Sir John Valentine Carden Survives. Part 2.
- Thread starter allanpcameron
- Start date
And the need to crank out Shermans definitely delayed conversion to the M26, after it had brought about the outright cancellation of the 90mm-armed "Persherman" variant.
So with less need for Grants, the Sherman starts perhaps as much as six months sooner; and with less need for Shermans, the Sherman design for US use evolves to the 90mm "Persherman" around November 1943, with Fisher Tank Arsenal and the Canadians continuing to build 75mm and 76mm Shermans for the Soviets, Canada, US users in the Pacific theatre, and others who wanted them, and all the other factories building 90mm Shermans for US infantry divisions. Then around July 1944, Detroit Tank Arsenal and Lima convert over to the M26, up-engined from the beginning with the Chrysler A65 V-12 aluminum version.
How would the M26 with the standard 90 and 650 hp compare to the Victor...which, for all intents and purposes, amounts to an earlier Comet/Centurion?
The OTL 17 pounder had a relatively high muzzle velocity HE round, which therefore required enough shell wall thickness to withstand the firing accelerations that the amount of HE was lessened and the fragmentation count was smaller, compared to contemporary, lower velocity 75mm and 76mm rounds. Does the Victor carry a HE round like that of OTL, or are its HE rounds a different, lower velocity design in order to achieve a greater fragment count?
The US 90mm L/53 gun's M71 HE was reputed to be significantly more effective against soft targets than optimized 75mm HE, such as that fired by the Mle1897 or the Sherman 75. The 90mm's M82 APC, presumably its AP at the proposed introduction, of course was significantly less effective OTL than the 17 pounder's AP capability. But, as has been noted many times, most WWII tanks fired much more against soft targets than hard ones.
The OTL 17 pounder had a relatively high muzzle velocity HE round, which therefore required enough shell wall thickness to withstand the firing accelerations that the amount of HE was lessened and the fragmentation count was smaller, compared to contemporary, lower velocity 75mm and 76mm rounds. Does the Victor carry a HE round like that of OTL, or are its HE rounds a different, lower velocity design in order to achieve a greater fragment count?
The US 90mm L/53 gun's M71 HE was reputed to be significantly more effective against soft targets than optimized 75mm HE, such as that fired by the Mle1897 or the Sherman 75. The 90mm's M82 APC, presumably its AP at the proposed introduction, of course was significantly less effective OTL than the 17 pounder's AP capability. But, as has been noted many times, most WWII tanks fired much more against soft targets than hard ones.
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Except that the M26 sucked, and would still suck ITTL. And even if they did eventually manage to fix it, that would almost certainly not happen until after the war:
Better, probably, but OTOH, it would be of comparable vintage to the Victor's successor.
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Yeah my guys used either on the 5 ton trucks most time multiple cans.
Modern discussions of the M26's inadequacies refer to its OTL version. We of course are in a different TL.
Part of the M26's shortfall was its inadequate power. That's proposed to be addressed. Part of the argument for it being addressed is that the US armor establishment would be very aware of the Victor, and particularly of its powertrain...and "keeping up with the Joneses" is a real element of weapon development. When you don't have proof that what you're proposing will be inferior, but you know it'll be cheaper, sometimes saving money wins out. But when a superior competitor already is in service, cost-target expectations tend to be adjusted.
Another part of the OTL M26's shortfall was its inadequate AP performance with M82. I don't know if HVAP reasonably can be proposed to have been ready earlier, given the screwed up situation with US AP capability development...but if McNair had never been part of the tank-specification-development chain of command, then maybe.
But in that case, the long US 90mm might make an appearance sooner as well, at least in tanks intended for armored divisions and to provide infantry forces with AT capability, and AP performance no longer would be a concern.
Part of the M26's shortfall was its inadequate power. That's proposed to be addressed. Part of the argument for it being addressed is that the US armor establishment would be very aware of the Victor, and particularly of its powertrain...and "keeping up with the Joneses" is a real element of weapon development. When you don't have proof that what you're proposing will be inferior, but you know it'll be cheaper, sometimes saving money wins out. But when a superior competitor already is in service, cost-target expectations tend to be adjusted.
Another part of the OTL M26's shortfall was its inadequate AP performance with M82. I don't know if HVAP reasonably can be proposed to have been ready earlier, given the screwed up situation with US AP capability development...but if McNair had never been part of the tank-specification-development chain of command, then maybe.
