Sir John Valentine Carden survives.

Going for an American design has the interesting result that it means that the USA is producing a ~400 hp V-engine prior to the M2 medium entering service, which may have the knock-on effect of the M3 Lee and M4 Sherman also going with that engine, thus giving those tanks a lower profile.

But still kept the oversized volume. Hull was large enough to fit the Wright R-1820 with slight modification.
It's totally possible to put a smaller engine in the M4 hull, but Armored Force wanted options to use all engines, large and small, even if was inefficient use of volume. Upthread I posted Israeli Shermans with cut down upper superstructure to lower the tank.
US could have done it, but didn't want to interfere with production, despite having way too many vendors making Shermans.

The original models used a radial engine, but if they have a viable alternative before the M3 is even in the design phase... Hells, depending on how much is known about the Valiant while the M2 design is going on we might not even see the OTL M3, as the desners might take some tips from the Valiant, and just install the main gun in the turret, rather than having a it casemated in the hull.
Honestly, I don't think it was the requirement to fit radials as an engine option that doomed the Sherman to be 'suboptimally' tall, but the lack of a decent transfer box to lower the crankshaft under the turret basket like was later used on the Hellcat. If someone gets that figured out early enough I think we can see the 'sleek Sherman' in TTL. Not sure about the timing though, we're already in early 1939 so there may or may not be time to make major changes to the M3, but I think declaring the M4 'it is what it is' a bit premature.

Well, my idea is to have something like the M3, but a MG turret and a 105mm howitzer in the side sponson for an interim support tank
TurretlessM3asAssaultGunKindaWorks.jpegCan't remember if this thing was posted in this thread or another, but a low-profile MG turret on the M3 and a big support gun in the hull is an idea I can get behind.
 
Honestly, I don't think it was the requirement to fit radials as an engine option that doomed the Sherman to be 'suboptimally' tall, but the lack of a decent transfer box to lower the crankshaft under the turret basket like was later used on the Hellcat. If someone gets that figured out early enough I think we can see the 'sleek Sherman' in TTL. Not sure about the timing though, we're already in early 1939 so there may or may not be time to make major changes to the M3, but I think declaring the M4 'it is what it is' a bit premature.
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M3 Lee with dual 6-71, note low drive shaft. This was done in October, 1941

The T6, pilot for the Sherman, was completed in September 1941

The M4 is baked in, as much as I wish it wasn't The design for what would be the M-18, that would have that transfer case to drop the drive shaft in December 1941.

Anytime after that, the hull could have been lowered.
But never was, over the next three years the Sherman was in production
 
I was thinking of a cutaway of (I think the M4) with the radial installed, showing the driveshaft running at an angle from the centre of the engine to the gearbox, clearly showing the need for a higher turret basket for clearance, something that's not needed for the other engine options like the one you've helpfully linked. The M18 was equipped with a transfer case (I think that's the right term) to drop the output of the radial down to the level of the gearbox so you could have the lower hull profile. That the M3/4 wasn't intended to have one from the outset is one of those design choices that mildly baffle me.
 
I was thinking of a cutaway of (I think the M4) with the radial installed, showing the driveshaft running at an angle from the centre of the engine to the gearbox, clearly showing the need for a higher turret basket for clearance, something that's not needed for the other engine options like the one you've helpfully linked.
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M3
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Ram II
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M4
 
That's the one, or rather, those are the ones, thanks!
Using a transfer case also means you don't need to mount the radial on an angle either, although I'm not sure it really makes a difference.
 
That's the one, or rather, those are the ones, thanks!
Using a transfer case also means you don't need to mount the radial on an angle either, although I'm not sure it really makes a difference.
Radials can even run flat, if the oiling system accounts for it
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Very little could interchange between Packard Merlins and Rolls Royce Merlins

That was because of the use of different fasteners. Packard engines used US fasteners, Rolls Royce engines, British one. The two sets of screws were completely different in shape. The Cylinders would be identical though and interchangeable. The British led the US in supercharger development.
 
Whilst the Sherman gets a lot of unfair stick one BIG thing to remember is that it was VERY easy to bail out of and crews had a far higher survivabilty rate than equivalent British tanks and indeed Soviet and German tanks.

