One last numberwang post, based on re-skimming the first half of TFW. Incomplete timeline attached if anyone interested. Some numbers that jumped out:

• British have 8 armoured divisions equipped with TFW Crusaders in 1940.
• Germans plan to have 25 armoured divisions fully equipped with TFW Panthers for spring 1941 (though it later appears they have mostly Panzer IIIs?), plus 1000 heavy and 1000 medium bombers and 2000 fighters (mostly FW 187s and 190s).

The numbers seem just possible but the quality does not. E.g. in OTL:

• The British got to this level a lot later and only with significant US tank production. The 36 division army plan pre-Dunkirk required 7,000 tanks and the 55-division plan post-Dunkirk 10,000.* Even on paper these would not be ready until late 1941, and actual production was even less.  I don't think this is something foresight can wave away while respecting historical budget constraints (yes tanks deserve a higher priority but you haven't said what gets a lower - see my previous post on naval tonnage).
• Germans started Barbarossa with 20 armoured divisions (>3000 tanks) that were roughly 2/3 Panzer III/IV and 1/3 older models. The number of aircraft also appears roughly comparable but of older and smaller types (e.g. they kept the Bf 109 until 1945 and it was their most produced fighter because it was cheap). So you're replacing 1-engined planes with 2-engined and 2-engined with 4-, making all the tanks bigger and newer - what are you building less of? (Capital ships for the Germans but I thought those resources were going into U-boats?)

There used to be an idea from the postwar bombing surveys that the Germans were just sitting around with their thumbs up their a***s (economically speaking) until after Stalingrad, but Overy and Tooze have put that to bed (see also this on the aircraft industry). And the British war economy was always considered pretty well run (shadow factories, rationing etc.) even if weapon quality is a different story.

*This looks like about 1000 tanks per armoured division (i.e. several times establishment strength): "In the summer of 1940 Mr. Churchill laid it down that the Army should, to begin with, contain not less than seven armoured divisions, and the programme of August 1940 was based on the assumption that the equivalent of about ten armoured divisions would be formed."  

P.S. not doing this to have a go particularly, just find this stuff fascinating and would like to see a bit more of it in the book. IMHO you mainly need to introduce the newer types in smaller numbers, although the British navy/army tradeoff needs to sacrifice some quantity as well.

Thanks for this - I do need to address those issues in more detail, I think. I have dug out my copies of "Design & Development of Weapons" and "British War Production" for some refresher reading...

dskellogg said:

) having saved-to-pdf many of your articles, including the alternative WW2 gun one on 57mm and 75s, would you still consider this to be the proper direction, or start from scratch altogether (perhaps pushing the 3-pdr/47mm caliber in various service configurations, closer to the aircraft P-gun in performance but years earlier

47mm 3pdr vickers is an option?

In production till 1936, it would be perfect as a "balanced" gun for tanks and a good size for an AT gun. It can use the heavy HE that Mr Williams suggest. A 3 pound AP and 4 1/2 pound HE.

The 47mm could be used as the Bofors round? Much more streamlined than separate 40mm and 57mm Bofors? 

The old pom-pom can be recycled as powered twins, and forget about 20mm peashooters!

You can skip the 57mm and pussy 75mm and head straight for a 15 pounder 77mm Comet tank. Fix the vertical armour and have a good all round 35 ton in 1943. It too can have Mr Williams heavy HE, a 22 pound smasher.

By 1944, have the Centurion with a 20 pounder with 30 pound HE, and HESH. 

Each Armored division have a heavy tank battalion, like the post war Ivan's T-10. 

hobbes154 said:

Can you afford a much bigger armoured force while building a similar naval tonnage to OTL (even if recycling 15-inch turrets and copying the Ark Royal makes the BB and CV builds quicker, that actually increases the demand for steel for the hulls in the short run)? Also if you are building faster turbine-powered corvettes to counter the electroboats (instead of the OTL reciprocating engines), what turbine-powered ships are you building less of (the gearing for turbines was a production bottleneck)?

No, the 4 mount design would have come out longer and heavier with less protection than the 3 mount design. Speed wouldnt have changed I believe as the longer finer waterline would counter the greater weight. The extra 60 feet of length iirc would have cost 2 inches of deck armour (to counteract the high up weight of C mount and the aft director which would need to be 2 decks higher than in the 14" ship) and a shallower torpedo defence, also the 5.25 battery would have had to be mounted closer together and a deck lower to counter blast from C mount. The only way to get the same protection in the 4 mount was to break the Washington treaty big time and that wasnt politically or economically possible when the design was sealed in 1936.

So you need more than 35,000 tons, more like 41,000 to 45,000 tons of Hood or Vanguard, and an extra six months of construction and 1000s of tons of steel. 

Spearthrower said:

47mm 3pdr vickers is an option? In production till 1936, it would be perfect as a "balanced" gun for tanks and a good size for an AT gun. It can use the heavy HE that Mr Williams suggest. A 3 pound AP and 4 1/2 pound HE. The 47mm could be used as the Bofors round? Much more streamlined than separate 40mm and 57mm Bofors?  The old pom-pom can be recycled as powered twins, and forget about 20mm peashooters!

