Future of AFVs

[rob89]

I still think that two cannons and related autoloaders, ammunitions and so on, in the same MBT is a conceptual error.
The future MBTs should be, if possible and "coeteris paribus", smaller and not larger.

 

The simplest (and current tech) solution to the APS problem remains, IMO, the saturation tactics.

If a volley of artillery/heavy mortar smart EFP falls on the MBTs' position in the same moment as they are under fire from 120/130mm APFSDS,  the APS has to choose and there are good chances that some shot (from above or from the front) will pass the barrier.

 

And, in any case, the possibilities of jamming the APS'sensors will be, almost surely, improved in the future.

[Mighty_Zuk]

6 hours ago, Bronezhilet said:

They work by acting on the fins of the APFSDS.

 

My understanding of the defeat mechanism comes mainly from this video:

Spoiler

 

In the video you can see multiple instances of interception of KEPs, and all showing the grenade detonating slightly before it meets the KEP's front tip (obviously when a force is applied closer to the end of a rod, it will have greater potential to tilt it), so I don't understand the necessity to hit the fins. 

What purpose does it serve to target the fins specifically, and why do you believe a KEP cannot be tilted and yawed via application of force at its frontal tip?

 

18 hours ago, LoooSeR said:

   For example "Shtandart" on Object 195 have probability to intercept KE rods of 0.5. This means that 50% of APFSDS are going to get through. Making them more resistant to inteception or harder to accurately track will bring this percentage to higher numbers.

 

Are you using low numbers for the sake of an example or do you actually believe the Afghanit is not as effective as advertised. It's one thing to be skeptical about official Russian announcements on matters of procurement, but the tech is already established, and has been so for quite a long time. I would be more surprised if its Pk wasn't scratching the 99% mark that contemporary APS designs have achieved.

I get what you're saying though. I just doubt that it's feasible, which I will explain why in the following replies below.

 

18 hours ago, LoooSeR said:

   APS systems have problems with doing anything serious with KE rods because of their speed, weight and material. There are no magic APS that can stop those rods mid air or make them disappear. So at first APFSDS design can fight against APS by making rods to be more damage resistant.

 

A defeat mechanism centering around breaking the rod is only one of few approaches. The approach that Iron Fist, Trophy (in its first iteration), and most likely also Afghanit (static launchers don't go well with MEFP tech, as MEFPs would limit its coverage), took, is inducing yaw to the rod but keeping it intact. Even when intact, a tilted rod will be able to concentrate only a fraction of its energy on the tip, and will not be aligned with its flight trajectory so even that lighter hit will not be backed by any 'new' material.

But I don't need to explain that to you. You know how all these APS work, so why even bother with this outdated approach of making rods more damage resistant when new APS are using a defeat mechanism that ignores the structural integrity of the KEPs.

 

18 hours ago, LoooSeR said:

 

When APS will advance far enough to be capable to reliably intercept APFSDS rods, it will be a time to go fo other options - fool APS via decoys, jammers, or overcomming APS using it's design restrictions. Idea is to avoid complication of already very complicated vehicle such as modern and future MBTs, thats why at first you go with chaning elements outside of tank design.

 

I don't understand why you don't believe that it's an established tech already. 2 countries should have MBTs with anti-KE APS in service within 2 years. Thousands such vehicles will be made by 2030, and these aren't systems with a laughable 50% success rate. 

All the ideas you've currently proposed are either only incremental, or standing in contrast with your opinion.

Fool APS via decoys? Well to make this as reliable as possible, knowing that APS categorize the threats and draw interception data from a library which almost nullifies the usage of decoys, one would have to use a decoy that is similar in size, trajectory, and velocity, to the projectile it's trying to mimic. Trajectory is a non-issue, but when mimicking size, shape, and velocity, you might as well just use a real KEP and at that point you're basically firing 2 rounds at the same target, which brings us back to the drawing board.

Jammers will have to be tank-borne and that adds complication to the tank. I'd say it adds even greater complication than an autocannon would, in terms of time and resources required to develop it and further maintain it (frequent software updates).

