# 3BM32/3BM42 performance proofs

Sourcework for context in mathematics:

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These are the first two longrods Russia has that could possibly be in the T80U in the upcoming update.

I found that the 3bm32's indicated length of 480mm turns out to make the alloy have a density of 14294.47kg/m^3, very odd and likely false density for a DU alloy. this would mean that the penetrator would have the following performance point blank at 0 deg and at 60 deg:

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If we were to assume 480mm and 14,294kg/m^3 was correct that would mean this round would be about the same performance as the correctly L-O'd M833 from the m68a1 gun. weird right?

but I did have somebody give me this random picture, I hope somebody here can tell me where it is from because it has alot more info despite being vague with velocity as well.

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when using this new information I can get the density to a much higher and imo much more agreeable 18,056kg/m^3, factoring in everything so far and I get the new L-O point blank calculations

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The current data is the reason why I am firmly believing people were eating up propoganda on 3bm32 performance I am more than willing to accept new information to disprove what is current, but it HAS to involve measurements of the round itself and/or velocities for L-O purposes

3BM42 performance:  (WiP)

update: its a jacketed penetrator, luckily the longrods.ch site supplied us with a jacket penetrator modification to the L-O equation.

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I am hoping to find better numbers for the WHA density because at this point it is a magical guess for their alloy type's specifications. again this image is WiP

Edited by CaptainBallistic
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I honestly think T-80U should come with 3BM22 as stock and 3BM26 as top round.

Or, alternatively, 3BM26 as stock and 3BM29 as top.

But I feel like 3BM32 and let alone 3BM42 would be just too much, those are the best and most modern shells Russia could get, it would be like adding M1A1 with M829A3 or Leopard 2A5 with DM53. Too much for now, even if I’m the future whern stronger tanks come it would be ok.

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2 minutes ago, SPANISH_AVENGER said:

I honestly think T-80U should come with 3BM22 as stock and 3BM26 as top round.

Or, alternatively, 3BM26 as stock and 3BM29 as top.

But I feel like 3BM32 and let alone 3BM42 would be just too much, those are the best and most modern shells Russia could get, it would be like adding M1A1 with M829A3 or Leopard 2A5 with DM53. Too much for now, even if I’m the future whern stronger tanks come it would be ok.

I'm still looking at the 3bm42 but really, the 3bm32 as of now looks very much like a useable round for Russia that ironically would be more balanced than a flat pen only 3bm22 that magically ignores armor angles in calculations.

it is not in any way like giving the m1a1 an m829a3, not even close

Edited by CaptainBallistic
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1 hour ago, SPANISH_AVENGER said:

I honestly think T-80U should come with 3BM22 as stock and 3BM26 as top round.

Or, alternatively, 3BM26 as stock and 3BM29 as top.

But I feel like 3BM32 and let alone 3BM42 would be just too much, those are the best and most modern shells Russia could get, it would be like adding M1A1 with M829A3 or Leopard 2A5 with DM53. Too much for now, even if I’m the future whern stronger tanks come it would be ok.

If you put it through L-O like he has you will see 3BM32 isnt a LOL pen round. The penetration numbers on that yellow and black graph are completely made up. There is rounds in game already better than the 3BM32. It doesn't even perform better than JM33 or OFL round of the AMX40. It's performance will be that of a fixed DM23 roughly. Its penetrator is only 380mm long and 30mm in diameter that's smaller than L23A1. The round relies on its velocity to get through armour, there is no way a 380mm long DU penetrator will outperform a 510mm long WHA penetrator. 3BM29/32/42 are basically Russia's first generation long rod penetrators.

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The volume has to be lower than what you're working out, because the projectile weight also includes the fins (which weigh 415 grams according to here: https://thesovietarmourblog.blogspot.com/2015/05/t-72-soviet-progeny.html) plus another 100-200 grams for nose cap and tracer.

And it appears the projectile weight is 4750 grams, not 4850 grams:

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And by pixel measuring this photo (3BM32 is 4th from left, 3BM9 is 5th, and 3BM15 is 6th), it appears 3BM32 has a projectile length of 500mm, not 480mm:

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Making things even worse on top of that is how the projectile thickens in the middle:

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It is really hard to make penetration estimates of this round as a result, but even with unrealistic 380x34mm at 18.6 g/cm^3 penetrator, it can't achieve the penetration the Soviets estimated it at.

