Whispering during 1930s ...

[Tony Williams]

"Secret Weapons of the Canadian Army" is a fascinating book on this subject.

Yes, I have a copy of that, and had some correspondence with the author, Roger Lucy. We combined our sources to end up with a comprehensive account of the Inglis cannon.

 

[riggerrob]

Why though? Given the threats of the day, it's a weapon without a purpose. You didn't need the mass volume of fire that an electrified Gatling gun can give you.

It could lead to useful short range anti-aircraft weapons for shipboard or vehicle use. Late in the war it might be very useful for countering the kamikaze threat. Perhaps you could get some sort of proto-Vulcan for larger twin engine or jet powered aircraft.

But again, why? For the aircraft of the day, a standard 20mm Oerlikon is more than enough. You don't need the "bullet hose" that a phalanx gives you until your threats are flying best or above Mach 1. You also really need the entire system to be effective. You need a radar guided and automatically aimed weapon to be effective with that rate of fire. Otherwise you're just wasting ammo. If this question was asked in the 50s, you'd be right on the money with the answer. But in the 30s, it's just too early

Dear SSgtC,
Late war closing speeds often approached Mach 1. Consider a Mustang diving - at more than 400 mph- at a Messerschmitt that is diving at 400 mph. That equals a closing speed of 800 mph. That's supersonic closing speeds in most calculations.
We agree that a multi-barrel Gatling gun is too heavy for WW2 airplanes, but it would come in hady as a deck-mount on a capital ship bothered by kamakaze dive bombers.

 

[riggerrob]

Dear Zen,
Britain definitely needed an SMG, but not ridiculously expensive, all machined MP18, Thompson or Lanchester. Lanchester may have been great for RN boarding parties. After firing all 50 rounds, it was still heavy enough to club enemy into submission!
OTOH the original STEN was designed to be hand-built in dozens of tiny shops equipped with little more than drill, hacksaw and files. STEN design was driven by Depression-era, British labour practices.

ATL What they really needed was a quick-to-produce SMG made of castings and sheet steel pressings .. like an Owen or Madsen M1946.

 

[riggerrob]

Grumman and CCF cooperate to design a new submarine-spotting airplane for the Royal Canadian Navy's Fleet Air Arm. It is a strut-braced, high-wing monoplane resembling a Curtiss-Wright Owl, but with the centre fuselage all clad in Plexiglass. The rest of the airframe is sheet metal, with half the parts-count of a Lysander. Crew is a minimum of 3, just to provide enough eyeballs for visual searching. The pilot's seat is high and forward of the wings' leading edge to provide maximum visibility. The RCN's "Snowy Owl" can take off from flight decks as short as Swordfish, but cruises a bit faster. Early versions have retractable landing gear - supplied by Grumman - but it is replaced by faired, fixed landing gear in later versions. Fixed main wheels are mounted on stub-wings more like Noorduyn Norseman.
Armament is limited to a pair of forward-firing MGs (ala. Sunderland).
The "big gun" is the radios and Aldis lamp to call on destroyers and corvettes with heavy depth charges.
Perhaps Robert Noordyun consults on a simple wing design that will provide STIOL performance, but without the complex leading edge slats (ala. Lysander). RCN Snowy Owl looks much a like slender version of Noordyun's ficticious Longboat.

 

[lordroel]

This is a take-off from Anthony Williams "Foresight War."
What if you time-travelled back to the 1930s and gained access to the ears of engineers, politicians and generals?
What would you suggest?
You are not allowed to "predict" World War 2.
To keep this thread "alternate" please do not repeat concepts that made it into production.
Please whisper "alternate" concepts into the ears of influential engineers, generals and politicians.

Are every influential engineers, generals and politicians on the planet allowed to be whispered to.

