Could the best available AA have saved Force Z?

[Admiral Beez]

Of the Royal Navy's fast BB/BCs, HMS Repulse had the worst AA of them all. Meanwhile HMS Prince of Wales had at best a sketchy AA radar suite and relied mainly on the mediocre 5.25" DP twins. Assuming some months for procurement and shipyard planning, what's the best reasonable AA and fire control we can give the two ships by October 1941? Putting aside feasibility, can it make a difference?

Unfortunately we're too early for the RN introduction of the 40mm Bofors, and years before the RN had proximity fuses. But we can give both ships advanced radar and AA fire control, add more 2pdr multiple pom-poms and Oerlikon 20 mm cannons, and swap out Repulse's low angle 4" for QF 4.5-inch like on HMS Renown.

 

[Alan Stevens]

Advanced AA suites like on USN BB in 1945 would have had a tough time defeating 35 high-speed torpedo bombers with high-speed torpedoes.

Substitute two Iowas and each will probably take two hits and maybe as many as four.

How well they handle the damage depends on where they are hit and on damage control.

 

[Alan Stevens]

x

 

[EwenS]

Of the Royal Navy's fast BB/BCs, HMS Repulse had the worst AA of them all. Meanwhile HMS Prince of Wales had at best a sketchy AA radar suite and relied mainly on the mediocre 5.25" DP twins. Assuming some months for procurement and shipyard planning, what's the best reasonable AA and fire control we can give the two ships by October 1941? Putting aside feasibility, can it make a difference?

Unfortunately we're too early for the RN introduction of the 40mm Bofors, and years before the RN had proximity fuses. But we can give both ships advanced radar and AA fire control, add more 2pdr multiple pom-poms and Oerlikon 20 mm cannons, and swap out Repulse's low angle 4" for QF 4.5-inch like on HMS Renown.

Why do you classify PoW's radar suite as "sketchy"? It was state of the art for the period.

Type 281 - Air warning only entered service at the end of 1940
Type 284 - main gunnery set only entered service on Nelson in June 1940
Type 285 - secondary gunnery sets, one on each secondary director. Entered service early 1941 a month or two behind 284.
Type 282 - on the Pom-Pom directors. Same tech as 284/285.
Type 273 - 10cm surface warning set. This was the big ship version of Type 271 which only went to see for the first time as an experimental set in March 1941 and operationally from May. Used a different aerial within the lantern. Type 273 entered service in Aug 1941 and PoW had received one of the first sets to be installed.

All these sets were improved as the war went on.

Now getting these sets to work properly was a bit of a black art at the time. But it was only the 273 set that PoW reportedly had trouble with at Singapore and that wouldn't have affected the ability of her Type 282 & 285 radars to produce range data for her AA suite. But the weather was good enough for Force Z on 10 Dec 1941 for the visual rangefinders in the director's to have produced the necessary range data.

The USA certainly had nothing better at this stage with installation of the Mk.3 & 4 gunnery sets lagging some months behind the RN. Mk.3 & 4 gunnery radars didn't appear on larger US ships until the latter part of 1941.

 

[ThomasP]

According to Japanese records (IIRC) Force Z shot down 4 (with a 5th crashing on landing?) and damaged over 20 of the attacking aircraft. Most of them by PoW. Considering that Force Z did not have proximity fuzes that is somewhat impressive.

If Renown (with her ~equivalent to PoW's AA suite) had been in Force Z instead of Repulse, presumably there would have been an increase in the attacking aircraft shot down and damaged proportionate to what was achieved by PoW.

But even if we assume the AA was twice as effective, it ends up depending on which aircraft get shot down - the ones that scored the hits, the ones that missed, the torpedo bombers, the level bombers, or a combination thereof. If they shot down the torpedo bombers that scored the first hits then the AA on PoW would have continued to do pretty serious damage on any attacking aircraft, and PoW would (probably) have survived at least long enough to be attacked again - maybe long enough to escape.

Approximately the same scenario would apply to the Renown (with her ~equivalent to PoW's AA suite) if she had been in Force Z instead of Repulse.

