The Night Battle That Never Was: Somerville vs. Nagumo, April 1942 (1 Viewer)

[Admiral Beez]

On 5 April 1942, Somerville's Force A, built around HMS Warspite, Formidable and Indomitable, approached to approximately 100 nautical miles of Admiral Nagumo's carrier force at one point. He had roughly 30 Albacore torpedo bombers potentially available for a night strike. I don't know if all, but some of these Albacore's were radar equipped. I believe, British reconnaissance aircraft had located Nagumo's force but did not maintain reliable contact. What do we need to change to make the night attack happen? And what are the most likely and best possible impacts can we expect? Sommerville also needs to do a runner asap, since if the British carriers remained within Japanese striking range after sunrise, Nagumo's surviving carriers will launch a massive counterstrike.

pacificeagles.net/indian-ocean-raid-colombo

In the daylight, there is no comparison.

Could the RAF participate in a night raid at sea? There were still 14 surviving Bristol Blenheims of No. 11 Squadron RAF on Ceylon on 5 April 1942. That might be outside their aircrew training, navigation and expertise. Perhaps in the morning of April 6th a Blenheim strike can hit any damaged carrier left behind. With all of four squadrons (1xBlenheims, 3xHurricanes), plus a few PBYs, it's a shame how little RAF presence there was on Ceylon. Just a few weeks after Nagumo's raid the RAF launched over one thousand bombers over Cologne in Operation Millennium.

 

[Alan Stevens]

delete

 

[Alan Stevens]

To make the night attack happen, the key change is not more aircraft but better contact reporting. Somerville's biggest problem was not lack of courage or lack of torpedo bombers; it was that he never had a sufficiently accurate and continuous fix on Nagumo's position. The historical operation was frustrated by poor tactical intelligence, even though the British had warning of Japanese intentions. [wikiwand

If we assume a reconnaissance aircraft maintains contact long enough to provide a good night interception solution, then a strike by roughly 30 Albacores becomes plausible. The British would also need favorable weather and successful navigation, since a night carrier attack against a moving fleet was still an exceptionally difficult operation in 1942.

Even then, I would not expect a British "Taranto in the Indian Ocean." The most likely outcome is one or two torpedo hits on a Japanese carrier or battleship, with perhaps one carrier damaged and temporarily out of action. Sinking a fleet carrier outright would be possible but not the most probable result.

The British advantage was that the Japanese had very limited night-fighter capability and little experience defending a carrier force against a large nocturnal torpedo attack. The Japanese advantage was that Nagumo had five fleet carriers and far more aircraft overall. If three or four carriers were still operational at dawn, Somerville would have to withdraw immediately or risk destruction by daylight carrier strikes.

As for the RAF, I am skeptical that the surviving Ceylon-based Blenheims would materially affect the outcome. A daylight follow-up attack against a crippled carrier might be conceivable, but early-war RAF anti-shipping attacks against maneuvering warships had generally produced poor results. Their value would probably be reconnaissance rather than decisive striking power.

Overall, I'd rate the most likely outcome as:
-- 60%: British attack finds only part of the Japanese force or achieves no hits.
-- 30%: One Japanese carrier or capital ship seriously damaged.
-- 10%: One carrier sunk or crippled badly enough to miss subsequent operations.

The decisive British victory some alternate-history writers envision would require not just contact but an unusually successful torpedo attack and a clean escape before dawn. That's possible, but it is several favorable assumptions stacked together.

Historically, Somerville's plan was actually one of the more promising Allied carrier concepts of early 1942. Had the British achieved reliable night contact, Nagumo might have received the first nasty surprise of the Pacific carrier war months before Midway. The problem is that finding the enemy at sea was often harder than hitting him once found.

 

[yulzari]

Somerville had only a small window of time between Nagumo being located reliably and having withdrawn himself far enough away to avoid retaliation. In that time he has to make the decision, launch his torpedo bombers, leave them to cruise to the target, carry out the attack and return and land in time for him to withdraw out of probable risk of retaliation. The only way to maximise it long enough to do all of this is having regular reliable knowledge of Nagumo's position, speed and direction. All of this at night. Maintaining a shadow in daylight will invite Nagumo's fighters to reach and engage with the shadowing aeroplane. Presumably a Fairey Fulmar from his meagre stock of fighters on his carriers. Just possibly along with some of the 44 Fulmars operating from Ceylon to assist in maintaining the shadowing aeroplane but the range for them leaves little time to loiter. It could all come together but it would be a matter of chance. If it came to using the Swordfish of HMS Hermes as well as the Albacores of the other carriers then the window becomes vanishingly small.

