Standardized British tank. 1942.

[Count of Crisco]

I could see the British going with a 12pdr in the late thirties, of course the idea of a tank trundling about the battlefield with a twin main gun armament is an interesting idea...
So then what would seem to be the consensus was that OTL Valentine could have been turned into a tank like the one asked for with modifications to its engine, turret and gun. All that is needed now is someone to push the development of this improved tank forward.

 

[Cryhavoc101]

Could the British 3" anti-aircraft guns which were being replaced by the 3.7" in the late 1930s have been converted into tank or anti-tank guns? They did try the same thing later on with the 3.7", which was adapted into first the 32pdr anti-tank gun and then as a tank gun.

At the same time the British Coast Artillery was replacing its 12pdr guns with a twin 6pdr. Could either of them have been adapted into a tank gun so that we don't have to wait for the 6pdr and 17pdr AT guns to be developed and then put into tanks?

The issue I have with this is the weight of the Gun and Breech - the 3" '20 cwt' AAA is about (20 'Imp' cwt = 20 x 112 LBs = 2240 IBs) 1 Imp Ton or Long Ton

I was looking for a gun that was not many times heavier than the 2 pounder (I can only find total weight of entire gun and carriage - 1795 Ibs)

I eventually settled on a 'modernised' 13 pounder / 9 CWT weapon based on the ww1 AAA gun which is about 450 Kilos (for Gun and Breech) - which is about the lightest 75mm type weapon (that retained a decent MV) I could find that would have been available to the British.

It was based on a 13 pounder gun with an 18 pounder breech - and used the 18 pounder charge to Fire a 12.5 Ib 75mm shell at 660 ms - already had both a solid, shrapnel and HE shell

It had a recoil travel of 24" in 1915 but I'm assuming that a 2nd Gen 1930s model is closer to 12" recoil travel (and possibly a bit lighter as well and possibly improvements in 'propellant might give a higher MV as well?)

 

[Admiral Beez]

You have to find a way to solve two basic problems to make this concept work.

1) There was a a standing requirement to make tanks that tanks fit within the very restrictive British Railway loading gauge. This limited the overall width of the vehicle. This in turn meant that the turret ring could not be made large enough to accept a gun larger than the 2 pdr.

Scrap this requirement through creating a armoured vehicle transporter, and, improve the reliability of tanks so they can drive themselves more to where needed once off the AVT.

Here are British tank transporters in WW2. Make this the standard transport for tanks from factory to front, WHEREVER train flatbeds won't work.

I see no reason the Antar can't be made earlier.... https://en.wikipedia.org/wiki/Thornycroft_Antar

 

[yulzari]

The 3" AA guns were put into a few Churchills but there was no production since WW1. It was the starting point for the 17 pounder/77mm HV with the 17 pounder started in 1940 IOTL. The 12 pounder had only a little over 100 in service in 1939 with the rest on naval vessels and in use. It went back to the Boer war and way too heavy. Again production ceased with WW1. As new production was necessary it was as well to make a new developed design to use later materials, techniques and machining.

With pre war budgets gun design had to be around the abilities of existing machinery to manufacture them so designers tended to look at what had been possible before and work that into the design.

 

[yulzari]

There was a a standing requirement to make tanks that fit within the very restrictive British Railway loading gauge. This limited the overall width of the vehicle. This in turn meant that the turret ring could not be made large enough to accept a gun larger than the 2 pdr.

Whilst there is some truth to this it was not as restrictive as is usually alleged. Firstly the loading gauge varied with the choice of line. With careful routing and scheduling the narrowest points could be avoided. Secondly existing designs could take more than the 2 pounder. Not only could the Valentine take guns up to the ROF 75mm but the Matilda II could (and did experimentally) take a 6 pounder so could also take a ROF 75mm. Fitting in 3 men was trickier and the 17 pounder was a stress too far. It certainly was ignored for the A29 contemporary with the A30 Cruiser MkVIII Challenger. Centurions routinely were transported by rail over the same lines as in WW2. Churchills exceeded the minimum width but normally they just de mounted the side radiators to let them use routine routings.

 

[tomo pauk]

thanks, good point

How fixable would the engine problem have been? Bearing in mind that British priorities were aircraft and the Navy, especially ASW, in 1940-42. Could enough Meteor engines have been allocated to improve British tanks early enough or is there another option than the Liberty?

