British 1936-42 purchase options, logistics and export/import of military hardware

[yulzari]

It is worth noting that planning up to May 1940 involved an overall and sensible assumption that it would be an Franco-British affair based in Metropolitan France and the joint industrial superiority aided by American purchases was to come to bear in 1941 at the earliest and could well be all over by 1943.

No sane planner would plan on the basis of what actually happened. A manifestation of this was the insertion of the Second BEF into France at the same time as the original BEF was working on being evacuated as France was where the war was to be fought.

 

[EwenS]

Going back to the wider topic of "What to make at home, what to import, what to export", this thread has gone more into improving aircraft and tank designs. Anyone think there are big macro-level changes in what the British should be producing themselves vs importing?

Worth remembering munitions were only a minority of Lend-Lease (scroll down for charts). Of that minority, aircraft were the biggest, then ammunition, then tanks.


I think the British should be producing a somewhat different mix of weapons themselves - more single seat fighters and fewer light bombers, more medium and fewer light tanks (and although it's strictly outside the topic, fewer big gun ships to free up resources for more tanks: those 1000 light tanks translate into perhaps 500 mediums which is max. 2 divisions without spares).

So how do you define "big gun ships"?

How do you deal with the Tirpitz in a potential action without the KGVs, construction of which started in 1937? With work on the Lions stopped in late 1939, the only battleship laid down was Vanguard in Oct 1941 and ever changing priorities saw her completion delayed until 1946.

As for cruisers, following the batch of orders for 6 Dido class and the acceleration of ordering 2 planned Fiji class in Sept 1939, the next 3 cruisers were laid down in 1941, with another 3 in 1942 and 1 in 1943, the latter not progressing very far by the end of WW2. Again ever changing priorities and delays saw only 2 of the first group complete during WW2. RN building programmes were already limited by the allocation of armour plate to both the RAF and Army from very early in the war.

The only "big gun ships" of questionable value were the 2 monitors Roberts and Abercrombie.

The RN/RAN started the war with 64 cruisers to cover their worldwide commitments, 27 of which were of WW1 design, with 19 new types under construction. They lost 30 between May 1940 (Effingham & Curlew) and Feb 1944 (Penelope) with another 2 being constructive total losses. By 1944 many of the WW1 era ships were being converted for secondary duties or laid up in Reserve to free crews to man more modern ships of all types. By Aug 1945 the number designed or refitted to fight a modern war was reduced to just 43 with quite a number of those still undergoing major refits to prepare them for war in the Pacific.

So there was not very much in the way of "big gun ships" to be cut back to allow more tanks.

 

[Shortround6]

A lot going on here.

I think the British should be producing a somewhat different mix of weapons themselves - more single seat fighters and fewer light bombers

Lets define "light bombers" shall we. For the British from 1936-1940/41 is was bomber with a 1000lb bomb load (or less), either single or twin.
and we can forget using Hurricanes as fighter bombers until they get the Merlin XX engines or you try putting Merlin VIII engines (Fulmar) in them which rather ruins them as fighters.
Merlin III even with a constant speed prop gave 880hp at sea level for take off. Hanging 1000lbs under the wings means long take-off. And a Hurricane without and under wing tank has got rather short range. Now with the engines showing up in late 1940 and 1941 things change significantly but you need the production facilities already set up.

more medium and fewer light tanks (and although it's strictly outside the topic

See below.

fewer big gun ships to free up resources for more tanks:

Well addressed by EwenS but in addition to the large number of WW cruisers the British went to war with 5 Revenge class battle ships with only minor refits. if war had not come or started several years later these would have gone to breakers yards as the KVGs went into service.

those 1000 light tanks translate into perhaps 500 mediums which is max. 2 divisions without spares)

you don't get 1 15 ton tank for 2 6 ton tanks and you need many (not all) of the light tanks for scouting, over seas use, and training.
Every body keeps blaming the light tanks when the true culprit of the shortage to British cruiser tanks in 1940-41 was the Covenanter, 2000 20 ton tanks that could not be used overseas.

The old 13-pdr 6cwt horse artillery gun was a very close match to the French 75 so a new gun loaded to higher pressures should be close to the 75mm QF.

