Very true. My gut feeling is that the Kestrel is modern design, they'll be optimising it for cost, so it will be noticeably cheaper than the Liberty, which didn't raise costs unacceptably. While the engine is more expensive that two big bus engines, you save all the mechanical faffing about of coupling them, which I suspect isn't cheap
The Forge of Weyland
- Thread starter Astrodragon
- Start date
Apparently the Merlin costs £2,000 in 1940. That's with the aero bells and whistles on. So my gut tells me around £1,500-ish for a tank Kestrel, going down if they go into full production. That's not terrible.
As in anything a factor of selling something is the quantity of spares that accompany it. In the case of the Rolls series of engines, they would have been comparatively expensive. A Rolls inline is not a Bristol radial or a Napier inline. I wonder why the Dagger was never considered for a ground mount? It weighed approximately 1,358 lb (616 kg), produced approximately 725 hp (541 kW) at 3,500 rpm at ground level and ran on 87 octane petrol. It was also aircooled. It would have made a fine engine for a tank IMO, apart from the vibration problems which could be damped out.
The Dagger had over-heating problems on the ground, to the point the RAF considered it impractical to even attempt to operate it in hot climates. It was also considered very noisy, I don't think it actually left air crew deaf but that fact that rumour went around is not a good sign.
Maybe if it got detuned to a lower rpm those problems would get better, but it is a bit of a gamble.
I suggested the dagger in Allan's thread, two issues spring to mind that may preclude it as being practical, servicing the plugs of the H pattern engine would be a swine if its mounted flat or horizontal and it's high revving nature is not ideal in a tank?
However if you can fit it in a way that makes it easy to remove, it would negate the servicing issues and a well matched transmission would make the most of its power.
The aircraft fitting used ejector exhausts with no muffler, a ground fit will have space for at least one set off baffle/muffler boxes.
The cooling issue will need a decent set of fans fitting which wasn't practicable in the tight fitting cowl used in aircraft, also as weight is less of an issue bigger cooling fins could be machined on to the engine.
I do remember reading that during one of the many Dagger installations iterations they finally managed to correctly cool the rear cylinders, at the cost of over-cooling the front cylinders to the point the oil started going viscous. I get the impression that Napier had not really considered cooling at all in their quest to make it as compact as possible.
That said the early, lower rpm/lower power version of Dagger appeared to work fairly well, even in tough applications like target tug towing (low speed but high power output needed). So it would probably work when de-tuned and put in tank. Probably.
Indeed. My father in law used to work for BAe. There was always a rumour that the accounting interview process involved being shown the costs of a production run, expected rate of return, miscellaneous expenses and incomings, and being asked how much the design should cost, per unit.
According to the scuttlebutt, working out the answer to the correct margin of error was considered a good answer, but the actual correct answer was to ask, "how much would you like it to cost?"
A new cruiser design
20th January 1936, Mechanisation Committee, War Office
Having dealt with the Egypt issue on the preceding day, the committee then turned to the subject of a specification for new tanks. This time they had been joined by a team from Vickers led by Sir John Carden, armed with plentiful notes and diagrams of their proposed solution to the medium tank required.
Sir John started by pointing out that it proved impossible to meet the original specifications for the A9 and A10 tanks, now termed cruiser tanks. The A9, which managing the requisite speed, was far too thinly armoured. The A10, while being better protected - although still not to a level the team had been happy with - was far too slow. The Vickers men blamed in the main the unreasonably low weight allowed, and also an insufficiently powerful engine and gun. Sir John's reputation had allowed him to be allowed to re-specify a tank that he thought would meet their needs, and permission, if the design went ahead, to develop it without interference, a degree of trust not given to any other tank designer.
Laying out diagrams of the intended tank, Sir John and his team then went into the details of the design. This was based on their initial thoughts on a better A9/A10, which they had been working on for some time, with regular talks with the tank brigade officers. They were calling this the A10*.
First, they had left aside the question of the weight, until they had a design which would meet the army needs. The two initial priorities were the gun, and the thickness of the tank armour. The new 3pdr gun had been selected as the weapon; this had considerably better penetration that the old 3pdr, and would be in production soon, well in time to fit into a new tank. The 3pdr could penetrate some 50mm of armour at 500 yards, 38mm at 1,000 yards and 25mm at 1,500 yards. Talks with the tank men had indicated that the chance of a shot at any longer range would be minimal in Europe, although possibly better in somewhere like the desert. This would be sufficient to kill any of the existing tanks they were likely to face, most of which only had around 15-20mm of protection. The next generation of tanks were expected to carry 30-40mm, at least on the front, and the gun should still be effective out to around 1,000 yards.
