Are ASB needed for this British tank spec?

[Admiral Beez]

I've got some ideas for a British tank specification for the late 1930s (1937 onwards), for a single British medium tank type to be in service by early 1940.

Do we see these as reasonable departures from OTL or ASB territory?

1) Abandonment of the cruiser and infantry tank model. Instead, Britain wants one medium tank type, with closer balance of firepower, mobility and protection.

2) Requirement of three man turret, with commander, loader and gunner. To reduce manpower can we get by with only one crew in the bow? This would eliminate the bow gunner and his help with the radio functions.

3) Focus on coordination of tanks, meaning radio communication between crews and tanks. Are such radios available in the late 1930s?

4) To be armed with the QF 6-pounder (with 2-pdr as place holder until gun is available), and also designed to accommodate the largest gun then conceived. This would be the QF 17-pounder, which was considered required even in 1938 when the 6-pdr was being developed.

5) Use of sloped armour (CSS Virginia demonstrated this 75 years earlier).

 

[Derek Pullem]

Least unlikely scenario is getting the rail transport criteria eased earlier. Unlikely that decision to move tanks by road only will be made prior to 1939.

With a less onerous width restriction the Chruchill and Cromwell designs are possible - Cromwell is more like your target design but it would require the Merlin to be available at the same time it is being slatted for Hurricane and Spitfire production.

Not sure if the Kestrel could be used in a similar role - much less power but as Merlin had to be restricted to save the suspension this may not be a dealbreaker.

Findling production facilities might though.

 

[BlueTrousers]

I've got some ideas for a British tank specification for the late 1930s (1937 onwards), for a single British medium tank type to be in service by early 1940.

Do we see these as reasonable departures from OTL or ASB territory?

1) Abandonment of the cruiser and infantry tank model. Instead, Britain wants one medium tank type, with closer balance of firepower, mobility and protection.

The cruiser/infantry split came about partly for cost reasons and partly because of engine limitations - if you choose speed or armour, you get a lighter, cheaper tank, and you can still run it on a Liberty engine. Spend more money or accept fewer tanks, and the first problem goes away. Shoot Lord Nuffield and the second problem goes away.

2) Requirement of three man turret, with commander, loader and gunner. To reduce manpower can we get by with only one crew in the bow? This would eliminate the bow gunner and his help with the radio functions.

Three-man turret is a no-brainer, you're stuck with the radio operator/bow gunner though - he was primarily there for the radio, the machine gun was to give him something to do when not required for signalling. Develop voice radio, and he becomes unnecessary, but that's a big ask. Drop the radio altogether, and you lose one of the big advantages of the British tank force.

3) Focus on coordination of tanks, meaning radio communication between crews and tanks. Are such radios available in the late 1930s?

See above about the radio operator. I believe that the British armoured force was one of the first to have a radio in every tank.

4) To be armed with the QF 6-pounder (with 2-pdr as place holder until gun is available), and also designed to accommodate the largest gun then conceived. This would be the QF 17-pounder, which was considered required even in 1938 when the 6-pdr was being developed.

A tank to take a 17pdr will be very large by the standards of 1937/1938, especially if designed as a full-dress medium. A 2pdr upgradeable to a 6pdr is probably plausible, though.

5) Use of sloped armour (CSS Virginia demonstrated this 75 years earlier).

Sloped armour isn't a panacea, but should be possible. You just have to accept the compromises it brings - chiefly cramped internal arrangements.

Build the Medium Mark IV with a 2pdr, upgradeable to a 6pdr, and a detuned Kestrel, to enter service 1939-1940. It'll be one of the best tanks going then. Upgrade to the 6pdr in late 1941/early 1942, and it's still one of the best tanks going. I'm envisaging something similar to a Crusader with more power and more armour.

The successor Medium Mark V will be fitted initially with a 6pdr (or 3.7" CS howitzer), entering service in 1943-1944. A revised turret with a 17pdr enters service from mid-1944.

To get the above, though, you're sacrificing infantry tanks. No big loss in manoeuvre warfare, but for set pieces like Normandy they were excellent. The mediums will fill the niche of the cruiser admirably, and there'll be more of them, but the Churchill was incredibly well suited to its' role. Also, the cut in numbers will hurt - late in the war the British Army had more tanks per man than the US Army, largely because Britain couldn't spare the manpower. Cut the tanks, and the men will suffer; any tank, even if it's a Matilda I, is better than no tank at all.