I really, really, really wish that everybody would just give up on the 13-pdr 6cwt horse artillery gun as a stepping stone to anything after WW I. They only built 416 of them before/during the war and only 114 were still in service at the end of WW I. It was not a very close match to the French 75. The 13pdr fired a 12.5 projectile, the French 75 fired a 16lb Shrapnel projectile just a little bit slower. When they started loading in better HE shells post war that around 14.6lbs the lighter weight helped with the increase in velocity along with the better powder and higher pressure.

1600 fps is not fantastic but still better than the 3/3.7" CS guns or the KwK 37 (going by the latter with APCBC, should easily beat the 2-pounder for penetration, assuming you can get a hit).

The German gun was over 1000lbs, the British 2pdr and the 3/3.7" CS guns were all under 300lbs, I think the 3.7" was 222lbs? Scale up your proposed tank to suit.
Penetration table is bit deceptive.
Table for the German gun is done at 90 degree impact angle (plate is vertical) and the two projectiles are good for 46 and 50mm at 1000m (1100yds).
British 2pdr, if they had gotten off their asses and built APCPC ammo before 1943, was good for 47mm against a plate sloped back by 30 degrees.
I would judge to be roughly equal as a hole puncher.
We can argue about the exact type and quality of armor but the 2pdr was crippled by the lousy projectiles/ammo and the shoulder aiming system and the sights.
You need to fix everything and not cripple a larger British gun by using the same faulty auxiliary problems.

Shortround, it's a bit funny to disparage the HE power of these options while also arguing 2-pdr HE was a big missed trick!

A 75mm firing HE would have been a big advantage for the British, but since the British didn't even get 2pdr HE ammo until 1943 the change as not even incremental (we can argue over how much the increment/s were) but going from non-extent (or 50mm mortar) to 75mm gun was huge.
British never even had parity to the French 37mm tank guns or 47mm tank guns, or to the Italian tank guns or to the Japanese 37mm tank guns as far as HE goes.
British didn't have parity to the German 20mm and 37mm tank guns or even sub parity to the 50mm tank guns.
And the British aiming system (shoulder piece and telescope) crippled the long range (over 800yds) use of the co-ax mg so the British tankers had few options.
None of them were good.
1. Rely on the CS tanks ( after a few years in NA they thought they needed twice as many as were being issued, that is 4 per squadron, not 2.)
2. Fall back and call for artillery support.
3. Charge until they got to 200-300yds where they could use the 2in bomb thrower (in the Crusader).

Fix all the stuff that was wrong with the 2pdr before installing fancy/short 6pdr guns or short 75mm guns.

 

[EwenS]

Well addressed by EwenS but in addition to the large number of WW cruisers the British went to war with 5 Revenge class battle ships with only minor refits. if war had not come or started several years later these would have gone to breakers yards as the KVGs went into service.

While RN plans in the early-1930s envisaged replacing the battlefleet from 1940 starting with the R class, with new construction begun in 1937, by the latter part of the 1930s it was clear that replacement would take longer due to industrial limitations. So a large refit / reconstruction programme was undertaken to extend the life of certain existing ships. By July 1939, when the Admiralty was looking forward to March 1944 to how their battlefleet would be deployed in the event of war in Europe and the Far East and with knowledge of Axis building programmes (or in the case of Japan, an educated guess) the battlefleet had expanded from 15 to 22 ships (including 5 KGV & 4 Lions). It also included retention of 3 of the old R class in the Far East to make up the numbers. It was then expected that Japan would still outnumber the RN in the Far East. That became one of the driving factors in acquiring Vanguard.

At that point the KGVs were expected to complete Dec 1940-April 1942 with the first two Lions in Aug 1942 and the next pair probably in late 1943.

So only Revenge, which was the worst of the bunch, and AN Other would have been removed from service as the KGVs completed.

 

[Shortround6]

Thank you.
It also seems that the British were under estimating the Japanese with the 3 Rs being considered useable against the Japanese.

Granted a lot of countries spent a lot money increasing battleship gun ranges during the the 1930s and we know from history that one of longest hit scored was by the Warspite at about 26,000yds.
However for the British at the start of WW II the Malaya, Barham, Repulse and the five Royal Sovereigns had not been up upgraded to 30 degree elevation and were limited to 20 degrees of elevation. The use of 6 crh shells increase range from 23,734 yds to a bit under 26,000yds. The use of supercharges raised the range to 28,800yds and some of the old ships got the supercharges, there is no record of them being fired in combat.

