The Soviet Tank Thread: Transversely Mounted 1000hp Engines

[Beer]

4 hours ago, Pascal said:

 

Yes it's variable and the gunner uses whatever RPM he has while the tank is on the move, i guess the gunner only controls the RPM trough the driver only while the tank is stationary.

 

That's what I meant. On the move it's uncontrolable for the gunner how fast he can turn the turret. It depends on the driver. If he accelerates or decelerates the turret don't rotate with constant speed. The higher gear he selects the slower the turret rotation is, the lower rpm he uses the slower the rotation is again. Way too many variables which the gunner can not affect. 

[heretic88]

16 hours ago, Jim Warford said:

It was killed by the anti-gun/pro-missile mafia, not because of any performance issues.

Yes it is true. Also the Objekt-268.

 

16 hours ago, Jim Warford said:

The numerous SU-100s weren't preferred, there was just a lot of them around and they were cheap.

Not just that. They used the same D-10 guns as the T-54/55, with the same ammo, this greatly simplified logistics. ISU-122 didnt have many advantages over the SU-100. The D-10 gun had better rate of fire, and had more advanced rounds than the D-25. BR-412D had higher penetration than BR-471D and had flatter trajectory. Also the D-10 had HEAT, which wasnt available for D-25. The 122mm gun's only advantage was the more powerful HE shells.

[Jim Warford]

2 hours ago, heretic88 said:

Yes it is true. Also the Objekt-268.

 

Not just that. They used the same D-10 guns as the T-54/55, with the same ammo, this greatly simplified logistics. ISU-122 didnt have many advantages over the SU-100. The D-10 gun had better rate of fire, and had more advanced rounds than the D-25. BR-412D had higher penetration than BR-471D and had flatter trajectory. Also the D-10 had HEAT, which wasnt available for D-25. The 122mm gun's only advantage was the more powerful HE shells.

heretic88; there are a few different issues here: first, comparing the SU-100 to the ISU-122 isn't a good comparison...the SU-100 is a tank destroyer, the ISU-122 is an assault gun. The ISU-122S with the D-25 successfully combined the abilities of both a tank destroyer and an assault gun, giving it significant advantages over the SU-100. According to documented discussions in 1944, a key factor in the Soviet decision not to use the 100mm gun on "JS" tanks was the significant advantage 122mm HE had over 100mm HE ammo. This decision was based on several factors to be sure, but they included the fact that, "JS tanks armed with the 122mm main gun are successfully repelling all counterattacks by German tanks of all types at all ranges (i.e. up to 1500 meters)."

 

Secondly, (IIRC) the D-25 did eventually get HEAT rounds although not until 1965/1966 (3BK9/3BK9M along with some others). And finally, the development of 100mm and 122mm AP ammo was done in parallel…and again (IIRC), they had the same level of technology until the late 1960s at least. Had the planned upgrade of the SU-122-54 taken place, it would have had the same ammo as the T-10M including the 3BM11 APDS round. It's also important to remember here that the SU-122-54 had the TDK-09 stereoscopic rangefinder which meant that it's D-49 (D-25TA) 122mm main gun was more accurate than the SU-100's main gun.              

 

         

[heretic88]

16 hours ago, Jim Warford said:

This decision was based on several factors to be sure, but they included the fact that, "JS tanks armed with the 122mm main gun are successfully repelling all counterattacks by German tanks of all types at all ranges (i.e. up to 1500 meters)."

 

I think it was somewhat a wishful thinking. Im not convinced that the 122 (especially its AP shells) was really that effective against Tiger II. But since it was a rare type, it didnt really mattered. But it soon changed after WW2. M48 tanks had very similar protection, and they were manufactured in significant numbers. According to a soviet document, the hull was completely invulnerable, even at point blank range. It is true that the same applies to the D-10, but it had a significant advantage compared to D-25: rate of fire. Im not entirely sure how ISU-122s were used in the cold war period. Heavy tank regiments which used assault guns had ISU-152s only as far as I know. Some medium tank regiments had a SU company, but they used SU-100s if Im not mistaken. ISU-122 actually fits to neither. If used as a tank destroyer, it has zero advantage over T-54/55 tanks. If used as an assault gun, it is significantly inferior to its big brother, the ISU-152. Probably this is t

he reason why was it eliminated from service so early. 