 

[Cryhavoc101]

The cruiser/infantry split came about partly for cost reasons and partly because of engine limitations - if you choose speed or armour, you get a lighter, cheaper tank, and you can still run it on a Liberty engine. Spend more money or accept fewer tanks, and the first problem goes away. Shoot Lord Nuffield and the second problem goes away.

Three-man turret is a no-brainer, you're stuck with the radio operator/bow gunner though - he was primarily there for the radio, the machine gun was to give him something to do when not required for signalling. Develop voice radio, and he becomes unnecessary, but that's a big ask. Drop the radio altogether, and you lose one of the big advantages of the British tank force.

See above about the radio operator. I believe that the British armoured force was one of the first to have a radio in every tank.

A tank to take a 17pdr will be very large by the standards of 1937/1938, especially if designed as a full-dress medium. A 2pdr upgradeable to a 6pdr is probably plausible, though.

Sloped armour isn't a panacea, but should be possible. You just have to accept the compromises it brings - chiefly cramped internal arrangements.

Build the Medium Mark IV with a 2pdr, upgradeable to a 6pdr, and a detuned Kestrel, to enter service 1939-1940. It'll be one of the best tanks going then. Upgrade to the 6pdr in late 1941/early 1942, and it's still one of the best tanks going. I'm envisaging something similar to a Crusader with more power and more armour.

The successor Medium Mark V will be fitted initially with a 6pdr (or 3.7" CS howitzer), entering service in 1943-1944. A revised turret with a 17pdr enters service from mid-1944.

To get the above, though, you're sacrificing infantry tanks. No big loss in manoeuvre warfare, but for set pieces like Normandy they were excellent. The mediums will fill the niche of the cruiser admirably, and there'll be more of them, but the Churchill was incredibly well suited to its' role. Also, the cut in numbers will hurt - late in the war the British Army had more tanks per man than the US Army, largely because Britain couldn't spare the manpower. Cut the tanks, and the men will suffer; any tank, even if it's a Matilda I, is better than no tank at all.

On radios

It was a full time job keeping a radio 'netted' in and in tanks like a firefly with only 4 crew this was possible as the Firefly in a given Battalion were usually crewed by the veteran crews and most if not all of the crew would be able to perform this role (and the radio was at the rear of the turret anyway).

However a less experienced crew would have to probably rely on the trained radioman and tank commander hence why it was important to have a 5th crewman who specialised in this job.

There are stories of tank units being seriously compromised after being rushed into combat from a reserve location - the units having 'netted in ' their radios to the BBC (other radio stations are available) and not having enough time to 'net' into the Troop/Squadron/Battalion

So don't dismiss the Radio guy so quickly - it was a skilled and time consuming task!

 

[Admiral Beez]

So don't dismiss the Radio guy so quickly - it was a skilled and time consuming task!

Several British tanks, including those with radios and three man turrets only had a single man up front. For example, the Matilda tank.

https://www.youtube.com/watch?v=VB0A9EwEeWg

 

[Sior]

Least unlikely scenario is getting the rail transport criteria eased earlier. Unlikely that decision to move tanks by road only will be made prior to 1939.

With a less onerous width restriction the Chruchill and Cromwell designs are possible - Cromwell is more like your target design but it would require the Merlin to be available at the same time it is being slatted for Hurricane and Spitfire production.

Not sure if the Kestrel could be used in a similar role - much less power but as Merlin had to be restricted to save the suspension this may not be a dealbreaker.

Findling production facilities might though.

https://en.wikipedia.org/wiki/Napier_Lion

The Napier Lion was a 12-cylinder broad arrow configuration aircraft engine built by Napier & Son starting in 1917, and ending in the 1930s. A number of advanced features made it the most powerful engine of its day, and kept it in production long after contemporary designs had stopped production. It is particularly well known for its use on a number of racing designs, in aircraft, boats, and cars.

http://www.quarryhs.co.uk/alt WW2 tank gun.htm

To get sloped armour on early British tanks you need to improve welding tech in Britain.
Up until the end of the war British tanks were still riveted together onto a frame work internal to the body of the tank. These rivets became projectiles inside the tank when hit with enough force (even if the projectile did not penetrate).

 

[hipper]

I've got some ideas for a British tank specification for the late 1930s (1937 onwards), for a single British medium tank type to be in service by early 1940.

Do we see these as reasonable departures from OTL or ASB territory?

