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Inside the Chieftain's Hatch: IS-7


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Daigensui #21 Posted Dec 10 2014 - 17:42

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View Postcollimatrix, on Dec 10 2014 - 08:35, said:

IS-7 in game has massively ahistorical gun depression for some reason.  IRL it was -3, in game it's -6.  DAV mentions that one of the prototypes had a mere 1.5 degrees.

 

Most uncomfortable.

 

Let me get the scalpels and chainsaws.....

mortuus82 #22 Posted Dec 10 2014 - 22:32

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i doubt this tank would bounce a 12.8cm cannon gun in real life..

Daigensui #23 Posted Dec 10 2014 - 22:43

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View Postmortuus82, on Dec 10 2014 - 13:32, said:

i doubt this tank would bounce a 12.8cm cannon gun in real life..

 

And the basis for your assumption is?

favrepeoria #24 Posted Dec 11 2014 - 01:23

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View Postmortuus82, on Dec 10 2014 - 15:32, said:

i doubt this tank would bounce a 12.8cm cannon gun in real life..
 

They specified the 12.8cm gun on the jagdtiger. It is a matter of comparison. They wanted that to be frontally protected from it(pak 44 L55). And also notice that they specified a distance at which it should be protected from this so it all depends on what the requirements that are specified. I mean I could make some ridiculous specification saying that the armor should be enough that an Abrams kinetic penetrator would fail. But I put in stipulation at 10 miles or something stupid like that and it is entirely possible because effective range is less than that in this case probably. 

 

TLDR: make sure you look at requirements before making a statement or any part for that matter cause over engineering something is just as bad as under engineering it



EnsignExpendable #25 Posted Dec 11 2014 - 01:40

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There's no such thing as "over engineering" or "under engineering". Something either meets requirements or it doesn't. The ability to withstand shots from your own gun at 1000 meters is a very common requirement for Soviet tanks, which the IS-7 met. You could argue that in the IS-7's case that was overkill, but that's a problem with requirements gathering, not with engineering.

Dominatus #26 Posted Dec 11 2014 - 01:47

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I'm fairly sure that nothing at the time short of a 120mm HEAT round could penetrate the IS-7. 128mm AP wouldn't do anything against it.

Edited by Dominatus, Dec 11 2014 - 02:11.


Blackhorse_Six_ #27 Posted Dec 11 2014 - 01:59

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View PostDaigensui, on Dec 10 2014 - 11:42, said:

Let me get the scalpels and chainsaws.....

 

Oh, we like an adventurous girl ...



Walter_Sobchak #28 Posted Dec 11 2014 - 08:22

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View PostDominatus, on Dec 10 2014 - 19:47, said:

I'm fairly sure that nothing at the time short of a 120mm HEAT round could penetrate the IS-7. 128mm AP wouldn't do anything against it.

 

Was 12.8 cm AP really all that much better than 8.8 cm L/71 in terms of penetration?

Daigensui #29 Posted Dec 11 2014 - 08:36

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View PostWalter_Sobchak, on Dec 10 2014 - 23:22, said:

 

Was 12.8 cm AP really all that much better than 8.8 cm L/71 in terms of penetration?

 

Posted Image

 

Quite a bit, it was 200 mm against 30 degrees (230 mm against vertical) at 1,000 meters, so it had slighter better penetration than the 130 mm S-70 after factoring in a 93% modifier to match Soviet standards.



Legiondude #30 Posted Dec 11 2014 - 08:38

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Well German Steel Armor Piercing Projectiles and Theory of Penetration has a graph which places the 8.8 L/71 at point blank penetrating around 190mm penetration at what appears to be a 30 degree offset. At the same range the 12.8cm strikes 225 and 255 ish

 

The pen table at the back of Encyclopedia of German Tanks of WWII rates the L/71 at the familiar 203mm at 100m and 30 degrees, but has dubious stats for the 12.8's rounds at 189 and 187mm(K40 L/61 curiously rated at 201mm)

 

WWII Ballistics and Gunnery rates the 88 L/71 with standard ammo at 232mm at 100m, while the 12.8cm strikes between 264 and 282mm depending on APC or APCBC

 

EDIT - Right, duh, 1000 meters

 

Nevermind then


Edited by Legiondude, Dec 11 2014 - 08:39.


mattwong #31 Posted Dec 11 2014 - 09:05

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View PostLegiondude, on Dec 11 2014 - 02:38, said:

WWII Ballistics and Gunnery rates the 88 L/71 with standard ammo at 232mm at 100m, while the 12.8cm strikes between 264 and 282mm depending on APC or APCBC

 

EDIT - Right, duh, 1000 meters

 

Nevermind then

 

Even without the range, 150mm at a 65 degree angle is an effective armour thickness of roughly 355mm.  So ... not a chance.

collimatrix #32 Posted Dec 11 2014 - 22:23

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It's 355mm LOS.  Against AP and APDS shells of the era, it's better than that because those types of projectile performed extra poorly against sloped armor.

 

IS-7 was insanely well armored.  120mm HEAT might have worked, but the fuzing might be iffy on that slope.

 

IS-7's frontal immunity against its own gun and the 128mm was confirmed in live-fire testing according to tanks expert Bojan.



Mother_Goose_ #33 Posted Dec 12 2014 - 01:49

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*shouts down hatch* Hows it like in there cheiftan! XD I would LOVE to see an IS-7, its an amazing vehicle. The top tanks I would want to see at kubinka are Maus, IS-7, SU-100Y, and Karl gerrat

LeuCeaMia #34 Posted Dec 12 2014 - 08:51

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View Postcollimatrix, on Dec 12 2014 - 05:23, said:

It's 355mm LOS.  Against AP and APDS shells of the era, it's better than that because those types of projectile performed extra poorly against sloped armor.

 

IS-7 was insanely well armored.  120mm HEAT might have worked, but the fuzing might be iffy on that slope.

 

IS-7's frontal immunity against its own gun and the 128mm was confirmed in live-fire testing according to tanks expert Bojan.

 

Well using the "WWII Ballistics: Armor and Gunnery" slope equation, 150 mm at 65 degrees is 633.43 mm effective against 12.8 cm APCBC.



collimatrix #35 Posted Dec 13 2014 - 03:10

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Great find; that jives with other material I've seen.

 

Contrary to what WoT shows, HEAT was a major improvement vs. sloped armor compared to APDS.



Legiondude #36 Posted Dec 13 2014 - 05:13

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View Postcollimatrix, on Dec 12 2014 - 20:10, said:

Great find; that jives with other material I've seen.

It reads like a textbook, but I can provide a DL link since it's out of print if you want it



kenhk117 #37 Posted Dec 15 2014 - 16:48

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"In the spirit of more dakka" That made my day. LOL

collimatrix #38 Posted Dec 16 2014 - 01:46

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View PostLegiondude, on Dec 13 2014 - 05:13, said:

It reads like a textbook, but I can provide a DL link since it's out of print if you want it

 

Thanks; I already have it sitting on my HD somewhere.

Shanzival #39 Posted Dec 16 2014 - 19:03

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View Postcollimatrix, on Dec 12 2014 - 21:10, said:

Great find; that jives with other material I've seen.

 

Contrary to what WoT shows, HEAT was a major improvement vs. sloped armor compared to APDS.

 

It certainly was and a reason why you saw a lot of the 'Speed > Armor' designs of the post-war period. HEAT became a lot better and AP rounds were slow to catch up.

Content_WG #40 Posted Dec 23 2014 - 20:31

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Check out the video and see what it's like inside the Soviet IS-7!

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