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M-47/ M-48


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#21 Doug Kibbey

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Posted 13 October 2012 - 0009 AM

Take the M48 turret, move the ventilator to the other side, change the cupola, call it an M60 turret. Two years later say, aw fuck, that needle nose shape we used on the M41 and M47 just might have had something to it.


And the M60A1/A3 turrets have significantly thicker armor at the front and on the sides. This shape is a compromise on both the internal volume requirement and the minimal weight requirement.

You can have a more ideal shape, or a more capacious turret, or less armor. But can't have all three if you have a weight requirement to meet.

I use (and have been in the position that it wasn't hypothetical) this system: if I have to go to war tomorrow with the following selection of tanks, what would I choose? I'd choose first the M60A3/A1 (at the time, the A3 hadn't been thunk of yet), then and M60, then and M48, then an M47, because from top to bottom, that's where this guy thinks his best chances of survival lay.
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#22 DKTanker

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Posted 13 October 2012 - 0032 AM

And the M60A1/A3 turrets have significantly thicker armor at the front and on the sides. This shape is a compromise on both the internal volume requirement and the minimal weight requirement.

You can have a more ideal shape, or a more capacious turret, or less armor. But can't have all three if you have a weight requirement to meet.

His original question was why not the M60A1 style turret from the beginning? It is historically self-evident that the designers of the day did believe the longer turret with the smaller frontal aspect did provide the best compromise. We see that first with the M41 (ignore the M26 which predated the M41, and ignore the M46 because it was an emergency lash up), then with the M47. Then inexplicably the turret shape changed for the M48 (the M60 was another emergency design to quickly get a 105mm fielded), and then the M60A1.

Bojan's question was, and remains, a quite valid one. I agree with you that it offered more volume for a given weight of armor. I disagree that the shape was believed the best possible ballistic design for fighting other tanks, rather (scratching what I thought about casting ability) it was believed the best design shape and compromise to survive on the nuclear battlefied.
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#23 Doug Kibbey

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Posted 13 October 2012 - 0118 AM


And the M60A1/A3 turrets have significantly thicker armor at the front and on the sides. This shape is a compromise on both the internal volume requirement and the minimal weight requirement.

You can have a more ideal shape, or a more capacious turret, or less armor. But can't have all three if you have a weight requirement to meet.

His original question was why not the M60A1 style turret from the beginning? It is historically self-evident that the designers of the day did believe the longer turret with the smaller frontal aspect did provide the best compromise. We see that first with the M41 (ignore the M26 which predated the M41, and ignore the M46 because it was an emergency lash up), then with the M47. Then inexplicably the turret shape changed for the M48 (the M60 was another emergency design to quickly get a 105mm fielded), and then the M60A1.

Bojan's question was, and remains, a quite valid one. I agree with you that it offered more volume for a given weight of armor. I disagree that the shape was believed the best possible ballistic design for fighting other tanks, rather (scratching what I thought about casting ability) it was believed the best design shape and compromise to survive on the nuclear battlefied.

Nor did I say that the shape was the best possible ballistic design. What I'm pointing out is that the "users' had three requirements, and that the hemisphere shape best met those requirements. In fact, given the specifications, no other shape would have been geometrically possible, it would have drawn itself with the requirements input. Geometry dictates that the most efficient shape (least surface area) into which a given volume will fit is a sphere. Since half (or more) of the contents of the turrent are in the hull, we are speaking of a hemisphere, or a fraction thereof. Have a look at the turrets of virtually all the Russian designs after the T34/85....(not KV and such, but the T54/55/62/72). All of them are sections sliced off of a sphere. Oh, there are subtle distortions to the shape, but the effect is a sectioned sphere....that's just math and geometry at work dictating the most efficient shape for a given volume. Happily, it also gives you an acceptable, if not ideal, ballistic shape. Anything else cannot help but intrude into the fighting space of the turret. The M48 design was the best that could achieve the priorities stated in the requirements. Additionally, I suspect that trying to cast compound shapes into a single casting is either much more difficult or cannot be done. I love the lines of the M41, too, but notice how many welds it has. The objective was a large, well armored turret cast in one piece (Bojan does not seem to consider welds as participants in structural integrity/ballistic goodness. Well, they are. The M48 turret was intened to be of one piece with no structural welds, which makes it stronger. (hatches, mantlets, infantry rails, etc. are hardly part of the main structure). Every joint is a weak spot and the M48 has fewer of them than other designs of the era since it is of one piece.