Obviously it would be ideal if their tank could fire on others at a range they could penetrate, while staying safe behind their own armour. The older specification had mentioned 30mm, but the Vickers team thought this might be a bit thin, given that there was a steady improvement in anti-tank guns. The new French Souma tank was thought to have at least 40mm of protection, although not as good a gun as their own 3pdr. This was felt a good tank to choose as one to be able to beat, and while the new A10* could kill the French tank at around 800 yards, based on the performance of its own gun, if they protected their tank with 40mm of armour the Souma would need to close to more like 100-200 yards to have a decent chance. This would allow a good time to fire at the enemy while remaining relatively safe. The tank men were quite happy with this idea.
Taking 40mm as the starting point, Vickers had then worked out the weight the tank would likely be. They had assumed a 5-man tank, with a 3-man turret as specified before. Their estimate was that the tank would be around 17 tons in weight. There was some discussion from the Army men about this - their original thoughts had been for a tank around 13 tons, but Sir John pointed out that such a weight simply couldn't give the necessary performance. He continued with the need for the tank to be reasonably fast, in order to satisfy its role of exploitation. The team suggested the Diesel Kestrel that they thought would give enough power that even a heavy tank like this would be nimble enough. Harry Riccardo had estimated that a production version would provide over 300hp, and with this they were expecting a speed of over 25mph on the road, maybe as high as 30mph, although this was more dependent on the suspension that pure power. An off-road speed around 20mph was forecast. The use of a diesel, while needing its own fuel rather than pool petrol, offered advantages, not least a good range of action without needing an oversized fuel tank. The Army were worried that a modified aero engine would be too expensive, but the Vickers team pointed out that there were simply no commercial engines in the right power range. The other options were either to link together two bus engines - which, while probably a bit cheaper, would be much more mechanically complicated with the associated reliability and maintenance issues - or have a custom engine built. While a custom engine would probably be an ideal propulsive solution, it would take at least a year, and be expensive for the numbers of tanks the Army normally ordered. The Kestrel had the advantage that they could get a couple from Rolls-Royce for development, and while a dedicated production line would be needed, this could easily be set up and running before they needed the engines.
Sir John was asked if reducing the armour would allow a cheaper engine, but he pointed out that this was exactly the reason the original A9 specification had proven inadequate. His design did use sloped armour as much as possible, to increase the effectiveness of the armour, and Vickers had also decided on welding the tank. They felt that as long as a reasonable number were ordered - including tanks needed for training, an armoured brigade would need about 150 tanks - the advantages of welding would make the initial setup costs worthwhile. Vickers had experience of welding in their shipyards, and certainly welding the demonstration tanks would be no problem. The Army took more time going through the detailed plans, but the tank men at least were very happy with what Vickers would be offering. The senior officers were a bit less sanguine - they could see a lot of non-technical issues that they'd have to deal with, but overall it did look like a very good tank that would keep them in the forefront of tank design. Vickers had suggested that, with a good sized order, they could produce the tank for about £12,000 apiece. Vickers also thought they could deliver such an order in about 12-15 months from it being placed - if they did get this contract, they were thinking of building a proper tank factory, they were confident that the way things were going internationally that would be very useful, and they might even get government support - the aircraft side of their business was already looking at expansion and the new 'Shadow Factories', and they didn't see any reason why the same thinking could not be applied to tanks.
All in all, both sides felt it had been a most productive meeting. Vickers and Sir John had got their technical points across, and the Army had been reasonably positive, especially the men who would actually have to fight in the tanks. Of course, there were a number of little technical issues that Sir John hadn't emphasised - after all, one wouldn't want to overburden the Army men with too much detail about the technicalities - but these could be dealt with once an order was agreed. For their part, the Army promised to discuss it further and come back to Vickers as soon as possible. They did ask when a prototype could be produced ready for evaluation, and were pleasantly surprised when told this would be 9 months at the most, and one in mild steel rather than armour could cut a couple of months off that; what they didn't realise, and the Vickers men didn't tell them, was that considerable work had been done on the old A9/A10 specifications that could be used or adapted to the new tank, so they weren't actually starting from a blank sheet of paper.
While originally the meeting had also intended to discuss the proposals for a heavy infantry tank, after going through all the issue regarding the Cruiser tank, this was postponed for a later meeting. At the moment the Cruiser was seen as the highest priority tank.