And last but not least, using the APS's weaknesses against it. Of course it's being done. Just look at how Rafael marketed their Spike LR 2 - an anti-APS weapon via a 70 degree dive, which is a direct reference to the Afghanit's inability to intercept top attack munitions.

But the Afghanit's radars can still observe the Spike LR 2 throughout its entire flight, and so retrofitting interceptors on the roof (e.g by replacing the large soft kill CM box on the turret roof with an interceptors' box) is the only thing required to overcome this issue. Adding a couple interceptors is the cheapest and easiest part of APS development.

 

18 hours ago, LoooSeR said:

 

   Some of proposed solutions are probably less wild as attaching additional cannons to a tank just to fire at APS on enemy tanks miles away. For example coating rods and shaping them to have less radar signature, while sabo parts acting as decoys (in close range fire) is not something too wild and can be done today or probably yesterday, if anybody wanted. 

 

Yeah, I found the ramjet-powered APFSDS to be a very neat idea, but for the reasons I explained above, unless these ramjets can be made into the same size as the main rod, it won't really work. 

And even if it's possible to make the ramjets the same size and same speed (which I am inclined to believe is possible), making an accurate discrimination is a matter of a relatively very simple algorithm.

Here's why I believe so:

1. The radar detects 3 objects flying side by side. Knowing the possible construction of such a system, it's safe to assume the middle rod is the real one and the remainder are fake.
2. Any maneuver of a rod to counter the problem in point #1 will have the APS classify it as a decoy, as real APFSDS cannot maneuver. Maneuvering at such ranges and such speeds is just seriously impractical for an APFSDS.
3. If maneuvers are taken out of the equation to avoid problem raised in point #2, then any interceptor powerful enough to induce significant yaw and pitch on a rod will almost necessarily have sufficient force to also defeat the ramjet decoys. It will also bring back problem #1.

Coating the tip may help, but stealth becomes less efficient as the distance to the radar decreases. Simple physics which you understand just as well as I do, perhaps better. 

It could work for a while, but it's a short term solution because an increase in computational power will allow radars to gradually reduce the minimum engagement range against KEPs, making stealth decreasingly important until it's completely irrelevant. Computational power is a resource developed extremely actively by the civilian industry, so it will always be abundant, and the retrofitting of new processors with substantially increased power will take a very short amount of time in terms of military procurement.

 

18 hours ago, LoooSeR said:

   Did i ever intended to release a munition from APFSDS hundrerds of meterws away from target at a greater speed than a rod itself? One of my ideas was to put a fragmenation warhead that will work as a shotgun shell, firing before APFSDS round enters interception zone, so tank will have APS system damaged as it will have no time to react to fragmentations and rod will be able to get to a tank armor. I guess exploding small warhead on rod tip will make fragments to fly fast enough, but timings and fragments shape/speed is a question of specific design work, not a forum post about concepts.

 

That is an interesting idea, but I believe it is still an incremental upgrade, to be implemented in layers.

18 hours ago, LoooSeR said:

 

   Under "turret" i meant tank main turret. That is not a good place to mount AC, as you will need to move whole turret to aim main gun at targets that were fired with AC, because windages and different elevations, plus turret will need to be locked for time of AC burst, to avoid turret rotation from AC recoil (5 tons peak recoil force on 2A42 for example), as AC will be off center. On top of that this thing will eat internal volume and space that could be used to mount a bigger gun or more rounds for coax MG and other actually useful equipment than an anti-APS AC.

 

Judging by the concepts shown in this thread, it seems to be a feasible idea, but I think it would be interesting to have a sort of competition for best design of AC in/on a turret as a practice. 

One idea off the top of my head is to make the gun retractable, but I'll have to think about how to make this feasible.

 

18 hours ago, LoooSeR said:

   I have my new Guards brigade tanks with 120-152 mm cannons and heavy IFVs with 57 mm ACs ready to attack capitalist West. Do you suggest to mount 57 mm AC coaxially to my main cannon and fire it in bursts?  Ammunition for it that is enough to make all KE shots "effective" against APS-eqipped AFVs would be carried where in order to not eat main ammunition? On gunner's laps? Tanks have other targets to fight with, not only enemy tanks and their APS.  

