Sloped Armour - isnt it obvious ?

[russellmz]

they sloped armor on merrimac/virginia class casement ships in the civil war.

[Bastables]

Originally posted by flamingknives:

Disagree the highly effective British composite armour due to it's properties tends to preclude slope armour (As did the PIII spaced armour), which is why we see slab/boxy armoured Leopard II, M1s and Challengers. The Soviet mania for sloping has meant less effective armour than the three NATO designs with internal space at a premium.

I strongly suspect that you mean curved and not sloped [/QB]

[Fly Pusher]

I was under the impression that the appearance of the T34 was a big shock to the Germans who had just finalised designs for the Tiger I (with essentially vertical armour). The replacement for the PzIV then on the drawing board was essentially scrapped and a new design (competition) started to design the 'answer' to the T34 - what eventually emerged as the Panther with (surprise !) sloped armour, followed thereafter by the Tiger II that also featured sloped protection.

Wouldnt this argue against the 'problems with production' school of thought and imply that the emergence of an effective enemy tank with sloped armour was essentially copied ? And if so this would imply that they didnt know about (or hadnt seriously considered) the merits of sloped metal so eloquently outlined by Rexford ?

Just a thought….

Edit: because I mixed up PzIV and VI

[ September 20, 2003, 05:38 AM: Message edited by: Fly Pusher ]

[Bastables]

Originally posted by Fly Pusher:

IWouldnt this argue against the 'problems with production' school of thought and imply that the emergence of an effective enemy tank with sloped armour was essentially copied ? And if so this would imply that they didnt know about (or hadnt seriously considered) the merits of sloped metal so eloquently outlined by Rexford ?

Just a thought?.

Edit: because I mixed up PzIV and VI

Not really as the decision to remain with "box" armour was a bureaucratic cost measure in the same vein of arming the PIII with the short 5cm gun. The appearance of the T-34 provided the impetus in actually installing the tooling and required machinery in factories to manufacture the Panther. If the concepts and engineering were not there the Panther would never have made it from drawing board to driving prototype in less than 11 months.

[ September 21, 2003, 05:18 AM: Message edited by: Bastables ]

[Bastables]

Originally posted by Fly Pusher:

I was under the impression that the appearance of the T34 was a big shock to the Germans who had just finalised designs for the Tiger I (with essentially vertical armour). The replacement for the PzIV then on the drawing board was essentially scrapped and a new design (competition) started to design the 'answer' to the T34 - what eventually emerged as the Panther with (surprise !) sloped armour, followed thereafter by the Tiger II that also featured sloped protection.

Edit: because I mixed up PzIV and VI

Disagree The torsion bar suspension with interleaved roadwheeled VK 20.01(M) that became the Panther began in 1940 with a almost 70 deg slope glacis plate and a PIV style driver plate at 10-20deg from the vertical. The Leaf sprung Krupp and DB drawings and mock ups show similar lines.

The appearance of the T-34 meant that the glacis-driver front plate was dropped in favour of just a single glacis plate at 55 deg in the VK 20.02(M). Then the VK20 project was cancelled and a new competition was created, the VK 30, the MAN entrant merely being an up-scaled version of their VL 20.02.

The VK 30 resulted the much loved myth of the superior DB T-34 Panther

The idea that a T34 copy would lead to mistaken identification on the battlefield was a minor strike against the eventual DB Panther, if at all. At this point, November 1941 MAN had been brought in by Wa Pruef 6 (to the VK30 project) to attempt to get somebody designing a chassis with interleaved torsion bar suspension. DB initially won the competition with

backdoor politics in discussions with the then Reich armament minister Dr Todt.

Dr Todt was killed in a plane crash in 1942 and was replaced by Albert Speer. The new Reich Minster while giving an inital order for the 200 DB T-34/Panthers instituted a Panzerkommission under IN 6 to take another look at the two proposals. The MAN Panther was unanimously chosen because DB turret design was still not evident and had a smaller turret ring by 50mm. The interleaved suspension of the MAN Panther gave a better ride, higher actual cross-country speeds and provided a better gun platform. Hitler endorsed the MAN design and that?s why the MAN Panther defeated the DB T-34/Panther, it was the better AFV.

The T-34 design patent was still a break through/cavalry veh in the same manner of the Sherman= armour heavy enough to deflect infantry anti tank guns and speed to exploit the break through. The Panther was designed to kill other tanks first and foremost. Guderian never references the T-34 in his speech to the Pz commission that resulted in the Panther. But interestingly he notes the need to beat Russian heavy tanks, 44 to 52 metric tons and describing armour and armament of the KV-I with appliqué (vertical) armour.