Edited by SunsetShimmers

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This is Nii Stali certified penetration of APFSDS up to BM46

11 hours ago, SPANISH_AVENGER said:

I honestly think T-80U should come with 3BM22 as stock and 3BM26 as top round.

Or, alternatively, 3BM26 as stock and 3BM29 as top.

But I feel like 3BM32 and let alone 3BM42 would be just too much, those are the best and most modern shells Russia could get, it would be like adding M1A1 with M829A3 or Leopard 2A5 with DM53. Too much for now, even if I’m the future whern stronger tanks come it would be ok.

Granted that between the likes of BM42 and M829A3 or DM53 theres a massive difference the latter one when fired from L55 can pen up to 700mm.
Source:

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Anyways, the ammo choice for T-80U depends on how Gaijin intends the tank gameplay to be like. If they want to keep the trend of soviet tanks being able to defeat frontally western tanks (except some spots in their turrets and/or the turret of the top british mbt), some ammo with capability to pen 500-550 should be the choice, so im betting on BM42 and/or BM32. Otherwise, the top shell should be BM29.

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6 hours ago, SunsetShimmers said:

The volume has to be lower than what you're working out, because the projectile weight also includes the fins (which weigh 415 grams according to here: https://thesovietarmourblog.blogspot.com/2015/05/t-72-soviet-progeny.html) plus another 100-200 grams for nose cap and tracer.

And it appears the projectile weight is 4750 grams, not 4850 grams:

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And by pixel measuring this photo (3BM32 is 4th from left, 3BM9 is 5th, and 3BM15 is 6th), it appears 3BM32 has a projectile length of 500mm, not 480mm:

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Making things even worse on top of that is how the projectile thickens in the middle:

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It is really hard to make penetration estimates of this round as a result, but even with unrealistic 380x34mm at 18.6 g/cm^3 penetrator, it can't achieve the penetration the Soviets estimated it at.

Thank you for the weight measurements that will be used to update the OP

Projectile length is not calculated for the perforation, the penetrator length is, so projectile length should not matter too much outside of calculating total volume of projectile to get a terminal velocity for firing tables.

(something I plan on making for ranged performance and a full stat card so again thank you for the input)

The diameter is calculated as average for all longrods. you may notice on other longrods that the penetrator diameter is not quite uniform, for example the m829 projectile has minimal differences in diameter as well across it's length.

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On 24/02/2019 at 10:48, CaptainBallistic said:

Thank you for the weight measurements that will be used to update the OP﻿

Projectile length is not calculated for the perforation, the penetrator length is, so projectile length should not matter too much outside of calculating total volume of projectile to get a terminal velocity for firing tables.

﻿﻿

(something I plan on making for ranged performance and a full stat card so again thank you for the input)

﻿

The diameter is calculated as average for all longrods. you may notice on other longrods that the penetrator diameter is not quite uniform, for example the m829 projectile has minimal differences in diameter as well across it's length. ﻿

The problem with projectile length being 500mm instead of 480mm, is that the penetrator only measures as 380mm in length with a 480mm long projectile. With a 500mm long projectile, the penetrator would be 396mm.

There's no way of knowing if the diagram from Fofanov's site is correct however, so it is really hard to work out the dimensions of 3BM32.

And yeah, working out an average for penetrator diameter seems to be the best approach. I prefer to use a density calculation; assuming a 380mm long penetrator for 3BM32 that is entirely DU, a 27.5mm diameter penetrator seems about right (of course, if the penetrator is longer than 380mm, then the average diameter will likely go down. It'll also go down a lot if actually it is jacketed).

Eg, Gaijin used maximum penetrator diameter of 44mm for 3BM9 (and probably used maximum diameter for 3BM4 too), when the average for 3BM9 is closer to 34.5mm.

Edited by SunsetShimmers

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In 1.87 the 3BM22 shell on the T-64B and T-80B was made the stock shell and 3BM42 Mango is now the upgrade shell for these tanks.

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2 minutes ago, Phaere said:

In 1.87 the 3BM22 shell on the T-64B and T-80B was made the stock shell and 3BM42 Mango is now the upgrade shell for these tanks.

It's actually hilarious they got retroactively buffed

Meanwhile, in the No Man's land known as Britain...