Having dealt with the Egypt issue on the preceding day, the committee then turned to the subject of a specification for new tanks. This time they had been joined by a team from Vickers led by Sir John Carden, armed with plentiful notes and diagrams of their proposed solution to the medium tank required.
Sir John started by pointing out that it proved impossible to meet the original specifications for the A9 and A10 tanks, now termed cruiser tanks. The A9, which managing the requisite speed, was far too thinly armoured. The A10, while being better protected - although still not to a level the team had been happy with - was far too slow. The Vickers men blamed in the main the unreasonably low weight allowed, and also an insufficiently powerful engine and gun. Sir John's reputation had allowed him to be allowed to re-specify a tank that he thought would meet their needs, and permission, if the design went ahead, to develop it without interference, a degree of trust not given to any other tank designer.
Laying out diagrams of the intended tank, Sir John and his team then went into the details of the design. This was based on their initial thoughts on a better A9/A10, which they had been working on for some time, with regular talks with the tank brigade officers. They were calling this the A10*.
First, they had left aside the question of the weight, until they had a design which would meet the army needs. The two initial priorities were the gun, and the thickness of the tank armour. The new 3pdr gun had been selected as the weapon; this had considerably better penetration that the old 3pdr, and would be in production soon, well in time to fit into a new tank. The 3pdr could penetrate some 50mm of armour at 500 yards, 38mm at 1,000 yards and 25mm at 1,500 yards. Talks with the tank men had indicated that the chance of a shot at any longer range would be minimal in Europe, although possibly better in somewhere like the desert. This would be sufficient to kill any of the existing tanks they were likely to face, most of which only had around 15-20mm of protection. The next generation of tanks were expected to carry 30-40mm, at least on the front, and the gun should still be effective out to around 1,000 yards.
Obviously it would be ideal if their tank could fire on others at a range they could penetrate, while staying safe behind their own armour. The older specification had mentioned 30mm, but the Vickers team thought this might be a bit thin, given that there was a steady improvement in anti-tank guns. The new French Souma tank was thought to have at least 40mm of protection, although not as good a gun as their own 3pdr. This was felt a good tank to choose as one to be able to beat, and while the new A10* could kill the French tank at around 800 yards, based on the performance of its own gun, if they protected their tank with 40mm of armour the Souma would need to close to more like 100-200 yards to have a decent chance. This would allow a good time to fire at the enemy while remaining relatively safe. The tank men were quite happy with this idea.
Taking 40mm as the starting point, Vickers had then worked out the weight the tank would likely be. They had assumed a 5-man tank, with a 3-man turret as specified before. Their estimate was that the tank would be around 17 tons in weight. There was some discussion from the Army men about this - their original thoughts had been for a tank around 13 tons, but Sir John pointed out that such a weight simply couldn't give the necessary performance. He continued with the need for the tank to be reasonably fast, in order to satisfy its role of exploitation. The team suggested the Diesel Kestrel that they thought would give enough power that even a heavy tank like this would be nimble enough. Harry Riccardo had estimated that a production version would provide over 300hp, and with this they were expecting a speed of over 25mph on the road, maybe as high as 30mph, although this was more dependent on the suspension that pure power. An off-road speed around 20mph was forecast. The use of a diesel, while needing its own fuel rather than pool petrol, offered advantages, not least a good range of action without needing an oversized fuel tank. The Army were worried that a modified aero engine would be too expensive, but the Vickers team pointed out that there were simply no commercial engines in the right power range. The other options were either to link together two bus engines - which, while probably a bit cheaper, would be much more mechanically complicated with the associated reliability and maintenance issues - or have a custom engine built. While a custom engine would probably be an ideal propulsive solution, it would take at least a year, and be expensive for the numbers of tanks the Army normally ordered. The Kestrel had the advantage that they could get a couple from Rolls-Royce for development, and while a dedicated production line would be needed, this could easily be set up and running before they needed the engines.
Sir John was asked if reducing the armour would allow a cheaper engine, but he pointed out that this was exactly the reason the original A9 specification had proven inadequate. His design did use sloped armour as much as possible, to increase the effectiveness of the armour, and Vickers had also decided on welding the tank. They felt that as long as a reasonable number were ordered - including tanks needed for training, an armoured brigade would need about 150 tanks - the advantages of welding would make the initial setup costs worthwhile. Vickers had experience of welding in their shipyards, and certainly welding the demonstration tanks would be no problem. The Army took more time going through the detailed plans, but the tank men at least were very happy with what Vickers would be offering. The senior officers were a bit less sanguine - they could see a lot of non-technical issues that they'd have to deal with, but overall it did look like a very good tank that would keep them in the forefront of tank design. Vickers had suggested that, with a good sized order, they could produce the tank for about £12,000 apiece. Vickers also thought they could deliver such an order in about 12-15 months from it being placed - if they did get this contract, they were thinking of building a proper tank factory, they were confident that the way things were going internationally that would be very useful, and they might even get government support - the aircraft side of their business was already looking at expansion and the new 'Shadow Factories', and they didn't see any reason why the same thinking could not be applied to tanks.
