20 May 1938. 11:00hrs. Newcastle-upon-Tyne. England.
allanpcameron
Donor
20 May 1938. 11:00hrs. Newcastle-upon-Tyne. England.
Work on the design for an alternative to Vulcan Foundry’s A12 was complete, it had the company codename of ‘Valiant’. Using the A9 and A10 as his starting point, Sir John Carden had increased the length of the new design to 19’4”, the height remained 8’8½”, while the width increased to the very limit of the rail gauge at 9’. The increased width allowed Carden to get the turret ring up to the 60” that he thought would be necessary for the next gun that would replace the 2-pdr.
As it was, the turret had enough room for a gunner, loader and commander, and there was plenty of room for ammunition storage. Just like the A9 and A10, the tank’s turret was designed for the 2-pdr gun and co-axial Vickers machine gun. There was work being done by the War Office on changing to an air-cooled machine gun to replace the Vickers. Until that appeared the water-cooled machine gun was what was offered. Carden had also designed a turret to carry the QF 3.7inch howitzer for a Close Support version.
Like the A10, the front hull was sloped without a hull mounted machine gun. He had kept the drivers position towards the side of the tank. When the driver’s position was at the centre of the tank getting in and out when the gun was facing forward was a problem. By off-setting the driver to the side Carden had managed to provide him with an adequately sized hatch for entry and exit. If the War Office insisted on a hull machine gun, then it would be slightly simpler to implement this, if the driver’s position and all the steering controls were already off-centre.
Carden’s ‘slow motion’ suspension system on the A9 and A10 hadn’t proven robust enough for the much heavier armour required on this A12 specification. He had designed the tank with the specified 2.75-inchs of armour (70mm) on the hull front and sides, with slightly thicker 3-inchs (78mm) on the front of the turret. With the tank now at 25 tons, Carden had opted to go back to the Horstmann designed suspension originally used on the A6E3. This used the leading and trailing bogies of the earlier Vickers’ ‘Japanese’ system, while the main central portion used a combination of coil springs and bell cranks. In 1936 this had been able to handle an 18-ton load at 30mph, so Carden was sure that it would be able to deal with the heavier load at more like the 20-25mph he expected the 400hp Ricardo diesel powered tank to produce. With lengthening the tank Carden had managed to increase the fuel capacity to give the tank a road radius of 120 miles.
The same Meadows No 22 clash gearbox was chosen as used on the A10, though Carden had looked at the Wilson epicyclic gearbox that Vulcan Foundry were using on the A12. As a company, Vickers was more confident in Meadow’s ability to supply their gear box than the new Wilson system. Carden was aware that later marks of his A12 alternative would likely have to look at alternatives, but it was important to get things moving as swiftly as possible.
The company executives signed off on the plans and prepared it to be presented to the War Office. A wooden mock-up was under construction and the prototype’s components were already ordered. The cost per tank, if it was to be accepted by the War Office needed to be less than Vulcan Foundry’s A12. Vickers knew that the production of the Vulcan A12 was likely to be quite slow, and so, as a sweetener, would offer to increase the workforce at their plant at Elswick build their Valiant much more quickly. If ordered ‘off the drawing board’ as the War Office had done with the A12, Vickers could promise that 100 tanks would be delivered within 18 months of being ordered, and would have the capacity to produce 30 tanks per month once full production was reached. The fact that the Valiant would be equally well armoured, but faster than Vulcan’s A12, and have the capacity to be upgraded because of the more powerful engine, meant that the company had high hopes that it would win the orders needed.
Work on the design for an alternative to Vulcan Foundry’s A12 was complete, it had the company codename of ‘Valiant’. Using the A9 and A10 as his starting point, Sir John Carden had increased the length of the new design to 19’4”, the height remained 8’8½”, while the width increased to the very limit of the rail gauge at 9’. The increased width allowed Carden to get the turret ring up to the 60” that he thought would be necessary for the next gun that would replace the 2-pdr.
As it was, the turret had enough room for a gunner, loader and commander, and there was plenty of room for ammunition storage. Just like the A9 and A10, the tank’s turret was designed for the 2-pdr gun and co-axial Vickers machine gun. There was work being done by the War Office on changing to an air-cooled machine gun to replace the Vickers. Until that appeared the water-cooled machine gun was what was offered. Carden had also designed a turret to carry the QF 3.7inch howitzer for a Close Support version.
Like the A10, the front hull was sloped without a hull mounted machine gun. He had kept the drivers position towards the side of the tank. When the driver’s position was at the centre of the tank getting in and out when the gun was facing forward was a problem. By off-setting the driver to the side Carden had managed to provide him with an adequately sized hatch for entry and exit. If the War Office insisted on a hull machine gun, then it would be slightly simpler to implement this, if the driver’s position and all the steering controls were already off-centre.
Carden’s ‘slow motion’ suspension system on the A9 and A10 hadn’t proven robust enough for the much heavier armour required on this A12 specification. He had designed the tank with the specified 2.75-inchs of armour (70mm) on the hull front and sides, with slightly thicker 3-inchs (78mm) on the front of the turret. With the tank now at 25 tons, Carden had opted to go back to the Horstmann designed suspension originally used on the A6E3. This used the leading and trailing bogies of the earlier Vickers’ ‘Japanese’ system, while the main central portion used a combination of coil springs and bell cranks. In 1936 this had been able to handle an 18-ton load at 30mph, so Carden was sure that it would be able to deal with the heavier load at more like the 20-25mph he expected the 400hp Ricardo diesel powered tank to produce. With lengthening the tank Carden had managed to increase the fuel capacity to give the tank a road radius of 120 miles.
The same Meadows No 22 clash gearbox was chosen as used on the A10, though Carden had looked at the Wilson epicyclic gearbox that Vulcan Foundry were using on the A12. As a company, Vickers was more confident in Meadow’s ability to supply their gear box than the new Wilson system. Carden was aware that later marks of his A12 alternative would likely have to look at alternatives, but it was important to get things moving as swiftly as possible.
The company executives signed off on the plans and prepared it to be presented to the War Office. A wooden mock-up was under construction and the prototype’s components were already ordered. The cost per tank, if it was to be accepted by the War Office needed to be less than Vulcan Foundry’s A12. Vickers knew that the production of the Vulcan A12 was likely to be quite slow, and so, as a sweetener, would offer to increase the workforce at their plant at Elswick build their Valiant much more quickly. If ordered ‘off the drawing board’ as the War Office had done with the A12, Vickers could promise that 100 tanks would be delivered within 18 months of being ordered, and would have the capacity to produce 30 tanks per month once full production was reached. The fact that the Valiant would be equally well armoured, but faster than Vulcan’s A12, and have the capacity to be upgraded because of the more powerful engine, meant that the company had high hopes that it would win the orders needed.