1) Abandonment of the cruiser and infantry tank model. Instead, Britain wants one medium tank type, with closer balance of firepower, mobility and protection.

2) Requirement of three man turret, with commander, loader and gunner. To reduce manpower can we get by with only one crew in the bow? This would eliminate the bow gunner and his help with the radio functions.

3) Focus on coordination of tanks, meaning radio communication between crews and tanks. Are such radios available in the late 1930s?

4) To be armed with the QF 6-pounder (with 2-pdr as place holder until gun is available), and also designed to accommodate the largest gun then conceived. This would be the QF 17-pounder, which was considered required even in 1938 when the 6-pdr was being developed.

5) Use of sloped armour (CSS Virginia demonstrated this 75 years earlier).

I give you the A10 heavy cruser

specifically designed as a Heavy cruiser tank with twice the armour of its predecessor with exactly equivalent armour to its german opposite number the Mk III

three man turret

could carry a 6 lber (in terms of turret space anyway)

at least 1/2 the frontal armour of this tank is sloped, its also mechanically reliable

its only problem is a lack of decent engine which restricted its size however the derivatives of this tank were the most produced British Tank..

Cheers Hipper

 

[Simon]

Abandonment of the cruiser and infantry tank model. Instead, Britain wants one medium tank type, with closer balance of firepower, mobility and protection.

The British had been developing 'universal' tanks but then the A6 and follow-on A7 tank development programmes in the 1930s ended up not being very successful for several reasons, one of was a lack of a powerful enough engine. Because of this they decided to split the programme into heavy infantry tanks and lighter cruiser tanks since it meant they could meet the two tasks with the current engines on offer. Have them develop a better engine and there would be no need for the infantry-cruiser split, or allow them to recombine them later on. There are several possibilities but my general favourite is converting the Rolls-Royce Kestrel aero-engine just as they did with the Merlin during WWII, they actually looked at converting either the Kestrel or the Merlin but decided to use the Merlin as whilst the Kestrel generated 475 bhp on pool petrol it missed out on being able to provide the 20 hp/tonne with the weight of the tanks they were considering later in the war. Here considering that the Matilda II's engine only generated 180 bhp or the Panzer IV's 295 bhp that would be more than enough.

Requirement of three man turret, with commander, loader and gunner. To reduce manpower can we get by with only one crew in the bow? This would eliminate the bow gunner and his help with the radio functions.

Are you saying that getting rid of the bow gunner would somehow help with the radio functions, or that a three man turret and one crew member in the bow would help with the radio functions and eliminate the bow gunner respectively? The three man turret would certainly help with regards to managing the wireless, also helps free up the commander to command. On the bow gunner in close country and urban environments I would have thought that they would be incredibly handy to have to help suppress infantry, a fifth body also helps when it comes to maintenance duties and sharing out guard duty shifts over night.

Focus on coordination of tanks, meaning radio communication between crews and tanks. Are such radios available in the late 1930s?

Not my areas of expertise but I would expect there to be. If the Germans were able to manufacture them then it's obviously not beyond the bounds of possibility and Britain had a pretty decent, even if not mass production, electronics industry.

To be armed with the QF 6-pounder (with 2-pdr as place holder until gun is available), and also designed to accommodate the largest gun then conceived. This would be the QF 17-pounder, which was considered required even in 1938 when the 6-pdr was being developed.

I can't give an exact date but the 6-pounder was first proposed in 1937 but due to bureaucratic inertia nothing happened immediately, and when they later did decide to act on the idea the following year there was a shortage of draughtsmen or similarly skilled types in the design office so it got shuffled to the back of the queue. When resources did become free it took 8-10 months for it to be designed, tested and approved for introduction. If you can find a way for someone with the necessary authority to smile on the original proposal in 1937 and see that it gets the necessary support it doesn't seem unreasonable to have it available in 1940.

Use of sloped armour (CSS Virginia demonstrated this 75 years earlier).

The General Staff specification for the Covenanter cruiser tank apparently set a minimum thickness of armour but also stated that it could be thinner if it was angled to provide equivalent protection so the idea was obviously known about and understood. I don't know exactly when the specification was issued but since the Covenanter was introduced into service in 1940 it must have been at least a year or two before that.


The two other areas that you'd need to look at would be suspension and gearbox. The British had been using Horstmann suspension since the early 1930s so no trouble there and I want to say that the Merritt-Brown gearbox was developed in the mid-1930s but can't be certain. Marry all these things together and you should hopefully get a tough, well-armed, and reliable tank that can see you through the next three years or so of the war until something like the Comet follows it in time for D-Day.