The Japanese had spent money repowering their ships and the 4 old 6 turret BBs could make around 24kts compared to the R class 21knots or under. The Japanese 14in guns had been given more elevation in the 1920s/early 30s? and could range to around 33,000yds at 33 degrees of elevation. The later change to 43 degrees and 43,770yds may have been a lot of money for not much result.

We can argue armor thickness and the advantages of 15in shells but even the worst Japanese BB (not BCs) were faster, had 50% more guns and could outrange the Rs should the visibility allow it.
Granted the British were not planning on the Rs being leading edge since the Rs could not stay in formation with newer/faster ships there is a problem. Japanese had the two 16in armed Nagato's and even assuming the Yamato had nine 16in guns the British needed at least 3 modern BB in the theater.
Something seems a bit off?

 

[tomo pauk]

Mainly for cost reasons, but also a bit more power and reliability, I would licence produce the R-2600 in at least some of the factories that made the Hercules.

Hercules was a good engine. Preferably, we'd want to take out the trash 1st. Among the aero engines, trash are/were the engines that offered almost nothing while occupying/wasting the production lines, time, manpower, resources and money. Among such British engines, we can count a few: Dagger, Tiger, and Pelides (not wasted a lot, but still). So having A-W, A-S or Napier making the R-2600 by 1939 would've been certainly a boon. Heck, even the R-1830.

I remember Tony Williams' Foresight War had a POD in 1934 which allowed a few more changes.

We can tell that Tony is far more of a gun guy than an aircraft guy when reading that book

 

[tomo pauk]

A 75mm firing HE would have been a big advantage for the British, but since the British didn't even get 2pdr HE ammo until 1943 the change as not even incremental (we can argue over how much the increment/s were) but going from non-extent (or 50mm mortar) to 75mm gun was huge.
British never even had parity to the French 37mm tank guns or 47mm tank guns, or to the Italian tank guns or to the Japanese 37mm tank guns as far as HE goes.
British didn't have parity to the German 20mm and 37mm tank guns or even sub parity to the 50mm tank guns.
And the British aiming system (shoulder piece and telescope) crippled the long range (over 800yds) use of the co-ax mg so the British tankers had few options.
None of them were good.
1. Rely on the CS tanks ( after a few years in NA they thought they needed twice as many as were being issued, that is 4 per squadron, not 2.)
2. Fall back and call for artillery support.
3. Charge until they got to 200-300yds where they could use the 2in bomb thrower (in the Crusader).

Fix all the stuff that was wrong with the 2pdr before installing fancy/short 6pdr guns or short 75mm guns.

A lot of that suff is fixed by defalut by installing a decent 75-76mm gun. Or even a good 57mm gun.
Falling from 57mm tank gun to 47mm during the interwar period can be chalked as an honest mistake. Doubling down with that fashion - opting from 47mm to 40 mm - was a thing for the gallows.

 

[Shortround6]

Going back to this.

The doctrine was not to fire whilst moving but that one could fire whilst moving and live fire trials found it was feasible to do so if needed. It allowed the tank to keep moving and maintain its status as a mobile target with a constantly altering range and possible jinking so making it a mobile target laterally also. Only then possible because the small size and weight of the period gun with its balance at the interior mantlet could be kept on target by the shoulder elevation of the gunner. What it could not do was hit an HE target given the gun in question which is a whole other matter. Once the gun got larger and heavier the shoulder elevation was no longer possible so the doctrine had to move to the same as other tank users. ie firing from the halt.

The entire doctrine was a flawed practice, however good it sounded in theory and any war games, practices, exercises may have been skewed to fit the theory/doctrine.