 

To be fair, I'm strongly against the induction of the 57mm gun into Russian army service. But even if it's added, then I assume it's still not too big of an issue. The turret bustle on the T-14 can store these rounds if it's extended. It doesn't need a crazy amount of ammo.

 

18 hours ago, LoooSeR said:

 

a) Drivers are more closer to go away than gunners in future

 

Current concepts of future MBTs such as Carmel and OMFV have omitted the gunner and now have the commander serve as a gunner, as much of the gunner's work has become automated, and portions of the commander's workload were also reduced by automation, allowing a dual qualification for roughly the same effort input.

The crews of these vehicles will consist of a driver and commander (I assume both will be trained in all roles - gunnery, driving, and commanding to a limited extent) as the core crew, and a 3rd crewman being a systems and UxV operator. 

 

A feasibility demonstration for such a vehicle, if everything went according to schedule, was already made in Israel this year.

 

18 hours ago, LoooSeR said:

   Yes, very hard.

 

While I find the idea of shutters extremely interesting, I don't think this is what @N-L-M envisioned, nor I. A shutter will have to look a bit like this:

Spoiler

 

The issue was not about how their motors would work, but how the whole system would react to saturation fire.

 

18 hours ago, LoooSeR said:

 Shutters on launcher can have small window that will be open to launch intercetping munition. APS can be designed to fire 2 or more of such intercepting subminitions if one of launchers was damaged. APS also can be designed to fire submunitions from launchers not visible in frontal projections, or protected from small arms and AC fire (example of such APS is Arena-M, where submunitions are covered by armor plates and launched upward, so launcher itself is not visible from front and sides).

 

Then the fittest APS by concept is the Quick Kill. If radars can really be protected and be completely undisturbed by protective sheets capable of defeating fragmentation from medium caliber munitions, then I'm sold.

 

18 hours ago, LoooSeR said:

So our APS now have high power lasers, EFPs, linear HEAT charges and shit but i am not allowed to fire decoys at enemies? 

 

Yes, Loooser. You don't have the privilege of Joo. That's probably why you call yourself "Loooser".

 

18 hours ago, LoooSeR said:

   Your way to deal with APS are even less effective and more fantasy fueled than anti-APS autocannons? Do we need to like solve puzzles during firing at enemy tanks? Wasn't one of first version of Kalanit simplified because gunners were confused how to use it?

 

Yeah, but I don't think it should complicate operation in any way if it's added as a single firing mode.

 

18 hours ago, LoooSeR said:

   Umm... what? Are we speaking about like ~30 years ahead or we are so far in future where 20th century level of tech like autocannons can effectively defeat all future tech and allow AP rounds to hit enemy tanks? What if in future there will be a high power laser APS that can melt small autocannon rounds right in mid air taking advantage of their long flight? 

   Also, if something was deemed in the past as viable does not mean it is still viable. People in old days thought that swords are good enough weapon, it doesn't mean we should attach swords to tank gun barrels.

 

I am under the notion that the past reasons for adding ACs aren't gone. They just got a little boost from 2 more reasons, and the disadvantages to their implementation were somewhat mitigated, which caused me to shift from being in the anti-AC camp to some level of intrigue, so I wanted to check this idea out with you guys.

[Bronezhilet]

11 minutes ago, Mighty_Zuk said:

My understanding of the defeat mechanism comes mainly from this video:

  Reveal hidden contents

 

In the video you can see multiple instances of interception of KEPs, and all showing the grenade detonating slightly before it meets the KEP's front tip (obviously when a force is applied closer to the end of a rod, it will have greater potential to tilt it), so I don't understand the necessity to hit the fins. 

What purpose does it serve to target the fins specifically, and why do you believe a KEP cannot be tilted and yawed via application of force at its frontal tip?

Of course, because things take time, the warhead has a certain velocity detonation waves have a certain velocity, shockwaves have a certain velocity and long rod penetrators have a certain velocity. Take all of these things together and it means that you have to detonate your warhead long before you reach the point you actually want to act on.

 

And come on Zuk, I thought you had at least a middle schooler's level of understanding of physics. The fins simply give a ton more surface area for the shockwave to act on.