On the other hand, SU-122/54 with M-62 would be a good companion to T-54/55. It had significantly better AT performance, and also had parts commonality with the tanks. Sadly this didnt happen. (btw, Im also a fan of this interesting vehicle! A pity there is only a single survivor remaining in reasonable condition)

16 hours ago, Jim Warford said:

It's also important to remember here that the SU-122-54 had the TDK-09 stereoscopic rangefinder which meant that it's D-49 (D-25TA) 122mm main gun was more accurate than the SU-100's main gun.              

Any sources indicating this? As for the D-10, it was a quite accurate gun, as I heard from old tankists.

 

 

[Wiedzmin]

1 hour ago, heretic88 said:

M48 tanks had very similar protection, and they were manufactured in significant numbers. According to a soviet document, the hull was completely invulnerable,even at point blank range.

not all soviet(any country) docs are good, if it says "we think that..." or "we calculated that..." it's BS in 90% of time

 

for example, T-10 cast hull nose variant(experimental) with 102mm/63° have Vпкп=750m/s which is 600 meters IIRC, and 102mm/60°  Vпкп=700m/s which is 1.2km IIRC

 

T-10 with rolled plates(serial tank) could withstand 122 blunt nose at 795m/s at upper part(point blank), and 710 m/s at lower(120mm/50°) 

 

so i'm not sure about M48 hull could resist 122mm PB, but yes not very easy to penetrate for sovet AP rounds 

[Pascal]

52 minutes ago, Wiedzmin said:

so i'm not sure about M48 hull could resist 122mm PB, but yes not very easy to penetrate for sovet AP rounds 

 

The upper hull supposedly could resist both 100mm and 122mm.

  

[Wiedzmin]

2 hours ago, Pascal said:

 

The upper hull supposedly could resist both 100mm and 122mm.

  

i wrote exactly about this report

 

and IIRC even T-54 UFP doesn't give PB protection vs 100mm AP-T

[heretic88]

16 hours ago, Wiedzmin said:

and IIRC even T-54 UFP doesn't give PB protection vs 100mm AP-T

Fully immune, at least against BR-412B. Confirmed by Yugoslav tests. In Hungarian tests it also proved to be ineffective, although it was tested only at 800,1200 and 1600m. 

[Wiedzmin]

1 hour ago, heretic88 said:

Fully immune, at least against BR-412B. Confirmed by Yugoslav tests. In Hungarian tests it also proved to be ineffective, although it was tested only at 800,1200 and 1600m. 

soviet tactical diagramm BR412B  gives 500 meters for UFP, 1000 LFP, don't know why, maybe it's about пкп(backface integrity limit), and not псп(full penetration limit)

 

 

brits during BR412B trials penetrated 90mm/60 RHA at 850m/s once(400 meters or so) IIRC, and 80mm/60 at 790 m/s(1-1,1km)

 

 

[heretic88]

1 hour ago, Wiedzmin said:

soviet tactical diagramm BR412B  gives 500 meters for UFP, 1000 LFP, don't know why, maybe it's about пкп(backface integrity limit), and not псп(full penetration limit)

Is it possible that they didnt take into account the actual quality of the T-54 armor, and they made the calculations for this diagram with a generic armor steel plate? The yugoslavs tested the M-47 Patton too, in theory the results would be the same as the T-54, same 100mm plate at 60 deg, but while the BR-412B couldnt do anything even at PB against the T-54, it penetrated the M-47 UFP at 750m. And it turned out that the armor of the T-54 was not only harder (290 vs 210 BHN), but much better quality too.