I'd like to see figures for the internal volume of an M60 turret vs an M60A1 turret. My suspicion is that the volume will be less (unless the turret was stretched to compensate, which I think it was) in the A1 because it was later determined that the width provided for on the m48 turned out no longer to be as critical as expected when it was designed....but that's hindsight and has nothing to do with why one should have preceded the other.

I'm having severe sinus problems right now and looking at the screen does not help. I may draw a picture tomorrow and post so it is more easily scene what the introduction of a narrowed, planar surface does to a sectioned spherical shape.

Edited by Doug Kibbey, 13 October 2012 - 0121 AM.

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#24 RETAC21

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Posted 13 October 2012 - 0233 AM


Did any of the European countries that got M47s investigate the possibility of upgunning them to the 105mm L7?


Spain did an upgrade to a 105mm on some of theirs.


And it was not very successful, it being too cramped.
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#25 Gavin-Phillips

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Posted 13 October 2012 - 0612 AM

I vaguely recall seeing a picture of a German-designed upgrade for the M47, including the mounting of a 105mm gun (possibly L7/M68, not sure) and the relocation of the driver to the centre of the hull, removal of 5th crewman & glacis MG position. Never heard anything about it being produced so I assume it was only a prototype?

With 8500+ of them produced, that's not bad for an interim vehicle really. Is there a total figure for all M48's built?
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#26 urbanoid

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Posted 13 October 2012 - 0617 AM



Did any of the European countries that got M47s investigate the possibility of upgunning them to the 105mm L7?


Spain did an upgrade to a 105mm on some of theirs.


And it was not very successful, it being too cramped.


Were they L7s or its derivatives or the French 105s, as in the AMX-30?
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#27 shep854

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Posted 13 October 2012 - 0754 AM

How much consideration was given to crew ergonomics (if the term was even in use back then) in these turret designs?
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#28 Old Tanker

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Posted 13 October 2012 - 0807 AM

I vaguely recall seeing a picture of a German-designed upgrade for the M47, including the mounting of a 105mm gun (possibly L7/M68, not sure) and the relocation of the driver to the centre of the hull, removal of 5th crewman & glacis MG position. Never heard anything about it being produced so I assume it was only a prototype?

With 8500+ of them produced, that's not bad for an interim vehicle really. Is there a total figure for all M48's built?


I tried to nail down M-48 production and came up with approx. 10,000 .
The only count that should matter is M-48, M-48A1 and M-48A2 everything else after the A2 was an upgrade. The M-48 production was only 200. I estimate the production run ( new hulls) was in the 85 month range .
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#29 Gorka L. Martinez-Mezo

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Posted 13 October 2012 - 1210 PM




Did any of the European countries that got M47s investigate the possibility of upgunning them to the 105mm L7?


Spain did an upgrade to a 105mm on some of theirs.


And it was not very successful, it being too cramped.


Were they L7s or its derivatives or the French 105s, as in the AMX-30?

The guns were German Rh-105, with the same ballistic properties as the L7/M68. The turret design was quite cramped, even when armed with the smaller 90mm gun. Both the M48 and AMX-30 had more internal volume and better ergonomics.

There were several upgunning proposals for the M47, the most curious one including a DEFA CN-105 gun as fitted to the AMX-30. Several companies proposed heaily upgraded M47s including GIAT, OTO-Melara, a German consortium and, of course, BMY, the designers of the M47M whose basic project was used by Iran and Spain,
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#30 thalb2000

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Posted 13 October 2012 - 1639 PM

How much consideration was given to crew ergonomics (if the term was even in use back then) in these turret designs?