 

[SaparotRob]

I recall reading that PoW's AA guns didn't have tracer ammo. The Japanese pilots didn't realize they were being fired upon. If tracers were used, it might have disrupted the incoming air attacks to some degree. It could have been a force multiplier of sorts for the AA fire.

 

[Admiral Beez]

How good were the Dido class AA-cruisers? I know they have the mediocre 5.25", but would adding two early five-turret Didos have helped? Did they have radar or advanced fire control to lay all ten guns onto one target? They certainly look impressive with up to ten barrels pointing skyward. Each 5.25" fired up to 7-8 rounds per min, so that's up to 80 rpm, until the lads tire.

 

[Admiral Beez]

According to Japanese records (IIRC) Force Z shot down 4 (with a 5th crashing on landing?) and damaged over 20 of the attacking aircraft. Most of them by PoW. Considering that Force Z did not have proximity fuzes that is somewhat impressive.

If Renown (with her ~equivalent to PoW's AA suite) had been in Force Z instead of Repulse, presumably there would have been an increase in the attacking aircraft shot down and damaged proportionate to what was achieved by PoW.

But even if we assume the AA was twice as effective, it ends up depending on which aircraft get shot down - the ones that scored the hits, the ones that missed, the torpedo bombers, the level bombers, or a combination thereof. If they shot down the torpedo bombers that scored the first hits then the AA on PoW would have continued to do pretty serious damage on any attacking aircraft, and PoW would (probably) have survived at least long enough to be attacked again - maybe long enough to escape.

Approximately the same scenario would apply to the Renown (with her ~equivalent to PoW's AA suite) if she had been in Force Z instead of Repulse.

We need to last until the RAF's Buffaloes arrive.

 

[EwenS]

How good were the Dido class AA-cruisers? I know they have the mediocre 5.25", but would adding two early five-turret Didos have helped? Did they have radar or advanced fire control to lay all ten guns onto one target? They certainly look impressive with up to ten barrels pointing skyward. Each 5.25" fired up to 7-8 rounds per min, so that's up to 80 rpm, until the lads tire.

View attachment 726345

View attachment 726346

Their AA fire control was as good as that in PoW. They had 2xHACS Mk.IV one forward & one aft. 2xquad pom-pom with directors plus smaller weapons varying by ship in 1941. Radars Type 279 or 281 for air warning, Type 284 on the main director for surface gunnery and 282 and 285 for the various AA directors just as in PoW. Type 272 was being added in a lantern on the foremast.

The ship in the second photo is the Argonaut, the first of the extra batch ordered 4 Sept 1939, and completed at the beginning of Aug 1942 (the only one of the batch to be completed with the 5 turret arrangement) with 4 single 20mm (bridge wings and abreast after director).

As AA ships the best 2 Didos were considered to be the two "Toothless Terrors" fitted with 4xtwin 4.5", Charybdis (completed Dec 1941) and Scylla (completed June 1942). The main reason for deciding to complete them with that armament was that it was already on order for D class cruiser conversions which were cancelled on the outbreak of war, in the hope of getting 2 more AA cruisers into service earlier. Unfortunately with all the additional work in the yards in the early war period it didn't work out and they took as long to build as most of the others. Note that the date given on Wiki for the laying down of Charybdis is incorrect. It should be 9 Nov 1938 and not 9 Nov 1939.

HMS CHARYBDIS, BRITISH DIDO CLASS CRUISER. 1941.

www.iwm.org.uk

As for helping Force Z survive? They would have added a lot more directed AA fire in the sky. Would it have made a difference? Anybody's guess.

 

[Thumpalumpacus]

Shipborne AA against planes in 1941 wasn't going to get 'er done even if both ships had the best suites available at the time, but still without fighter cover -- not against that flock.

Beezy, you should define "advanced radar and AA fire control", so we know how much time-travel is involved.

 

[Admiral Beez]

Beezy, you should define "advanced radar and AA fire control", so we know how much time-travel is involved.

Whatever was the best available and readily installable by October 41.

 

[Thumpalumpacus]

Whatever was the best available and readily installable by October 41.

Pack a Mae West.