[Xlucine]

Shouldn't add too much parasitic mass to include a timed fuse in the base of an APFSDS, so that just outside the interception range it goes pop and sheds the fins (~100g? The OICW grenades seem to be around that, and it's not much extra weight with several kilos of W). I wonder how early you could do it and still be stable enough when you hit the target?

[LoooSeR]

53 minutes ago, Mighty_Zuk said:

 

Are you using low numbers for the sake of an example or do you actually believe the Afghanit is not as effective as advertised. It's one thing to be skeptical about official Russian announcements on matters of procurement, but the tech is already established, and has been so for quite a long time. I would be more surprised if its Pk wasn't scratching the 99% mark that contemporary APS designs have achieved.

   Shtandart's 0.5 probability to intercept APFSDS comes in same paragraph with 0.9 probability to intercept HEAT (RPG/ATGM) type of rounds AFAIK.

 

55 minutes ago, Mighty_Zuk said:

A defeat mechanism centering around breaking the rod is only one of few approaches. The approach that Iron Fist, Trophy (in its first iteration), and most likely also Afghanit (static launchers don't go well with MEFP tech, as MEFPs would limit its coverage), took, is inducing yaw to the rod but keeping it intact. Even when intact, a tilted rod will be able to concentrate only a fraction of its energy on the tip, and will not be aligned with its flight trajectory so even that lighter hit will not be backed by any 'new' material.

this idea out with you guys.

   Thats why i was also suggesting "duplex" rods and decoys, to avoid main penetrator to be acted upon in the first place (on top of other posted suggestions, like stealth-shaped/coated rods).

 

58 minutes ago, Mighty_Zuk said:

I don't understand why you don't believe that it's an established tech already. 2 countries should have MBTs with anti-KE APS in service within 2 years. Thousands such vehicles will be made by 2030, and these aren't systems with a laughable 50% success rate. 

   Let's see them in action, how they perform in reality, than we can work out practical ways to defeat them. It is not like tomorrow Russian tanks are going to launch WW3 or something like that.

 

1 hour ago, Mighty_Zuk said:

All the ideas you've currently proposed are either only incremental, or standing in contrast with your opinion.

some level of intrigue, so I wanted to check this idea out with you guys.

   And anti-APS autocannons that can be easily countered with 1950s tech is totally the Great bright future of tank vs tank combat? Maybe before declaring my ideas as incremental, you should watch at your own suggestion without pink glasses.

   Also, number of my ideas can be retrofited to older tanks as well, because changes will be done with shells, not with tank layout/design.

   And what is standing in contrast with my own "opinion"? My opinion is to resist complication of tank, thats why we are going to change element outside of tank - ammunition design, instead of trying to carve out another weakspot in turret frontal armor for anti-APS cannons that could be countered by Soviet tech older than my father.

 

1 hour ago, Mighty_Zuk said:

Fool APS via decoys? Well to make this as reliable as possible, knowing that APS categorize the threats and draw interception data from a library which almost nullifies the usage of decoys, one would have to use a decoy that is similar in size, trajectory, and velocity, to the projectile it's trying to mimic. Trajectory is a non-issue, but when mimicking size, shape, and velocity, you might as well just use a real KEP and at that point you're basically firing 2 rounds at the same target, which brings us back to the drawing board.

   We don't know how well those future APS can spot a differense between real and decoy KE, as APS will see a tip and fins of our rod penetrator, which could be mimicked and played around with. There are 2 suggestions that don't really care about how well APS can recognize type of APFSDS - round with fragmentation programmable warhead and round that separates in 2 before entering APS interception zone.

   Also, sending 2 KE penetrators per shot is not wild idea, stuffing them into 152 mm cannons would not be a big problem. Ramjets also could be used for decreased load on gun breach and gun barrel to push increased mass.

 

1 hour ago, Mighty_Zuk said:

1. The radar detects 3 objects flying side by side. Knowing the possible construction of such a system, it's safe to assume the middle rod is the real one and the remainder are fake.
2. Any maneuver of a rod to counter the problem in point #1 will have the APS classify it as a decoy, as real APFSDS cannot maneuver. Maneuvering at such ranges and such speeds is just seriously impractical for an APFSDS.
3. If maneuvers are taken out of the equation to avoid problem raised in point #2, then any interceptor powerful enough to induce significant yaw and pitch on a rod will almost necessarily have sufficient force to also defeat the ramjet decoys. It will also bring back problem #1.

