Set a Ceylon trap for Nagumo, March 1942

[RCAFson]

Formidable: 16 Martlet, 6 Fulmar, 22 Albacore
Indomitable: 12 Fulmar, 10 Sea Hurricane, 24 Albacore

At Just about the same time, while at Freetown in early April , Illustrious had increased her air complement to 25 Martlets, 2 Fulmars and 21 Swordfish.

 

[Kevin J]

Illustrious is doable, and she can ferry a deck load of RAF aircraft. To me, much of the trap is a RAF affair. The RN have their strike and reconnoitre role, but the heavy fist will be the RAF. Without the benefit of radar, the IJNAF won't see the Beaufighters coming.

The Japanese have the Mk 1 Eyeball, thousands of them. They will not only see them, but hear them, Beauforts though, not Torbeau. Unless you have a time machine of course.

 

[Admiral Beez]

The Japanese have the Mk 1 Eyeball, thousands of them. They will not only see them, but hear them,

Of course they'll see them when they're overhead, but only the very few, if any Zeros on CAP will be able to intervene. I'm envisioning over two hundred torpedo strike aircraft approaching from all directions, followed by dive bombers (Skua, maybe Chesapeake?) and level bombers (Battle, Wellington, Blenheim, etc), all escorted by Spitfires, Fulmars and Hurricanes. The size of the British strike must be large enough to overwhelm any IJNAF CAP. Too soon for Beaufighters; so the torpedo strike falls to Beauforts, Hampdens, Swordfish, Albacores and finally the poor chaps of Ceylon's 273 Squadron, the RAF's last Vilderbeest unit.

Do we have enough time to apply any learnings from the RAF and FAA's failed attempt to stop the Channel Dash on Feb 11/12, 1942? Approximately 450 strike and fighter aircraft failed to do any damage to the German battlefleet sailing just off the English coast. Can they do better at Ceylon seven weeks later?

 

[Peter Gunn]

Here's a pretty concise (actually long winded) and reasonably researched account:

Armoured Aircraft Carriers

 

[cherry blossom]

There is also "A Detailed Analysis of the Loss of Cornwall and Dorsetshire" by Robert Stuart at http://www.combinedfleet.com/CornwallDorsetshireX-RStuart-Adobe.pdf.

 

[Kevin J]

Of course they'll see them when they're overhead, but only the very few, if any Zeros on CAP will be able to intervene. I'm envisioning over two hundred torpedo strike aircraft approaching from all directions, followed by dive bombers (Skua, maybe Chesapeake?) and level bombers (Battle, Wellington, Blenheim, etc), all escorted by Spitfires, Fulmars and Hurricanes. The size of the British strike must be large enough to overwhelm any IJNAF CAP. Too soon for Beaufighters; so the torpedo strike falls to Beauforts, Hampdens, Swordfish, Albacores and finally the poor chaps of Ceylon's 273 Squadron, the RAF's last Vilderbeest unit.

Do we have enough time to apply any learnings from the RAF and FAA's failed attempt to stop the Channel Dash on Feb 11/12, 1942? Approximately 450 strike and fighter aircraft failed to do any damage to the German battlefleet sailing just off the English coast. Can they do better at Ceylon seven weeks later?

I'd want to do a night strike as far away from Ceylon as possible. I'm sure both Catalinas and Hampden would be ideal. Bombs for oilers, mines dropped everywhere, torpedo strikes by Hampdens although this would involve a massive redeployment of forces from other commands. Perhaps Sea Hurricanes with two 45 IG drop tanks escorting Fulmars carrying 500 lb bombs for a daylight strike. The Sea Hurricane Ib can do 317 mph at 7000 feet so much faster than an A6M2 in level flight at that altitude, a Fulmar over 410 mph in a dive, so again faster than an A6M2 in a dive. Albacores and Swordfish for recce with radar and night strike respectively. I'd leave any Martlets behind for CAP and perhaps as escorts for daytime recce Albacores. All 4 armoured carriers are required. All must have deck parks for Sea Hurricanes.

 

[Freebird]

At Just about the same time, while at Freetown in early April , Illustrious had increased her air complement to 25 Martlets, 2 Fulmars and 21 Swordfish.

Yes, and if Illustrious hadn't collided with Formidable in Dec, then it very likely could have been in the Indian Ocean by then.
For this hypothetical you might assume that it arrives in the Indian Ocean by late Mar

 

[The Basket]

Scary stuff that report

Brought up some very odd issues.

