Why no WW2 tanks with ammo in bustle?

Today's MBTs generally store the main gun ammunition in the turret bustle that overhangs the rear hull. Two benefits are that the ammunition is easily accessed in all aspects of turret rotation (vs. ammo located throughout hull, under the basket, beside driver, in the sponsons, etc.) thus improving ROF; and that blow out panels on the bustle roof combined with a blast resistant access door for the loader can enable the crew to survive a main magazine explosion.

Why wasn't this done, at least for the first reason, with WW2 tanks? Sure some tanks had a few ready rounds in the bustle, but I'm referring to ALL the rounds in the bustle, behind a blast door.
 
Pre-war doctrine held that ammo stored in the turret basket or under the floor was less likely to get hit by incoming rounds. After WW2, British Operations Analysts concluded that ammo fires wrecked hundreds of tanks, more than fuel fires.

Turret weight was a major factor since early war turrets only had manual traverse (e.g. most German tanks) which was slow at engaging new targets in close combat.

By late war, Sherman etc. had hydraulic traverse which allowed heavier turrets to traverse rapidly.

Not many WW2 tanks had bustles. The only Shermans with bustles were Fireflies which housed radios in their bustles. The welded on bustle helped balance the weight of the longer 17 pounder gun. Keep balance in mind when increasing turret weight.

Large turret bustles also make the tank more visible when it tries to hide in a hull-down defensive position.

In the end, every tank is a compromise between mobility, armour, armament, communications, ease of maintenance and cost of manufacture.
 
Today's MBTs generally store the main gun ammunition in the turret bustle that overhangs the rear hull. Two benefits are that the ammunition is easily accessed in all aspects of turret rotation (vs. ammo located throughout hull, under the basket, beside driver, in the sponsons, etc.) thus improving ROF; and that blow out panels on the bustle roof combined with a blast resistant access door for the loader can enable the crew to survive a main magazine explosion.

Why wasn't this done, at least for the first reason, with WW2 tanks? Sure some tanks had a few ready rounds in the bustle, but I'm referring to ALL the rounds in the bustle, behind a blast door.

When you say most tanks - you mean American tanks - because modern British and Russian tanks have their ammo below the turret ring

I think only the Abrams keeps all 40 rounds in the rear of the turret - I know that the Leo2 keeps some in the hull with some ready use rounds to hand in the turret but I'm not as familiar with that design

But to your question - WW2 tanks generally started (1930s designs) with small turrets with a small gun and the ammo was kept in the hull due to space issues.

Also although turrets got bigger, the number of people in the turret went from 1 or 2 to 3 and the guns got bigger and so did the ammo - for example the 76.2mm shells for the Firefly's 17 pounder were twice as long with much larger diameter cases than the standard 75mm Sherman gun - and on the Firefly they had to remove a crew member (bow gunner/RTO) in order to find somewhere to keep the shells (in this case to the right of the Driver - who sits on the left) and moved the radio into a 'bustle' on the rear of the turret - as their was simply no room left inside!
 
When you say most tanks - you mean American tanks - because modern British and Russian tanks have their ammo below the turret ring

I thought C2 had the ammo in the bustle as well. But perhaps only a portion is in the bustle?

challenger2_interiordetail.jpg


As for Russian tanks, I imagine the autoloading system requires the ammunition to be stored around the basket, like the T-72 cutaway below.

t72-109_zps5a660ed4.jpg


But regardless, I didn't mean to suggest that ALL modern tanks have all their ammunition in the bustle, so I'll clarify that now.
 

hipper

Banned
I thought C2 had the ammo in the bustle as well. But perhaps only a portion is in the bustle?

challenger2_interiordetail.jpg


As for Russian tanks, I imagine the autoloading system requires the ammunition to be stored around the basket, like the T-72 cutaway below.

t72-109_zps5a660ed4.jpg


But regardless, I didn't mean to suggest that ALL modern tanks have all their ammunition in the bustle, so I'll clarify that now.

the C2 stores shells in the turret bustle, the propellant is stored below the turret ring.
 
the C2 stores shells in the turret bustle, the propellant is stored below the turret ring.
Thanks, good info.

I wonder where the one-piece ammunition for the C2 upgrade to the Rheinmetall 120 mm gun will be stored? Presumably they'll use both the bustle and the prior turret ring space.

The upgrade seems a waste of money really. Better to buy Leo IIs, since the Abrams and C2 are no longer in production. Outside of the Leo II are there any western MBTs in production? Japan's Type 10 is still produced (but not available for export), and I believe Leclerc and Ariete are out of production.
 
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Thanks, good info.

I wonder where the one-piece ammunition for the C2 upgrade to the Rheinmetall 120 mm gun will be stored? Presumably they'll use both the bustle and the prior turret ring space.

It won't be, there's no money for the upgrade and the designers apparently managed to fit a grand total of six shells into the CR2. The only things that will happen with the CR2 now (at the very most) are desperately trying to stave of obsolescence in the sights and electronics until we finally bow to the inevitable and buy some M1 or Leo3 (whatever the new German/French tank will be called) in the mid-2020s (if someone at the MOD finds something down the back of the sofa).
 
Getting back to WW2 tank design, if we get powered traverse, something like the below seems possible.

ac9de58a8053073fe03f7cdd147472c8.jpg


The Panzer III below looks ideally suited. Take that tool box off the back and extend the turret.

pz3cutaway.jpg
 

thorr97

Banned
Just as a point here...

All the major tanks of WWII already had powered traverse on their turrets. Manual traverse was intended solely as a backup for when the power mechanism was unavailable - it broke or was damaged in combat. Late war German tanks did dispense with powered traverse as their supply situation was so dire. But, in general, for all but the smallest and lightest of turrets on tanks, powered traverse was the rule.
 
Looking at this loading of a Panther Schmalturm one has to think a bustle would have been good for improved loading. putting the magazine in the bustle would have enabled the loader to more easily service the gun. Though presumably the shells would still be pulled out base first.

2gv1t87.jpg


26.jpg
 
Yet they were used as Tanks. Note added armor in top photo.

What added armour the aplique armour bosses were never used as far as I know. Unless you mean the overhead plating which was not in any way shape or form armour it was to keep the rain out and protect the crew from Shell/Mortar splinters. I dont even know if it was fitted in WWII the only action photos I have seen of M36s with it fitted are Korean or Yugoslavian Civil War.
 
What added armour the aplique armour bosses were never used as far as I know. Unless you mean the overhead plating which was not in any way shape or form armour it was to keep the rain out and protect the crew from Shell/Mortar splinters. I dont even know if it was fitted in WWII the only action photos I have seen of M36s with it fitted are Korean or Yugoslavian Civil War.

Field mods done in 1945, later official.

TM 9-745 90-mm Gun Motor Carriage M36B2, dated July 28, 1945 https://archive.org/details/TM9-745
 
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