[ September 20, 2003, 07:06 AM: Message edited by: Bastables ]

[Bastables]

Originally posted by Fly Pusher:

I was under the impression that the appearance of the T34 was a big shock to the Germans who had just finalised designs for the Tiger I (with essentially vertical armour).

No the VK 45.05(H) (Tiger) was part of the project to counter the Matilda and Char B met in France 1940. The VK45.05 was it self just up scaling of the VK 36 project initiated in 1937, meaning it was just a green lighting of a Pz first conceptualised at the same time as the PIV and PIII with the same engineering restrictions.

[rexford]

Redid the calculations, summarized results.

80mm/55 degrees with 0.915m height and 3m width uses 0.442 cubic meters of steel

202mm vertical with same height and width plus 20mm hull top plate at 20mm uses 0.638 cubic meters.

Above analysis does not include side plates, where sloped armor uses 50% less side armor within nose area.

Trade-off is 50% less internal volume with 80mm/55 degrees within nose area compared to 202mm vertical.

[flamingknives]

Nope I've been using slope and curved to refer to none "boxy" vertical armoured tanks.

*blink* *blink*

Have you not seen a Challenger? the Glacis and turret front are far more sloped that those seen on Soviet tanks.

Chobham armour (composite used on Challenger and Abrams) can't be cast, meaning that the tank cannot be constructed with the smooth, curved shapes that typify the Chieftain, M60 and Conqueror.

Leopard 2A5 and 2A6 models have very heavily sloped turret fronts, and even the Abrams has 20-30 degrees of slope on the turret. All have significant slope on the glacis, with slightly less on the lower hull, as they are intended to fight hull-down.

The only places where Soviet tanks have better slope is turret sides and rear and possibly lower hull.

[Siege]

I really have to disagree that the British didn't know about the concept of sloped armor early in the war. What they thought of it's effectiveness is a different story. It seems that the lighter tanks used initially in the war made use of various levels of sloped armor, but the more heavily armored tanks seemed more dependant on sheer thickness.

If you look at a most of the cruiser tanks prior to the Cromwell, you see increased usage of sloped armor as time goes on. Just look at the turrets of the Crusaders! The Mark VI light tank is almost entirely dependant on it's slope for what little protection it had. Even the Valentines and Matilda II's had a sloped front hull as well as in other areas as the design permitted.

While not as elegant made, or as widespread as the usage by tanks like the Panther or T-34, it was something the Brits employed to an extent. In fact it more seems the Brits seemed to gravite TO vertical plate as German AT firepower increased. Perhaps the design philospy was more aimed at thickness of the armor and gun size, with the shape and angle of the armor as a secondary concern.

-Hans (Siege)

[Bastables]

Originally posted by Siege:

I really have to disagree that the British didn't know about the concept of sloped armor early in the war. What they thought of it's effectiveness is a different story. It seems that the lighter tanks used initially in the war made use of various levels of sloped armor, but the more heavily armored tanks seemed more dependant on sheer thickness.

I-Hans (Siege)

Yes you're quite right, even the vickers mediums had sloped glacis of 60 degs in the 1920-30.

[Bastables]

Originally posted by flamingknives:

</font><blockquote>quote:</font><hr /> Nope I've been using slope and curved to refer to none "boxy" vertical armoured tanks.

*blink* *blink*

Have you not seen a Challenger? the Glacis and turret front are far more sloped that those seen on Soviet tanks.

Chobham armour (composite used on Challenger and Abrams) can't be cast, meaning that the tank cannot be constructed with the smooth, curved shapes that typify the Chieftain, M60 and Conqueror.

Leopard 2A5 and 2A6 models have very heavily sloped turret fronts, and even the Abrams has 20-30 degrees of slope on the turret. All have significant slope on the glacis, with slightly less on the lower hull, as they are intended to fight hull-down.

The only places where Soviet tanks have better slope is turret sides and rear and possibly lower hull. </font>

[Other Means]

Bastables:

Not really as the decision to remain with "box" armour was a bureaucratic cost measure in the same vein of arming the PIII with the short 5cm gun.

i thought that was as a result of mis-reading the AAR's from france, where the long & short gun were both carried? initially it appeared that the short 5cm had a better kill ratio. however later this was found to be an error in reading the battlefield reports & was rectified to the longer gun?

[Bastables]

Originally posted by Other Means:

</font><blockquote>quote:</font><hr />

Bastables:

Not really as the decision to remain with "box" armour was a bureaucratic cost measure in the same vein of arming the PIII with the short 5cm gun.

i thought that was as a result of mis-reading the AAR's from france, where the long & short gun were both carried? initially it appeared that the short 5cm had a better kill ratio. however later this was found to be an error in reading the battlefield reports & was rectified to the longer gun? </font>

[Other Means]

yeah but my mate down the pub said...

obviously i bow to your knowledge & acknowledge you grog.