 

[Cockroach]

I give you the A10 heavy cruser

Direct ancestor of the Valentine infantry tank (and not notably quicker despite being a cruiser tank). Eh, so if you bring the Valentine in a couple of years early and equip it with a three man turret from day zero...

 

[MattII]

The cruiser/infantry split came about partly for cost reasons and partly because of engine limitations - if you choose speed or armour, you get a lighter, cheaper tank, and you can still run it on a Liberty engine. Spend more money or accept fewer tanks, and the first problem goes away. Shoot Lord Nuffield and the second problem goes away.

Hate to say it, but Nuffield ain't the problem (leastways, not in 1940), the Liberty was plenty powerful enough to wreck the drive systems on the Matilda II and Valentine, which were equipped with even less powerful engines than that one, often only about 200 hp, vs the Liberty's 340 hp. Now sure by 1942/3 you're in trouble, but in 1940, no it was a good engine at that point.

A tank to take a 17pdr will be very large by the standards of 1937/1938, especially if designed as a full-dress medium. A 2pdr upgradeable to a 6pdr is probably plausible, though.

How about a 25 pounder?

Sloped armour isn't a panacea, but should be possible. You just have to accept the compromises it brings - chiefly cramped internal arrangements.

Actually, it will often slightly increase the amount of internal volume (the conventional designs had a step it which the slope would smooth over), but at the cost of making the driver's sight and bow machine-gun harder to integrate.

 

[Cryhavoc101]

Several British tanks, including those with radios and three man turrets only had a single man up front. For example, the Matilda tank.

https://www.youtube.com/watch?v=VB0A9EwEeWg

Yep and that crew was probably very over worked!

In the context of your OP - any midwar tank (Cromwell/later PZ IV/Sherman) equivalence is going to have a 5 man crew

Late war designs with the advent of smaller and better radios can dispense with a 5th man

Back to your original question - a couple of PODs that might result in a universal tank by 1939......

The Experimental Mechanized Force is maintained throughout the 30s and not disbanded in 1929 - the foibles and fortes of I and C tanks are better understood by the late 30s and I believe that this would have laid the ground work for a 'universal tank' (as well as tracked APCs etc!)

The Tank Design Department is not shut down in 1923

John Carden lives longer

 

[Admiral Beez]

How about a 25 pounder?

Wasn't that an artillery vs. anti-tank gun? The next gun up from the 17-pdr was the Centurion's QF 20 pounder https://en.wikipedia.org/wiki/Ordnance_QF_20_pounder which was itself replaced by the 105mm L7.

Actually, (sloped armour) will often slightly increase the amount of internal volume, but at the cost of making the driver's sight and bow machine-gun harder to integrate.

Can we do a sloped front without exposing the driver's hatch akin to the T-34?

 

[Admiral Beez]

To get sloped armour on early British tanks you need to improve welding tech in Britain.
Up until the end of the war British tanks were still riveted together onto a frame work internal to the body of the tank. These rivets became projectiles inside the tank when hit with enough force (even if the projectile did not penetrate).

The Italians had good sloping on their riveted tanks. That doesn't suggest the rivets don't fly about inside the tank as you suggest, only that sloping and riveting can go together.

 

[MattII]

Wasn't that an artillery vs. anti-tank gun? The next gun up from the 17-pdr was the Centurion's QF 20 pounder https://en.wikipedia.org/wiki/Ordnance_QF_20_pounder which was itself replaced by the 105mm L7.

The 20-pounder wasn't around in 1940, the 25-pounder was. Also, the Australians used dual 25-pounders to mimic the recoil of the 17 pounder for when they redesigned the Sentinel turret.

Can we do a sloped front without exposing the driver's hatch akin to the T-34?

Probably. The driver's hatch on the Valentine was located on the side, just the the rear of his sight, so it shouldn't be affected.

 

[Admiral Beez]

The 20-pounder wasn't around in 1940, the 25-pounder was.

Here is the 25-pdr on a tracked chassis. I wouldn't want to try to conceal this vehicle.

Would a flat trajectory, close range hit from a 25 pdr HE round kill a Panzer IV or bigger?

 

[MattII]

Here is the 25-pdr on a tracked chassis. I wouldn't want to try to conceal this vehicle.

Well obviously a quick conversion of a tank into a SPG isn't going to be the most graceful, but a turret for the 25-pounder as a tank gun rather than an artillery gun will work out better.