The practical problem was that the gunner's shoulder did not stay stationary when the gun fired, even if the tank was stationary. The gun moved when it recoiled and disturbed the aim which affected follow up shots. In fact in later tests they found that even the gunner pulling the trigger disturbed the aim and threw shots off, they were demanding a trigger that took less effort to fire the gun. This has nothing to do with the size of the gun, it is simply a poor system.
Now at close ranges (under 800yds?) it may give acceptable results from a stationary tank. Unfortunately for the British after France and Greece they were fighting in a theater were 2000yd shots were possible, even if not common. But 800 to 1500yd shots were often needed and it was this range band where the British really suffered.
Germans used electric firing system. British used the gunner's hand muscles to work the firing mechanism. Germans locked the gun in elevation so the gun returned to original point of aim (or a lot closer) after firing the first shot.
Now for some reason the Germans could engage HE targets with their 37mm and 50mm guns at longer ranges (or at least come close).

The other side is the inexpensive ( I am trying to kind) scope the British used. Simple cross hairs and some marks off to one side to show the suggested old over at at longer ranges. Gunner had to position the crosshairs above the target (hoping that the crosshairs did not block the view of the target) and hope that the lines on side of the scope were close enough.
Then fire the gun and hope that the commander could spot the shot (tracer) or he himself could, to see how much it missed by so he could try to either hold a little higher or not quite so high depending on needed correction. Now since the whole gun/mount moved when the gun fired it was pretty much starting over each shot.

German sight moved the aiming mark inside the scope when the gunner changed the range setting. If the commander called for 200meters up he set the range for 200meters more and then put the aiming mark (a triangle) on the target (using a wheeled elevation control, not his shoulder) with point of the triangle at the bottom of the target, no covering up the target with the vertical cross hair. Same sight picture all the time.

Basically the British system sucked no matter what the size of the gun. British figured their 7.9mm BESA gun was good for about 800 yds (meters?) while the Germans had range scales of the 7.9mm MG34s to 1200-1400metes depending on type of sight. British tankers grabbed all the captured German 7.9mm AP they could find, Not for accuracy but it went through gun shields on AT guns several hundreds further away. But now ask what the British tanker was supposed to do even firing his machine gun at over 800yds. Hold the cross hairs how high over the target and put the vertical cross hair right on the target so he can's see it and judge how high the horizontal cross hair has to be so the little range mark near the out side of scope reticule is the same height as the target he can't see anymore? Then he holds higher or lower using his shoulder following the commanders instructions.
German tank gunner adjusts sight range for MG and desired distance. Puts the little triangle just under the target. Commander calls correction, gunner adjusts the sight for the new distance and turns the wheel to adjust the gun and fires again. Repeat as necessary for both gunners. British system is going to need a lot more tries at long range.

The British system might be better at close range, But the Germans could also shortcut. Just pick something like 500 or 600 meters and hold up or down a little with the triangle for a quick correction (not for the short 75mm) Even a short 50mm will be on a tank sized target to about 700 meters if you don't mind hitting at the bottom or top from a center of mass aiming point. 2nd shot should be an easy correction.

 

[Shortround6]

Hercules was a good engine. Preferably, we'd want to take out the trash 1st. Among the aero engines, trash are/were the engines that offered almost nothing while occupying/wasting the production lines, time, manpower, resources and money. Among such British engines, we can count a few: Dagger, Tiger, and Pelides (not wasted a lot, but still). So having A-W, A-S or Napier making the R-2600 by 1939 would've been certainly a boon

OK, WHICH R-2600 do the British license/invest in tooling for?
The 1600hp version with the aluminum crankcase or the 1700hp version with the steel crankcase (and a lot of other different stuff).
The 1600hp version wasn't in production in numbers until the last 4 months of 1939. Sept was the first month with double digits, 26 engines and 29 in in Oct. Jan and March both saw zero engines built, 1 in Feb.
When do the British start converting over a factory for this engine?
The 1700hp version doesn't seem to show up until June of 1941? (5th production engine)

a lot of us tend to overlook the actual time lines of some engines/weapons

 

[tomo pauk]

OK, WHICH R-2600 do the British license/invest in tooling for?
The 1600hp version with the aluminum crankcase or the 1700hp version with the steel crankcase (and a lot of other different stuff).

1600 HP version.

a lot of us tend to overlook the actual time lines of some engines/weapons

I think that we have the better grip on that issue now, than it was the case 10-15 years ago

 

[EwenS]

Thank you.
It also seems that the British were under estimating the Japanese with the 3 Rs being considered useable against the Japanese.

