the 5th at the earliest."
(2) We were still fog-bound on the morning of 3 June [June 2 local time]. Were we to proceed on our course and speed, we would be unable to meet the operation schedule for N-day. We finally broke radio silence, therefore, at 1030 to order a change of course. We presume that this gave the enemy an opportunity to detect us. The fog lifted somewhat by 1250, but this was after we had gone on the air.

http://midway1942.com/docs/usn_pub_02.shtml

We are bound to note the interesting distinction between "discovered" and "detected".

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Re: Nagumo with 7 carriers at Midway

#180

Post by glenn239 » 06 Oct 2017, 15:23

Eugen Pinak wrote:
There was nothing risky in Nagumo's decision. All he could reasonably expect to encounter, were submarines and some surface ships - nothing too dangerous for his force.
As for Nagumo's "caution", I know about two contemporary sources, claiming him to be over-cautions: Combined Fleet HQ (that liked to put his force in harm's way and than complained, that he could do better - universal complaint :) ) and admiral Yamaguchi (who obviously aimed at Nagumo's place so he never hesitated to voice some slander about his boss).
If Yamaguchi has any strikes against him it's that on the morning of the Midway battle he signalled Nagumo asking to attack at 0830 when he should have gone over his head and asked Yamamoto by radio. In terms of Nagumo's conduct, he had a habit of withdrawing from situations where it was not clear why he needed to do so. In order to win the war Yamamoto deemed it necessary to take risks with the carriers, but having taken those risks "up front", Nagumo would always withdraw as quickly as possible. Hawaii was the most famous instance, but Port Darwin was even a more glaring example of this tendency. Kusaka, his chief of staff, seemed unable to grasp the concept that approaching to battle was the biggest risk, making the failure to exploit a risk in itself. Given the pattern Yamamoto probably figured he personally had to go to Midway to keep Nagumo from withdrawing to Japan after one strike. :^)
After the war Genda could tell anything he want - hindsight is always 20/20 ;)
Genda is the most reliable guide we have available as to what Genda was thinking.
The problem with Furuta's account is, that there were no dive-bombers from "Kaga" included in this attack force.
The problem with Furuta's account is that he said his plane was where it wasn't "supposed" to be. The battlefield is down there and will be mapped. We'll see where his plane was.

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