All in all, both sides felt it had been a most productive meeting. Vickers and Sir John had got their technical points across, and the Army had been reasonably positive, especially the men who would actually have to fight in the tanks. Of course, there were a number of little technical issues that Sir John hadn't emphasised - after all, one wouldn't want to overburden the Army men with too much detail about the technicalities - but these could be dealt with once an order was agreed. For their part, the Army promised to discuss it further and come back to Vickers as soon as possible. They did ask when a prototype could be produced ready for evaluation, and were pleasantly surprised when told this would be 9 months at the most, and one in mild steel rather than armour could cut a couple of months off that; what they didn't realise, and the Vickers men didn't tell them, was that considerable work had been done on the old A9/A10 specifications that could be used or adapted to the new tank, so they weren't actually starting from a blank sheet of paper.
While originally the meeting had also intended to discuss the proposals for a heavy infantry tank, after going through all the issue regarding the Cruiser tank, this was postponed for a later meeting. At the moment the Cruiser was seen as the highest priority tank.
Driftless
Donor
Fishing proverb: Get the fish in the boat before you brag about how big it is. Sir John seems to be working along those lines. First get agreement on the cruiser before proceeding to the infantry tank. Getting the Treasury on board for either is a different (but related) battle.
I think using the Souma as your standard for comparison is a very good one. The concept of an 'immunity zone' where your armour is considered proof against enemy shot wouldn't be lost on the Army Committee, despite being a naval idea. Indeed, if a decent engine can be found for the new A10* the combination of speed, armament, and armour will lend itself nicely to naval comparisons.
I expect if someone in the press gets wind of Vickers' little project we might see headlines about 'Vickers plans Land Dreadnoughts' or 'Army adopts new Battle-Cruiser tanks'.
The idea of an immunity zone was, I believe, ignored in OTL as they assumed they would be hammering away at close range. Its now been pointed out that as they have a good gun, they should take advantage of it. There will be repercussions from this 
marathag
Banned
So many were made, and so little demand,were being sold for scrap weight price in the late '20s
French tanks seem the logical comparison point, as they seem to be the only country making medium/heavy tanks (they don't really know what the Russians are up to yet). So designing a tank or anything else, really) to take on the best opposition makes sense
I wonder if it will make a resurgence in this TL? You never know...
Driftless
Donor
Might the Italian scare around Egypt and the possibility of fighting in open desert open some minds to the likelihood of shooting at a distance as a real possibility? The powers-that-be should have something more than traversing the farms, fields, and woodlots of Flanders and the Alsace to bear in mind. Of course, there are generations of mental inertia, from some in command, to pivot.The idea of an immunity zone was, I believe, ignored in OTL as they assumed they would be hammering away at close range. Its now been pointed out that as they have a good gun, they should take advantage of it. There will be repercussions from this
marathag
Banned
It's been reported that internally, Ford Motor Company under Henry Ford weighed departmental invoices with a scale, than working out how things really cost. and one of the huge things Henry Ford II did after taking over operations was to introduce a real accounting system in 1946
Changes like this are one of the things coming out of the 1934 and subsequent exercises. The additional time and testing has given them a somewhat different doctrine (not a perfect one, there are still big errors in it) which will lead to a different idea of what an armoured force should be. This is one of the things that is taking the tanks they want in a slightly different direction.
I wonder how long it'll take before the old 'firing on the move' doctrine will get deemphasized in tactical concepts in place of 'stop, then aim'.
Probably as OTL really, when the guns had to be bigger than an operator could aim them with his shoulder. I suspect Carden's advice about the usefulness of engaging at range will also help, since it's very hard to make an accurate shot at a thousand yards while bumping around at anything more than a walking pace (and even then...).
Probably as OTL really, when the guns had to be bigger than an operator could aim them with his shoulder. I suspect Carden's advice about the usefulness of engaging at range will also help, since it's very hard to make an accurate shot at a thousand yards while bumping around at anything more than a walking pace (and even then...).