sherman jumbo

So what made the Jumbo so different over the ordinary sherman?I'm guessing extra armour,but what else?
john.

 

From what I know about the Jumbo, the extra armor and new turret are the only new things going for it. The Jumbo lacked the HVSS suspension and Wet Storage compartment for ammunition that other Shermans had. It had a thick gun shield, thick frontal armor, and was designed to engage and destroy static defenses.

Some were field-adjusted with the 76mm M1 gun and used for anti-tank work, but I don't know exactly how successful they were since they are such a small, often overlooked percentage of the Shermans in the ETO.

 

Were the motors uprated to cope with the extra weight?

 

M4A3E2 "Jumbo" Assault Tank

Because of the vastly greater number of tanks available to the Allies, they did not have to resort to the use of limited traverse weapons like the Stug III or StuH 42. U.S. Tank Destroyers and 105mm Howitzer armed Shermans performed the same function as the German Stug’s. Nonetheless, in view of armors role as a supporting force against strongpoints, and with the assault of the much-touted Siegfried Line in mind, attempts were made to produce a heavily armored assault tank capable of absorbing more punishment in breaching enemy fortified positions. The T14 assault tank proved to be unsuccessful, suffering from track and suspension problems, and as an expedient measure, it was decided to add armor to an existing model of the Sherman.

The M4A3 (75mm) with the new 47o glacis hull was chosen, although dry ammunition stowage was retained. The front and sides had 1 ½ inch thick plate welded over them, giving a front thickness of 4 inches and the upper hull sides 3 inches. A new cast transmission housing of 5 ½ inches was fitted. The obvious increase in bulk of this modified hull led to the M4A3E2 nickname “Jumbo”.

The turret for the ‘E2 was a completely new design though obviously influenced by the T23 turret previously adopted for the 76mm Shermans. It was an immensely thick casting having 3 inch of frontal armor – further protected by a 7 inch block-shaped mantlet – and 6 inch thick sides. The rear was 2 ½ inch thick and the 1 inch roof plate was welded on during assembly, leaving a welded seam around the roof. In view of its role as an assault tank, the M4A3E2 retained the 75mm gun M3, since the 76mm weapon had no advantage in firing HE ammo.

Because of the increased weight – to 42 tons – all M4A3E2s were permanently fitted with extended end connectors. Performance fell from 26mph to a maximum road speed of 22mph and operational range was reduced. However, the added armor made the ‘E2 assault tank extremely resistant to German anti-tank guns and tanks. PzKpfw IV’s had to use their heavily rationed APCR solid shot at all but point blank range, and even Panthers couldn’t puncture the frontal armor at long range. M4A3E2s eventually became popular for leading armored columns, as they often absorbed hits that would have destroyed standard Shermans, and gave other vehicles warning of German anti-tank guns.

----------------------------------------------------------------------------------

Plagiarized directly from my handy-dandy copy of...

 

Wow! Imagine a 17 pounder shoehorned in and an, uprated motor,what a difference that would have made!
pity more of them weren't produced.
It appears to have been somewhat underrated.
yours john.

 

By the way relagiarism.........I wont tell anyone if you wont!

 

plagiarism is bad i thought

 

re

the jumbo was to perform a similar function to the chirchill tank, although it wasnt as good in armour in other respects it certainly was better(i.e speed). and a jumbo firefly would have been awesome.

 

The M4A3E2's armor was sloped, giving it an overall protection of 191mm RHA compared to the Churchill's flat 150mm RHA.

 

but the britsh cast armour was of a higher quality.

The churchill armour was cast and had a bhn of 293-332. so an average of 312.
cast armour is 5% less effective than rha generaly but german documents place british cast armour as equal to rha.

usa rha from 76-125mm thick has an bhn of 240-260. equals about 250 bhn.

So the british bhn is about 62 higher, roughly 25%.

so the churchills flat 150mm is equal to 188mm of us armour.

.Also you have to take into account the thickness to diameter ratio, the bigger the size of the plate in width of a certain thickness the more resistant it is.

Lastly the infrastructure of the tanks is somewhat different, i believe about 25mm for the jumbo and 40 mm for the churchill.

 

plus only about 300 jubo's were made. compared to about 6,000 churchills.

 

I'de like to know your sources for British steel BHN.

And as far as I know, the superstructure of the M4A3E2 is another sloped 102mm.