 

[zen]

Dear Zen,
Britain definitely needed an SMG, but not ridiculously expensive, all machined MP18, Thompson or Lanchester. Lanchester may have been great for RN boarding parties. After firing all 50 rounds, it was still heavy enough to club enemy into submission!
OTOH the original STEN was designed to be hand-built in dozens of tiny shops equipped with little more than drill, hacksaw and files. STEN design was driven by Depression-era, British labour practices.

ATL What they really needed was a quick-to-produce SMG made of castings and sheet steel pressings .. like an Owen or Madsen M1946.

If I want a SMG to club someone to death with, I'll take a Suomi and one hit and they stay dead!

 

[SSgtC]

Dear SSgtC,
Late war closing speeds often approached Mach 1. Consider a Mustang diving - at more than 400 mph- at a Messerschmitt that is diving at 400 mph. That equals a closing speed of 800 mph. That's supersonic closing speeds in most calculations.
We agree that a multi-barrel Gatling gun is too heavy for WW2 airplanes, but it would come in hady as a deck-mount on a capital ship bothered by kamakaze dive bombers.

Closing speed, not relative speed. And as you yourself said, it's just too heavy to practically mount on an aircraft. And if you're mounting it on a ship, then you're back down to 300-400 MPH and existing system were effective against those threats. It wasn't until Aircraft and missiles began flying at or above Mach 1 that the bullet hose became a need as you may only get a half second or a second to intercept the target and you need as many rounds fired as possible in that time.

 

[Tony Williams]

ATL What they really needed was a quick-to-produce SMG made of castings and sheet steel pressings .. like an Owen or Madsen M1946.

A Sterling would do just fine.

 

[Grey Havoc]

At a bare minimum, allow the Royal Navy and the USN to start building new heavy cruisers, stat.

 

[RanulfC]

Another thought.....nothing actually excluded the development of printed circuit boards, even if it's very chunky.

Another thought.....nothing actually excluded the development of printed circuit boards, even if it's very chunky.

If printed circuit boards proved more reliable, they would be worth the effort. Even if those pcbs still connected vacuum tubes, they would probably still prove more durable.

Wire Wrapped Circuit Board assembly... I do NOT miss those things one bit

Wire wrap - Wikipedia

en.wikipedia.org

Randy

 

[Fluff]

Another thought.....nothing actually excluded the development of printed circuit boards, even if it's very chunky.

Another thought.....nothing actually excluded the development of printed circuit boards, even if it's very chunky.

If printed circuit boards proved more reliable, they would be worth the effort. Even if those pcbs still connected vacuum tubes, they would probably still prove more durable.

Wire Wrapped Circuit Board assembly... I do NOT miss those things one bit

Wire wrap - Wikipedia

en.wikipedia.org

Randy

Paxolin

 

[Tony Williams]

At a bare minimum, allow the Royal Navy and the USN to start building new heavy cruisers, stat.

Why would the RN want more heavy cruisers (assuming that by this you mean 8 inch guns)? Historically, they elected to fit their later 10,000 tonners with 12 x 6 inch rather than 8 x 8 inch.

 

[Lascaris]

At a bare minimum, allow the Royal Navy and the USN to start building new heavy cruisers, stat.

Why would the RN want more heavy cruisers (assuming that by this you mean 8 inch guns)? Historically, they elected to fit their later 10,000 tonners with 12 x 6 inch rather than 8 x 8 inch.

They had already built 13 Counties, 2 Yorks besides the 3 Hawkins extant in 1930. First London article 16 was limiting them to 15 heavy cruisers and 146,800 tons. The Counties and Yorks alone amounted to 146,500 tons and 15 vessels. Putting 8in guns to the later ships would be in direct violation of the treaty.

 

[Tony Williams]

They had already built 13 Counties, 2 Yorks besides the 3 Hawkins extant in 1930. First London article 16 was limiting them to 15 heavy cruisers and 146,800 tons. The Counties and Yorks alone amounted to 146,500 tons and 15 vessels. Putting 8in guns to the later ships would be in direct violation of the treaty.

I will have to study Friedman!