Would a flat trajectory, close range hit from a 25 pdr HE round kill a Panzer IV or bigger?

Don't know, but I wouldn't want to be in a bunker and get hit by one.

 

[Admiral Beez]

Well obviously a quick conversion of a tank into a SPG isn't going to be the most graceful, but a turret for the 25-pounder as a tank gun rather than an artillery gun will work out better..

That's a fair point. I wonder if the need for high elevation made the Bishop's turret so tall.

Here's a German Heuschrecke self propelled gun, with a 105mm howitzer installed in a tank chassis. This is neatly designed into an overall low height vehicle, more in line with your comments above. https://en.wikipedia.org/wiki/Heuschrecke_10

http://www.ww2incolor.com/german-armor/DL_2047-B#.html

 

[Admiral Beez]

The British had been developing 'universal' tanks but then the A6 and follow-on A7 tank development programmes in the 1930s ended up not being very successful for several reasons, one of was a lack of a powerful enough engine. .

Is there a British or American diesel engine that would have been useable?

https://en.wikipedia.org/wiki/Diesel_engine

AEC was making diesel engines for British trucks and buses for years before the war, https://en.wikipedia.org/wiki/Associated_Equipment_Company

As an alternative, the Valentine tanks built in Canada had American 138 hp GMC 6004 diesel engine and US-made transmission. Now that is low hp, but the torque curve was likely good. Detroit Diesel was making their Series 71 engines from 1938 onwards https://en.wikipedia.org/wiki/Detroit_Diesel_Series_71

 

[Simon]

Problem with sourcing a diesel engine is that the UK had a vehicle tax at the time, the RAC horse-power formula, which distorted the market and alongside not starting a proper motorway market until well after WWII discouraged the development and production of large diesel engines. On the AEC front the Matilda II did use a pair of linked diesel engines from either AEC or Leyland as its propulsion but since their combined output was only 190 hp it wasn't any great shakes. That's generally why I usually suggest the converted Rolls-Royce Kestrel - even if you're overly cautious and only expect it to give 400 hp output rather than the 475 hp it generated in 1941 that's still double what the linked diesels made. I want to say that most of the British military lorries used petrol engines as well so it would cut down on logistic issues unlike diesel.

 

[marathag]

did this post awhile ago

A better Valentine.

A few PoDs. Sir John Carden doesn't die in that 1935 crash, but lives

Sir John was not impressed with the new A.12 Infantry Tank specification that the Royal Arsenal was working on in 1936, and knew he could do a tank with nearly the same armor, but better designed and more mobile, based on his A.10

Vickers has a tank in 1938 as a private Venture, and updated to be a combined Cruiser and Infantry tank, all in one chassis, a 'Heavy' Cruiser.

70mm armor basis on the front, 60mm sides and 25mph speed, back to what the A.9 had.

uses the W-12 Napier Lion, detuned to run on 70 Octane, still higher than the standard Pool Petrol rating of 63. It gets 400HP, and that engine is still in production for Marine uses, so has availability, and far more power than the AEC Comet 6 cylinder, even though the rear deck had to be slightly raised and angled differently to house it and the relocated fuel tanks. Also more reliable than the slightly older Liberty V-12

A Three-man turret was adapted from the A.10, so the Commander could do his job unimpeded, while the gunner and loader could deal with their job
of fighting the 2 pdr or 3" howitzer, while having much thicker armor. It used an electric motor for traverse, mount balanced for the gunner to quickly adjust elevation.

The completed tank is 21 tons. It is 1938, and in trials against the A.12 built by Vulcan is found to be nearly as good protection wise, but twice the speed, but 4 tons lighter. Best of all, Vickers could build cheaper than Vulcan, and in larger quantities, if needed. It was easier to build, with few complex castings.

Some downsides were that the tracks were unreliable, with a number of pins sheared in operation, and the drivers preferred the Wilson gearbox on the A.12. It was decided by Sir John to switch from the 5 speed Meadows to the preselector 6 speed Wilson, and improving the tracks

When War breaks out, Vickers has completed 110 Valentine tanks, while Vulcan has completed less than a dozen A.12. Vickers could make 10 a week, and Sir John was sure that production could be raised to over 40 per week, once some of his associated facilities had orders.

BTW, had a ring diameter of 1466mm , actually bigger than the T34/76 with 1420mm, so has room to grow to 6 pdr/QF75