As other people pointed out, neither RN nor RAF need the Napier Lion that much after when, 1930-35? The tooling/production line is around, Napier has no major production contract for any other engine (Rapier and Dagger don't add anything to the RAF), so let's churn out the 'Land Lions' like hot rolls.
Similar is situation with RR Kestrel - after 1935 it does not feature in any RAF's plans, and as an engine for trainers can and will be replaced by Mercury. Twing Wasp Junior can be also bougth for same job. So the tooling/production line is around, lets produce the Kestrels.

But, mind you - Nuffield Liberty even in the (no-risk) 340 HP form produces far more power than it is needed for historical Matilda II and Valentine...

 

[PMN1]

With the Meadows engine on the Covenentor, did it have other problems apart from the cooling which was as a result of the design of the tank itself.

 

[NOMISYRRUC]

As other people pointed out, neither RN nor RAF need the Napier Lion that much after when, 1930-35? The tooling/production line is around, Napier has no major production contract for any other engine (Rapier and Dagger don't add anything to the RAF), so let's churn out the 'Land Lions' like hot rolls.

IIRC from Liddell Harts history of the RTR the Army had the opportunity to buy the RAF's entire stock of Napier Lions at their scrap value. I think he wrote that there were 500 of them.

Could any of Napier's diesel engines have been used as a tank engine? They eventually evolved into the Deltic.

 

[tomo pauk]

With the Meadows engine on the Covenentor, did it have other problems apart from the cooling which was as a result of the design of the tank itself.

Do we know for sure that tank's design is to blame, rather than the engine itself.
At any rate, with 4 more or less viable hi-power powerplants reasonably available (Liberty, Kestrel, Lion, Bedford twin six) and 5th in the pilpeline (Meteor), spending any amount of money on the elusive Meadows engine is a waste IMO.

IIRC from Liddell Harts history of the RTR the Army had the opportunity to buy the RAF's entire stock of Napier Lions at their scrap value. I think he wrote that there were 500 of them.

(my emphasis)
Oh boy.

Could any of Napier's diesel engines have been used as a tank engine? They eventually evolved into the Deltic.

Napier have had the Culverin in 'limited production', 1st flown in 1938. Apart from the height, seems like a good engine?

 

[NOMISYRRUC]

Would the Lion have fitted into the A6 and A7 light tanks prototypes? If so how much would it cut of the £15,000 unit cost of a production Medium Mk III by?

Edit

IIRC from the same source a Carden-Lloyd death trap, I mean Tankette cost £400. Carden's rival Martel of Morris-Martel fame's intention was that an infantry battalion in tankettes would cost the same to run as 2 normal infantry battalions.

IIRC from the same source a Light Tank Mk I cost £1,200 or put another way £15,000 would pay for what at the time was the best tank in the world or 12.5 not very good Light Tanks.

 

[PMN1]

Do we know for sure that tank's design is to blame, rather than the engine itself.
At any rate, with 4 more or less viable hi-power powerplants reasonably available (Liberty, Kestrel, Lion, Bedford twin six) and 5th in the pilpeline (Meteor), spending any amount of money on the elusive Meadows engine is a waste IMO.



(my emphasis)
Oh boy.



Napier have had the Culverin in 'limited production', 1st flown in 1938. Apart from the height, seems like a good engine?[/QUOTE

My understanding was it had to fit into the low profile of the covenanter.

Meadows are building the engine anyway so they are making use of resource that does not impact at all on the aero engine industry as even developing an existing engine is going to take some resourcez

 

[fastmongrel]

As Napiers made such a mess of producing the Sabre I think its a bit unfair to put the poor tankies through hell with an engine that makes the liberty look good.

 

[Simon]

The Kestrel was estimated at 450bhp...

No estimations required, Rolls-Royce converted both a Kestrel and a Merlin engine in our timeline when they were asked to investigate the possible use of aero engines in tanks with the Kestrel generating 475bhp on pool petrol. IIRC driving the fans and associated systems took 75-95bhp leaving you with roughly 380-400bhp to drive the vehicle.

 

[marathag]

As Napiers made such a mess of producing the Sabre I think its a bit unfair to put the poor tankies through hell with an engine that makes the liberty look good.

Eh?