   Nobody said that each time only middle one will be real. Any weight non-symmetry of round will be countered by sabo shape, weights and decoy placements.

 

1 hour ago, Mighty_Zuk said:

Jammers will have to be tank-borne and that adds complication to the tank. I'd say it adds even greater complication than an autocannon would, in terms of time and resources required to develop it and further maintain it (frequent software updates).

   Some sort of jammers being a standart part of equipment for future tank is something more probable than anti-APS autocannons. Soft kill systems exists, EM mine sweapers kits exists, urban survival kits with IED and drone jammers are also a thing that is actually used even by Russian troops in Syria today and yesterday.

 

1 hour ago, Mighty_Zuk said:

Coating the tip may help, but stealth becomes less efficient as the distance to the radar decreases. Simple physics which you understand just as well as I do, perhaps better. 

   It is easy and very quick way to counter APS for some time, it is also cheap and can be used on any tank that can fire APFSDS rounds. Upgrade of whole fleet with new APS models will require time, which can be used to improve or design more advanced anti-APS shells for tank cannons.

 

1 hour ago, Mighty_Zuk said:

It could work for a while, but it's a short term solution because an increase in computational power will allow radars to gradually reduce the minimum engagement range against KEPs, making stealth decreasingly important until it's completely irrelevant. ted to check this idea out with you guys.

   Well, i expect it to have way longer life span than anti-APS ACs. Stealth aircrafts in active exist for 20 years now and nobody is dropping that idea, so there are reasons to belive that it is viable. Taking into account small size of KE penetrators and future materials, coating may give KE penetrators enough time to get into a zone of APS where it will have no time to react, or reaction will be to late to change anything.

 

1 hour ago, Mighty_Zuk said:

That is an interesting idea, but I believe it is still an incremental upgrade, to be implemented in layers.

   AHEAD tip on APFSDS is also relatively cheap concept and retrofittable to older tanks, without trying to slap anti-APS cannon on them. May work against some types of APS models, but that should be more tested. Exactly how incremental it will be depends on specific implementation of concept - penetration capability of fragments, their spread and density of fragments "wave", etc.

 

1 hour ago, Mighty_Zuk said:

Judging by the concepts shown in this thread, it seems to be a feasible idea, but I think it would be interesting to have a sort of competition for best design of AC in/on a turret as a practice. 

One idea off the top of my head is to make the gun retractable, but I'll have to think about how to make this feasible.

   Everything i know on a subject will not be practical for AC firing at tank combat ranges in attempt to hit APS modules hard enough to make it incapable of doing its job. If you go with something small, managable and not eating much space inside, you end up with crappy ballistics, low range and bad effect on target, which translates to increased ammunition to get the job done and finally hit APS enough times to render it inactive/incapable. If we go with AC powerfull enough to hit enemy tank at ranges at which KE are usefull, have good effect on target and workable ballistics, we end up with large size weapon that will produce a lot of recoil and will have big ammo, etc.

   Another problem with anti-APS ACs (outside of them being ineffective against APS with any sort of protection kit at tank combat ranges) that older tanks can't mount them without serious work done with re-designing them or creationg some sort of RCWS contraption. My suggestion about working with shells will allow to arm older tanks with ways to engage newer tanks. Example of concept is GL-ATGMs. After such ATGMs were made for new tanks, older tanks like T-55 and T-62 were also armed with them, and concept went even futher - to IFVs as well (Arkan for BMP-3).

 

1 hour ago, Mighty_Zuk said:

To be fair, I'm strongly against the induction of the 57mm gun into Russian army service. But even if it's added, then I assume it's still not too big of an issue. The turret bustle on the T-14 can store these rounds if it's extended. It doesn't need a crazy amount of ammo.

   Arming heavy IFVs with weapon that can't even pen enemy "classic" IFVs frontally is great idea? 57 mm autocannon allows for growth potential for round designs and firepower of vehicle in general, also it allows for HIFV to fit into "quasi BMPT" role. 

