Comprehensive Technical Review: BM “Oplot,” “Duplet”/”Nozh” Dynamic Protection System, and Modeling Deficiencies

This document is based on open-source technical data (specifically, materials from btvt.info) and the results of field and combat tests of the “Duplet”/“Nozh” Explosive Reactive Armor (ERA) system.


I. Fundamental Advantage of the “Nozh” and “Duplet” Dynamic Protection Systems

The “Nozh” (KhSCHKV) ERA is a modular element serving as the key active component of the “Duplet” complex. “Duplet” is a tandem, multi-layered (2-3 layers) system officially adopted by the Ukrainian Armed Forces in July 2009.

A. The Revolutionary Operating Principle

Unlike 2nd-generation ERA (such as “Kontakt-5” or “Relikt”), which rely on the principle of plate expulsion (largely ineffective against modern APFSDS), “Nozh” operates on the principle of a cumulative counter-explosion.

  • Upon initiation, directed cumulative jets are generated, striking the approaching APFSDS rod or HEAT jet laterally.
  • This action leads to the destabilization, fragmentation, and complete destruction of the projectile core.

B. Effectiveness Table (Comparison with Analogues)

The technical level of the “Duplet” ERA significantly surpasses Russian analogues, particularly against kinetic and tandem threats:

Threat Type “Duplet” (Ukraine) “Nozh” (Ukraine) “Relikt” (Russia) “Kontakt-5” (Russia)
Non-Tandem HEAT 95% 90% 60% 60%
Tandem HEAT 95% 45% 25% < 5%
APFSDS (Kinetic) 95% 80% 50% 20%

A. Tests Against Kinetic Rounds (APFSDS)

The “Nozh” system (using UKZ-19 and UKZ-34 devices) achieves high effectiveness by generating a cumulative jet with momentum and significant length. This allows it to deflect and fragment the attacking projectile (APFSDS, shaped charge jet, or “explosively formed penetrator”).

Specific Test Results with 3BM42 “Mango” APFSDS:

Tests were conducted using the 3BM42 APFSDS (rated penetration ~500 mm) at a distance of 100 m.

The residual depth of penetration into the control plates protected by the “Nozh” ERA was:

  • In the central part: 76 mm.
  • In the upper part: 65 mm and 72 mm.

CONCLUSION: The residual depth of penetration is only 65–76 mm. The “Duplet” ERA reduced the penetration capability of the 500 mm penetrating round by more than 5 times.

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“In the photo, the left side shows the impact point of an APFSDS round on an armor plate protected by a ‘Nozh’ module . Traces of the activation of the ‘Nozh’ module’s elongated shaped charges are visible. The right side shows the penetration made by an APFSDS round on an area not protected by ERA (Explosive Reactive Armor).”

(Impact characteristics on the plate after being hit by 3BM42 APFSDS, with visible traces of the “Nozh” ERA activation)


B. Tests of the “Nozh” Dynamic Protection System (Against Shaped Charges)

Against Non-Tandem PG-9S Grenade (Penetration ~400 mm):

After the detonation of the PG-9S shaped charge, the final depth of penetration of the cumulative jet was only 34 mm.

The experiment was conducted with a single KhSCHKV-34P element (a single layer of “Nozh”-type ERA).
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!

(Result after the detonation of the PG-9S anti-tank grenade)

Against PG-7VS Grenade:

As a result of the PG-7VS grenade impact, the armor penetration capability was reduced by 100% and measured 0 (zero) mm.

[ Знімок екрана 2025-09-28 095519.jpg ]
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(Setup of the PG-7S grenade at a 30∘ angle to the armor plate with “Nozh” protection)

***[size=4][center]

B.Testing of the Duplet Explosive Reactive Armor (ERA)

Against OFL F1 APFSDS (600+ mm Penetration):
Along with providing protection against tandem High-Explosive Anti-Tank (HEAT) warheads , the complex demonstrates increased effectiveness against Armour-Piercing Fin-Stabilized Discarding Sabot (APFSDS) rounds . The tandem Explosive Reactive Armor (ERA) ‘Duplet’ provides protection against 120 mm and 125 mm APFSDS rounds fired from minimal distances.

This effectiveness is confirmed by trials conducted in the United Arab Emirates in 2003. The firing was carried out by a ‘Leclerc’ tank using the OFL 120F1 APFSDS round (analogous to the DM43).

As a result of the tests to determine the actual penetration capability of the 120 mm OFL 120F1 APFSDS, it was established that the penetration capability is in the range of 600 to 650 mm, which ensures the defeat of modern tanks when attacking from the frontal projection.