 

[uk 75]

The key reason for war in 1939 was the weakness of France. France had created its allied nations to Germany's East. It then "hid" behind the Maginot line. This left Poland and the Czechs at the mercy of both Germany and Russia. A more serious appreciation by French poliicians and soldiers of what supporting these countries entailed should have been a full military alliance with effective land and air forces exercising together NATO style. Then when Hitler turns up, they simply roll into the Rhineland and kick him out.

 

[Dilandu]

The key reason for war in 1939 was the weakness of France. France had created its allied nations to Germany's East. It then "hid" behind the Maginot line. This left Poland and the Czechs at the mercy of both Germany and Russia. A more serious appreciation by French poliicians and soldiers of what supporting these countries entailed should have been a full military alliance with effective land and air forces exercising together NATO style. Then when Hitler turns up, they simply roll into the Rhineland and kick him out.

Well, who West could blame other than themselves for their political stupidity in late 1930s - when they allowed Fascists to overthrew the Spanish Republic, put a blind eye toward German rearmament, and then antagonized USSR by betraying Czech in 1938?

 

[Tony Williams]

At a bare minimum, allow the Royal Navy and the USN to start building new heavy cruisers, stat.

Why would the RN want more heavy cruisers (assuming that by this you mean 8 inch guns)? Historically, they elected to fit their later 10,000 tonners with 12 x 6 inch rather than 8 x 8 inch.

They had already built 13 Counties, 2 Yorks besides the 3 Hawkins extant in 1930. First London article 16 was limiting them to 15 heavy cruisers and 146,800 tons. The Counties and Yorks alone amounted to 146,500 tons and 15 vessels. Putting 8in guns to the later ships would be in direct violation of the treaty.

The question would surely be whether buying more of the expensive 8" gunned treaty cruisers was worth it. Obviously, buying more of them would mean buying fewer of the 6" ships, due to budget restrictions and practical limits on the number of warships which the country could build. So the combat record of 8" and 6" cruisers would need to be compared, to see how often the larger calibre was useful.

 

[Lascaris]

At a bare minimum, allow the Royal Navy and the USN to start building new heavy cruisers, stat.

Why would the RN want more heavy cruisers (assuming that by this you mean 8 inch guns)? Historically, they elected to fit their later 10,000 tonners with 12 x 6 inch rather than 8 x 8 inch.

They had already built 13 Counties, 2 Yorks besides the 3 Hawkins extant in 1930. First London article 16 was limiting them to 15 heavy cruisers and 146,800 tons. The Counties and Yorks alone amounted to 146,500 tons and 15 vessels. Putting 8in guns to the later ships would be in direct violation of the treaty.

The question would surely be whether buying more of the expensive 8" gunned treaty cruisers was worth it. Obviously, buying more of them would mean buying fewer of the 6" ships, due to budget restrictions and practical limits on the number of warships which the country could build. So the combat record of 8" and 6" cruisers would need to be compared, to see how often the larger calibre was useful.

Britain's preference was for cruisers about the size of HMS Arethusa in the 5,000t range in order to be able to build them in sufficient numbers and low enough cost. The obvious problem is that when everyone else in building 10,000t ships in large numbers your 5,000t ship is to put it mildly insufficient. On the debate between 12x6 or 8-9x8 I am a bit agnostic, probably the higher volume of fire evened out with the bigger hitting power of an individual 8in sell. But there is here one more factor namely how well you could armour a ship against 6in and 8in fire. You could build a 10,000t ship protected against 6in, the French did it at a tonnage as low as ~7,500t with the Montcalms. Way more difficult to do so with a 10,000t ship, not impossible again as evidenced by Algerie but way more difficult. So when you have something like the proposed Surrey class heavy cruisers or Algerie who can stand up to 8in fire take on one of the Towns that have 12x12 6in but are not even completely protected against 6in guns, the first will have a distinct advantage. One that the heavy cruisers built in the 1920s do not share of course.

 

[Tony Williams]

At a bare minimum, allow the Royal Navy and the USN to start building new heavy cruisers, stat.