Granted a lot of countries spent a lot money increasing battleship gun ranges during the the 1930s and we know from history that one of longest hit scored was by the Warspite at about 26,000yds.
However for the British at the start of WW II the Malaya, Barham, Repulse and the five Royal Sovereigns had not been up upgraded to 30 degree elevation and were limited to 20 degrees of elevation. The use of 6 crh shells increase range from 23,734 yds to a bit under 26,000yds. The use of supercharges raised the range to 28,800yds and some of the old ships got the supercharges, there is no record of them being fired in combat.

The Japanese had spent money repowering their ships and the 4 old 6 turret BBs could make around 24kts compared to the R class 21knots or under. The Japanese 14in guns had been given more elevation in the 1920s/early 30s? and could range to around 33,000yds at 33 degrees of elevation. The later change to 43 degrees and 43,770yds may have been a lot of money for not much result.

We can argue armor thickness and the advantages of 15in shells but even the worst Japanese BB (not BCs) were faster, had 50% more guns and could outrange the Rs should the visibility allow it.
Granted the British were not planning on the Rs being leading edge since the Rs could not stay in formation with newer/faster ships there is a problem. Japanese had the two 16in armed Nagato's and even assuming the Yamato had nine 16in guns the British needed at least 3 modern BB in the theater.
Something seems a bit off?

The allocation was:-
Home (Med was assumed to come from this group as required)
2x1939 Lions
5xKGV
3xbattlecruiser

To counter:-
5xnew capital ships (incl 2 Bismarcks)
2xScharnhorsts
3xDeutschland (pocket battleships)

Previously the Deutschlands were to have been countered by the County class heavy cruisers. But with 5 Hippers built or building that was no longer seen as possible.

Far East
2x1938Lions with 16"
2xNelrod with 16"
5xQE (3 modernised, 2 unmodernised) with 15"
3xR with 15"

To counter:-
4xnew capital ships (details unknown - see below)
2xnew 12" battlecruisers (battlecruisers in RN terms. super Type A cruisers in IJN terms - see below)
2xNagato with 16"
4xFuso with 14" & speed 24-25 knots
4xKongo with 14" & speed 30 knots

Hence the need for a "Vanguard" type vessel that would reuse old guns so saving construction time. That ship type would be useful to both bolster the battleline and to chase down the new Japanese battlecruisers.

The expectation of the USN and the RN was that the new Japanese capital ship would be in the order of 40-45,000 tons with a main armament of 16" guns. It was into 1944 before enough intelligence came to hand about the true size and armament of the Yamatos.

Following the 1940 US Two Ocean Navy Act the IJN decided to pursue the design of a "super-Type A cruiser" that emerged as the B-65 design in early 1941 armed with 9x31cm/50 guns displacing 31,400 tons standard. Effectively a counter to the USN Alaska class. Construction was to start in 1942 as part of the Circle 5 Programme, but was postponed on 6 Nov 1941 and dropped altogether after Midway. Another 4 were tentatively planned for the Circle 6 Programme, but were postponed indefinitely in Sept 1941 and dropped altogether after Midway.

Design B-65 cruiser - Wikipedia

en.wikipedia.org

So in 1939 RN/USN intelligence was way wide of the mark with regard to both these types, even though sketchy outlines of a 4 ship class purportedly relating to them was included in Janes Fighting Ships 1940 & 1942 editions.

Three other points of note:-
1. This assumes that the RN would be fighting the whole IJN battlefleet alone. No mention of USN assistance or the IJN having to split their battlefleet.
2. It treats the Kongos as part of the IJN battleline. What was probably not known at the time was that the IJN did not intend to use those ships that way. They were intended for use as back up to the submarines, destroyers, & heavy cruisers to attrite the USN fleet as it crossed the Pacific to fight the IJN in the final showdown in the western Pacific. In other words to help the smaller IJN vessels break through USN defensive cruiser & destroyer screens.
3. The aftmost pair of turrets in Ise & Hyuga didn't get the increase to 43 degrees elevation as there wasn't physical room in the ships to deepen the gun wells.
4. As for range, the RN preferred to fight at shorter ranges whenever possible, IIRC around 16,000 yards was considered their sweet spot. Against a moving target the longest ranged hit is usually stated to be Warspite at Punto Stilo in 1940 at around 26,000 yards, with Scharnhorst hitting Glorious at a similar range in June 1940. It is a subject hotly disputed on internet forums over many years and I really don't want to get into an argument about it. Massachusetts reportedly hit a stationary Jean Bart at Casablanca in Nov 1942 at over 30,000 yards.
5. While the IJN ships have a speed advantage on paper, much would depend on their speed on the day under probably deep load displacement figures or close thereto