[Jim Warford]

On 4/22/2020 at 6:21 AM, heretic88 said:

 

I think it was somewhat a wishful thinking. Im not convinced that the 122 (especially its AP shells) was really that effective against Tiger II. But since it was a rare type, it didnt really mattered. But it soon changed after WW2. M48 tanks had very similar protection, and they were manufactured in significant numbers. According to a soviet document, the hull was completely invulnerable, even at point blank range. It is true that the same applies to the D-10, but it had a significant advantage compared to D-25: rate of fire. Im not entirely sure how ISU-122s were used in the cold war period. Heavy tank regiments which used assault guns had ISU-152s only as far as I know. Some medium tank regiments had a SU company, but they used SU-100s if Im not mistaken. ISU-122 actually fits to neither. If used as a tank destroyer, it has zero advantage over T-54/55 tanks. If used as an assault gun, it is significantly inferior to its big brother, the ISU-152. Probably this is t

he reason why was it eliminated from service so early. 

On the other hand, SU-122/54 with M-62 would be a good companion to T-54/55. It had significantly better AT performance, and also had parts commonality with the tanks. Sadly this didnt happen. (btw, Im also a fan of this interesting vehicle! A pity there is only a single survivor remaining in reasonable condition)

Any sources indicating this? As for the D-10, it was a quite accurate gun, as I heard from old tankists.

 

 

heretic88; first of all...the quote I included above regarding the performance of the 122mm gun is from official Soviet sources...that's not my opinion. As far a performance against the M48 is concerned, I've dug-up reports that claim that the bow (or lower glacis), and the turret front can be penetrated by the D-25...also, a lot of the reporting available on the performance of the D-25 relates to testing of the BR-471 APHE and BR-471B APBC rounds, not the more capable BR-471D APCBC round. It's important to remember that according to authoritative Israeli sources, IDF M48s were knocked out by Egyptian IS-3s in 1967. So far, I haven't been able to confirm the AP rounds the Egyptians were using...it's possible that in combat, the significant amount of force created by being hit by a full-bore 122mm AP round alone did enough damage to knock out the Israeli tanks.

 

According to previously classified US reports, Soviet assault gun organizations used 122mm-armed assault guns at least through 1969/1970...including both the ISU-122S and the SU-122-54. Getting organizational details about the SU-122-54 is challenging since most of the details were highly classified at the time. You're right about medium tank regiments having an "SU" company, but it was more than "some" and included MRRs as well. According to official US references, both tank divisions and mechanized divisions had 122mm-armed assault guns. Some of the references include: 1955 = SAU-122 company, 1958 = SU-122 assault gun company, and 1964 = assault gun battery. In rifle divisions, by far, most of the regimental assault gun/tank destroyer companies were equipped with SU-100s. In some select cases however, those were replaced by SU-122-54s...confirmed in the 128th Guards Motorized Rifle Division for example (when they were deployed in Czechoslovakia during Operation Danube in 1968). It's likely, that the ISU-122S was pulled from front line service when the tank division Heavy Tank/Assault Gun Regiment was dropped and replaced by a third Medium Tank Regiment in the 1962-1964 timeframe.

 

IMO, it's much more likely that the ISU-122S was finally removed from service because the MBTs it was supporting evolved to the point where they simply no longer needed assault guns or gun-armed tank destroyers. That's also the likely reason that (AFAIK), the SU-122-54 wasn't ever seen supporting T-62-equipped units...only T-54/55 units. As far as gun accuracy is concerned, the D-10 is an excellent gun...with a good gunner, it could be very accurate. The advantage the SU-122-54 and it's D-49 main gun had was the use of the TKD-09 stereoscopic rangefinder. As a retired "Tankist" myself, I have a lot of experience with rangefinders...and I know what a good gunner can do with a rangefinder...especially at longer ranges. This system gave the SU-122-54 an accuracy advantage over all other fielded Soviet assault guns, tank destroyers, and tanks until the introduction of the T-64.

 

Finally, there are actually two surviving SU-122-54s; the one at Kubinka (which I have seen in person), and the one at the military museum in Krasnodar. The Krasnodar SU-122-54 is shown below:

 

 

 

[ZloyKrolik]

Why did the Soviets use 122mm for howitzers and guns? Why that particular diameter?

[That_Baka]

6 hours ago, ZloyKrolik said:

Why did the Soviets use 122mm for howitzers and guns? Why that particular diameter?

Because they had russian empire guns of same caliber. Same with 105mm howitzers .