As I see it Nagumo's purpose was to assess the freedom to operate in the Indian Ocean in making the raid on Ceylon. It may be been enough for him to learn that his fleet was located by a Royal Navy fleet at night in mid ocean for a potential night attack and cause him to withdraw having found the answer to his question. Especially as his fleet was removed to the Pacific afterwards where it was needed.

 

[Admiral Beez]

Overall, I'd rate the most likely outcome as:
-- 30%: One Japanese carrier seriously damaged.

If this occurs the night of April 5 1942, (hopefully Sommerville's carriers are not destroyed in the morning), unless Japan can pull a Yorktown-type rush repair, Nagumo will be down a carrier for Coral Sea less than a month away, starting May 4. And I'm not convinced that Japan can fix a damaged carrier quickly, for example Shōkaku (hit by three USN bombs May 8, 1942) needed 67 days in dock before returning to service in mid-July. IJN carriers seem to withstand torpedo hits better than bombs, with five ships (Jun'yō, Hiyō, Ryūhō, Taiyō, and Un'yō) withstanding torpedo hits and returning to service; so Sommerville's Albacores might wish that they'd brought bombs instead.

At Coral Sea, Japan committed two fleet carriers, Shōkaku and Zuikaku, plus the light carrier, Shōhō. The other four fleet carriers, Akagi, Kaga, Sōryū and Hiryū plus the light carrier Zuihō were in Japanese home waters refitting, replenishing and preparing for Midway, while Ryūjō was still returning from operations in the Indian Ocean and East Indies; Jun'yō had only just commissioned; and the obsolete Hōshō was assigned to secondary duties. Unless another carrier is pulled from the refit, the IJN will enter Coral Sea with only two ships, which may see USS Lexington survive the battle and serve at Midway.

Mention of Ryūjō above has me thinking, after damaging one of Nagumo's carriers above, could Sommerville have then attacked this small carrier operating alone in the Bay of Begal?

 

[EwenS]

Two points about the damage to Shokaku:-

1. she was hit by 3 x 1,000lb HE bombs, one of which knocked a nasty hole in the side of her bow that caused a lot of water to be taken on board as she made her way home in heavy seas (there were worries she might capsize). The RAF / FAA aircraft available were limited to 250lb & 500lb bombs only, so barring a lucky hit the damage is likely to be less severe.

Her damage control crews did very well controlling the fires those bombs started so catastrophic fires as happened at Midway cannot be guaranteed to occur.

2. The repairs themselves did not take 67 days. That period takes you from 8th May when she was hit to 14th July 1942. Included in that is the time taken for her to transit back to Japan. The timeline reads like this:-

1010 on 8th May Shokaku detached from IJN fleet to return home. Passage slowed by damage and heavy weather.

Evening of 17th May arrives at Kure where there are difficulties mooring her due to anchors lost in the bombing. As was the IJN practice for damaged ships she was placed in Reserve until repairs could be completed. Her damage was then inspected (apparently photos exist showing that probably taken about 3 days later).

16th June enters dry dock for repairs

27th June leaves dry dock repairs complete. A type 21 radar was also fitted at this time.

14th July reassigned to Cardiv 1 and leaves Kure on 18th to join Zuikaku & Zuiho at Hashirajima anchorage.

The IJN carriers and supporting vessels left Hashirajima on the morning of 27th May 1942 for Operation MI, Midway. So it was probably clear by the time she was inspected that even if she could be docked immediately it was highly unlikely that work could be completed in time for Operation MI. And that is without considering how her air group, and that of Zuikaku, could be brought back up to strength following losses and transfers of personnel to other carriers. So the urgency disappears.

Why the delay in docking her? Probably at lesst in part to the need to complete the works on all the ships intended to take part in Operation MI. Following the first four months or so of effort a lot of IJN vessels were in need of refits which took place in April & May 1942 and were keeping the Navy Yards busy.