 
Whilst the Sherman gets a lot of unfair stick one BIG thing to remember is that it was VERY easy to bail out of and crews had a far higher survivabilty rate than equivalent British tanks and indeed Soviet and German tanks.

An important factor. I wonder if it will ever come to Carden's attention. Another couple of factors in the Sherman's favour is its extreme reliability, and its ease of maintenance. Now the British do have something on the latter, given that the entire powerpack is at the rear, rather than having a prop-shaft running the length of the crew compartment, but On the former... Yeah, British tanks have a reputation for unreliability. I do wonder if Carden will be able to help that some (more than he already is anyway).
 
An important factor. I wonder if it will ever come to Carden's attention. Another couple of factors in the Sherman's favour is its extreme reliability, and its ease of maintenance. Now the British do have something on the latter, given that the entire powerpack is at the rear, rather than having a prop-shaft running the length of the crew compartment, but On the former... Yeah, British tanks have a reputation for unreliability. I do wonder if Carden will be able to help that some (more than he already is anyway).

Well if Carden can keep away from the Chrystie type suspension and go with the one he's got on the Valiant which was less work intensive, there's also new tracks to counter the piss poor track quality the UK had OTL. It all really depends on the engine and the ergonomics for the crew. As ya pointed out, the rear mounted engine and rear drive cuts down on complexity, and would be easier to remove even if its obviously nothing like a modern power pack.
 
Now the British do have something on the latter, given that the entire powerpack is at the rear, rather than having a prop-shaft running the length of the crew compartment, but On the former... Yeah, British tanks have a reputation for unreliability.
Also slightly unfairly. The problems were with the early war tanks and largely down to rushed development by companies that never even saw a tank first and inadequate testing before entering service.
 
Also slightly unfairly. The problems were with the early war tanks and largely down to rushed development by companies that never even saw a tank first and inadequate testing before entering service.
The Cromwell wasn't as reliable as the Sherman, yes it was reliable by British standards but by most standards thats barely better than 1st batch of Panthers or asking a Ferdinand to go up a hill and not blow out its clutch/engine in terms of reliabilty. The Valentine and Matilda II were adequately reliable, the Crusader broke down if you looked at it funny and the Churchills when introduced basically arrived in a a box with SOME ASSEMBLY REQUIRED written on the side as the worlds largest Mechano set.

Its why the Brits liked the Grant/Lee, because they were reliable.
 
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Well if Carden can keep away from the Chrystie type suspension and go with the one he's got on the Valiant which was less work intensive, there's also new tracks to counter the piss poor track quality the UK had OTL. It all really depends on the engine and the ergonomics for the crew. As ya pointed out, the rear mounted engine and rear drive cuts down on complexity, and would be easier to remove even if its obviously nothing like a modern power pack.
I'm not sure it does cut down on complexity much TBH, as there's a bunch of linkages running backwards from the driver's position to the gearbox. What it does reduce is the time needed to work on the drive-train when compared to the German tanks.

Also slightly unfairly. The problems were with the early war tanks and largely down to rushed development by companies that never even saw a tank first and inadequate testing before entering service.
Anything using the Liberty engine was going to have terrible reliability.
 
On the Valiant engine issue.

I think we have all missed something here. The initial purchase of the Lion's was in 37 I think? I'm pretty sure I am getting that right. When that was made and engineers from Vickers looked them over they would have realised all the problems we are now figuring out surely. Even if they weren't able to then Harry Ricardo would have, of that I am sure. Now obviously that isn't an issue for the first 500ish tanks built because the engines are already built. Carden however will have begun looking for an alternative or solution pretty much straight away. I can think of a few potential's right off the bat. I will admit though that I am no expert in engine manufacture etc. I know just enough to be dangerous so would appreciate you input.

