Sir John Valentine Carden survives.
- Thread starter allanpcameron
- Start date
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10 May 1938. 15:00hrs. Farnborough, England.
allanpcameron
Donor
10 May 1938. 15:00hrs. Farnborough, England.
With the Mark VI light tank in full production there had been no great desire from the War Office to look at a successor light tank design. When Vickers has shown drawings back in 1936 for what they were now calling the Vickers Mark VII light tank, it hadn’t met with any great interest, though the line of development had been given the General Staff designation of A17, and Vickers had continued developing it for the commercial market.
With Sir John Carden’s time being completely caught up with the A9, A10, A11 and alternative A12 projects, it had fallen to Leslie Little to work on the A17. Little had designed a light tank with 14mm armour thickness, the same as the Mark VI, even though the fighting in Spain had already shown that for anything other than small reconnaissance machines this would be insufficient.
Little had previously worked, alongside Carden and Loyd on the Bren Carrier and had taken the idea of the steering system and up-scaled it to the A17. There were four large diameter wheels, the rear acting as drive sprocket, each of which were fitted with an armoured hub to protect the wheel and inner hull. The road wheels were all pivoted on brackets and linked to the steering wheel. Movement of the steering wheel by the driver would make all eight wheels to lean and turn, the complicated geometry making the track curve and so steer the tank, rather than having to skid a track. It gave the tank the ability to drive around curves less than 94 feet, though for tighter turns, skid steering was necessary.
Not only was the steering system revolutionary, but Little had done away with springs for the suspension, each wheel was suspended on tubular struts containing a pocket of air and a cushion of oil, which did give each wheel excellent independent springing.
At the MEE when the A17E1 was put through it paces the problems began to mount up. Getting the tank to drive around curves wasn’t an easy thing for the driver to achieve, it took extraordinary strength to do so. Since the tracks were to curve, the pin joints were purposely made loose, in order to keep the best contact between track and wheel, however that meant that when skid steering, even at the lowest speeds, the tracks kept jumping off. Little said he would look at the design of the wheels and tracks, currently using a ball section, and change it to a square section to alleviate the problem with shedding the tracks.
Further problems came from the Meadows horizontally opposed twelve-cylinder engine producing 180hp. There were cooling problems with this new engine which would take a lot of fixing. The other thing that the MEE noted was that Little had placed the fuel tanks in front of the driver, at the very front of the tank. Little explained that in a small tank space was at a premium, and noted that a 14mm bulkhead could be fitted between the fuel tank and the driver’s position. He also said it would be possible to organise the fuel storage compartment with a drainage system so that the fuel would drain downwards through the floor if the compartment was penetrated.
The tank seemed to fall between two stools. It was a light tank in terms of speed and protection, but had cannon armament, rather than just machine guns. The A9 and A13, which were more regularly being called ‘cruiser’ tanks, were around 13 tons compared with the A17’s 7.5 tons. Was the A17 a ‘light cruiser’ or a ‘heavy light’ tank? It wasn’t entirely clear what the role would be, and the War Office weren’t keen on ordered a tank whose place wasn’t assured. It was noted that the 180hp engine could allow the tank to take heavier armour, though whether the steering system could cope was another matter. Once the changes were made to the A17E2 they might be in better position to judge whether or not a role could be found for it in the army.
With the Mark VI light tank in full production there had been no great desire from the War Office to look at a successor light tank design. When Vickers has shown drawings back in 1936 for what they were now calling the Vickers Mark VII light tank, it hadn’t met with any great interest, though the line of development had been given the General Staff designation of A17, and Vickers had continued developing it for the commercial market.
With Sir John Carden’s time being completely caught up with the A9, A10, A11 and alternative A12 projects, it had fallen to Leslie Little to work on the A17. Little had designed a light tank with 14mm armour thickness, the same as the Mark VI, even though the fighting in Spain had already shown that for anything other than small reconnaissance machines this would be insufficient.
Little had previously worked, alongside Carden and Loyd on the Bren Carrier and had taken the idea of the steering system and up-scaled it to the A17. There were four large diameter wheels, the rear acting as drive sprocket, each of which were fitted with an armoured hub to protect the wheel and inner hull. The road wheels were all pivoted on brackets and linked to the steering wheel. Movement of the steering wheel by the driver would make all eight wheels to lean and turn, the complicated geometry making the track curve and so steer the tank, rather than having to skid a track. It gave the tank the ability to drive around curves less than 94 feet, though for tighter turns, skid steering was necessary.
Not only was the steering system revolutionary, but Little had done away with springs for the suspension, each wheel was suspended on tubular struts containing a pocket of air and a cushion of oil, which did give each wheel excellent independent springing.
At the MEE when the A17E1 was put through it paces the problems began to mount up. Getting the tank to drive around curves wasn’t an easy thing for the driver to achieve, it took extraordinary strength to do so. Since the tracks were to curve, the pin joints were purposely made loose, in order to keep the best contact between track and wheel, however that meant that when skid steering, even at the lowest speeds, the tracks kept jumping off. Little said he would look at the design of the wheels and tracks, currently using a ball section, and change it to a square section to alleviate the problem with shedding the tracks.
