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Sir John Valentine Carden survives.

I've seen multiple assessments of the Archer, ranging from "complete joke" to "quite useful in its designed role". Viewed as a straight-up replacement for a towed anti-tank gun, it has a number of obvious advantages, the only real downside being that it's harder to hide. Viewed as a tank-destroyer in the M10/ Marder/SU-76 mould, it has a really obvious problem.

I take the word of the users over that of casual observers. The RA users of the Archer were quite happy with it. They kept it until the 1950s IIRC. Sure, the rear facing gun was not the best but it got the job done.
 
1) The 17-pounder hasn't been conceived yet, let alone designed or built.
2) The Tank mounted 17 pounder wouldn't be the best gun to mount, a stonking big thing, with limited accuracy (the Sabot rounds were useless at any significant range), and no HE round.
limited accuracy? It could put rounds into a 12 by 18” area at 1500 meters. So in other words more accurate than most at guns with exception of the 76mm at that range. The sabot was only really needed for the biggest of cats but they were rarely encountered. The lack of accuracy of the sabot didn’t stop British tankers using it at every opportunity.
 
limited accuracy? It could put rounds into a 12 by 18” area at 1500 meters. So in other words more accurate than most at guns with exception of the 76mm at that range. The sabot was only really needed for the biggest of cats but they were rarely encountered. The lack of accuracy of the sabot didn’t stop British tankers using it at every opportunity.
I will point at this video. Sabot was considered pointless by the British at ranges over 500 yards, the Americans, even less. The Americans tried hitting a target at 1,000 yards, and after 18 shots just gave up.
 
Wasn't the accuracy problems mostly fixed with further development like the sleeve and pot head versions of the Sabot?

Besides, its a bit too earlier to discuss the 17-pdr now.
 
Wasn't the accuracy problems mostly fixed with further development like the sleeve and pot head versions of the Sabot?

Besides, its a bit too earlier to discuss the 17-pdr now.
Not during the war as I understand it. Anyway the Sabot and HE thing is not really an issue as very few tanks encountered from late 44 when issued warranted a sabot and while the HE wasn’t as good as it could have been it was still a Big Bang and in late 44 for every 17 pounder armed AFV there was several 75mm armed AFVs within the same call sign.
 
12 January 1937. 09:00hrs. Mannheim, Germany.
12 January 1937. 09:00hrs. Mannheim, Germany.

The contract to build Sonderkraftfahrzeug (Sd.Kfz.) 141 had arrived and the Daimler Benz team were working out the practicalities for putting it into production. The basic requirement which the Daimler-Benz prototype had successfully embodied weighed 15 tonnes, with the armour on the front, sides and rear of the tank chassis and turret being 14.5 mm thick. Only the gun mantle and front of the turret were slightly thicker at 16 mm. Powered by a Maybach HL 108 TR 250 hp engine its five large road wheels, with coil spring suspension, had two track return rollers. The specification was for the 3.7cm KwK 36 L/46.5 gun, with three machine guns, two co-axial with the main gun, the other in the hull. It was expected to be able to travel up to 165km at a maximum speed of 35km/h. The problem for the production team was that they were successful car and truck makers, the experience of building panzers was new to them.

The company had been involved in making parts of the superstructure and turret for the Sd.Kfz 101 and 121 (Pz.Kpf.W. "Panzerkampfwagen" I and II), but building a complete panzer would be a challenge. Knowing that the journey of a thousand miles starts with a single step, the production team began to write the detailed manufacturing specification. The design, specification and procurement of machine tools would be done and detailed manufacturing drawings would be acquired from the draughtsmen. The tooling and jigs would have to be prepared, with the company plant having to sort out the production facilities. The procurement of materials, components, and assemblies would have to be managed, as would the recruitment and training of the workforce, all before the first panzer could be built. There was a lot to do, and there was some pressure to getting it done in a timely fashion. The winning of the contract to build the Pz.Kpf.W. III was a great boon for the company, but it would involve a great deal of work to get it done.
 
This should be the original Pz III A with Christie suspension which went through development hell (the suspension really did not enjoy the extra weight).
 
This should be the original Pz III A with Christie suspension which went through development hell (the suspension really did not enjoy the extra weight).
Pzkpfw-III_Ausf-A.png
Ausf A Coil Spring
h3VwvUW.jpg
Ausf B Leaf Spring
EDXuqSy.jpg
Ausf C another Leaf Spring
03PjWJ8.jpg
Ausf D and one more try Leap Spring

And never tried the Mk IV Leaf Spring setup, that got it right the first time, before going with Torsion Bars

From the later version
1601225123730.jpeg


Notice the lack of hatches for the crew in the hull. going to torsion bars allowed the side hatches. Before that, the 'oh my god, the tank is on fire'
would not go well for driver and Radio Operator
 
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Ironically, Krupp made a successful leaf spring suspension for the Pz IV but failed with its first torsion bar suspension. Truly a case of companies being complementary.
 