Cardiv 5, Shokaku & Zuikaku, were diverted to Operation MO on 18th April while en route back to Japan, as reinforcement of the forces already allocated. If either was not available, Cardiv 2, Soryu & Hiryu could have been detached instead.

For any large IJN vessel damaged in the IO, the nearest large dry dock in the area was Singapore. However it has never been clear to me exactly when in 1942 the IJN were able to reactivate it. It was available by Dec. Like so much of the final days the record of supposed v actual destruction leaves doubts. The IJN did establish some repair facilities there in March 1942.

Overseas (Ship Repair) Naval Construction and Repair Departments

Enough to repair a carrier? Would depend on nature of damage. Patch up maybe? Complete repair highly unlikely?

 

[EwenS]

Now the subject has been raised, it is interesting to compare the damage to Shokaku with that to Yorktown and the work undertaken by way of repairs to both immediately following the action. Shokaku clearly came of worst.

Looking at the damage to CV-5 Yorktown at Coral Sea her damage report can be found here.

U.S.S. Yorktown--Action Report of the Battle of the Coral Sea

Points to note:
1. she was hit by a single bomb from a dive bomber. While estimated to be an 800lb AP weapon in the report, it can't have been that heavy. The standard D3A Val dive bomber was limited to a weapon no bigger than 250kg / 550lb. So it was probably an SAP weapon. It exploded deep in the ship but the explosion was contained there. Fire damage was minor and quickly controlled.

2. one near miss near the bow caused only splinter damage above the waterline. Another caused some underwater damage to fuel tanks from sprung plates. In total there were 8 near misses.

3. Yorktown was hit on 8th May at Coral Sea. She didn't arrive at PH until 27th May trialling oil and her speed limited. Full repairs were estimated to take 90 days and would have needed a trip to the Puget Sound Navy Yard, probably the best part of a week away. Most importantly her flight deck and hangar escaped with minimal damage. So she was patched up in 72 hours, made combat capable and sent back to sea with an air group including many aircraft and personnel drawn from Saratoga's air group (left behind when she went for repair in Feb 1942). Repairs were still ongoing, with the last of the repair crews disembarking at sea the day after she left. That does not diminish the effort put in to getting her back to sea.

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The Battle of Midway (June 4-7, 1942) is widely recognized as one of history’s greatest U.S. naval victories. Some historians attribute the triumph to the interception of Japanese communications in…

shipyardblog.wordpress.com

"Only the most urgent repairs were made. Instead of individually fixing the hull's ruptured seams, an enormous steel plate was welded over the damaged section."

Battle of Midway: Repairing the Yorktown After the Battle of the Coral Sea | Defense Media Network

A history of the emergency repairs conducted on the USS Yorktown after the Battle of Cora Sea in order for the ship to participate in the Battle of Midway.

www.defensemedianetwork.com

A series of photos of the damage to Shokaku after Coral Sea can be found here. Note the damage to the flight deck, aircraft lifts, bows and forward end of hangars.

Shokaku Japanese Aircraft Carrier - Destination's Journey

Photos of Shōkaku an aircraft carrier of the Imperial Japanese Navy, She took part in several battles of WW2 ,sunk by a US submarine

www.destinationsjourney.com

As can be seen, the work required on Shokaku to make her operational again went far beyond a simple "patching up" job as was able to be carried out on Yorktown at PH. By the time Shokaku left dry dock on 27th June 1942 she had been fully repaired and ready to take her place on the front line again in plenty of time to participate in the Battle off the Eastern Solomons at the end of Aug 1942.

Had Yorktown survived Midway, she would still have needed months of repair work back on the US West Coast.

 

[Admiral Beez]

A series of photos of the damage to Shokaku after Coral Sea can be found here. Note the damage to the flight deck, aircraft lifts, bows and forward end of hangars.

Shokaku Japanese Aircraft Carrier - Destination's Journey

Photos of Shōkaku an aircraft carrier of the Imperial Japanese Navy, She took part in several battles of WW2 ,sunk by a US submarine

www.destinationsjourney.com

Those are some of the best IJN carrier photos I've ever seen, thanks for sharing.

Given that Sommerville's night strike on April 5th is reliant on torpedoes, not bombs I suppose we're unlikely to cripple an IJN carrier with even two hits.

 

[ThomasP]

Just some thoughts.

As already mentioned, keeping reliable contact would be necessary (at least similar to the level that was accomplished in the Bismarck action) if a well planned and executed strike was to occur.