 

[Shortround6]

1600 HP version.



I think that we have the better grip on that issue now, than it was the case 10-15 years ago

Requires a lot faith to start tooling up in 1939

Also means you are sort of locked into the 1600hp version without a lot of retooling.
Wright built a whole new plant to build the 1700hp version.

We also have to remember that the R-2600A was good for 1600hp for take-off and 1600hp at 2,000ft military power rating with no ram. In high gear it was good for 1400hpat 10,800ft, no ram.
And that was as good as got, ever.

 

[tomo pauk]

We also have to remember that the R-2600A was good for 1600hp for take-off and 1600hp at 2,000ft military power rating with no ram. In high gear it was good for 1400hpat 10,800ft, no ram.
And that was as good as got, ever.

50-100% better than the Taurus, Dagger, Tiger or Pelides - where do I sign?

 

[Shortround6]

R-2600.............................1920lbs(?)
Taurus..............................1300lbs(?)
Dagger............................1390lbs
Tiger.................................1290lbs
Pelides.............................1475lbs

Now you could have used a R-1820 Cyclone and beat the stuffing out of Dagger, Tiger or Pelides on a power to weight ratio.

But the production facilities for the bottom 3 engines are not large enough to handle the amount of engines needed. Pelides was never flown, it may not have even been produced with all English parts as a test engine.
Tiger was just junk to be polite. And was made at around 100 engines a year(?)

Again the problem is timing. In mid/late 1939 the Air Ministry was not buying the Tiger or the Pelides. They also were not buying any more Daggers and most of the Herefords that had been ordered with Daggers were converted (or finished on the production line) as Hampdens.
The Timing is that all 3 of these engines were pretty much finished before the R-2600 really was a finished product (being made in more than a handful a month).
The Hercules was only British competitor.
The Taurus couldn't even compete with the R-1830.

Now the Question is if anybody in Britain except Bristol and RR can even make an R-2600?

 

[SaparotRob]

…a lot of us tend to overlook the actual time lines of some engines/weapons

I don't overlook it. I just choose to ignore it.

 

[hobbes154]

OK, so since everyone is going straight to the nitpicking I'll take that as a "no" on any really big changes in trade patterns.

So how do you define "big gun ships"?

Battleships and cruisers as you have done.

How do you deal with the Tirpitz in a potential action without the KGVs, construction of which started in 1937?

Periodically bombing her and using older BBs for convoy escort - they just have to drive her away, not catch her. If the weather is too bad for aircraft carriers it is too bad for ranges >20k yards to matter so who cares about the elevation? And frankly looking at the relative size of merchant losses to U-boats, aircraft and merchant raiders vs BBs and cruisers, yeah I'm willing to take one or two more PQ17s (a few hundred thousand tons in loss out of the >11 million for the war). But of course the actual losses to PQ17 were to U-boats and aircraft, and having better tanks and say cleaning the Italians and Afrika Corps out of North Africa early means all those resources that went into protecting the Malta convoys could be moved to the Arctic (let alone my daydream of actually not losing in France 1940).

More generally if you think the historical build of "big gun ships" was the best use of resources at the time, I don't think either of us is going to convince the other.

Lets define "light bombers" shall we.

I want more Spitfires and Hurricanes and fewer Battles and anything else that gets in their way (Merlin-engined Whitleys?). I don't accept that with four years' warning you can't tweak the production lines to have a bit more of one Merlin subtype and (smaller) aircraft and less of another. (I also want a Mercury-engined Whirlwind-style fighter-bomber instead of the Blenheim, and to start making the Bristol 133 as well as the Gladiator, but that is more a Williams '34 POD than '36.)