15 March 1937. 12:00hrs. London, England.
15 March 1937. 12:00hrs. London, England.

The Cabinet had approved the deficiency programme of the Army over the next five years and the figure was agreed at £214 million. The Air Defence of Great Britain (ADGB) was a new requirement for the army and the Cabinet had approved an immediate £37 million to this role. The Regular Field Force would have £80 million for materials and ammunition. While the Territorial Army would receive £9 for training equipment, there was no increase in their budget for war equipment or reserve. The agreement by the Cabinet the previous month that the Territorial Army should be trained on the same equipment as the Regulars meant that the extra funding would have to be approved. The War Office hoped that the extra funding for training equipment would eventually work through to having the equivalent of two full regular division’s worth of equipment by April 1940. Much of the increased funding was not so much for immediate army requirements, but for what was described as measures to increase the industrial facilities for armament production or the technical phrase to “augment the war potential.”

The ordering of 107 Mark VIB light tanks from Vulcan Foundry during 1936 was part of that programme. The decision to award the contract for the A12 to Vulcan required that the company should have some knowledge and experience of building tanks. The light tanks would be a simple exercise in preparing them for the much more complex responsibility of designing and building an infantry tank. The Royal Ordnance Factory at Woolwich was the only other facility, besides Vickers-Armstrong who had any experience of producing tanks. Woolwich, however, was focussed primarily of orders for the Admiralty and Air Ministry, so their ability to build tanks was limited.

With Nuffield Mechanisation and Aero taking on the specification for the A13 that meant another company joining in the expansion of the ‘war potential’. Vickers, however, that was the only company currently capable of building and delivering tanks in any numbers. Within their own subsidiaries, Vickers was looking at the possibility of outsourcing some of the work that was hopefully coming their way. The A11, with its thick armour, would probably have to be built in-house. The company were looking at Harland and Wolff in Belfast to take on some aspects of building the A9 if contracts were awarded. Likewise, they were also approaching the Birmingham Railway Carriage & Wagon Company and Metropolitan-Cammell Carriage & Wagon Company for work on the A10.

One of the problems with the increased armour in the A10 over the A9 was how it was going to be fixed. One school of thought was to build the hull from thinner plate, riveted to the structural frame, then screwing outer panels to the shell to create the required thickness. This kind of ‘composite’ armour had various advantages, it was economic in the use of hardened plate, and it would be easier to assemble. However, Sir John Carden was aware that a single thickness of armour would give better protection, and ultimately this was the reason for the War Office specification of an inch of armour. When the prototypes of the A10 were being built one had been made using rivets and bolting plates together. The other had been welded. This had saved weight on the tank, but the management had been unhappy at using such an expensive method. The welders, borrowed from the shipbuilding part of Vickers-Armstrong, had found some of the welds difficult, there were some cramped and awkward spaces they had to work in. Overseeing this work had given Carden an appreciation of the work welders did, and some thoughts about when designing something considering how it would be put together.

The two prototypes for the A10 were nearing completion but were overdue to be transported to Farnborough. The design and production team had had to take make the same changes to the A10’s suspension that had fixed the problems in the A9’s trials. As well as the spacing of the bogies, the tracks had to be wider to spread the increased weight. The obvious deficiencies in the ‘lubricated’ tracks on the A9 had meant that a different design of track had had to be worked on, which added to the delay of the project. The difficulty of having to shoehorn the large Rolls-Royce Eagle engine into one of the prototypes had also caused delays, but with help from Rolls-Royce engineers, the old engine was running smoothly and providing the kind of horsepower and torque that Carden had hoped it would. The engine compartment of that prototype looked very untidy, and the team were a bit concerned with the temperatures that the engine was reaching when working hard.

The decision had been taken to put the AEC engine into the slightly lighter welded prototype, in the hope that it would help with the power to weight ratio. If Farnborough pushed for a timely arrival of the A10E1 tank, then Vickers could send off this tank first, it was judged to be just about ready to be put through its trials.
 
The decision had been taken to put the AEC engine into the slightly lighter welded prototype, in the hope that it would help with the power to weight ratio. If Farnborough pushed for a timely arrival of the A10E1 tank, then Vickers could send off this tank first, it was judged to be just about ready to be put through its trials.

Oh dear this may cause some issues
 
Hopefully the second prototype isn't delayed too much and comparative trials can be held. Perhaps a third prototype could be built combining the lighter hull with the more powerful engine.
 