Sommerville's nominal aircraft strength was (I think):
__________Formidable_____Indomitable____Total
Albacore______21_____________24_________ 43
Fulmar________ 3(+?)__________12_________ 15
Martlet_______ 12______________0_________ 12
SeaHurricane__ 0______________ 9__________ 9

Q: How many of the above aircraft were operational at the time?

Q: As already asked, how many of the Albacore had ASV?

Q. Did Sommerville have any ASV equipped Fulmars? If so, would Fulmars be used to shadow the Japanese fleet at night as was done with the Bismarck?

Achieving multiple hits with torpedoes - if things went to plan - should not have been a problem with 30 or more Albacore.

Q: What combination of hits would effectively prevent Nagumo's forces from accomplishing their subsequent operations?

1 hit on each carrier - with the result of maybe 1 carrier being crippled via hit to the steering or propellers, and 2 or 3 of the of other carriers taking on enough water to matter (ie significantly reduced speed or other operational need messed up)?

2 or more carriers crippled?

1 carrier effectively sunk, with another 1 or more with significant damage?

Q: How much damage would the Albacores have to accomplish in order to put a serious crimp in the IJN's plans?

Q: If Sommerville managed to escape with minimal loss, would he be able to strike again the next night? (Nominal torpedo loadout for the RN carriers was usually [1.5] per Swordfish or Albacore, but were they carrying that many in this instance?)

Q: Regardless of whether Sommerville could strike again the next night, how would Nagumo react to the first night's strike - if serious damage was received - and he did not know if Sommerville could strike again the next night? Would the uncertainty and morale maybe be a deciding factor?

 

[Admiral Beez]

Q: Regardless of whether Sommerville could strike again the next night, how would Nagumo react to the first night's strike - if serious damage was received - and he did not know if Sommerville could strike again the next night? Would the uncertainty and morale maybe be a deciding factor?

I wonder if Sommerville could have dispatched his destroyers to attack the following night. Matapan redo.

 

[EwenS]

Just some thoughts.

As already mentioned, keeping reliable contact would be necessary (at least similar to the level that was accomplished in the Bismarck action) if a well planned and executed strike was to occur.

Sommerville's nominal aircraft strength was (I think):
__________Formidable_____Indomitable____Total
Albacore______21_____________24_________ 43
Fulmar________ 3(+?)__________12_________ 15
Martlet_______ 12______________0_________ 12
SeaHurricane__ 0______________ 9__________ 9

I don't believe Formidable carried any Fulmars at this point. It was 25th April before 803 squadron went aboard having been shore based at Ceylon during the IJN raids on 5th & 9th April.

Two, maybe three, of Formidable's Martlets had been put ashore at Trincomalee.

On 5th April one of the 827 squadron Albacores on Indomitable was shot down by an IJN A6M Zero during a search operation. Another made it back to the carrier about 1745 badly shot up (40 bullet holes and a burst type) with its TAG wounded.

Q: How many of the above aircraft were operational at the time?

Q: As already asked, how many of the Albacore had ASV?

We have looked at this before. Probably none of Indomitable's but possibly all Formidable's. Why would this be so?

Somerville tasked Indomitable's squadrons with the daylight search for the IJN (e.g. 4 from 827 on a search in the afternoon with one shot down and another badly damaged). It was aircraft from Formidable that were employed on the night searches.

But there is I believe more evidence to support that. Having looked at the individual aircraft histories, carrier movements and details of radar development the following becomes apparent:-
1. While ASV.II was able to be fitted to the Swordfish from March 1941, there were unspecified difficulties fitting it to the Albacore. I suspect that those related to the transmission aerial location, as the set up on the Albacore ended up different from the Swordfish. The result was that it was only towards the end of 1941 that it began to be fitted on the Albacore.

2. Indomitable left Britain in Oct 1941 and after that only seems to have received a handful of replacement aircraft either in the Caribbean or at Ceylon. Therefore in April 1942 the vast majority of her Albacores were produced before she left Britain. Formidable on the other hand didn't leave Britain until Feb 1942 and most of her Albacores were produced in the last few months of 1941 and early 1942. Her squadrons were even swapping out early airframes for later production in the period Nov 1941 to Jan 1942.