Yes I know you want more Battles for training and various auxiliary roles, fill them with something that doesn't use your best engines and stressed-skin constuction.

I really, really, really wish that everybody would just give up on the 13-pdr 6cwt horse artillery gun as a stepping stone to anything after WW I. They only built 416 of them before/during the war and only 114 were still in service at the end of WW I. It was not a very close match to the French 75. The 13pdr fired a 12.5 projectile, the French 75 fired a 16lb Shrapnel projectile just a little bit slower. When they started loading in better HE shells post war that around 14.6lbs the lighter weight helped with the increase in velocity along with the better powder and higher pressure.

I was going off the Wiki figures for the 12.5 lb HE shell. But OK say it's a little weaker than the 75. I still think it is a more useful all round tank gun than the 2-pdr even loaded to WW1 levels let alone uploaded. If there aren't enough left to actually use a significant number of parts or ammo it's still a good starting point to indulge the British predilection for reusing old cartridge cases, use 3" machinery the British have lots of, and illustrate the minimum dual (triple?) purpose gun size to fit in the smallest possible tank and turret ring. I have nothing against the 75 but if we're starting early we don't have all that free American ammo. Or the necked down 18-pdr (13-pdr 9 cwt) but it's maybe a big bigger than absolutely essential in 1940 and I want to fit this thing in a 3-man turret (within the British loading gauge?) and as much ammo as possible in the hull. (Might be good as a Zis-3 type gun instead of the 6-pdr though?)

Fix all the stuff that was wrong with the 2pdr before installing fancy/short 6pdr guns or short 75mm guns.

Why? It's 1936, you're not locked into the 2pdr as a tank gun yet (except on the A9/A10), and installing a bigger gun will actually help force to fix some of the issues (shoulder elevation, no HE, small turret rings) and not make the others any harder (crappy sights & shells).

you don't get 1 15 ton tank for 2 6 ton tanks and you need many (not all) of the light tanks for scouting, over seas use, and training.
Every body keeps blaming the light tanks when the true culprit of the shortage to British cruiser tanks in 1940-41 was the Covenanter, 2000 20 ton tanks that could not be used overseas.

Not sure about that, the Sherman appears to be twice or more the mass of the Stuart and typically cost less than twice as much (just from Wiki). But if so that makes my point even stronger - we need more resources into tank production and less of something else. (I'm tempted to say heavy AA as well.)

By all means ditch the Covenanter (and both Matildas) for I guess some Valentines and Cruiser III/IVs with slightly bigger turret rings (based on the great data above I'm looking to increase the turret ring about 4" from Valentine to Churchill size), less side armour for the Valentines to at least maintain speed, and less speed and more armour for the cruisers - I guess I am aiming for something close to the Centaur/Cavalier but with 340 instead of 410 hp and maybe Horstmann instead of Christie, better sloped armour of course). But the 1000 light tanks is referring to the outbreak of war so won't pay off until a bit later.

I would also upgrade the Vickers Lights a bit to say a French 25mm or 2-pdr pom-pom (manually loaded) - there were some export models to Belgium and Latvia that did the latter. (I don't mean you could swap them on existing tanks but less change to the production lines than tooling up for an entirely new model).

Requires a lot faith to start tooling up in 1939

Compared to tooling up for the Hercules (or the Sabre, or the Vulture)? At least the R-2600 has crossed the Pacific and Atlantic by that time

We can tell that Tony is far more of a gun guy than an aircraft guy when reading that book

His aircraft timelines are a little optimistic, sure.

Doubling down with that fashion - opting from 47mm to 40 mm - was a thing for the gallows.

I don't know. The 40mm was a much better hole puncher and I'm unconvinced even 3-pdr manually loaded HE is that much better than a coax against an AT gun or whatever.

OK, WHICH R-2600 do the British license/invest in tooling for?

I'm also happy with the 1600hp first version to prove the concept, then if that works produce the 1700hp later on in parallel (like was done with different types of Merlin). There were multiple factories that eventually produced the Hercules so it's more/less not either/or.

Now the Question is if anybody in Britain except Bristol and RR can even make an R-2600?