   Turret bustle on T-14 is already used for more important stuff than anti-APS ACs. Making it larger kind of decreases gains from having unmanned turret. 

 

 

[Toxn]

Side note, but does anyone else get the impression that future APS systems are rapidly going to develop into layered systems in pretty much the same way that CWIS systems did?

 

So you'll end up with one or two radars, an electro-optical system, short and long-ranged interceptors, decoy/chaff/smoke etc, but all miniature?

[LoooSeR]

41 minutes ago, Toxn said:

Side note, but does anyone else get the impression that future APS systems are rapidly going to develop into layered systems in pretty much the same way that CWIS systems did?

 

So you'll end up with one or two radars, an electro-optical system, short and long-ranged interceptors, decoy/chaff/smoke etc, but all miniature?

   To a degree - maybe, but boats have way more space and have less problems with weight limitations.

[Xoon]

23 hours ago, Bronezhilet said:

You should take a look at linear actuators. They're basically hydraulics but electric, but also retardedly quick. 50 kg pushing force at 1 m/s is standard for these things. Add a lever action or gearing or whatever and suddenly you can open and close heavily armoured shutters in milliseconds.

Hydraulics are better suited, much cheaper, the same performance for simple dead stop applications.

 

Electric linear actuators are more suited for precision, were they justify their price. Though they might be preferable to avoid a hydraulic aggregate. 

[Ramlaen]

I like the idea of a KETF tip on an APFSDS, but I don't see it being a viable option for long rods due to the limited payload you could use without drastically effecting the performance of the penetrator.

 

What about something like a duplex round, where the projectiles are stacked and seperate due to the mass/drag difference? (instead of splitting and traveling in parallel)

[Bronezhilet]

7 minutes ago, Xoon said:

Hydraulics are better suited, much cheaper, the same performance for simple dead stop applications.

 

Electric linear actuators are more suited for precision, were they justify their price. Though they might be preferable to avoid a hydraulic aggregate. 

Hydraulic fires are fun, right?!

[Lord_James]

6 minutes ago, LoooSeR said:

have less problems with weight.

 

The Washington naval treaty would like to have a word with you. 

 

 

But technology also gets smaller: mechanical loading systems were on warships long before they were on tanks; radar and radar countermeasures, too; as well as computers; and active defense systems (CIWS). 

[LoooSeR]

5 minutes ago, Lord_James said:

The Washington naval treaty would like to have a word with you. 

   Do heaviest ships have something like 65-70 tons max weight requirement?

[Xoon]

4 minutes ago, Bronezhilet said:

Hydraulic fires are fun, right?!

Depends on your belief in KISS and how much you are willing to pay.

 

If you believe hydraulic fires are a big enough hazard for the crew, even if the crew is isolated from the hydraulics, then electric actuators are the way to go. Though, big as high current cables can be fun too.  If you have ever welded, you know the deal.

[heretic88]

58 minutes ago, Bronezhilet said:

Hydraulic fires are fun, right?!

This one was lucky:

(btw, note the pressure! Imagine this in a tank!)

 

[Zadlo]

5 hours ago, LoooSeR said:

Arming heavy IFVs with weapon that can't even pen enemy "classic" IFVs frontally is great idea? 57 mm autocannon allows for growth potential for round designs and firepower of vehicle in general, also it allows for HIFV to fit into "quasi BMPT" role. 

 

But do you know that Russians didn't invent this idea?  

They have stolen it from Polish concepts made in the mid-90s  

[LoooSeR]

8 hours ago, Zadlo said:

 

But do you know that Russians didn't invent this idea?  

They have stolen it from Polish concepts made in the mid-90s  

Which idea? Arming HIFV with weapons that allow vehicle to do its job? 