3. For some unexplained reason the squadrons on Indomitable swapped a number of aircraft with those on Formidable at the end of April 1942 and before Operation Ironclad. A reasonable explanation might be to spread the ASV fleet across both ships when they would be operating separately, thereby giving Indomitable a capability she previously didn't have..

4. By early March 1942 the Albacore squadrons on Victorious in the Home Fleet had ASV.II for their attack on Tirpitz.

Somerville's strike force is also reduced by the number of Albacores dispatched on night ASV search missions to find the IJN.

Q. Did Sommerville have any ASV equipped Fulmars? If so, would Fulmars be used to shadow the Japanese fleet at night as was done with the Bismarck?

Somerville did use some of the Fulmars for a daylight search on 5th April. As he reported:-

"33. From 0645, an air A/S patrol was maintained ahead of the Fleet. INDOMITABLE also sent 4 Fulmars to commence a search to the eastward. This search covered the area between the arcs 55 degrees to 105 degrees to a depth of 215 miles. It proved negative except for the sighting of one enemy seaplane at 0855, 76 degrees 150 miles from Force A. This suggested that the enemy was carrying out reconnaissance in a south-westerly direction by means of cruiser aircraft, or a seaplane carrier, in a position 70 miles southwest of the main enemy force. There was no indication that this aircraft sighted any of our surface forces or our air search."

The use of Fulmars against Bismarck was a failure. Six aircraft of 800Z flight intended to lead Hurricanes to Malta were used as an emergency measure in view of there only being 9 Swordfish intended for AS cover not torpedo strike. Aircraft had not had compasses swung or radios properly tuned. While pilots were reasonably experienced the Observers were just out of training, which had been cut short, and were not fully trained in all shadowing techniques, something that Victorious' CO seems to have been unaware of. One pilot grounded with toothache. Three launched after the Swordfish strike took off. Despite the late hour it was still daylight in those northern latitudes and it remained so for over two hours, and visibility was described as good with occasional showers. Only one aircraft definitely found Bismarck and was able to report back. Two were lost when the homing beacon in Victorious failed and they couldn't find their way back to the carrier (1 crew recovered by a passing merchantman). Two aircraft launched as follow up about 15 mins after sunset. One landed back on immediately when unable to retract its undercarriage. The other located Bismarck but could not hold it for long. Tovey noted in his report

"Night shadowing is a task which tries the most experienced of crews and it is not surprising in these difficult conditions that they failed to achieve it".

Achieving multiple hits with torpedoes - if things went to plan - should not have been a problem with 30 or more Albacore.

Q: What combination of hits would effectively prevent Nagumo's forces from accomplishing their subsequent operations?

1 hit on each carrier - with the result of maybe 1 carrier being crippled via hit to the steering or propellers, and 2 or 3 of the of other carriers taking on enough water to matter (ie significantly reduced speed or other operational need messed up)?

2 or more carriers crippled?

1 carrier effectively sunk, with another 1 or more with significant damage?

Q: How much damage would the Albacores have to accomplish in order to put a serious crimp in the IJN's plans?

Q: If Sommerville managed to escape with minimal loss, would he be able to strike again the next night? (Nominal torpedo loadout for the RN carriers was usually 2 per Swordfish or Albacore, but were they carrying that many in this instance?)

As designed the Illustrious class were designed to accommodate 45 torpedoes (for the intended air group containing 30 TSR) and Indomitable 54 (for her intended 45 TBR). When stored aboard ship warheads and torpedo bodies were separated and each held in dedicated compartments not the bomb magazines. Even with the change in mix of aircraft aboard there is no reason to suppose any change by April 1942.

Experience in the Med showed about a 10% hit rate in night torpedo attacks by the FAA.

But probably not all the Albacores would have been carrying torpedoes. Some would certainly be used as flare droppers to silhouette IJN warships for torpedo attack by the non-ASV equipped aircraft, and perhaps also as bombers. Night dive bombing under the light from flares had been practised in the Western Desert. A mix of loads was used at Taranto for example.

Q: Regardless of whether Sommerville could strike again the next night, how would Nagumo react to the first night's strike - if serious damage was received - and he did not know if Sommerville could strike again the next night? Would the uncertainty and morale maybe be a deciding factor?