 

[don4331]

The best available anti aircraft solution would be Sea Hurricanes (initial operation off HMS Furious in July, '41) operating off HMS Hermes (could have been in theatre); close 2nd would be Fairey Fulmars - you can pack more onto Hermes thanks to folding wings.

While Hermes is probably too slow to operate in concert with PoW and Repulse, she could provide CAP for both herself and the capital ships even if they were a hundred miles distant.* Fulmar's probably have the speed advantage at sea level to be able to intercept Mitsubishi Nells and Bettys during their bombing runs.

*Being a hundred miles distance would provide Hermes enough of a head start to be able to get back under the coastal defenses in Singapore before being caught should Force Z bump into Japanese surface forces.

 

[Admiral Beez]

The best available anti aircraft solution would be Sea Hurricanes (initial operation off HMS Furious in July, '41) operating off HMS Hermes (could have been in theatre); close 2nd would be Fairey Fulmars - you can pack more onto Hermes thanks to folding wings.

I agree, and I hate to play the contrarian. But Hermes' T-shape 36 by 36.6 feet (11.0 by 11.2 m) lifts are too narrow for Sea Hurricanes and too short for Fulmars. The lack of crash barrier and outriggers precludes permanent deck parking. Buffaloes would fit, but the FAA rejected the type. Folding Martlets would be ideal, but they won't be available until 1942. The fighter-bomber Skuas were withdrawn from service by summer 1941 - too bad as I'd like to see a single type CAG of twelve to sixteen Skuas to really hit those landing ships while offering some degree of fleet air defence - even though a loaded Betty or Nell would be difficult to catch. So, it's Sea Gladiators.

But if we forget Hermes as a fighter carrier, her CAG of a dozen Swordfish might still be helpful in extending Force Z's lifespan. For starters Hermes' Swordfish can add to Phillips' Shagbats for reconnaissance, plus an added strike capability, meaning Force Z needn't try to engage any IJN landing ships with surface ships, and can keep his ships further from FIC.

If only the RN had more luck with HMS Glorious, Courageous and Ark Royal. The first pair had wide lift ideal for Sea Hurricanes. Losing three fast fleet CVs pre-PacWar was a bummer. A favourite of mine.

Better luck for the RN carrier force 1939-1941

Sept. 1939 - HMS Courageous is hit by three torpedoes per OTL, but ITTL only two detonate, causing significant, near-fatal damage. Her escorts chase off U-29 and then take the carrier under tow. Mind you, Courageous has a long tow from her location, so we may need to reduce the level of damage...

ww2aircraft.net

 

[elbmc1969]

The best available anti aircraft solution would be Sea Hurricanes (initial operation off HMS Furious in July, '41) operating off HMS Hermes (could have been in theatre); close 2nd would be Fairey Fulmars - you can pack more onto Hermes thanks to folding wings.

While Hermes is probably too slow to operate in concert with PoW and Repulse, she could provide CAP for both herself and the capital ships even if they were a hundred miles distant.* Fulmar's probably have the speed advantage at sea level to be able to intercept Mitsubishi Nells and Bettys during their bombing runs.

Could you do the math for both the SHurr and the Fulmar? How many fighters could you maintain over both Force Z and Hermes at the same time?

 

[Shortround6]

There were a few of these floating around

four twin 4in but only on Quad pom-pom?
Most British modern (after E class) Cruisers had a better AA set up than the Repulse had.
Might not have had enough magazine space.


Air cover for Force Z was easy.
Use the bloody RADIO!!!
Keeping the location of Force Z secret by using radio silence so your own land based planes don't know where you are wasn't the smartest trick ever pulled.

 

[Admiral Beez]

Could you do the math for both the SHurr and the Fulmar? How many fighters could you maintain over both Force Z and Hermes at the same time?

The Bettys and Nells were unescorted. If this remains so, they should be chewed apart by either.... if another carrier, one that is Sea Hurricane compatible is available. That would have to be HMS Indomitable, Furious, Eagle or little Argus. Everything else has too narrow lifts for the Sea Hurricanes. Everything except Hermes can operate the Fulmar.