Why would the RN want more heavy cruisers (assuming that by this you mean 8 inch guns)? Historically, they elected to fit their later 10,000 tonners with 12 x 6 inch rather than 8 x 8 inch.

They had already built 13 Counties, 2 Yorks besides the 3 Hawkins extant in 1930. First London article 16 was limiting them to 15 heavy cruisers and 146,800 tons. The Counties and Yorks alone amounted to 146,500 tons and 15 vessels. Putting 8in guns to the later ships would be in direct violation of the treaty.

The question would surely be whether buying more of the expensive 8" gunned treaty cruisers was worth it. Obviously, buying more of them would mean buying fewer of the 6" ships, due to budget restrictions and practical limits on the number of warships which the country could build. So the combat record of 8" and 6" cruisers would need to be compared, to see how often the larger calibre was useful.

Britain's preference was for cruisers about the size of HMS Arethusa in the 5,000t range in order to be able to build them in sufficient numbers and low enough cost. The obvious problem is that when everyone else in building 10,000t ships in large numbers your 5,000t ship is to put it mildly insufficient. On the debate between 12x6 or 8-9x8 I am a bit agnostic, probably the higher volume of fire evened out with the bigger hitting power of an individual 8in sell. But there is here one more factor namely how well you could armour a ship against 6in and 8in fire. You could build a 10,000t ship protected against 6in, the French did it at a tonnage as low as ~7,500t with the Montcalms. Way more difficult to do so with a 10,000t ship, not impossible again as evidenced by Algerie but way more difficult. So when you have something like the proposed Surrey class heavy cruisers or Algerie who can stand up to 8in fire take on one of the Towns that have 12x12 6in but are not even completely protected against 6in guns, the first will have a distinct advantage. One that the heavy cruisers built in the 1920s do not share of course.

All good points, but of course you would not be putting up one 5,000 ton ship against one 10,000 ton, but two (at least) for the same cost. You are then getting into something of a Battle of the River Plate scenario.

 

[Lascaris]

At a bare minimum, allow the Royal Navy and the USN to start building new heavy cruisers, stat.

Why would the RN want more heavy cruisers (assuming that by this you mean 8 inch guns)? Historically, they elected to fit their later 10,000 tonners with 12 x 6 inch rather than 8 x 8 inch.

They had already built 13 Counties, 2 Yorks besides the 3 Hawkins extant in 1930. First London article 16 was limiting them to 15 heavy cruisers and 146,800 tons. The Counties and Yorks alone amounted to 146,500 tons and 15 vessels. Putting 8in guns to the later ships would be in direct violation of the treaty.

The question would surely be whether buying more of the expensive 8" gunned treaty cruisers was worth it. Obviously, buying more of them would mean buying fewer of the 6" ships, due to budget restrictions and practical limits on the number of warships which the country could build. So the combat record of 8" and 6" cruisers would need to be compared, to see how often the larger calibre was useful.

Britain's preference was for cruisers about the size of HMS Arethusa in the 5,000t range in order to be able to build them in sufficient numbers and low enough cost. The obvious problem is that when everyone else in building 10,000t ships in large numbers your 5,000t ship is to put it mildly insufficient. On the debate between 12x6 or 8-9x8 I am a bit agnostic, probably the higher volume of fire evened out with the bigger hitting power of an individual 8in sell. But there is here one more factor namely how well you could armour a ship against 6in and 8in fire. You could build a 10,000t ship protected against 6in, the French did it at a tonnage as low as ~7,500t with the Montcalms. Way more difficult to do so with a 10,000t ship, not impossible again as evidenced by Algerie but way more difficult. So when you have something like the proposed Surrey class heavy cruisers or Algerie who can stand up to 8in fire take on one of the Towns that have 12x12 6in but are not even completely protected against 6in guns, the first will have a distinct advantage. One that the heavy cruisers built in the 1920s do not share of course.