[Guest Mike]

I always thought the "technological" problems the Brits had with tank design were in manufacturing and design capability rather than in what they could put into a tank itself.

So they hadn't tried sloped armour much pre-war, and hence didnt' have the required design training, performance formulae, etc for it.

Also their designs seem to have been riveted for longer than many other nations, so perhaps they weer a bit behind in welding technology - which is a must have for sloped armour.

[Bastables]

Originally posted by Mike:

Also their designs seem to have been riveted for longer than many other nations, so perhaps they weer a bit behind in welding technology - which is a must have for sloped armour.

Sort of, 1920 riveted British tank designs such as the Vickers medium still had sloped glacis of 50 to 60 deg. Christies the first to conceptualise and manufacture slope armour did so with riveting in the year 1917.

The German designers were faced with using more limited shaping capabilities of welded armour (with better protection) until the 1940s or reverting to riveting armour on to "skeletons" with the loss of protection and inefficient protection (errr inefficent production) and weight that that entails.

[ September 23, 2003, 05:30 PM: Message edited by: Bastables ]

[Bastables]

Originally posted by Other Means:

yeah but my mate down the pub said...

obviously i bow to your knowledge & acknowledge you grog.

Tell uncle Sena after you've put the boot in.

[Spent Case]

In addition to all the reasons listed here, the main reason that the British army didn't use sloped armor was that in their mind, the sloping was relative. That is, if a friendly tank was moving down a hill, it would then be more vulnerable to an incoming shot or shell. Since tanks would be in all sorts of positions and angles, why bother sloping it at all.

It does smack of putting one's head in the sand and trying to ignore all the details.

If anyone cares, I can try to find where I read this. It might have been in one of Ian Hogg's books.

SC

[Mr. Tittles]

Originally posted by rexford:

One of the advantages of sloped armor is the slope effect, where the effective resistance is much greater than the horizontal distance that must be pierced.

IMPORTANT NOTE

Projectiles do NOT penetrate sloped armor by moving through it horizontally. The first reaction during penetration is a tendency of the round to rotate nose up and start to ricochet. While the rotation is going on a plug is formed which starts to be driven out. The projectile then changes direction suddenly and pierces the plate going DOWNWARD, with the nose bouncing against the hole and it moves thru.

There is alot going on and that is why 80mm/55 degrees resists like 202mm vertical instead fo 139.5mm vertical.

I have seen quick action photos that demonstrate this. Thye may be somewhere on the Panzer Elite website.

Reports I have read state that T34s were hard to 'burn' from shooting at them from the front. This supports the 'ricochet' down effect. I have also read reports of shermans getting holed from the front and the entering shell scooting down and sticking somewhere under the floor boards.

I would imagine the following might be true:

a AP gun firing at 45 degree armor and failing to penetrate would likely ricochet strait up. As the gun moves closer to the armor, the shell would gouge more armor and have a tendency to not go strait up but at a decreasing angle. At the range that the AP shot just manages penetration with remaining energy, it takes the path of least resistance and ricochets downward (maybe at 90 degrees through the plate it just came through).

This is bad news for drivers/bow mgers. Good news for turret men.

I wonder if lower hulls like the panther would actually ricochet the shot upward? This would make a bad situation worse since that armor was thin.

I wonder what effect, if any, the rotation energy of these AP rounds have on penetration/ricocheting. They actually spin quite fast. A simple physics fact is that a rotating body does not like a change of direction (gyro).

[PJungnitsch]

I'd hold with the manufacturing issue of building and welding together large slabs of heavy armour plate. The one undisputed area in which 'stepped' glacis designs like the Tiger or Churchill have an advantage is that they can be made up with relatively short pieces of plate, while a Panther or Centurion must use one that is very long.

Light armour was always much easier to work with and so light tank and half track designs had large areas of sloping plate much earlier.

Once the manufacturing and welding process caught up a sloped Panther-type hull is a very simple design, no double part of the reason the Panther was so cheap to build.

[Guest Mike]

Originally posted by Paul Jungnitsch:

Light armour was always much easier to work with and so light tank and half track designs had large areas of sloping plate much earlier.

Yeah - this is what I meant - I should have said welding was required for reasonably thick sloped armour - lots of pre-war tanks had slopes of some degree or other, but the armour was only proof vs small arms.

[Mr. Tittles]

http://www.battlefield.ru/guns/defin_2.html

this shows a nice animation and some math also. I dont agree with the animation exactly. I would claim that the change of direction happens AFTER the AP penetrator is inside the sloped armor. I have seen photos that actually show this on a sloped piece of test armor.

[ September 24, 2003, 03:38 PM: Message edited by: Mr. Tittles ]