Challenger Mk.2 still has APDS stock hahaha

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On 23/02/2019 at 19:50, Alan_Tovarishch said:

Granted that between the likes of BM42 and M829A3 or DM53 theres a massive difference the latter one when fired from L55 can pen up to 700mm.
Source:﻿﻿﻿

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Those figures are not for the L55 gun, but the 'estimated' performance through the Ukranian KBM2 which is an L50.

Estimated performance of the DM53 through the L55 varies from 750-850mm RHAe @ 60 & 2km. DM63A1 is said to be approaching 1 metre in penetration.

Edited by Panthera_Pardus
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6 hours ago, Panthera_Pardus said:

Estimated performance of the DM53 through the L55 varies from 750-850mm RHAe @ 60 & 2km. DM63A1 is said to be approaching 1 metre in penetration.

Doubt that. DM63 is just DM53 with TIPS.

The muzzle velocity and penetrator are not stated to be different, it has better accuracy and lower barrel wear.

Edited by RoflSeal

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1 hour ago, RoflSeal said:

Doubt that. DM63 is just DM53 with TIPS.

The muzzle velocity and penetrator are not stated to be different, it has better accuracy and lower barrel.

Don't bother trying to convince him, I told him this several times with proof and he's always ignored it.

The length of BM32 is in-fact 380mmx30mm, this is the commonly known value and it matches the cut-away picture.

The weight then almost matches up, it does have a weird geometry and I'm not sure if 30mm is entirely correct as an average value.

BM42 is a bit different and can only be "calculated" with the jacketed equation from L/O.

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On 12/03/2019 at 15:25, scavenjer said:

Don't bother trying to convince him, I told him this several times with proof and he's always ignored it.

The length of BM32 is in-fact 380mmx30mm, this is the commonly known value and it matches the cut-away picture.

The weight then almost matches up, it does have a weird geometry and I'm not sure if 30mm is entirely correct as an average value.

BM42 is a bit different and can only be "calculated" with the jacketed equation from L/O.

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its strange how russian tanks got new rounds... and yet the M1 and M1IP still haven't gotten anything new  so now  RU has over 100+pen over the American top tier tanks except the Glass cannon of the m1a1

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On 13/03/2019 at 07:25, scavenjer said:

The length of BM32 is in-fact 380mmx30mm, this is the commonly known value and it matches the cut-away picture.

The weight then almost matches up, it does have a weird geometry and I'm not sure if 30mm is entirely correct as an average value.﻿

380x30mm cylinder would have a volume of 268.6 cm^3. With typical DU alloy being 18.6 g/cm^3, that is 4996 grams.

That is close to BM32's weight of 4850 grams, but 4996 grams is far too high as that is for penetrator alone, when the projectile has the weight of fins, tracer, nose cap and any lighter metal sheathing.

According to this source: https://thesovietarmourblog.blogspot.com/2015/05/t-72-soviet-progeny.html

Quote

Mass of the stabilizer fins: 0.435 kg

So that's 435 grams. Tracer and nose cap are probably another 100-200 grams, PLUS the penetrator weight.

As for 30mm, that's the average diameter of the projectile, not the minimum diameter of the projectile nor the diameter of the penetrator.

Same source as above:

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Total projectile length: 480mm
Penetrator rod length: 380mm
Maximum diameter of the projectile rod: 34mm
Average diameter of the projectile rod: 30mm

Here's the diagram from Fovanov's site:

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From nose-tip to end of the fins, it is 415 pixels. Assuming a length of 480mm (ignoring evidence from above showing the round might be about 500mm for the moment), it is possible to then measure the dimensions of the penetrator.

Penetrator section:

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Approximately 327 pixels in length by 22, 23 or 24 pixels in diameter.

That equates to 378mm long by 25.44, 26.60 or 27.76mm in diameter.

The thicker part of the projectile is interesting:

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That 'bulge' section is approximately 175 pixels by 29 or 30 pixels in diameter.

That equates to 202mm by 33.54 or 34.70mm in diameter.

Assuming a 380x27mm penetrator, that's a volume of 217.6 cm^3 for a mass of 4047 grams. That's a bit on the lightweight side, but that bulge has to be accounted for; it is likely a form of steel sheathing.

If the DU penetrator is 27mm in diameter and the outer diameter of the bulge is 34mm, then the volume of the steel wrapped around the DU to form that bulge would be 67.7 cm^3. With a given density of steel at 7.8 cm^3, that is 528 grams.