All good points, but of course you would not be putting up one 5,000 ton ship against one 10,000 ton, but two (at least) for the same cost. You are then getting into something of a Battle of the River Plate scenario.

I'm not entirely certain cost wise. The Arethusas cost on average 1.25 million pounds apiece. The more or less contemporary Counties somewhat below 2 million (HMS Kent for example 1.97 million). Cost wise this means you were getting roughly 2 Counties for the cost of 3 Arethusas. And in terms of maintanance the Arethusas needed 500 man crews when the Counties had 685. Again 2 Counties needed somewhat less crew than 3 Arethusas.

 

[A Tentative Fleet Plan]

The Royal Navy in this period has a requirement for anywhere from 50 to 70 cruisers (later increasing to 100). 50, let alone 70 or 100 Counties is utterly unaffordable, not to mention that the the Counties could not perform all of the roles the Royal Navy required cruisers for (for example leading destroyer attacks).

 

[Siberia]

The question would surely be whether buying more of the expensive 8" gunned treaty cruisers was worth it. Obviously, buying more of them would mean buying fewer of the 6" ships, due to budget restrictions and practical limits on the number of warships which the country could build. So the combat record of 8" and 6" cruisers would need to be compared, to see how often the larger calibre was useful.

My gut reaction would be for more 6-inch light cruisers rather than a smaller number of 8-inch heavy cruisers, although if research showed the latter to be more effective so be it.

Mention of the Naval Treaties reminds me of a couple of things to take care of. It was the British who argued for a decrease in the displacement of aircraft carriers so it shouldn’t be too hard to convince the right people to argue for a slightly higher limit of 25,000 tons, with a bit of luck that would result in something like the Implacable-class being built. The reduction in displacement for light cruises from 10,000 tons to 8,000 tons, avoiding that allows you to develop the Town-class design rather having to make compromises. I'm of two minds about the limit of 14 inches for battleship main guns, the King George V-class seem to have performed adequately with 14-inch guns and I can't remember offhand any cases where 15-inch guns would have provided a decisive improvement.

 

[Lascaris]

The question would surely be whether buying more of the expensive 8" gunned treaty cruisers was worth it. Obviously, buying more of them would mean buying fewer of the 6" ships, due to budget restrictions and practical limits on the number of warships which the country could build. So the combat record of 8" and 6" cruisers would need to be compared, to see how often the larger calibre was useful.

My gut reaction would be for more 6-inch light cruisers rather than a smaller number of 8-inch heavy cruisers, although if research showed the latter to be more effective so be it.

Mention of the Naval Treaties reminds me of a couple of things to take care of. It was the British who argued for a decrease in the displacement of aircraft carriers so it shouldn’t be too hard to convince the right people to argue for a slightly higher limit of 25,000 tons, with a bit of luck that would result in something like the Implacable-class being built. The reduction in displacement for light cruises from 10,000 tons to 8,000 tons, avoiding that allows you to develop the Town-class design rather having to make compromises. I'm of two minds about the limit of 14 inches for battleship main guns, the King George V-class seem to have performed adequately with 14-inch guns and I can't remember offhand any cases where 15-inch guns would have provided a decisive improvement.

Do completely away with the 2nd London naval treaty. Even in 1936 when it was signed it should had looked like a suicide pact. Not a single one of its clauses made any sense when it was already known that every single one of the proposed clauses was being broken by one or more non signatory. Battleships? The Littorios have already been laid down and Germans and Japanese are planning theirs. Cruisers? The Japanese and Germans are already building 8in cruisers. Aircraft carriers? The Japanese are again planning new ones and don't want to join the treaty.

I really cannot understand what the British had in mind when proposing the reductions they did and what was the underlying logic. It just makes no sense.

 

[zen]

At least one scheme during the process that led to the much deferred Ark Royal was a carrier of standard displacement of 25,000tons.

With my eye on the future, expanding some drydocks to between 900ft to 1000ft would help a lot.