 

[don4331]

A Admiral Beez : Shame on me for not confirming SHurr and Fulmar would fit on Hermers. (when they're repairing bow, we just need to get them to restore the aft elevator to original dimensions - then Fulmars would work, SHurr won't work unless we shorten the engine by couple cylinders/side or make folding wing version). So, it would need to be Skuas (Did more research - while Skua's were pulled from front line operations in '41, they were still available through '45 for training/target towing. Southern Hemisphere wasn't front line yet, so operating Blackburn's fighter off Hermes isn't impossible. Sea Gladitors were rare by end of '41, no many made initially, quite a few lost before war even started, and then 2 years war really thinned their numbers.)

E elbmc1969 : I would hope that Hermes would be able to operate 4 plane cap over each of Forces Z and my slow force of Hermes/Durban/Stronghold. Add 4 more planes on deck - ( 2 and 2 replacements/ the ability to surge CAP). The remaining 4 to 8 planes aboard Hermes would be to ensure serviceability/losses/restore CAP over the carrier force. And that's as good as any single carrier could provide in '41. I'm taking advantage of Skua being fighter/bomber/observation plane (and limited numbers) to justify single airframe. Any other carrier is going to want squadrons of attack aircraft, so have no more fighters for CAP in '41.

I recognize that has only 4 planes over Force Z, and it takes 30 minutes for the 8 planes from carrier CAP/on deck planes to get to Force Z, but the Japanese didn't all attack simultaneously. And as A Admiral Beez said at start - we're holding the fort until the cavalry arrives in form of Brewster Buffalos. Note: CAP can be relaying Force Z position to Hermes, and Hermes to land station without Force Z breaking radio silence.

S Shortround6 : HMS Carlisle is still pre-war thinking - that the danger is the high altitude bomber/no one would be crazy enough to flying to the long range barrage able to be put up by HAA. 2pdr was just a "mop up" weapon. As we see during the war, RN was replacing even HAA with additional 2 pdrs - the high altitude bomber not being threat it was thought to be and enemy was more than willing to risk the barrage fire. (But you knew that)

 

[Shortround6]

HMS Carlisle is still pre-war thinking - that the danger is the high altitude bomber/no one would be crazy enough to flying to the long range barrage able to be put up by HAA. 2pdr was just a "mop up" weapon. As we see during the war, RN was replacing even HAA with additional 2 pdrs - the high altitude bomber not being threat it was thought to be and enemy was more than willing to risk the barrage fire. (But you knew that)

The 4in was sort of an in-between weapon. Turns out it was one of the better heavy (over 40mm) weapons the British had. The 4in could fire about twice as fast as the 5.25 and it trained and elevated faster. It actually did fairly well at Crete. A number of the British losses were after the ammo was depleted.
The actual goal is not to shoot down the torpedo bombers, the goal was to make them miss.

Ideally. with the aid of retrospectroscope, the British should have rounded up just about every 40mm Bofors gun in British commonwealth (around 100?) and mounted them on the PoW and Repulse in Oct of 1941 before sail the ships to the far east after pulling any less than main battery guns needed to allow for deck space and weight.

From a more realistic view and knowing with hindsight that the 5.25 was crap for this sort of work what could have been done to beef up the AA of Force Z, short of a several month refit (or more than several months) for two ships involved?

Quick answer was to transfer several light cruisers or destroyers to help with AA fire.
We know now that the Dido's were something of a dud for AA use and the British destroyers except for a very few exceptions (four of the L class) had more than enough trouble defending themselves.

That leaves the old C class AA cruisers and/or perhaps a couple of Leander's (?)

You can pretty much forget 20mm weapons. the Tracers may have been a distraction but the 20mm would have been revenge weapons, shooting down a torpedo bomber after it had dropped the torpedo.

The 2pdr pom-pom was an individual ship defensive weapon. It didn't have the range to engage aircraft that were attacking a neighboring ship as a general rule. The Bofors gun had more range and were more useful.


So basically it was 4in guns for fleet/formation/area defense and 2pdrs for individual defense.