As for what Nagumo might or might not do in the event of one of his ships is torpedoed, bear in mind that he was over 1,600 nautical miles from a port (Singapore), able to even begin to patch that vessel up. Getting there will take days (at 10 knots at least 6 days for example) And it doesn't need to be one of the 5 carriers that gets hit. There were also the four Kongos, Tome, Chikuma and Abukuma and 9 destroyers.. H either:-

1. sinks the damaged ship(s) himself - unlikely for anything bigger than a destroyer
2. detaches the torpedoed ship to make its way, or be towed, to Singapore, which probably means detaching an escort for it so reducing the escorts for the untouched ships, and continues operations the next day.
3. abandons Operation C altogether having failed in his primary task of destroying the Eastern Fleet (which he failed to do anyway when he found that they weren't at Colombo)

If he chooses option 2, the first thing he has to do on the morning of 6th April is find Somerville, whose intention was to retreat as far out of range as possible after recovering his strike. That recce will consist primarily of cruiser / battleship floatplanes as was IJN doctrine at the time maybe augmented by a couple of Kates. That will take hours and may not even succeed given how widely spread the IJN tended to deploy its recce. Their strategy for recce was a weakness that occurred repeatedly up to and including Midway.

Nagumo was a cautious character. IMHO a torpedo in any of his big ships means calling off the whole operation.

I doubt Somerville would hang around to make a second strike the following night. For one thing the fuel state of his ships would play on his mind. While Force A had refuelled at Addu Atoll on 4th April (having priority over Force B), there would have been a lot of high speed steaming to get into a position to make the strike and again afterwards as part of the withdrawal. That guzzles fuel quite rapidly. He was back at Addu Atoll again on the 8th April to refuel (Force B having priority over Force A on this occasion).

 

[EwenS]

I wonder if Sommerville could have dispatched his destroyers to attack the following night. Matapan redo.

The Eastern Fleet was short of destroyers throughout 1942. Highly unlikely he would waste what he had on a long shot. Again distance to / from the enemy needs to be considered v high speed fuel consumption. Remember also that there was an IJN sub threat with plenty of warnings and sub-search operation. The Albacores were maintaining a constant daylight patrol looking for them usually involving 1-2 aircraft at a time.

Force A only had 6 destroyers with a total of only 26 torpedoes between them.

Force B had 7 destroyers including the old WW1 S class Scout and the Dutch Isaac Sweers. (HMAS Vampire having been dispatched back to Trincomalee with Hermes)

All the RN ships were reduced to a single set of TT by this stage of the War. Only Sweers would have retained both sets.

For Operation Ironclad at the beginning of May most of the destroyers in direct support came down from home or Med waters. IIRC only two came from the Eastern Fleet. Lack of escorts and the IJN sub campaign against merchant shipping were what caused mush of the Eastern Fleet to be forced to remain in harbour just a few months later.

 

[ThomasP]

Whoops! You are correct, EwanS, re the ratio of of torpedoes to Swordfish & Albacore stowed on the carriers. I have corrected my post up-thread.

As built, the Illustrious. Formidable, & Victorious, had magazine stowage for 54 torpedoes.

Q: Indomitable's nominal air group was larger (48) than the Illustrious air group (36), but does this mean she carried 1.5 x 48 = 72 torpedoes? Or did they use a different rational for her planned air group / mix of aircraft types? ( I think I have the as built nominal load-out of munitions for Indomitable somewhere, but am unable to find it at the moment.)

Operationally, during the war I do not think Indomitable ever carried more than 24x Albacore, Barracuda, or Avenger.

Even if she only carried the same number of torpedoes as Formidable, then Sommerville would have had enough torpedoes (108 total) for at least a 2nd strike, and maybe even a 3rd.

 

[EwenS]

Whoops! You are correct, EwanS, re the ratio of of torpedoes to Swordfish & Albacore stowed on the carriers. I have corrected my post up-thread.

As built, the Illustrious. Formidable, & Victorious, had magazine stowage for 54 torpedoes.

54 as built? The figure I have is 45 from Friedman. Where does yours come from? Have I missed something?

Q: Indomitable's nominal air group was larger (48) than the Illustrious air group (36), but does this mean she carried 1.5 x 48 = 72 torpedoes? Or did they use a different rational for her planned air group / mix of aircraft types? ( I think I have the as built nominal load-out of munitions for Indomitable somewhere, but am unable to find it at the moment.)