 

[SSgtC]

I really cannot understand what the British had in mind when proposing the reductions they did and what was the underlying logic. It just makes no sense.

They were broke. That was the major motivator for the treaty. Limiting the cost of new construction and "winning" a naval arms race by stopping it before it could start.

 

[Lascaris]

I really cannot understand what the British had in mind when proposing the reductions they did and what was the underlying logic. It just makes no sense.

They were broke. That was the major motivator for the treaty. Limiting the cost of new construction and "winning" a naval arms race by stopping it before it could start.

In 1921 maybe. In 1936? Nope.

 

[Tony Williams]

They were broke. That was the major motivator for the treaty. Limiting the cost of new construction and "winning" a naval arms race by stopping it before it could start.

The most economical way of providing new RN battleships would have been to argue for a "compromise" 15 inch gun calibre, then use the existing turrets from Courageous and Glorious plus those from the old R class battleships, which would enable six new ships to be provided quickly at a much lower cost (given that the main armament of the battleships was their greatest single cost element and took the longest to make).

I did use this solution in The Foresight War, and only afterwards discovered that the Admiralty had this in mind as a follow-on to Vanguard.

 

[robunos]

A few whisperings on the subject of AFVs, some more specific than others . . .

Scrap those Vickers light tanks, and replace them with something able to carry a decent antitank gun, like the Vickers Six-Tonner. That way, the BEF will have more firepower available against the Panzers.
On tanks, replace the OQF 2-Pounder with the 'modernised' 6-Pounder 8cwt, as discussed on Tony Williams' website HERE :-
That sorts out the situation at the start of the war, now for the follow-up vehicles . . .
First get the Department of Tank Development to act like the Air Ministry; get out of the design business, just issue requirements and specifications to the industry, and see what they come up with . . .
Get Napiers to develop a tank engine version of the Lion, to replace the Liberty. This should prove more compact and powerful than the latter engine, as well as more reliable.
Drop the 'Infantry/Cruiser' tank concept. Go for a 'Standard Tank' design, able to perform both roles, and armed with a dual-purpose gun, of at least 75mm calibre. Also to be produced in 'Assault Gun' ( a British StuG ), and 'Self Propelled Anti-Tank Gun' variants, with casemate mounted guns. The former to be armed with a derivative of the 25-Pounder, the latter with a high-velocity weapon, possibly derived from an anti-aircraft gun. The second generation of this tank would take the same path as the Soviet T-34, and mount the guns from the casemate variants into a larger rotating turret on the existing tank hull.

cheers,
Robin.

 

[SSgtC]

The most economical way of providing new RN battleships would have been to argue for a "compromise" 15 inch gun calibre

How did you get the US and Japan to agree to that? Because the USN hasn't used 15" guns since the Civil War. And they were smoothbore guns at that. It was my understanding that the main reason the UK settled for a 14" limit, was that, of the three big navies (RN, USN, IJN), only the RN used 15" guns and the other two basically on either a 14" or 16" limit. So how do you get the USN and IJN to agree to a gun calibre that they have never used in a modern warship?

 

[Fluff]

A few whisperings on the subject of AFVs, some more specific than others . . .

Scrap those Vickers light tanks, and replace them with something able to carry a decent antitank gun, like the Vickers Six-Tonner. That way, the BEF will have more firepower available against the Panzers.
On tanks, replace the OQF 2-Pounder with the 'modernised' 6-Pounder 8cwt, as discussed on Tony Williams' website HERE :-
That sorts out the situation at the start of the war, now for the follow-up vehicles . . .
First get the Department of Tank Development to act like the Air Ministry; get out of the design business, just issue requirements and specifications to the industry, and see what they come up with . . .
Get Napiers to develop a tank engine version of the Lion, to replace the Liberty. This should prove more compact and powerful than the latter engine, as well as more reliable.
Drop the 'Infantry/Cruiser' tank concept. Go for a 'Standard Tank' design, able to perform both roles, and armed with a dual-purpose gun, of at least 75mm calibre. Also to be produced in 'Assault Gun' ( a British StuG ), and 'Self Propelled Anti-Tank Gun' variants, with casemate mounted guns. The former to be armed with a derivative of the 25-Pounder, the latter with a high-velocity weapon, possibly derived from an anti-aircraft gun. The second generation of this tank would take the same path as the Soviet T-34, and mount the guns from the casemate variants into a larger rotating turret on the existing tank hull.

cheers,
Robin.