4047 + 528 grams is 4575 grams; too much considering the rest of the projectile has to weigh 500 grams.

Assuming a 380x26mm penetrator, that's a volume of 201.75 cm^3 and a mass of 3753 grams. Adjusting the volume of bulge sheathing to account for smaller diameter DU interior, it has a volume of 76.15 cm^3, for a mass of 594 grams.

Combined, that's 4347 grams; add 500 grams for the rest of the projectile and it is only 3 grams off from the correct weight of 4850 grams.

So in conclusion, the penetrator of BM32 is probably only about 26mm in diameter, not 30mm. Which gives it a length/diameter ratio of almost 15.

Of course, if the projectile is actually 500mm long, then it becomes more complicated. But I'm uncertain if 500mm length is true or not, given there's no confirmation the projectile pictured in my previous post is BM32, and due to the angle the pixel measurements I made of that photo are a fair bit less reliable.

Edited by SunsetShimmers

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3 minutes ago, SunsetShimmers said:

end of the fins, it is 415 pixels. Assuming a length of 480mm (ignoring evidence from above showing the round might be about 500mm for the moment), it is possible to then measure the dimensions of the penetrator.

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That 'bulge' section is approximately 175 pixels by 29 or 30 pixels in diameter.

That equates to 202mm by 33.54 or 34.70mm in diameter.

you can also better pixel measure the diameter using that picture to the right showing the frontal view of the sabot, in fact, they line up perfectly as needed for a technical drawing.

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4 minutes ago, CaptainBallistic said:

you can also better pixel measure the diameter using that picture to the right showing the frontal view of the sabot, in fact, they line up perfectly as needed for a technical drawing.

If I assume the sabot diameter is 125mm, I get shorter dimensions than what I've been working with; penetrator section ends up being 368mm for example.

Still editing my post above though!

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13 hours ago, SunsetShimmers said:

-snip-

Yes, I know about the difficulties in getting the dimensions etc right, but as I pointed out, 380x30mm is the commonly known values and are probably the closest to reality.

Weight is a fickle thing, there's many round that don't reach "known" performance with their given weight.

As for pixel counting the picture of BM32... it's a bit hard to get exact figures since it's so low resolution.

It could very well be that their DU alloys are less dense than US/UK ones.

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3 hours ago, scavenjer said:

Yes, I know about the difficulties in getting the dimensions etc right, but as I pointed out, 380x30mm is the commonly known values and are probably the closest to reality.

Weight is a fickle thing, there's many round that don't reach "known" performance with their given weight.

As for pixel counting the picture of BM32... it's a bit hard to get exact figures since it's so low resolution.

It could very well be that their DU alloys are less dense than US/UK ones.

Pixel measurements is all we have for more data, and as the source I linked says, 30mm is the average diameter, not the minimum projectile or penetrator diameter.

There's also this photo, although being at a slight angle pixel measurements are a bit less reliable:

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Total projectile length is about 255-260 pixels.

Penetrator section is about 200 pixels.

Minimum projectile diameter is 13 or 14 pixels.

Maximum projectile diameter is 16, 17 or 18 pixels.

With a projectile length of 480mm, that works out to the following:

Penetrator length = 369-376mm

Minimum projectile diameter = 24-26mm

Maximum projectile diameter = 30-34mm

With a projectile length of 500mm:

Penetrator length = 385-396mm

Minimum projectile diameter = 25-27mm

Maximum projectile diameter = 31-35mm

While it is hard to confirm if that genuinely is a photograph of 3BM-32 Vant, it does match the details from Fofanov. And that is more evidence the minimum projectile diameter is less than 30mm.

As for DU alloy density, with a 380x30mm penetrator the density would have to be just 16.2 g/cm^3 (actually even lower when you consider the bulge) for those dimensions to be viable.

I'm hardly an expert on DU alloys, but such a low density sounds rather unrealistic to me.

EDIT: eg, the lowest density tungsten alloys used in military ammunition from this company is 17.1 g/cm^3: https://www.agescaninternational.com/images/Agescan Company and Defense Product Profile (1).pdf

Edited by SunsetShimmers

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4 hours ago, SunsetShimmers said:

-snip-

Usually the density of DU alloys is around 18.5-18.7g/cc for US alloys, but there's other alloys in use for autocannons used by the Navy that might be lower (haven't looked into it).