 

http://www.freeweb.hu/gva/weapons/briti ... s_veh.html
thats my source. qouting livingston and jentz.

And by infrastrutre i meant internaly structure not hull armour.

 

The Churchill was the British standard infantry tank as of 1943, which meant that it was mass-produced to support British infantry in any and every mission. The Jumbo Sherman was a specialized conversion of the standard American tank, designed and produced for special tasks such as bunker (Siegfried Line) assault. It's none too surprising, then, that more Churchills were made than Jumbos.

On the other hand, more than 40,000 Shermans of all types were produced during the war, and only about 6000 Churchills.

 

true but then the churchill had the best performence in normady out of all allied tanks.
And was just as capable at attacking bunkers if not more so.

 

It had the best statistics in terms of gun and armour, but Normandy, or "Bocage" as a terrain type is very different from pretty much any other campaign or area of the war. It suited slow speed and thick armour, which sums up the Churchill, which didn't perform quite as formidably in other environments or situations.

 

It's rather comical how your very own source states with all certainty that British BHN is impossible to determine with the sort of precision as other countries.

You are also ignoring the effect of the sloping on the Jumbos armor, effectively putting it at a higher shell resistance than the Churchill. We have determined that the Jumbo has a thicker superstructure than the Churchill.

Churchill 150mm plate at 0o = 150mm.

M4A3E2 100mm plate at 47o = 147mm.

They both have practically the same amount of armor that an incoming shell must penetrate. Now, if I may quote Greg Pitts:

Therefore, going by Richard M. Ogorkiewicz, the ballistic protection value created by the M4A3E2's slant effectively puts it at 191mm RHA protection. By your calculations, the Churchill is stuck at 188mm. This difference in thickness is doubtful to have much of an effect on performance of AT guns against these two vehicles, but the Sherman's slope will render it better protected since most attacks in a battlefield situation don't come straight on, meaning the Shells will have to face two axis of sloping. The shape of the Churchill means that an attack will come from an almost dead on angle, or hit the side armor.

 

taken from
WO 185/118, DDG/FV(D) Armour plate experiments
an offical ww2 war office file.

"The hardness of the plates
in the range 60–102mm was 257–310 Brinell which was essentially the same as that of British plates of
the same thickness."
Good enough?

 

its refering to the armour of the tiger tank. so british and german armour quality were essentialy the same. so my calculations are correct.

And again your ignoring the internal structures of the tanks. which is a factor.

And the thickness to diamater ratio.

Okay so i will conceed the sherman jumbo is possibly tougher than the churchill. but the effect of the slope is somewhat over stated.

http://wargaming.info/armour02.htm

check the site.

NOTES:

"This table shows the "real" angle of plate based on the firer's angle of attack in the horizontal plane. For example an M4 Sherman comes barrelling around a corner in the Bocage, and encounters a Tiger II. The King Tiger is 150 yards away, and the Sherman is off centre. Let us say the Sherman is at an angle of 40º from directly in front of the King Tiger. The Sherman is faced with a Tank that has front superstructure armour of 150mm, but it is at an angle of 50º, so its real horizontal plane thickness is 233mm. But because we are at a 40º angle the equivalent slope of the armour is 60½º giving an equivalent horizontal plane thickness of 304mm - Boy is that Sherman in trouble! Note how the angle has more than doubled the thickness of the Armour Plate!

This of course assumes both vehicles are on perfectly level ground, and does not take account of the actual angle of impact for the projectile (over 150 yards there should basically be no "dipping" of the projectile nose to alter the angle). This could easily increase the angle if the Target (the Tiger) is on marginally higher ground than the Firer (the Sherman)."

so if you attack a slope of 50 degrees at a40 degrees you get an angle of 60 degrees.

attack a plate at 5 degree's at 40 degrees you get an angle of 40 degree's.

slope multipler for 60 degree's is 2.5, so 100mm multipled by 2.5 equals 250mm.

188mm multipled fby 40 degree.s is 1.5 so is 282mm.

The churchill this way atleast is somewhat tougher.

So my calculations for britsh bhn may be out by 10% but then you still get about 255mm.

 

btw the thickness to diameter ratio is not to be confused with overmatching of the incoming projectile.
Its the ratio between a thickness of a plate and its width.
i.e a 100mm thick plate of 50mm width is less resistant than a 100mm plate of 100mm width.