Lions were far more reliable in air service in the '20s when it was in common use.

Liberty was shown the door as soon as Curtiss did the D-12. The only advantage of the Liberty in the interwar era was there were warehouses full of them: rather than rebuilding a Liberty it would get junked, and you pulled a factory boxed 'new' one from 1918 that you could buy for scrap metal cost and run that till it clapped out.

 

[Cryhavoc101]

Scrap this requirement through creating a armoured vehicle transporter, and, improve the reliability of tanks so they can drive themselves more to where needed once off the AVT.

Here are British tank transporters in WW2. Make this the standard transport for tanks from factory to front, WHEREVER train flatbeds won't work.

I see no reason the Antar can't be made earlier.... https://en.wikipedia.org/wiki/Thornycroft_Antar

The Scammel was available from the time when the Experimental Armoured force was plying its trade in 1929/30

Several were bought but the treasury was not interested and the next ones were not bought until HMG went "Oh Sh1T...Nazi's....err have a little bit more money" in 1937

Had the Force become a proper Brigade in 1931 then 10 odd years of development would have had a major impact in British Armour and Mechanization development and doctrine and its likely IMO that the Scammel would have undergone further development and have been present in far greater numbers than was the case in 1939.

No need for a 'perfect' Antar when the Scammel was 'good enough' (logging companies in the UK were still using them well into the 'Noughties')

 

[Admiral Beez]

No estimations required, Rolls-Royce converted both a Kestrel and a Merlin engine in our timeline when they were asked to investigate the possible use of aero engines in tanks with the Kestrel generating 475bhp on pool petrol.

How about an early intro of the Merlin's diesel variant, the Rolls-Royce Meteorite?

 

[Simon]

How about an early intro of the Merlin's diesel variant, the Rolls-Royce Meteorite?

Doubtful, as far as I'm aware the UK of the time period didn't have much in the way of experience with Diesel engines. There's also the logistics factor - all the army's cars, lorries, and other vehicles for the most part ran on petrol, I'd expect they'd want to keep everything using the same type of fuel as much as possible.

 

[hipper]

Doubtful, as far as I'm aware the UK of the time period didn't have much in the way of experience with Diesel engines. There's also the logistics factor - all the army's cars, lorries, and other vehicles for the most part ran on petrol, I'd expect they'd want to keep everything using the same type of fuel as much as possible.

hmm both the Matilda and the Valentine ran on Deisel engines, so I doubt the army was too bothered at least in the early war years.
The later tanks were all petrol driven but that seems to be related to the lack of a suitably powerful Deisel engine and aim sure logistics commonality was a factor too.

 

[tomo pauk]

The RR Condor C.I. was the diesel, for aircraft use. 480 HP, 680 kg, developed from 1932.

 

[fastmongrel]

Eh?

Lions were far more reliable in air service in the '20s when it was in common use.

Liberty was shown the door as soon as Curtiss did the D-12. The only advantage of the Liberty in the interwar era was there were warehouses full of them: rather than rebuilding a Liberty it would get junked, and you pulled a factory boxed 'new' one from 1918 that you could buy for scrap metal cost and run that till it clapped out.

You are looking at it from the wrong side of the pond I am talking about the British built Nuffield Liberty which is a different re-engineered engine and for its time was reasonably reliable. The arrangement of the cooling in the Crusader was poor which led to problems but the Cruiser Mark IV was reliable in the early Desert campaigns till they wore out chasing Italians. Nuffield Liberty engines stayed in Britiah Army service till the late 1940s when there must have been plenty of spare Meteors available.

Napiers factory in the 1930s was almost a Victorian museum they had lathes and milling machines which were 40 years old they were fine building a small number of hand made engines but asking them to make W12s by the thousand is not going to happen. It took English Electric nearly 2 years to get the Sabre reliable and they did that by building a foundry and machine shop and bringing in new workers that were trained to build on a production line rather than filing to fit. Casting rejection because of inclusions and blowholes in the old Napier factory were over 50% compare that to Rolls Royce who at the same time had a casting rejection rate in the tens %.

If the Lion W12 was the answer to a question why didnt the army use it and why did the RAF stop ordering aircraft using it after 1928 and get rid of it. The last RAF Lion engined aircraft seems to have been the Blackburn Ripon which went out of service in 1934.