Somerville knew of the 2 Japanese carriers not 5. So he had intel but intel was wrong. So had he faced the IJN he only knew of 2 carriers. He could have walked right into a big fight without knowing.

Dates were right but the IJN was delayed. So Somerville had correct info but was wrong because of delay.

His report on the 2 carriers sighted were wrong as they quickly changed course. So he didn't know where they were.

The RN didn't know the IJN warplanes so just compared them to Albacores. Big mistake as the Vals and Kates were more capable.

The 2 cruisers were shadowed but they didn't send a report straight away.

The IJN had two reports on the 2 ships. One called them destroyers and one cruisers with different locations. So either 4 ships or 2 ships and bad location. So Nagumo believed they were destroyers so only sent Vals where If they were cruisers then he would have sent Kates as well. Some of the Vals carried normal bombs as they were planned to attack Colombo.

The 2 cruisers were so violently attacked and sunk in such short order that no action report was sent and Somerville had no indication that they were sunk other than no further comms from them.

So lots to chew on and startling similar to Midway.

So it was a typical fog of war stuff where stuff happened and there was no real idea of what was going on other than fumble about and hope for best.

 

[The Basket]

So based on this the thread is incorrect.

Somerville did have enough forces based on 2 carriers.

The IJN were poor on recon but they did have eyes airborne so to say they were negligent is not strictly true.

The initial Intel was correct on dates but the delay made it look as though Intel was wrong.

The Albacores did see 2 carriers but they changed direction so a night attack by the Albacores couldn't have happened because the 2 carriers which I believe was Soryu and Hiryu was not where they would have supposed to have been.

Since the 2 IJN carriers were the main strike force and according to the Intel the only IJN carriers then it may be interesting to see if the RN knew they were up against 5 and not 2.

Another interesting point is Japanese battleships. The Kongos are fast where as the IJN battleships were slow. So based on Nagato or Mutsu top speed then the fleet would be moving much slower. So interesting if the speed of the fleet was based on Nagato or Kongo since reports only mentioned battleships.

 

[Admiral Beez]

Yes, and if Illustrious hadn't collided with Formidable in Dec, then it very likely could have been in the Indian Ocean by then.
For this hypothetical you might assume that it arrives in the Indian Ocean by late Mar

Seems reasonable enough. Let's do it.

So, Sommerville has Illustrious, Formidable, Indomitable and Hermes. What do we do with Hermes?

 

[Shortround6]

The Kongos are fast where as the IJN battleships were slow. So based on Nagato or Mutsu top speed then the fleet would be moving much slower. So interesting if the speed of the fleet was based on Nagato or Kongo since reports only mentioned battleships.

Top speeds were off by 5-6 kts, however few ships (or formations) cruised at top speed or within 4-5 kts of it. Often fleet speeds were more like 15-20 kts. Greater chance of breakdowns at high speed and the fuel consumption goes up almost exponentially.
The Battleships and cruisers (and carriers) can keep up relatively high average speeds longer than the Destroyers could. If the planes could estimate the speed, fine but basing estimated speeds/future locations based on top speeds of different classes of ships can also lead to mistakes.

 

[Admiral Beez]

This would be Midway before Midway and pure carrier action. So all about the airpower.

Agreed, all about the airpower, but it's not pure carrier action. With Nagumo bringing his fleet to within two hundred miles off Ceylon's southern coast, the RAF has a major role to play here with their long range Catalina reconnaissance and intel gathering, and multi-engine torpedo strike aircraft and high performance fighters.

1941 was a very bad year for British battleships so best will in the world what can you send? Hood? Barham? Prince of Wales and so on and so.

Leave all the battleships in home waters. Sommerville has no use for HMS Warspite and the four unmodernized Revenge-class battleships. This Ceylon trap is an air power affair.

I do fear a repeat of the Channel Dash debacle may occur, with failures in coordination between RAF and FAA and overall inability to stage mass attacks. Look at the below map of the FAA and RAF strikes, penny packets of small groups of bombers with insufficient fighter escort. Imagine instead if, when the Germans were off Folkestone all the FAA and RAF strength was concentrated in one mass strike.

Map from Channel Dash

Sending in separate waves of penny packet bombers will be swept away by the Zeros, limited only by their ability to cycle for ammunition and fuel. The first British strike must be the largest, before Nagumo's 100+ Zeros get into the air.

