ISU 152 vs. ISU 120

[desertrat1943]

Dear Uber-grogs,

Looking at the stats of the ISU-152 and the ISU 120 I happened to notice that armor-penetration figures for the 120 are better than those for the 152. However, in reality the ISU-152 was far superior to the ISU-120 in armor killing (wasn't the 152 nicknamed the "animals killer" or something?). Besides, logic dictates that a 152mm should have a punch greater than a 120mm using the same kind of rounds, right?

I did not run tests in CMBB to see whether the 120 busts more tanks than the 152 but, again, from the stats it seems to me that there is someting wrong here.

[Ari Maenpaa]

Well it was the SU-152 which was called Zvierboy, the animal hunter. IMHO the name didn't come because the SU-152 was particularly efficient Tiger/Panther killer, but because it was broadly taken the only Soviet vehicle which could do it frontally at the time. SU-152's (or ISU-152's) slowish muzzle velocity and two-piece, slow to load ammunition, tell about something else than superior AT-capability.

Ari

[Shosties]

Take a close look at the pictures of the ISU-122 and the ISU-152. Notice anything? The gun barrel of the 122mm L/? A-19 and ML-20S cannon the ISU-122/ISU-122S sports is much longer than the barrel of the 152mm L/? D-25S. Longer barrel = more working distance for the expanding gasses of the burning propellent charge to accelerate the shell and hence generally a higher muzzle velocity. Two major factors in armor penetration are sectional density of the projectile (mass/longitudinal cross section) and the velocity. I'm not sure about the former, but the latter is defiantely going to be higher for the 122mm cannon all other things being equal.

An analgous situation exists with German cannon... the Panther's 75mm L/70 is actually somewhat better for anti-armor work than the Tiger I's 88mm L/56. The King Tiger and Jagdpanther have the best.. the longer 88mm L/71.

The 100mm L/56 D-10S cannon of the SU-100 was actually the best anti-armor weapon fielded by the Soviets during the war, but they had difficulty mass producing it apparantly.

By the time the ISUs were fielded, there were T-34/85s, SU-85s, KV-2s, and eventually SU-100s to fight the armor battle with the big cats on more even terms than when the Tigers, Elephants, and Panthers first appeared (and the SU-152, **not the ISU-152**, developed its reputation). So the ISUs were mainly meant to serve as mobile direct fire artillery against infantry positions and fortifications. Because of this, the 152mm with it's greater weight of shell (higher blast value in CM) was preferred... but 122mm production was such that were plenty to mate to the ISU chassis so this was done.

Both indeed could be potent tank destroyers, with the ISU-122 having an edge there, but that was not their main mission.

Some online refs:

http://www.battlefield.ru/su152.html

http://www.battlefield.ru/isu122_152.html

http://www.battlefield.ru/su85.html

http://www.battlefield.ru/su100.html

[ October 07, 2002, 07:40 PM: Message edited by: Shosties4th ]