The rear end is also quite a bit thinner as that screws into the fin assembly, losing some weight, lastly we don't know dimensions for sure, but there's little reason to doubt the 380mm length, width is most probably the section at the middle (might even include the threads).

Same thing with M829 btw, often overestimated and quite light for how good it supposedly is.

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2 hours ago, scavenjer said:

Usually the density of DU alloys is around 18.5-18.7g/cc for US alloys, but there's other alloys in use for autocannons used by the Navy that might be lower (haven't looked into it).

The rear end is also quite a bit thinner as that screws into the fin assembly, losing some weight, lastly we don't know dimensions for sure, but there's little reason to doubt the 380mm length, width is most probably the section at the middle (might even include the threads).

Same thing with M829 btw, often overestimated and quite light for how good it supposedly is.

Yeah, I'd say 380mm penetrator length is highly probable, given multiple sources say it. I reckon that if a pixel measurement produces approximately 380mm penetrator length, then it is probably reasonably accurate; if it doesn't, then the reference measurement is probably off.

If you can find data on other DU alloys it'd be useful, I did some google searching earlier and came up with nothing.

Incidentally, a 380x30mm penetrator with 16.2 g/cm^3 density is going to have substantially less penetration than a 380x26mm penetrator at 18.6 g/cm^3.

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And that's without accounting for the bulge material, which reduces available weight for the penetrator, so it must actually be even lower in density if it were 380x30mm.

Given the middle bulge does appear to be 34mm in diameter, a 380x30mm rod would have a volume of 268.61 cm^3 with the bulge material being 40.61 cm^3. It'd almost certainly be steel, with a typical density of 7.8 g/cm^3, for 317 grams in weight.

With at least 500 grams in fins, tracer and nose cap, plus 317 grams in steel for the bulge, that leaves only 4033 grams remaining for the penetrator material, so it'd have a density of 15.01 g/cm^3.

Penetration with that density:

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EDIT: derp, fixed an error in my calcs

Edited by SunsetShimmers

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16 hours ago, SunsetShimmers said:

If you can find data on other DU alloys it'd be useful, I did some google searching earlier and came up with nothing.

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US DU alloys.

Can't find info on USSR ones atm.

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1 hour ago, scavenjer said:
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US DU alloys.

﻿ Can't find info on USSR ones atm.﻿

Thanks, interesting they don't vary much in density. I'm also curious about the importance of elongation with APFSDS rods; is high or low elongation desirable?

I think it is fairly likely the Soviets would have realised low density alloys meant significantly reduced penetration though, so I suspect they would have used alloys with similar density to those above, although without solid evidence that is only an assumption.

Assumption based on logical reasoning aren't so bad when there isn't any other data available though.

Interesting thing about the 'bulge' with 3BM32; 3BM46 and 3BM59/60 appear to have a similar area, although not as pronounced.

3BM46 from Fofanov's site:

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3BM59 or 60:

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I'm not sure what it is for, but given it is where the sabot wraps around the projectile, I'm guessing it is something to do with maintaining proper contact between the projectile and sabot until the round leaves the barrel.

Edited by SunsetShimmers

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It may be to reduce bending. The thicker cross section could help prevent the penetrator from snapping against heavily slopped NERA inserts. That's just my guess.

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Think I may have figured out 3BM32 Vant...  The info on Fofanov's sight may be outdated by a lot.  I used the length of 470mm from this, with the 30mm diameter.

The density took some trial and error.  But I came up with 17,200kg/m3.  Using the same velocity loss as 3BM42, so 1530m/s at 2000m.  One thing I've learned over time, is the Russians didn't use the highest density version of alloys.  For example their tungsten alloy is usually around 17,000kg/m3.  So it wouldn't surprise me at all of their DU alloy was also close to that.

3BM32

L:470mm D:30mm

Uranium-Nickel-Zinc

Density 17,200kg/m3

Target

Density 7850kg/m3

260BHN

Vertical

10m = 465mm

100m = 464mm

500m = 457mm

1000m = 448mm

1500m = 438mm

2000m = 428mm

60 Degree

10m = 272mm

100m = 271mm

500m = 267mm

1000m = 262mm

1500m = 256mm

2000m = 250mm