The Jumbo Sherman- Why weren't all US tanks outfitted like this?

Similar, maybe, but a 'Combat Loaded' M4a3e2 comes in at 84,000lbs, whereas a 'standard' mid-production M4a3 would be 66,700lbs (Hunnicutt), and both ran the same Ford GAA engine.
Jumbo didn't come with those duckbills from the factory for nothing.

I'd perhaps like to re-state that 'Jumbo' was no slight adjustment or field mod, as I believe sometimes sneaks into discussion of it.
'Limited Standard' or not, it was a fairly radical remodelling of the base vehicle - a more distinct 'type' than many other M4 variants.

The Shadock has a very good page on it:
Fisher M4A3E2 Jumbos
And I'd say the Ordnance Ground picture there gives a pretty clear indication of just how much extra weight was being considered for 'Assault' work on the M4. (Duckbills too, even at that apparently weight-testing stage) :

 

I see many commenters on this thread writing things that might have a reader who didn't know better thinking that the Sherman Jumbo wasn't effective... it was very effective. Feedback from the users of the tank was that they loved it and wanted more. Especially since units started receiving them in October as the European rainy season goes into full swing ('44 had a record rainy season). This meant that the tanks would be tied to the roads and that was the Jumbo's forte.

 

Look at this monster. Looks like something from a Mad Max movie. Not bad for a field modification though. The side turret armor looks pretty beefy.

 

According to Steven Zaloga in the Osprey book on the Sherman, the extra armor of the Jumbo did press the chassis and engines to the limit. The sandbags and track plates added to standard Shermans had the same effect, without even offering any real improvement in protection. The Jumbo was certainly valuable (especially with the 76mm gun) and more would have been very nice, but the basic Sherman design had reached the limit of development. The real answer was a completely new design, that being the M26.

By the way, does anyone know if the British were interested in the Jumbo? A 76mm Jumbo might have made a nice partner for the 75mm Churchill in the army tank units.

 

And also it's weakness.
It was a specific tool for a very specific task, and yes it actually performed that task pretty well, but the whole thrust of WW2 armour development was that attempt to create 'The Universal Tank'; something Jumbo wasn't.
(Oh, and I'm enjoying your poking of old armour threads here, Dave - welcome aboard, mate.)

Good question on British use, TTH.
Dunno. British Jumbo in service doesn't ring many bells, though I seem to recall it was they who first enquired as to whether a beefier M4 could be produced.

 

Thanks von Poop, I've read alot of your posts. I've read these forums for years but only just recently felt like I might be able to add something. I've had a lifelong obsession with WW2, particularly aircraft and dogfighting tactics and have logged thousands of hours of ww2 sim flight time.
For the last couple of years though it's been ww2 tanks and infantry I'm positively obsessed. I'm a huge US tank fanboy (I'm an American) and have read many US tank and TD battalion AARs from the combined arms research library as well as the US "green books" about NW Europe. I also like to play tank Sims but I find the offerings don't really give as well rounded an experience as the flight Sims but they're still fun.

 

Never feel that a contribution has to be 'significant', chap.
In my experience, the weirdest, off-the-wall, seemingly insignificant queries often raise the most interesting thoughts in reply.
They force us dryer nerds to go 'Ooooh, hang on a minute. Never thought of that.'

Wolfy, who started this thread, used to really keep us on our toes as to 'WTF??' moments.

 

I have to state my opinion that the US should have stuck to improving the Sherman instead of trying to develop different tank models. The Sherman's only flaws that couldn't be fixed with improvements was it's high silhouette and external suspension.I think many people really overestimate how much of a problem that was. The Sherman was the same height as the Panther and only a foot taller than the t34-85. This obviously affected armor efficiency, my amateur opinion is by about 10 to 15 percent. The suspension was very easy to fix because they were bolted on.

 

My dog-eared old copy of Chamberlain and Ellis (British and American Tanks of WWII) seems to suggest that the M26 really grew out of such an effort. The US developed a rather interesting tank design called the T23, essentially an M4 with a much lower silhouette and a 76mm gun in a new turret. A fairly large trial batch was made but the T23 had some changes to the drive (I think) from the M4 and that did not work out so well. Anyway, the T23 was developed progressively through the T20 (new torsion bar suspension added) to the T25 (90mm gun added) and finally the T26 which was the M26 Pershing. So essentially US designers did what you are suggesting, starting out with a redesigned Sherman and ending up with a virtually new design. And by the way, don't worry if you think your opinion may be amateur; none of us here knows everything.