Well all the shadow factories that made Hercules (and Merlins though I don't want to lose those). Presumably Wright can tell them what to do just as well. (Actually Wright had a lot of problems but IIRC the outsourced factories in the US actually worked better than the parent company.)

Of course this depends on the R-2600 actually having a significantly lower production cost than the Hercules. I'm relying on the various cost sheets someone put up a while ago (indirect comparison - Hercules vs Merlin in the UK and then Merlin vs R-2600 in US). But then in Calum Douglas' book the Germans estimated they took similar man hours and the BMW 801 a lot more. Maybe Bristol was just forcing the Air Ministry to amortise the horrendous development costs? Set up one factory to produce the 1600hp version first and see what happens.

 

[hobbes154]

The only "big gun ships" of questionable value were the 2 monitors Roberts and Abercrombie.

Seriously though they built 2 of the Didos with 8x4.5" which is destroyer armament.

 

[SaparotRob]

Seriously though they built 2 of the Didos with 8x4.5" which is destroyer armament.

That was their point, being anti-aircraft cruisers like the Atlantas.
Unless you meant they didn't build enough of them, with which I can agree

 

[EwenS]

Seriously though they built 2 of the Didos with 8x4.5" which is destroyer armament.

You clearly don't understand how that came about.

Scylla & Charybdis were ordered as part of the 1938 shipbuilding programme and were laid down in April 1939 and Nov 1938 respectively (not Nov 1939 as per Wiki & some other sites). By Sept 1939 It was clear that their completion would be delayed due to production problems and delays with the 5.25" turrets they were designed to carry. Three of the four 1940 completions, Bonaventure, Dido & Phoebe, went to sea with only 4 turrets as a result of those real delays. Only Dido eventually acquired her fifth turret during repairs in the latter part of 1941 for damage suffered off Crete.

So, in Sept 1939 in an effort to get S & C completed ASAP, the Admiralty decided to redesign them to carry 4 twin 4.5" guns. These weapons had already been ordered in light of pre-war plans to convert the 8 WW1 vintage D class cruisers to AA ships in 1940/41. Plans for the D class conversions were cancelled on the outbreak of WW2 as they were needed in the fleet. So the plan was to make best use of the hulls and guns already on order. In Sept 1939, their estimated completion dates were in Nov & Dec 1940, thereby slicing 12-18 months from their projected build time as 5.25" ships.

Unfortunately events in WW2 meant they ended up taking as long to build as the 5.25" ships, something that was not foreseeable in Sept 1939. For example, the Scotts yard at Greenock building Scylla, was heavily damaged by Luftwaffe bombing in March 1941 after she was launched which delayed completion of her and a number of other warships. Sirius was another of the class whose completion was significantly delayed by Luftwaffe bomb damage while building at Portsmouth.

It is also worthy of note that when in mid-1939 the Admiralty drew up its plan of action for the outbreak of war, it included plans for 4 additional Dido class. However in fact they ordered 6 Didos on 4 Sept. It seems clear that those extra two hulls were ordered to absorb the 5.25" turrets ordered for S&C and then surplus to immediate requirements.

Of those 6, only Argonaut completed to the original 5 turret design in Aug 1942. The other 5 faced periods of suspension in 1940 after the crisis in France in May before being redesigned with 4 turrets and greater light AA. They completed between Aug 1943 & Jan 1944.

So you can criticise S & C as much as you want, but as AA cruisers they were considered in some quarters as the best the RN had.

 

[EwenS]

Seriously though they built 2 of the Didos with 8x4.5" which is destroyer armament.

The 4.5" gun was designed around 1935 as an AA gun intended for carriers (starting with Ark Royal), reconstructed capital ships like Queen Elizabeth, Valiant & Renown, naval auxiliaries and the planned D class AA cruiser conversions. It was 1942 before it was selected as a weapon to arm destroyers in succession to the 4.7" that had been used previously.

The open backed Upper Deck Mk.III mount fitted in Scylla & Charybdis had 80° elevation, weighted 29.7 tons and the gun fired a 55lb shell.

The equivalent twin 4.7" destroyer twin mount, the CPXIX as fitted in the Tribal & J/K/N classes, had 40° elevation, weighed 25 tons and the gun fired a 50lb shell.

So the guns and mounts fitted to S & C were not "destroyer armament".