From the point of view of Don, the planning would be to keep the tanks and their armament effective, maintaining an edge over the OTL German Pz III and IV as they evolve, but not excessively so otherwise that would just encourage the Germans to accelerate their development of heavy tanks, thereby making all of the earlier ones obsolete. That would be undesirable, as it would disrupt tank manufacture in the UK.

The 40mm Bofors is definitely one of the "untouchables" given its significance in OTL, so using the same ammo for the first generation of AT and AFV guns is an obvious rationalisation. The 57mm Bofors is a "nice to have" rather than a "must have", but the same applies.

The 20mm Oerlikon remained a significant weapon throughout the war, until the Japanese kamikaze tactic was adopted.

Spearthrower said:

hobbes154 said: Can you afford a much bigger armoured force while building a similar naval tonnage to OTL (even if recycling 15-inch turrets and copying the Ark Royal makes the BB and CV builds quicker, that actually increases the demand for steel for the hulls in the short run)? Also if you are building faster turbine-powered corvettes to counter the electroboats (instead of the OTL reciprocating engines), what turbine-powered ships are you building less of (the gearing for turbines was a production bottleneck)?

No, the 4 mount design would have come out longer and heavier with less protection than the 3 mount design. Speed wouldnt have changed I believe as the longer finer waterline would counter the greater weight. The extra 60 feet of length iirc would have cost 2 inches of deck armour (to counteract the high up weight of C mount and the aft director which would need to be 2 decks higher than in the 14" ship) and a shallower torpedo defence, also the 5.25 battery would have had to be mounted closer together and a deck lower to counter blast from C mount. The only way to get the same protection in the 4 mount was to break the Washington treaty big time and that wasnt politically or economically possible when the design was sealed in 1936. So you need more than 35,000 tons, more like 41,000 to 45,000 tons of Hood or Vanguard, and an extra six months of construction and 1000s of tons of steel. 

The first point to bear in mind is that the much earlier MAC ships and carriers (including smaller ones based on cruiser hulls) is a huge "force multiplier". Having aircraft constantly patrolling over convoys was proved to be so effective in OTL that hardly any ships were lost when so protected, compared with the carnage without air cover. So fewer escorts would be needed, and they could mainly be deployed as "hunter/killer" groups. This would of course be countered by the improved performance of the electroboats, but the general principle of aircraft doing the "spotting" would still apply.

Similarly, the high demand for RN cruisers (they wanted 70) had a lot to do with the need to patrol sea lanes to keep the merchant ships safe from surface commerce raiders. But a small force concentrated around a cruiser-hulled carrier with recce and strike planes would be able to protect a vastly greater sea area with fewer ships. 

As far as the battleships are concerned, ones with only six 15" guns would be unacceptable - OK for a couple of fast battlecruisers, but not as a replacement for battleships. Given that the major threats to battleships turned out to be torpedoes, followed by bombs, the main belt was actually the least significant aspect of protection. Building-in the ability to absorb punishment and cope with it, eg through more of a focus on a combination of compartmentation and protected pumps for each compartment, would be of more value and allow weight economies to be made in the vertical armour.

autogun said:

The first point to bear in mind is that the much earlier MAC ships and carriers (including smaller ones based on cruiser hulls) is a huge "force multiplier". Having aircraft constantly patrolling over convoys was proved to be so effective in OTL that hardly any ships were lost when so protected, compared with the carnage without air cover. So fewer escorts would be needed, and they could mainly be deployed as "hunter/killer" groups. This would of course be countered by the improved performance of the electroboats, but the general principle of aircraft doing the "spotting" would still apply.

The response to aircraft in the real world flak boats. Without universal radars on multiple escorts, u-boats did most of their hunting at night. Until you have enough escorts, the carriers are as much a target as the conveys. 

Once the u-boats go silent - minimal radio - the whole show changes,

Add elektic boats hunting closer the Great Britain, again rebalances airpower. Instead of Type 23 close in, type 21 around the main approaches. 

Subs with long submerged times needing masses of escorts to sweep 

autogun said:

As far as the battleships are concerned, ones with only six 15" guns would be unacceptable - OK for a couple of fast battlecruisers, but not as a replacement for battleships. Given that the major threats to battleships turned out to be torpedoes, followed by bombs, the main belt was actually the least significant aspect of protection. Building-in the ability to absorb punishment and cope with it, eg through more of a focus on a combination of compartmentation and protected pumps for each compartment, would be of more value and allow weight economies to be made in the vertical armour.

Did I not state 2" of deck armour lost!!!

Less torpedo defence!!

Warships already have compartmentization and  I did not raise anything about main belts,

so why the red herring response?

The extra 60 feet of length iirc would have cost 2 inches of deck armour (to counteract the high up weight of C mount and the aft director which would need to be 2 decks higher than in the 14" ship) and a shallower torpedo defence, also the 5.25 battery would have had to be mounted closer together and a deck lower to counter blast from C mount. 

Deck armour is more valuable than the main belt, as it protects against plunging shells (at medium/long range) and bombs.  The main belt becomes useful in a short-range slugging match, and even then compartmentation will likely prevent the damage becoming critical. 

Spearthrower said:

The response to aircraft in the real world flak boats.

Axis flak boats joining Allied convoys?