[heretic88]

13 hours ago, Jim Warford said:

As a retired "Tankist" myself, I have a lot of experience with rangefinders...and I know what a good gunner can do with a rangefinder...especially at longer ranges. This system gave the SU-122-54 an accuracy advantage over all other fielded Soviet assault guns, tank destroyers, and tanks until the introduction of the T-64.

Yes, it is definitely true. The problem is, that the TKD-09 was a stereoscopic rangefinder. As I read in numerous sources, unlike coincidence rangefinders, not everybody is able to use them. 

 

13 hours ago, Jim Warford said:

 

Finally, there are actually two surviving SU-122-54s; the one at Kubinka (which I have seen in person), and the one at the military museum in Krasnodar. The Krasnodar SU-122-54 is shown below:

Yes, thats why I said only a single Su-122-54 remains in good condition. The one in Krasnodar is sadly nothing more than an empty shell. Too bad in russia restoring stupid T-34s is always more important than bringing back these awesome beasts to life. I'd love to see the SU-122 in running order, or a T-10M, maybe the Objekt-770... Well, maybe one day...  

[Wiedzmin]

 

[Jim Warford]

5 hours ago, heretic88 said:

Yes, it is definitely true. The problem is, that the TKD-09 was a stereoscopic rangefinder. As I read in numerous sources, unlike coincidence rangefinders, not everybody is able to use them. 

 

Yes, thats why I said only a single Su-122-54 remains in good condition. The one in Krasnodar is sadly nothing more than an empty shell. Too bad in russia restoring stupid T-34s is always more important than bringing back these awesome beasts to life. I'd love to see the SU-122 in running order, or a T-10M, maybe the Objekt-770... Well, maybe one day...  

It's true that not everyone can successfully use stereoscopic rangefinders...but they were still used around the world (M48, M103, Type 61, etc.), and selected for the SU-122-54. It still gave the vehicle a significant accuracy advantage...

 

You're also right about the interior of the Krasnodar SU-122-54 (see photos below); but for me, it's still better than nothing. I'm still hoping that one or two more SU-122-54s will be uncovered some day...             

 

 

 

[ZloyKrolik]

17 hours ago, That_Baka said:

Because they had russian empire guns of same caliber. Same with 105mm howitzers .

But why did the Russians pick that particular caliber? I get that 76.2 mm is 3", but why 122 mm? Why not 127 mm which is 5".

[Zadlo]

But Russians didn't use inches but lines.

[heretic88]

On 4/24/2020 at 5:37 PM, Jim Warford said:

 

You're also right about the interior of the Krasnodar SU-122-54 (see photos below); but for me, it's still better than nothing. I'm still hoping that one or two more SU-122-54s will be uncovered some day...             

Very, very unlikely. Most were converted to prototypes (BTS-600, Objekt-610), MTP-3 ARVs,  BMR-1 mine clearing vehicles. Small number of BMR-1s are still in service in the ukrainian army and maybe one or two in DNR/LNR militias. These are the longest serving SU-122/54 variants, and they were quite successful in their new role.

[ZloyKrolik]

7 hours ago, Zadlo said:

But Russians didn't use inches but lines.

OK. 76.2 mm is 30 lines,  so 122 mm is 48 lines.  Why did they decide on that particular caliber? Most nations had field artillery of around 3" (75/76.2 mm), but next up in size is around 4" or so (105 mm)  for medium artillery before they jump to around 6" for heavy artillery (150 mm/152/ 155).

[SuperComrade]

I found this technical document on the SU-76M that states that the maximum road speed was limited to only 30 km/h instead of the rated 41 km/h due to transmission vibration issues. Was this ever fixed?

https://imgur.com/QUJCzFJ

[Beer]

 

From https://twitter.com/RALee85/status/1256976815152758784

[LoooSeR]

2 hours ago, Beer said:

 

From https://twitter.com/RALee85/status/1256976815152758784

 

   Kek

 

[LoooSeR]

   Typhoon-K next to MaxxPro MRAPs

[T___A]

 

 

 

@EnsignExpendable Awesome video. Would love to see more.