Further problems came from the Meadows horizontally opposed twelve-cylinder engine producing 180hp. There were cooling problems with this new engine which would take a lot of fixing. The other thing that the MEE noted was that Little had placed the fuel tanks in front of the driver, at the very front of the tank. Little explained that in a small tank space was at a premium, and noted that a 14mm bulkhead could be fitted between the fuel tank and the driver’s position. He also said it would be possible to organise the fuel storage compartment with a drainage system so that the fuel would drain downwards through the floor if the compartment was penetrated.
The tank seemed to fall between two stools. It was a light tank in terms of speed and protection, but had cannon armament, rather than just machine guns. The A9 and A13, which were more regularly being called ‘cruiser’ tanks, were around 13 tons compared with the A17’s 7.5 tons. Was the A17 a ‘light cruiser’ or a ‘heavy light’ tank? It wasn’t entirely clear what the role would be, and the War Office weren’t keen on ordered a tank whose place wasn’t assured. It was noted that the 180hp engine could allow the tank to take heavier armour, though whether the steering system could cope was another matter. Once the changes were made to the A17E2 they might be in better position to judge whether or not a role could be found for it in the army.
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allanpcameron
Donor
Ricardo used the Kestrel for the land speed records, but is going to use the Napier Lion for Carden's tank. I'm working with @marathag's estimation of "For a diesel Lion, that should be in the 350-400hp range."
allanpcameron
Donor
The Matilda 2, the A12 designed by Vulcan Foundry will be the same as OTL. The A11 (Matilda 1) is improved OTL, with 40mm Vickers pompom cannon, slightly better engine and size will make it more effective, but still very limited. The Vickers alternative A12, which Little designed as the Valentine, will be called Valiant (the next update will give its full spec.)
Ah, so the Valentine/Cardentine will be getting the Lion engine? That's going to give the Germans a nasty surprise in North Africa. Make it good enough and you might even vanish the Americans' M3 Lee to its proper place on the scrap-heap.
It won't impact the M3, just how many Britain acquires if any. The US Army needs them as at least a stopgap and training tool.
Actually, like with the Matilda II/Valentine, keeping the M3 factories running as long as they did delayed the production of the M4 Sherman. With far fewer M3s needed, the Sherman will appear earlier.
Also, if you have the spare resources, you could hand the tooling for the A11 off to the Australians, get them producing a semi-decent tank sooner, rather than wasting time on developing the Sentinel, which will never see service anyway.
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So the Tetrarch is as OTL, and no doubt about as useful (or otherwise) as OTL.
With speed and a 2-pdr there might be role for them in the early war as light tank-destroyers, but with dodgy tracks, dodgy cooling and dubious survivability there's a strong case for dropping the whole project rather than spend resources on them.
With speed and a 2-pdr there might be role for them in the early war as light tank-destroyers, but with dodgy tracks, dodgy cooling and dubious survivability there's a strong case for dropping the whole project rather than spend resources on them.
Thanks. Haven't found the exact book but a search with Google suggests that it's by an arm of the British government from H.M. Stationery Office since there are publications with similar layouts.
allanpcameron
Donor
The thing about the M3 was it gave the British the first shot at a 75mm and showed them the value of the HE and AP capability.
I can't imagine the American development to be much different, except if the Valiant (my ATL Valentine) is good enough to stop the British needing as many American tanks.
Interesting idea, but I'm not sure about the Australians. I can see the Canadians making Valiant as they did the Valentine. The Aussies and New Zealanders capability to build tanks is going to be limited. It may be that the Matilda IIs, if they aren't quite as good as my Valiant, might be better sent to them, would do OK in the Pacific, especially the CS/flame-thrower version. You maybe right about the Sherman coming along sooner.
marathag
Banned
The Mineral Industry of the British Empire and Foreign Countries Statistical Summary 1936-1938. Not finding the full version to view anymore....
However the 6 pounder might come in earlier and has HE and only needs rebarrelling to use French US type 75mm shells. Having the same performance as the US M2 gun.
marathag
Banned
Engine supply was the real problem, follwed by gearbox and then suspension. Casting for Armor wasn't
So that's a lot of tooling.
marathag
Banned
big delay was building up casting facilities to cast the Hull and Turret, and welding rolled plate even longer
The first M4A1 Cast Hull Pilot at Lima was finished in February 1942, and Pressed Steel in March 1942
The Welded Hull M4 was also done first at Pressed Steel Company in June 1942, followed by Baldwin in January 1943, ALCO in February, Pullma in May, and Detroit Tank Arsenal in August 1943
The Welded Hull M4A2 started production at Fisher Body and Pressed Steel in April 1942
That would have been a cruel and unusual punishment for the poor tank...
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