  1. Immediately start work with Napier on a replacement W12 engine. If designed from the outset as a Diesel tank engine and using Harry Ricardo it should be the ideal platform and be able to give more power and be upgradeable. This is an (almost) entirely new engine, could it be ready in 18-24 months so that when the order is placed it is available?
  2. Use a different old aircraft engine from the start, several were mentioned like the Kestrel. The problem with most of these is that they are now out of production and while it is possible to set up a new production line their are cost issues as well as space issues. Where do you build the engines in a factory churning out aircraft engines as fast as possible and who pays for all the tooling etc?
  3. Use a non aircraft engine, this does kind of go against the premise and gets you a less impressive engine and affects tank performance and reliability so less than ideal.
  4. Use a new aero engine as the basis as your Tank engine. The obvious candidate would be the Merlin/Meteor. This offers you an up to date, modern engine that is in production as a base for the tank engine you need. It has more than enough power, either in Petrol or Diesel form and is reliable. Now their are several issues stopping this option, least of all the Air Ministry but it could be achievable. Firstly if you can source manufacture from somewhere other than Rolls Royce on a licensing agreement you aren't impacting aircraft production. Two if the engine is made using non aircraft spec components then even better. Thirdly if it is diesel it is an almost new engine. If the engine is petrol you could sell it as mutually beneficial as their will be a certain level of parts interchangeability between both engines easing the burden on getting some spare parts. Particularly where both forces may be operating together away from home shores.
Thoughts? Yes their are potential engine problems but they aren't insurmountable. I also know the Meteor this early is pushing the boundaries of a Wank but the post detailing the Air Ministry's apoplexy would be worth it I feel.
 
Option 1 is the most likely as they're already redesigning the Lion into a diesel engine. It just makes sense that while they're doing that they fix as many of the other issues as possible.
 
Who pays for all the tooling? The Government of course. They are the ones letting the contract and ultimately they who will have to pay for what they want.
 
Option 1 is the most likely as they're already redesigning the Lion into a diesel engine. It just makes sense that while they're doing that they fix as many of the other issues as possible.

That was my thought as well. The thing is given the number of changes likely required it will almost be a new engine so will take a while to get ready. Not as much of an issue if you start in 37 say but the closer to war you get the more challenging it becomes. If it is a new(ish) and more powerful engine say 450-500hp that can be upgraded some and is mass produce-able you have the perfect engine for WW2 tanks. The thing is can you do it in time? Also if Napier start focusing on a new tank engine what does that mean for the Sabre? how does the air ministry respond?

Can Napier produce at least two engines a day though? And are the parts going to be interchangeable?

2 a day? it is more likely to be 13-17 a day if the Valiant really enters serious mass production. Napier cant manage that, Ford UK can and if Napier and Ford together with new factories will be able to crank out more than enough as well as derivative engines. The issues are will ford be able/willing to get involved and will the engine if mass produce-able be ready in time anyway?

Who pays for all the tooling? The Government of course. They are the ones letting the contract and ultimately they who will have to pay for what they want.

In 1939 yes the Government pays for the tooling, 38 it's a tossup and in 37 almost no chance. The thing is are you willing to wait to set up production of your tank engine?.
If you are using something like the Kestrel then their aren't stocks of unused engines sitting around so you will need to make new ones. If you want to have engines ready to put in the Valiant you need to have the factory ready in 39 not starting to be built.
 
In 1939 yes the Government pays for the tooling, 38 it's a tossup and in 37 almost no chance. The thing is are you willing to wait to set up production of your tank engine?.
If you are using something like the Kestrel then their aren't stocks of unused engines sitting around so you will need to make new ones. If you want to have engines ready to put in the Valiant you need to have the factory ready in 39 not starting to be built.
Who do you think orders the vehicles in the first place? Who uses the vehicles after they are delivered? The Government via the Army. Therefore, the customer pays or they don't get what they want, right?
 
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2 a day? it is more likely to be 13-17 a day if the Valiant really enters serious mass production. Napier cant manage that, Ford UK can and if Napier and Ford together with new factories will be able to crank out more than enough as well as derivative engines. The issues are will ford be able/willing to get involved and will the engine if mass produce-able be ready in time anyway?
Oh sure, I was just going with the initial 40-50 per month figure. If they can't, it might be worth looking around so see if there's another engine in production (even in the USA), that is both powerful enough, and available in sufficient quantities.
 
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