 

[Admiral Beez]

If done right, a significant flaw in the Zero's design will play a part, that of the A6M1/2's and A6M3's low ammunition load.

 

[RCAFson]

AIUI, in the late afternoon/early evening of 5 April, Somerville was ~100nm from Hiryu and Soryu, which had become separated by about 20-30nm from the IJN main body. At that point in time, Formidable and Indomitable could have hit Hiryu and Soryu and sank them both in very short order, with a massed dive bomber strike using his Albacores, during the early evening of 5 April 1942. Historically, the RN was preparing an Albacore TB strike, which was not ideal, IMHO, but given the design of Hiryu and Soryu, they should have been vulnerable to torpedo attack as well.

If Somerville had Hermes and her 12 Swordfish, he could have increased his own early evening recon with those Swordfish and hopefully maintained contact with Hiryu and Soryu long enough to have hit them. With Illustrious and her 21 ASV equipped Swordfish Somerville would have been able to maintain contact and maybe hit the other 3 IJN carriers before morning.

Similarly, with some additional recon, Somerville would have been able spot the IJN early enough to have caught them at dawn on 5 April either before or just after they sent off their strike against Ceylon.

 

[pinsog]

Does anyone else shudder at the thought of Swordfish and Albacores doing a daylight attack on 2 Japanese fleet carriers?

As far as light ammo load on the Zero goes, Zeroes carried plenty of 30 caliber ammo, more than enough to down unarmored open cockpit biplanes

 

[RCAFson]

We can see how close Nagumo came to Ceylon. Well within range of a Spitfire-escorted heavy RAF strike.

We can see how close together the two fleets were at ~6pm, 5 April.

Also the RAF had almost no aircraft in India to cover the Bay of Bengal, Even 3 -5 Squadrons of Fairey Battles/Skuas/Rocs on Ceylon or along the Indian Coast would have added immensely to Allied recon and striking power.

 

[RCAFson]

Does anyone else shudder at the thought of Swordfish and Albacores doing a daylight attack on 2 Japanese fleet carriers?

As far as light ammo load on the Zero goes, Zeroes carried plenty of 30 caliber ammo, more than enough to down unarmored open cockpit biplanes

First off, on 5 April, any strike would have arrived just before or just after sunset, and there's a high probability that even a late evening/dawn daylight strike would not have been spotted in time for the IJN CAP to have engaged it before it could attack.

 

[Admiral Beez]

Does anyone else shudder at the thought of Swordfish and Albacores doing a daylight attack on 2 Japanese fleet carriers?

No, because done right the Stringbags and Applecores will be in the company of many Hampdens and Beauforts. And the Zeros have their work cut out for them, as from above will come Skuas and Fulmars dive bombing and level bombers, plus Spitfires, etc. The IJN have no radar, and IIRC the Zeros on CAP did not have radios to alert the fleet.

 

[Shortround6]

The IJN have no radar, and IIRC the Zeros on CAP did not have radios to alert the fleet.

But do they have any Vals or Kates (or float planes from cruisers/battleships ) flying as search or early warning aircraft?

Assuming the Japanese are going to do a "Glorious) and steam around with zero aircraft doing any search/perimeter patrol aside from a Zero's without radios(?)

All it will take is one 2 seat aircraft to get a radio message out before being shot down for the whole ambush to fall in the crapper. Maybe the recon plane doesn't get the message out, but if it does?

 

[The Basket]

AIUI, in the late afternoon/early evening of 5 April, Somerville was ~100nm from Hiryu and Soryu, which had become separated by about 20-30nm from the IJN main body. At that point in time, Formidable and Indomitable could have hit Hiryu and Soryu and sank them both in very short order, with a massed dive bomber strike using his Albacores, during the early evening of 5 April 1942. Historically, the RN was preparing an Albacore TB strike, which was not ideal, IMHO, but given the design of Hiryu and Soryu, they should have been vulnerable to torpedo attack as well.

If Somerville had Hermes and her 12 Swordfish, he could have increased his own early evening recon with those Swordfish and hopefully maintained contact with Hiryu and Soryu long enough to have hit them. With Illustrious and her 21 ASV equipped Swordfish Somerville would have been able to maintain contact and maybe hit the other 3 IJN carriers before morning.

Similarly, with some additional recon, Somerville would have been able spot the IJN early enough to have caught them at dawn on 5 April either before or just after they sent off their strike against Ceylon.

And then on to Tokyo Bay and shoot the Emperor.