As a result of the ‘Duplet’ trials, the armor penetration capability was reduced by 100% and was 0 mm in all experiments. During the tests, armor damage was observed only as a deflection (bulge) of the armor plate by 15 to 20 mm. No cracks or fractures were found. The armor deflection was solely due to the kinetic energy of the projectile.

Based on the results of the 120 mm OFL F1 APFSDS trials, it can be stated that protection is ensured against rounds of similar design, such as the M829A2, M829A3, and DM53 developed in the USA and Germany.

By its level of protection against APFSDS, the tandem ‘Duplet’ ERA surpasses all existing global analogues. For example, the currently most advanced Russian ERA, ‘Relikt’, provides protection against the M829A2 APFSDS only at a distance of over 1 km, which does not meet modern requirements, and the ERAWA-2 ERA developed in Poland does not provide protection even against obsolete DM33 APFSDS rounds.
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This is what remains of the projectile/round.


C. Incorrect Upper Frontal Hull (UFP) Design

  • Actual Composition: The multi-layered UFP composition has a thickness of 820 mm along the path of the projectile, of which 472 mm is the steel equivalent excluding the ERA. The actual composition includes: 16 steel + 50 air + 1 KhSCHKV 34 + 45 air + 1 KhSCHKV 34 + 60 steel + 35 fiberglass + 50 steel (at 68 degrees).
  • Modeling Issue: Screenshots of the in-game model indicate that key components, such as the 35 mm fiberglass and the 50 mm steel inner layer, are either missing or modeled with incorrect thicknesses/positions, significantly reducing overall protection. **** *
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Знімок екрана 2025-09-28 094252T-80UD on the left, and BM Oplot on the right.

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(Technical schematic of the UFP)*

D. Side Armor Deficiencies

  • Underestimated Base Thickness: The base side armor thickness of the hull (behind the turret ring) should be 80 mm, while the in-game model often indicates 70 mm.

Analysis of the Side ERA Module Structure (BM “Oplot”)

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The following analysis details the assumed layout of the Explosive Reactive Armor (ERA) elements and the calculation of the residual steel thickness within the side armor projection of the BM “Oplot” tank.

Calculation of the Residual Thickness of the Side Module (248 mm)

We use the provided characteristics of the HSCHKV elements (Height = Thickness) and the known total module thickness (248 mm).

Element Type Height (Thickness)
HSCHKV-34P 36 mm
HSCHKV-19A 24 mm

Calculation of Total ERA Thickness (TERA​)

Assuming the tandem package (layer) uses one HSCHKV-34P element and two HSCHKV-19A elements:

TERA​=(1×T34P​)+(2×T19A​)TERA​=(1×36 mm)+(2×24 mm)TERA​=36 mm+48 mm=84 mm

Calculation of Residual Thickness (Steel + Spacing)

The residual thickness is the portion of the module that is not ERA, representing air gaps, structural elements, and the main hull armor.

Residual Thickness=Total Module Thickness−TERA​

Residual Thickness=248 mm−84 mm=164 mm

Approximate Steel Layout

The calculated 164 mm represents the combined thickness of all passive elements (steel plates, spacers, internal structure) within the 248 mm module depth.

This residual 164 mm thickness is approximately steel.

The possible layered structure of the side module, incorporating the ERA elements, is suggested as follows:

Structure≈15 mm (Steel)+HSCHKV-19A+60 mm (Steel)+HSCHKV-19A+89 mm (Steel)+HSCHKV-34P
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(This suggested layout implies a total steel thickness of 15 mm+60 mm+89 mm=164 mm, with the ERA elements and air gaps placed between these steel layers).

Lack of external fuel tanks

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List of Cited Sources / References

​All sources (testing documents) are referenced on this website; it is a reliable platform with verifiable information. However, I might have made a mistake and not sent all the sources.

No. Description / Topic URL
1 Main Battle Tank BM “Oplot” in service Танк БМ «ОПЛОТ» (Объект 478ДУ9-1)
1.1 Results of the Firing Trials of the Armor Protection of the Advanced BM Oplot Tank." – Kharkiv: State Enterprise Kharkiv Morozov Machine-Building Design Bureau (SE KMDB), 2009. ru - Результаты испытаний обстрелом броневой защиты усовершенствованного танка БМ «Оплот». – Харьков: КП ХКБМ, 2009
2 Dynamic Protection “Duplet” / “Nozh” on T-64BM “Bulat” Динамическая защита «Нож» танка БМ «Булат»
3 Dynamic Protection Complex “Duplet” Тандемная динамическая защита «Дуплет»
3.1
​I.B. Chepkov, V.O. Khitrik. Dynamic-Type Protection Devices Against Tandem-Warhead Shaped-Charge Ammunition. Artillery and Small Arms. No. 3 2008.
​Patent of Ukraine No. 28225
​Sabot Projectile with Increased Armor Penetration Capability Provided by an Enlarged Core // German Patent DE4023482 (A1), application DE19904023482 dated 24.07.1990.
​Design of a Sabot Projectile Core // European Patent EP 2597416A2 application 12193724.7 dated 22.11.2012.
​Evaluation of the Effect of a Dynamic-Type Protection Device on an Armor Barrier / A. V. Kuchinsky, M. I. Vaskovsky, I. B. Chepkov, A. N. Negovsky // Artillery and Small Arms. - 2006. - No. 4.
ru- 1. И.Б. Чепков, В.О. Хитрик . Защитные устройства динамического типа от тандемных кумулятивных боеприпасов. Артиллерийское и стрелковое вооружение. №3 2008.
  1. Патент Украины № 28225