There was a vickers light with the 2pdr, but only one....Would have been straightforward.

Pre-40 a 75 would have been seen as crazy talk, the 6pdr 57mm should have been seen as a logical step, and should have been specified as a known upgrade for any tanks above the lights. Then when you made that move, obviously you now need the next step - a 75...

I;m not sure on the assault guns, they really developed from the german lash-ups. If you have the industry why would you limit yourselves - that said I would have thought half the Lee/grants would have had their 37mm turret removed, save on crew, and profile, maybe stick the mg turret back on, could have lead the way to a sherman STUG.

Sexton/priest is so obvious, but maybe they were prioritizing 'tanks' - but should have been prototyped earlier.

 

[robunos]

I'm aware of the 2-pdr armed Vickers Light Tank, the disadvantage was that the turret was open-topped. Also, I'm not certain that the turret had all-round traverse. My main objection to the Vickers Light Tank, is that it's just too small, too light, and too thin-skinned to be useful as anything other than reconnaissance or mobile MG support for perimeter patrols, etc. The Six-Tonner, being that little bit larger and heavier, is more useful in a 'proper tank' role, especially if armed as suggested in my post upthread . . .
Regarding a 75mm tank gun, if the tanks are re-armed as suggested in Tony Williams' article, we're already up to 57mm, so 75mm-ish IS the next logical step . . .
The new tank with the larger gun and and SP variants, wouldn't have gone into service until mid-1941 at the absolute earliest. The idea is to develop a British T-34, with variants carrying different armament, and amounts of armour, but with a common basic hull, engine, transmission, and running gear. Ideally, the Assault Gun and SP-AT versions would differ only in their weapon and ammunition stowage, and be fairly easily convertible, obviously not in the field, but certainly at Base Workshops' level.
As to the reason for these versions, lower silhouette, bigger gun and thicker armour than the turreted versions, at the acceptable cost of reduced mobility, at least initially. An APC could also be developed from a fixed-casemate variant . . .
The examples you give with the Grant / Sherman / Sexton are perfect, the Sherman is the Gun Tank, and a Grant / Sexton hybrid for the other two, gun on the centre-line, and a fully enclosed and armoured hull. Applique armour could be used to improve protection on the SP-AT version.

cheers,
Robin.

 

[Fluff]

Oh, I wouldn’t see the Vickers as the main tank, just it would have been good, even in a 1 to 2 ratio, a bit like firefly, in the lights/recon.

British t34 would Cromwell/comet with sloped armour.

if you did have STUG, I always see them as mixed in with tanks, thus overcoming their main limitation.

then as a heavy, the Churchill, starting with 57mm, quickly moving to 75mm.
Can we find an aa tank?
Vickers light with twin polsen ?

 

[Tony Williams]

The most economical way of providing new RN battleships would have been to argue for a "compromise" 15 inch gun calibre

How did you get the US and Japan to agree to that? Because the USN hasn't used 15" guns since the Civil War. And they were smoothbore guns at that. It was my understanding that the main reason the UK settled for a 14" limit, was that, of the three big navies (RN, USN, IJN), only the RN used 15" guns and the other two basically on either a 14" or 16" limit. So how do you get the USN and IJN to agree to a gun calibre that they have never used in a modern warship?

The proposal was for 14 inch, with 16 inch as a possibility. France, Italy and Germany all went for 15" in new ships, so I don't see any problem with the UK deciding to do the same. The USN can go to 16 inch if they want, and Japan ignores all limitations anyway.