I will point at this video. Sabot was considered pointless by the British at ranges over 500 yards, the Americans, even less. The Americans tried hitting a target at 1,000 yards, and after 18 shots just gave up.

Sorry I was reacting to you claiming the gun had 'limited accuracy' - if you are only referring to the SABOT round then fair enough - that was an issue not resolved until after the war

Mind you there was little the standard AP round could not handle and was accurate (generally if they could see it they could hit it and if they hit it they would kill it) and while the HE round did not have as big a bang as a 75mm for example it still had a 'big bang' having at least 2/3rds the explosive charge as the 75mm rounds

I got the 'grouping' of the 17 pounder APCBC from the same video you quoted.

The SABOT round gave the gun the ability to kill a T2 at 500 m across the frontal arc and in Normandy (once it was made available) it was the only gun capable of doing that - the inaccuracy issue at longer ranges was also down to spotting the fall of shot as the 'miss' was more difficult to spot unlike the larger rounds and therefore more difficult to correct.

Interestingly the 77mm gun on the comet used the same SABOT round (different smaller case of course giving it a slightly lower MV) and did not seem to suffer from the stability issues impacting the 17 pounder SABOT accuracy.
 
Overseeing this work had given Carden an appreciation of the work welders did, and some thoughts about when designing something considering how it would be put together.
Oh ho ho! If this little jaunt into welding experience can save the Covenanter from getting shackled with shoddy rivetted construction it'll be worth it.
 
20 April 1937. 16:00hrs. Farnborough, England.
20 April 1937. 16:00hrs. Farnborough, England.

The testing of the A9E2 had been completed and as the tank was driven off to the depot there was a general feeling of cheerfulness around the team from Vickers. The changes to the engine and suspension had solved the problems of the previous model, it was able to maintain the top speed of 25mph on the road, and an average of 15mph cross country. The suspension had behaved itself over the roughest country, and the gunner was confident that it provided a stable enough platform for firing on the move. The tracks had been tinkered with and, while still more fragile than desirable, they were far less likely to come off or break than previously.

The single machine-gun position in the hull, rather than the two turrets, was generally thought of as an improvement, and the company had added a little more armour to the turret and forward hull to improve it to 0.75 inch. The army had been unhappy with the positioning of the radio in the hull, but Vickers had used an internal intercom system borrowed from the Vickers Wellington bomber aircraft that was currently under development. The system gave the tank commander and the hull gunner/radio operator the ability to communicate clearly, likewise with the driver and the loader. There would have to be some training and testing to see if this would actually work in practice. There were also questions about the training of radio operators, this generally had been reserved to tank commanders, nobody wanted to have to have one crew member from the Royal Signals rather than the Royal Tank Corps. On the other hand, there were quite a few people who thought that relieving the tank commander from yet another role would be helpful.

Sir John Carden had asked what radio sets for tanks were under development, if space was needed for bigger sets this would be important to get right. The current radio systems, No 2 and No 7 Wireless sets were used in the Medium and Light tanks respectively. The No 2 had a range on R/T (voice communications) of about 12 miles, though the tank had to be stationary to achieve this. The No 7 set had only about 3 miles range, and since they were still new, the majority of Light tanks were making do with modified No 1 sets. He was informed that new sets, designated No 9 and No 11, were under development at the Signals Experimentation Establishment. A request was made that the tank designers should be involved, or at least kept up to date, in that development process as the space and power needed for the radios was an important part of a successful tank design. The A9E2 would be equipped initially with the No 2 Wireless Set until the No 9 was available.

What pleased the team from Farnborough was that the tank had travelled over 1000 miles with no major breakdowns. The engine had red-lined a few times in steep climbs, it was just at the limit of what it was capable of. The changes to suspension had evened out the ride of the tank, and the five-man crew were relatively comfortable. The tracks had improved but were still capable of further work. There were a number of little niggles that could easily be put right in the production model, the Vickers team had already taken note of many of these. The recommendation of the Mechanisation Experimental Establishment to the War Office was that the A9E2 had successfully passed its trials, and should be put into production.
 
In this TL the A11 is going to be a bit better than OTL. It's going to go a bit faster and thanks to a 40mm gun it's going to have some use against dug in machine guns and light tanks. This means that the A11 will be obsolescent instead of obsolete in 1940. Does this mean that production will last longer and more will be produced compared to OTL? The two good things about the A11 was it's heavy (for the time) armour and it's being cheap as chips. Could we see some of these tanks sent out to other secondary theatres and garrisons when better tanks become available? If so there could be some significant butterflies and the A11 could have a much more interesting and illustrious history ITTL!
 
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