The term was not invented yet. The concept behind it was well understood, however.
American tanks were considered superior to their foreign counterparts in this respect from the 1940 onwards. The most useful are the accounts of foreigners: The British left their own tanks behind and went on to win the war with American Sherman;, those Soviet tankers having the opportunity to choose between the T-34 or the M-4 generally called the Sherman the better machine.
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#31 Hittite Under The Bridge

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Posted 13 October 2012 - 1640 PM

The M60A2 had the ultimate in narrow turrets and look what became of that.


Hunchbacked loaders?

Edited by Hittite Under The Bridge, 13 October 2012 - 1645 PM.

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#32 shep854

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Posted 13 October 2012 - 1702 PM


How much consideration was given to crew ergonomics (if the term was even in use back then) in these turret designs?


The term was not invented yet. The concept behind it was well understood, however.
American tanks were considered superior to their foreign counterparts in this respect from the 1940 onwards. The most useful are the accounts of foreigners: The British left their own tanks behind and went on to win the war with American Sherman;, those Soviet tankers having the opportunity to choose between the T-34 or the M-4 generally called the Sherman the better machine.

Wouldn't it be neat if the 'experts' on the History/Military channels read some of those memoirs?
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#33 urbanoid

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Posted 13 October 2012 - 1704 PM





Did any of the European countries that got M47s investigate the possibility of upgunning them to the 105mm L7?


Spain did an upgrade to a 105mm on some of theirs.


And it was not very successful, it being too cramped.


Were they L7s or its derivatives or the French 105s, as in the AMX-30?

The guns were German Rh-105, with the same ballistic properties as the L7/M68. The turret design was quite cramped, even when armed with the smaller 90mm gun. Both the M48 and AMX-30 had more internal volume and better ergonomics.

There were several upgunning proposals for the M47, the most curious one including a DEFA CN-105 gun as fitted to the AMX-30. Several companies proposed heaily upgraded M47s including GIAT, OTO-Melara, a German consortium and, of course, BMY, the designers of the M47M whose basic project was used by Iran and Spain,


Thanks, I just wondered if it wasn't the French CN-105 like some of the French M47s had, as Spain operated AMX-30s with the same gun at the time.
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#34 bojan

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Posted 13 October 2012 - 1737 PM

...those Soviet tankers having the opportunity to choose between the T-34 or the M-4 generally called the Sherman the better machine.


Some did, some did not. Really, both T-34/85 and Sherman are quite cramped and not really up the "modern ergonomic standards". Wartime production wise Sherman was slightly more comfortable but some of users did not like existance of turret basket. Compared to both T-55 feels like a house.
On the other hand they were better then Pz-III or IV - how the hell they managed to fit 5 men in Pz-IV or Pz-III?

Edited by bojan, 13 October 2012 - 1738 PM.

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#35 DKTanker

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Posted 13 October 2012 - 1743 PM

On the other hand they were better then Pz-III or IV - how the hell they managed to fit 5 men in Pz-IV or Pz-III?

I guess the same way the M24 managed to fit five, slather the crew with lard then stuff them in the hatches.
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#36 Mikel2

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Posted 13 October 2012 - 1938 PM


On the other hand they were better then Pz-III or IV - how the hell they managed to fit 5 men in Pz-IV or Pz-III?

I guess the same way the M24 managed to fit five, slather the crew with lard then stuff them in the hatches.


I guess the yoots of 1944 were quite a bit smaller than today's...
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#37 Lieste

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Posted 13 October 2012 - 2002 PM

The British didn't exactly discard home developed equipment. Cromwell, Challenger, Comet, Churchill and a number of other types were operated alongside M4 units.

Centurion was one of the more successful British wartime designs, and was built in some numbers and saw some active use in the post war world ;)
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#38 Archie Pellagio

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Posted 13 October 2012 - 2201 PM

Centurion was one of the more successful British wartime designs, and was built in some numbers and saw some active use in the post war world ;)


Have you got a source for that?

:P


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#39 DKTanker

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Posted 13 October 2012 - 2212 PM


Centurion was one of the more successful British wartime designs, and was built in some numbers and saw some active use in the post war world ;)


Have you got a source for that?

:P

He means Korean War. Right? :huh:
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#40 shep854

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Posted 13 October 2012 - 2224 PM

"...active use..." The Beatles also used a few as movie props.

Edited by shep854, 13 October 2012 - 2225 PM.

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