 

I also am of the opinion that the US needed heavy tanks during ww2 and the Jumbo fit the roll very nicely. All of the other combatants had heavy tanks and for good reason.
The Sherman was very suited for uparmoring for a couple reasons, it's very robust power train and it's ease of repair. Sherman maintenance queens were very different than German ones. That being said the US got its heavy tanks right when it needed them most. The rainy season had started and the US needed a road hog. Even with end connectors the Sherman's for the next few months were going to be stuck on the roads, for the most part, because of mud. Hellcats could handle mud OK but they were far from tanks.If the HVSS had been available at that time it might not have been as big of a problem but as it was it was a HUGE problem. One division commander referring to the Jumbo said "Our efforts are canalized (referring to having to stick to the roads) send us more of these tanks they have a chance!"

 

The problem with the m26 in my opinion is that here you had an unproven design (it turned out to be quite unreliable and underpowered) taking up factory space and time and 90mm guns when they could have literally just plopped that new turret right onto a Sherman. Or just built more M36b1s (Sherman's with the m36 turret). The m26 didn't have any effect on the war whatsoever and consumed valuable resources and just wasn't a very good tank. The design didn't really come into its own until the m46 (which was a beauty of a tank).

 

The M26 had its flaws, yes, but then so did the Sherman. Maybe the Pershing was underpowered, but it had wider tracks and combined both a better gun and better armor. It could take on a Tiger on even terms, something which was much more difficult for a Sherman to do. You say the M26 had no effect on the war, but of course when it was designed and produced we could not know that the war would end when it did. If the war in Europe had lasted into the autumn of 1945 then the M26 would have seen much more field service. If we had invaded Japan as we planned to do that autumn, then the heavier armor and gun of the M26 would have proven very helpful against Japanese defenses. Looking beyond, we were very lucky to have some M26s available in 1950, when the M4 was outclassed by the T34/85. As to the M36, why put a gun in a vulnerable open-topped turret on an obsolescent chassis when you can put the same gun in a tank which is fully capable of taking on another tank? A TD is not a tank, and while US TDs did good work in the war in a variety of roles the limitations of the TD concept were surely evident by late 44. Anyway, how many 90mm guns were really available in the late summer-autumn of 44 for a crash conversion/installation program on the Sherman chassis? What was the rate of gun production? As to putting the M26 turret on the M4 chassis, I don't know what the dimensions of the turret rings were or whether the M26 turret could have been made to fit. Maybe it would have fit, but in so far as it was fully enclosed and better armored than the M36 turret I imagine that it would have weighed more. How would that have worked out on a Sherman chassis? There are an awful lot of technical questions here. I don't have the answers for them but some others here may. In any case, it seems clear to me that by 1944 the Americans and British had both squeezed about the last they could out of the basic Sherman design. With the addition of more powerful guns (17pdr, 76mm, 105mm how) and some extra armor and other improvements the Sherman managed to stay competitive with German armor, but newer designs were needed. The British had come to the same conclusion as well, hence the Centurion.

 

M36b1 slap 1 inch of plate on the roof... 90mm Sherman tank. M4 outclassed by the t34-85? Bite your tongue. The m4 had a 3 to 1 ratio against it.

 

The turret ring diameter of the Pershing and Sherman are the same.

 

One huge advantage the Pershing had over the Sherman was reverse speed. One isn't so reluctant to go around a blind corner if you can quickly go back. But that also was fixable they just never did it. I'm not sure how the HVSS Sherman's compared to the Pershing in ground pressure, but judging by their respective reputations for mobility in Korea, probably pretty favorably. I know that hindsight is 20/20 but I'm not saying anything Mr. George Patton himself didn't say..And took alot of flack for as well.

 

As I said the Pershing's only real advantage over the Sherman was roughly a 10 to 15 percent armor efficiency increase.

 

And the gun? You have 90mm over 76mm.

 

The Sherman could accept the 90mm gun. See these fine examples. Yep one of those pictures is a Sherman with a M26 turret.

 

No, the British did not receive any M4A3E2. The French did, at least one is recorded with French First Army at the end of the war. All 76mm-armed M4A3E2 were theater conversions BTW.