But in that case, the long US 90mm might make an appearance sooner as well, at least in tanks intended for armored divisions and to provide infantry forces with AT capability, and AP performance no longer would be a concern.
A good portion of the M26's inadequacies was the unreliability of its drive-train. Another (few) point(s) of contention was logistical, namely, it was too wide for most of the railroads, and too heavy for any of the army's bridges. I'm also pretty sure it would have been too heavy for many cranes, thus limiting the number of ports that could get it on and off the ships.
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Derek Pullem
Donor
Doubt it - they have decent British designs to build and have the "Jumbuck" joint project with Australia.
Like other, I do wonder if the surplus of Sherman capacity might be repurposed to delivering something the British haven't got i.e. a legitimate heavy tank to take on the Tiger. ITTL the development work on T20/22/23 is superfluous as they already know the British (and likely Germans) are ahead of them. So a jump in development to T25/26 is not unreasonable and may advance the prototypes by up to a year. Whether they get past the US Army resistance to deployment is another question.
Not sure the reliability was that much worse than similar tanks (Tiger, early Centurion)
Another option is something akin to the 'Bazooka Charlie' approach. Yes, I know, there's going to be rockets, but I suspect more recoilless rifles can be packed under the wings than can rockets, even if they don't have the range or damage potential.
A few issues here:
1) Tigers are rare, and while the Victor might not be able to kill a Tiger II in a one-on-one tank duel, I think it would probably be able to deal with a Tiger I or Panther reasonably well, and would almost certainly always have a numbers advantage.
2) Without the T20 series developments, it's likely that the Shermans will be stuck with the 75mm, as it was the T23 turret that saw them develop a mounting/turret for the 76mm gun that Armoured Board would actually accept.
3) The logistical concerns of being too big and/or heavy will likely still exist.
Probably not, but OTOH, the Pershing has to come across the Atlantic, whereas the Tigers were coming from the same land-mass, and the Centurions not much further away. Also, whatever the follow-up to the Victor is ITTL, I suspect Carden is going to do his damnedest to get hold of some Griffon engines for it.
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Two may not be needed. Using QF 75mm based upon the 6 Pounder will give a far more effective HE shell for the job at the same rate of fire. Even for tanks as you are probably not aiming at the frontal armour.
Yes. Much more HE (~2X), and able to have much thinner walls due to the lower acceleration resulting from the much lower muzzle velocity. Thinner walls mean many more fragments, of more optimized size for soft targets, with higher projection velocity.
But note that there was no option to increase that muzzle velocity. The gun utilized a six pounder barrel, bored out to a larger caliber, so it had much thinner chamber walls...so it had a much lower capability to withstand chamber pressure. And it's chamber pressure that directly results in muzzle velocity.
With manual loading, maybe. The shells were light enough that a single man could handle either type/caliber at about the same motion-speed. But with an autoloader such as the Molins, no. The mechanism speed is very much affected by the mass being moved. The lighter the shell, the faster it can be autoloaded, and vice versa. And the 75mm HE shell weighed ~ twice the 57mm HE shell.
I think what's being said here is that the QF 75mm would be more effective with AP shells. I'm pretty sure not. Armor penetration is second-order dependent on velocity, which is much lower for the 75mm gun version, and only first-order dependent on mass, which is higher for the 75mm version.
Historically, the QF 75mm was the preferred gun version for HE, but the six pounder / 57mm gun version was preferred for AP.
If you're mounting it in an aircraft, you probably don't want a higher velocity anyway.
Automatic loading I'd assume, for an aircraft.
That's not at all what's being said. What's being said is that the higher AP capability of the 6-pounder won't be terribly important.
That's a myth, all the barrels were new and specially designed. Pressure was lower due to the area/volume increase rather than inability to withstand. The QF was not a low pressure gun, it fires exactly the same shell as the American M3 used by the Grant/Sherman.
Speaking of guns, I was just looking at the calibres used across the British (or at least Vickers) designs, and found an interesting sequence:
Matilda 1 (40mm), Valiant +17mm (40/57mm), Victor +18mm (75mm).
Continuing this trend, the follow up to the victor would have a gun 19mm larger than the 75mm, which is...(drumroll)... 94mm/3.7".
Matilda 1 (40mm), Valiant +17mm (40/57mm), Victor +18mm (75mm).
Continuing this trend, the follow up to the victor would have a gun 19mm larger than the 75mm, which is...(drumroll)... 94mm/3.7".