  2. Подкалиберный снаряд с повышенной бронепробивной способностью, обеспеченной сердечником увеличенного размера // Патент ФРГ DE4023482 (A1), заявка DE19904023482 от 24. 07. 1990.

  3. Конструкция сердечника подкалиберного снаряда // Европейский патент EP 2597416A2 заявка 12193724.7 от 22.11.2012.

  4. Оценка действия защитного устройства динамического типа на броневую преграду / А. В. Кучинский, М. И. Васьковский, И. Б. Чепков, А. Н. Неговский // Артиллер. и стрелковое вооружение. - 2006. - № 4.
    |4|Video reference (YouTube)|https://youtu.be/0jh830svq78?si=VBwOREZnJSGTtN7o|
    |5|Video reference (YouTube)|https://www.youtube.com/watch?v=Boq7VKAUJeE|

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Third-party fan sites are not reliable sources.

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All sources (testing documents) are referenced on this website; it is a reliable platform with verifiable information.

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These external fuel tanks can be sth

It says here that there is a rubber damper between the KhSChKV layers. Have you even read the primary sources of what you’re throwing off? That website contains a person’s personal opinion, not documentary evidence, just pictures and nothing more.

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Right…

And game says construction steel dampener :shrug:.

Anyone who still believes in rubber dampeners used in Oplot is not seriously discussing the topic and only saying things to make the tank as bad as possible.

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It turns out that the developers OVERESTIMATED the characteristics of the Oplot armor

I just quoted data from the source “Патент Украины № 28225”, which was uploaded by the author of the topic himself.

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Duplet doesn’t increase protection by a significant amount over Nizh vs 3BM42

…after being hit by BM-42 armor-piercing sub-caliber shells from a distance of 100 m, the residual penetration depth measured at an angle of 90° to the surface of the test plate was:

  • in the central part of the models with “Noz” ERA protection - 76 mm;
  • in the central part of the models with “Duplet” ERA protection - 58 mm

And this is also confirmed in this image where 3BM42 penetrates the first steel armor layer of the hull behind the Duplet module and you can see the STEF layer underneath

If there was a 50mm plate seperating the two ERA cassetes in the Duplet module, I would doubt that 3BM42 could penetrate the first layer of the hull behind the Duplet module, because on its own, a setup of ~15mm RHA + ERA cassette+ 50mm RHA should leave a residual penetration of ~26mm in the surface of the witness plate mounted behind that setup. This setup is functionally just Nizh.
Instead the residual penetration after the Duplet module (which is 15mm RHA + ERA + middle layer + ERA) is over twice that.

As for the sideskirts. 164mm of steel in the sideskirts is total fantasy unless the Oplot weighed in excess of probably 80 tons. The interior of the sideskirts seem to just be polystyrene as spacers for the ERA casettes to stay in the correct orientation and a layer of STEF in the middle. The only steel is the outside casing which looks ~15-20mm, typical of a heavy flyer plate. Ingame it’s only 5mm, to me it can be argued that it looks quite a bit thicker then 5mm
image

As far as I am concerned for the front hull ingame performs as expected to the info we have. It defeats DM43 and 3BM42 at 100m ingame. People expecting it to defeat DM53 are expecting too much

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image
T-80UD on the left, and BM Oplot on the right.
The general layout and structure of the hull front armor in the BM “Oplot” are fundamentally similar to those found in the T-80UD.

However, there is a crucial difference in the composition of the filler within the primary armor array:

  • In the T-80UD and other previous designs, the array’s cavities were typically filled with passive composite materials such as glass-textolite .
  • In the BM “Oplot”, these cavities are used to integrate elements of the “Duplet” Explosive Reactive Armor (ERA).
    With respect to the test-firings of the “Nizh” and “Duplet” ERA (which are approximately 15 years old), there is indeed a multitude of videos, photos, and reports available in open sources. In most cases, effectiveness certainly depends on the angle of impact and the type of projectile.