[Zadlo]

Whole 57mm idea

[Xlucine]

Putting a 57mm gun on something intended to support infantry goes back over a century

[skylancer-3441]

Soviets actually had considered for some time an idea of putting 57mm autocannon on HIFV in late 80s, when they were developing one, under designation of BMPT - even though in the end (back in 1989-90) they decided against it.
There are 3 rather well-photographed prototypes which survived - all without 57mm, - objects 781 sb.7-1, 781 sb. 7-2, 781 sb.8 - which sometimes were called objects 781 and 782, 
but two years ago there was a post on otvaga forum, which claimed that there was 4th one  - 781 sb.9 - which had that 57mm autocannon, and that according to some rumors it was lost in fire during transportation.
Another text which claimed that they had considered 57mm autocannon in late 80s BMPT development, but does not mention that any prototype with such armament was built, - was published in August issue of 2018 in russian Technika i Vooruzhenie magazine.

[LoooSeR]

1 hour ago, Zadlo said:

Whole 57mm idea

Yes, without Polish ideas Russians would never get to idea of putting higher caliber ACs on IFVs in enviroment of increasing frontal protection of IFVs... wait what?

[LoooSeR]

57 minutes ago, skylancer-3441 said:

Soviets considered an idea of putting 57mm autocanon on HIFV in late 80s, when they were developing one, under designation of BMPT. There are 3 rather well-photographed prototypes which survived - objects 781 sb.7-1, 781 sb. 7-2, 781 sb.8 - which sometimes were called objects 781 and 782, 
but two years ago there was a post on otvaga forums, which claimed that there was 4th one  - 781 sb.9 - which had that 57mm autocanon, and that according to some rumors it was lost in fire during transportation.
Another text which claimed that they had considered 57mm autocanon in late 80s BMPT development, but does not mention that any prototype with such armament was built, - was published in August issue of 2018 in russian Technika i Vooruzhenie magazine.

   Do you know planned caliber(s) of autocannons for Object 299 HIFV?

[skylancer-3441]

Allmost 2 years ago Gurkhan (Aleksey Khlopotov) said on otvaga that 299-based HIFV was supposed to have 76mm autocannon, with two-section ammunition and some flexible hose feed system, and rate of fire of 60 rds/min.
there is also an article from Vestnik Bronetankovoy Techniki 1986-03 http://btvt.info/5library/vbtt_1986_03_avtomat_76.htm  on some 76mm cannon feed system prototype, which kinda fits that description, even though they only mention light armored vehicles.
...
BTW, If that picture of the same vehicle is to be trusted:

visible barrel lenght of depicted cannon is about 3.8 meters, and also it's rather thin.
...
of course, an artist which made both of those two pictures, could've followed his imagination and could've depicted something else entirely.

...

It is also known (from article in Technika i Vooruzhenie 2012-05 on BMD-3, which is also available on otvaga website) that in mid-80s as armament for BMP-3 they were considering some 76mm cannon, which is described elsewhere as medium-velocity, and some 45mm autocannon
...

 

Spoiler

Somewhere there are (obviously) much more information available on that, although of course whether those who probably have some of it (for example it's interesting to see that Weidzmin posted same picture of 299-based HIFV in march of 2015, some 2 years earlier than it appeared on btvt.info) would share - is another matter entirely. Anyway, it's inspiring to see that Gurkhan now also has a blog at zen.yandex.ru

 

[Zadlo]

On 1/3/2019 at 3:54 PM, LoooSeR said:

Yes, without Polish ideas Russians would never get to idea of putting higher caliber ACs on IFVs in enviroment of increasing frontal protection of IFVs... wait what?

 

If Russians went the same way as the Western Europe, we would see 37mm or 45mm autocannon at Russian IFVs.

 

Around 1995 Poles analyzed the most cost-effective autocannon's NATO caliber for BMP-1 replacement and they realized that the best solution is 35mm autocannon (30mm was unknown at that time) and it hasn't changed since that time. But they saw also that Oto Melara 60/70's ammunition had significantly better performance against armor than 35mm and 40mm AP rounds at that time. And the conclusion was that armament of new IFVs should be a mix of smaller (30mm or 35mm) autocannon and bigger (~60mm) (auto)cannon. And this mix should have appeared at the platoon level.

[rob89]

US Army's different opinions about future

 

https://mwi.usma.edu/heavyweights-battlefield-us-army-will-need-largest-armored-vehicles-next-war/

 

https://mwi.usma.edu/light-mobile-many-rethinking-future-armor/