 

[EwenS]

There were a few of these floating around
View attachment 726586
four twin 4in but only on Quad pom-pom?
Most British modern (after E class) Cruisers had a better AA set up than the Repulse had.
Might not have had enough magazine space.

The plans to convert the old WW1 vintage C & D class cruisers to AA ships emerged following the Abyssinian Crisis in 1935 when it was realised that there was a need for upgunning the AA firepower of the Fleet.

2 ships were converted as an emergency programme (Coventry & Curlew) with 10 single 4" on Mk.III mounts (recycled from other warships being upgraded around that time) and two octuple pom-pom (one of the pom-poms was replaced in 1938/39 with 2xquad 0.5" as the former were in short supply for fitting elsewhere in the Fleet) and 2 HACS Mk.III directors. Designed as a low cost upgrade. Curlew was sunk of Norway in May 1940 while Coventry survived until sunk in the Med in Sept 1942.

A further evaluation of AA needs occurred 1936/37 which broke down into 2 parts:-

1. Class I to modernise the ships of the main Fleet
2. Class II to provide trade-protection AA ships, which was to provide for conversion of C & D class cruisers, V&W class destroyers (eventual 15 WAIR conversions) and AA sloops and a number of merchant ships.

As far as the C class went the programme started with the intention of converting all of the remaining 11 ships, but was then cut down to 8 (with the 3 oldest of a slightly different layout being dropped). Not being of the highest priority in the run-up to war, in late 1938-early 1940 4 more conversions were undertaken being Cairo, Calcutta, Curacao & Carlisle as pictured above with armament as noted plus 2xquad 0.5". The start of the war saw the rest of the C & D conversion programme abandoned. Calcutta was lost in the Med in June 1941, Cairo in Aug 1942 and Curacao was run down by the RMS Queen Mary in Oct 1942. Carlisle was irrepareably damaged in the Aegean in late 1943.

In late 1940 the Admiralty looked at the USA and the 5"/38 and Mark 37 director and the US agreed to convert Delhi in 1941. She was to have been followed by a second ship, once the Admiralty were satisfied with the system but US entry to the war meant that this was cancelled. Then in 1942/42 Caledon & Colombo were also converted to AA cruisers with a sligtly different armament layout..

These ships however spent much of their war in Home Waters or the Med escorting convoys and not the Fleet, as was the original intention.

Air cover for Force Z was easy.
Use the bloody RADIO!!!
Keeping the location of Force Z secret by using radio silence so your own land based planes don't know where you are wasn't the smartest trick ever pulled.

Undoutedly he should have used the radio around 1015-1020 that fateful morning once he had been detected by the Japanese recce aircraft. The First Sea Lord criticised hime for that. Instead it was 1158 when Repulse signalled Singapore, 1215 before the 6 Buffalos took off, and around the time PoW sank (c1320) before they reached the Force Z's position, too late to do anything. They stayed on station for about an hour before heading home short of fuel.

Had he radiod Singapore around 1015-1020, then those 6 Buffalos could have arrived around 1135 in time to hurt the first TB attack if not stop it altogether. The last attack was at 1246. I can't recall how many other Buffalos might have been available that morning as a follow up to the original flight dispatched. At combat speeds they would have burned fuel faster.

But it is highly unlikely that any British officer would have used the radio before that. SOP in the RN was to use the WT as little as possible. Lessons learnt during WW1 meant that the RN had developed a worldwide direction finding service to locate enemy ships (Y service) and accordingly kept radio and even radar transmissions down to prevent an enemy doing that to them. As for radar transmissions Type 79/279/281 signals could be detected at anything up to 100-200 miles away and in the Med Fleet in 1941 orders had been issued not to use it at night so deferring daylight attacks until a few hours later in the day. Even in 1945 I've come across cases of instructions to Arctic convoys not to use radio or radar until it was clear that the convoy had been detected. The Japanese had set up such a DF system in the 1920s.

USNI article here has some info on Japanese capabilities in relation to signals intelligence, albeit with the emphasis on the Pearl Harbor attack

How the Japanese Did It

Careful planning and preparations including completely fooling the enemy are the keys to explaining the success of the Pearl Harbor attack.

www.usni.org