However, in nearly all of these materials, both “Nizh” and “Duplet” demonstrate high effectiveness. Even in photos showing damage, it is clear that the ERA activated and absorbed a significant amount of the projectile’s energy.

The Core Issue is with the Game Model:

My main point is not that “Duplet” cannot be penetrated, but that the in-game model of the BM “Oplot-T” is inaccurate and, as a result, understates the tank’s real survivability.

  1. Complex Structure: “Duplet” ERA is not just steel plates, but a multi-layered system with complex construction, including two types of ERA elements (HSCHKV-19A and HSCHKV-34P) within specialized cassettes.
  2. Side Thickness: Based on our calculations, the side module has a total thickness of 248 mm, of which 164 mm is attributed to the steel and intermediate layers, which is not reflected in the in-game X-ray view.
  3. Logical Basis: If this ERA were truly so ineffective, it would not have been integrated into the “Oplot’s” front armor in place of the passive glass-textolite filler.

There are many discussions where I and other users could provide comprehensive evidence to correct the model. However, due to certain forum rules (which prohibit direct quoting of classified material), we cannot fully reference technical documentation (such as the Thai Manual, which is declassified according to Ukrainian MoD Order No. 152 of 28.05.2009).

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IMG_1746

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Screenshot_2025-08-31_201133

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Your “secret” manual is just a textbook.

Spoiler

image
image

I will make a few points to address your claims,

  1. Firstly, regarding the kinetic protection provided by Duplet:

According to the data provided, assuming the plate was angled at 68 degrees (same as T-64/72/80/84/90), 58mm penetration after encountering duplet, means 155mm residual penetration from LOS.

In-game, 3BM42’s penetration at 60 degrees at 100m is 524mm (the link you provided claims the penetration would be >550mm). Lets take the lowest figure of 524mm (Even in-game this number would be higher because BM42 effective penetration increases with the angle of the plate):

In game number for 60 degrees: 524-155=369mm penetration defeated.
Claimed real life number: 550-155 = 395mm penetration defeated.

This also lines up with my calculations of the tests done on the turret:
Approximately 120mm LOS penetration was observed at a firing angle of about 60 degrees. Taking the in-game number at 60 degrees, 524-120 = 404mm penetration reduction.

Averaging all these numbers, Duplet, including its covers and dampeners should stop 390mm of kinetic penetration.

Remember, the 369mm reduction is actually false because it uses BM42 penetration figure for 60 degrees not 68, so the average is actually lower than it should be.

In-game, Duplet stops approximately 292mm of kinetic penetration, including the protection provided by all covers and dampeners. 100mm less protection than it should provide.

Additionally, all of this is calculated for BM42, which has a segmented core, allowing it to perform better against ERA, mono-block projectiles such as BM60 or OFL F1 would be affected to an even greater degree. (As stated in the blog you linked)

  1. Regarding the 50mm steel plate of the BM Oplot.

I agree with your assessment that such a plate would have shown different results from the turret tests, and we should have observed very little residual penetration after two layers of ERA.

The issue is, BM Oplot certainly has this plate, there is no doubt about it, it can be seen in any factory images of the module, and the blueprint of the module mounted on BM Oplot confirms that this plate exists and is made of the same RHA as the rest of the module.

My personal theory is that the duplet module tested against BM42 was made according to the patent and did not contain this plate, but only dampeners similar to turret ERA, which is why it performed similarly to the turret ERA. However, ofc this is my theory, and I don’t have any concrete evidence to prove it.

  1. Conclusion:

If we model the Oplot’s armour without this 50mm plate, the ERA’s effectiveness against kinetic rounds should still be increased by about a 100mm at the very least.

If we take into account the increased protection against monoblock projectiles, and the 50mm plate, this protection should be even higher, but 390mm of reduction against Kinetic rounds is an absolute must.

As for the side skirts, its values should be adjusted according to the ERA performance calculated above, but overall I don’t have much issues with how they’re modelled in game. They seem to be accurate to the Thai version of the tank.

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Can the side skirt deflect ammunition, they don’t in game now

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It should be capable of defeating almost all shaped charge ammunition, and some APFSDS fired at an angle. Fixing the side armour thickness should also help with this.

According to the manual, the side ERA contains one model 34 ERA and 2 model 19. So in theory it should provide less protection than normal Duplet

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Btw do we have any info on the roof armour of BM Oplot? In game it is modelled to be around 25mm, in comparison, T-90M is 45mm, its why Oplot is so easy to over-pressure by hitting the sight with HE or HEAT.

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https://community.gaijin.net/issues/p/warthunder/i/tjNFRUTF1IzA

A report regarding an armour hole found on the turret was accepted, we can expect to see stronger resistance against overpressure.

Although I am still not sure where 25mm roof armour was found by the devs.

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