This is where aircraft complements with these ships gets complicated. Design v actual carried on service entry were not the same and how other things then get affected.

Illustrious class as designed 36 (6 x Fighter Dive Bomber aka Skua and 30 x TSR aka Swordfish). All about 36 ft long in a 456ft long hangar three abreast. By 1940 when the ships begin to enter service total reduces to 33 due to adoption of Albacore & Fulmar each 40ft long (21 and 12 respectively). So 45 torpedoes was designed to give 1.5 loads per TSR but stretched to just over 2 when in service due to the reduced number of TSR / TBR being carried..

The 1938 carrier (Implacable) was designed around an air group of 48 TBR (i.e Albacore @ 40ft long) with no fighters with an upper hangar 456ft long and a lower hangar 208ft long carried 3 abreast. Designed torpedo capacity was initially 54 increased to 63 in 1939. So a drop to 1.3 loads per TBR.

Indomitable was an Illustrious with the adoption of as many features of the 1938 carrier as could be incorporated. So her re designed air group was intended to total 45 TBR (i.e. Albacore @ 40ft). Do the maths and you find her hangars are not long enough to hold 48 given that her upper hangar was 40ft shorter (416ft v 456ft) than that of both an Illustrious or an Implacable. With 54 torpedoes as designed that is 1.2 per TBR but increases to 2.25 per TBR come 1942 due to the reduced number of TBR and the increased number of fighters being carried.

Go back further to Ark Royal with a final designed air group of 72 (48 TB & 24 Osprey) the torpedo complement was 72 (but 96 warheads were to be carried). So again 1.5 torpedoes per TSR. But by the time she entered service the mix was 42 TSR Swordfish and 18 FDB Skua. So the torpedo load had increased to 1.7 per TSR.

Late in WW2 for simplifying aircraft acquisition and air group planning the Implacables and Indomitable were treated as equivalents despite the different hangar sizes.

Operationally, during the war I do not think Indomitable ever carried more than 24x Albacore, Barracuda, or Avenger.

In 1944 the squadrons intended for Indomitable were sent out to the IO in March as part of the response to the arrival of the Japanese fleet in the waters around Singapore. Indomitable then sailed out from Britain in June to join them. The aircraft numbers in each squadron varied slightly over this period. So while Indomitable was working up her air group in late July / early Aug she actually embarked 28 Barracudas and 28 Hellcats.

However when she sailed for her first operation, Operation Banquet, on 18th Aug 1944 the numbers had been reduced to 24 Barracudas and 24 Hellcats. And by Dec 1944 it was 21 Avengers and 29 Hellcats.

Indomitable became the flagship of 1st ACS because of her radar fit (she was the only ship in the Eastern Fleet / BPF fitted with the US SM-1 fighter direction radar in 1944) With the extra staff aboard to support an admiral she was more overcrowded than other carriers so aircraft numbers had to be reduced to compensate. In 1945 aircraft numbers weren't helped by a shortage of Hellcats in the BPF.

Even if she only carried the same number of torpedoes as Formidable, then Sommerville would have had enough torpedoes (108 total) for at least a 2nd strike, and maybe even a 3rd.

There is having the weapons on the one hand and the ability to deliver them on the other i.e. the fuel to dart in and out at high speed to avoid the counterattack should it develop.

 

[Admiral Beez]

Go back further to Ark Royal with a final designed air group of 72 (48 TB & 24 Osprey) the torpedo complement was 72 (but 96 warheads were to be carried). So again 1.5 torpedoes per TSR. But by the time she entered service the mix was 42 TSR Swordfish and 18 FDB Skua. So the torpedo load had increased to 1.7 per TSR.

Poor Ark Royal, with her design focus on maximizing CAG rather than protection she was made for this very event. One can only imagine her in 1943 operating folding Martlets and Albacores, and eventually Hellcats and Barracudas. Britain's USS Enterprise (CV-6).

Anyway, if Sommerville had gone northward in advance of Nagumo's offensive, perhaps with his fastest ships, could his force have defeated Vice Admiral Jisaburō Ozawa's Malaya Force of the light carrier Ryūjō, five cruisers (CAs Chōkai, Kumano, Suzuya, Mogami, and Mikuma, plus CL Yura) and four destroyers? That seems like better odds for the British.