General AFV Thread

[LoooSeR]

 

[Ramlaen]

 

[LoooSeR]

   VT-4 during Pakistan day parade

 

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[LoooSeR]

   Milosh UGV used by Serbian troops during exercises.

 

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[Beer]

Something new regarding Czech IFV tender. After several months of internal disputes about MoD financing vis-a-vis covid situation there is now a request from the ministry of industry and trade to enlarge the required value of the offsets. At the moment it is expected that by late April the trials of the vehicles shall finally restart and by early May the competitors shall receive the conditions for their final bid. The size of the order stays on 210 vehicles. 

https://www.irozhlas.cz/zpravy-domov/bvp-bojova-vozidla-pechoty-tendr-ministerstvo-prumyslu-ministerstvo-obrany_2104141347_ako

[h44]

I have a question to ask. Why is it that Russian/Chinese tanks seem to have significantly worse recoil absorption when compared to western tanks such as M1, Leopard but also K2.

This obscure video demonstrates it. The video describes it as a comparison between stabilizers but I think it has more to do with hydraulic/recoil springs, recoil length, turret weight more than capability of the stabilizer.

But it seems the Russians/Chinese didn't really place much design emphasis on this. Are they just cutting cost as usual? Does the superior recoil absorption provide a significant practical advantage? One advantage I can think of is crew comfort. But in a tank where you're only shooting once every roughly 10 seconds does this really provide much practical advantage?

[Collimatrix]

4 hours ago, h44 said:

I have a question to ask. Why is it that Russian/Chinese tanks seem to have significantly worse recoil absorption when compared to western tanks such as M1, Leopard but also K2.

This obscure video demonstrates it. The video describes it as a comparison between stabilizers but I think it has more to do with hydraulic/recoil springs, recoil length, turret weight more than capability of the stabilizer.

But it seems the Russians/Chinese didn't really place much design emphasis on this. Are they just cutting cost as usual? Does the superior recoil absorption provide a significant practical advantage? One advantage I can think of is crew comfort. But in a tank where you're only shooting once every roughly 10 seconds does this really provide much practical advantage?

I'm not sure if strong conclusions can be taken from that one video.  Different ammo types produce radically different amounts of recoil.  Discarding sabot training ammo doesn't produce too much recoil, while HE-FRAG is firing a big, heavy shell with a lot more momentum.

 

Aside from that, it occurs to me that the 120mm armed tanks listed are all heavier than the 125mm armed ones, although the weight of the K2 and T-14 overlap.

 

How a tank responds to the recoil of its gun firing is a function of the total momentum of the shot, the mass of the vehicle, the moment of inertia about the recoil axis (which is affected by which way the turret is facing), suspension stiffness, suspension damping, and recoil system length and forces.  You are correct in thinking that the stabilizer doesn't have very much to do with it.  In addition, I suspect that the K2 may enjoy very low recoil when firing from a stationary position, as it has adjustable suspension.  The rear hydropneumatic stations can be filled with additional gas pressure, which increases the K* of the stations, which reduces the amount that the tank rocks when firing provided the gun is pointed more or less forward.

 

The most effective way for light vehicles to deal with high trunnion loads from their cannons is to have very long recoil lengths for their cannons' recoil systems, but this comes at a cost.  The longer the recoil path of the cannon, the more empty space needs to be reserved to accommodate the movement of the breech.  This makes the turret more voluminous and taller.

I don't think that it's a significant cost driver.




*Compressed gas doesn't act exactly like a spring, but close enough.

[delete013]

6 hours ago, Collimatrix said:

I'm not sure if strong conclusions can be taken from that one video.  Different ammo types produce radically different amounts of recoil.  Discarding sabot training ammo doesn't produce too much recoil, while HE-FRAG is firing a big, heavy shell with a lot more momentum.

 

Aside from that, it occurs to me that the 120mm armed tanks listed are all heavier than the 125mm armed ones, although the weight of the K2 and T-14 overlap.

 

How a tank responds to the recoil of its gun firing is a function of the total momentum of the shot, the mass of the vehicle, the moment of inertia about the recoil axis (which is affected by which way the turret is facing), suspension stiffness, suspension damping, and recoil system length and forces.  You are correct in thinking that the stabilizer doesn't have very much to do with it.  In addition, I suspect that the K2 may enjoy very low recoil when firing from a stationary position, as it has adjustable suspension.  The rear hydropneumatic stations can be filled with additional gas pressure, which increases the K* of the stations, which reduces the amount that the tank rocks when firing provided the gun is pointed more or less forward.

 

The most effective way for light vehicles to deal with high trunnion loads from their cannons is to have very long recoil lengths for their cannons' recoil systems, but this comes at a cost.  The longer the recoil path of the cannon, the more empty space needs to be reserved to accommodate the movement of the breech.  This makes the turret more voluminous and taller.

I don't think that it's a significant cost driver.




*Compressed gas doesn't act exactly like a spring, but close enough.

So what is the important factor here? I assume it is the question whether the recoil affects accuracy. Or whether ealignment is needed? I guess if sights are independent from the barrel and wobble doesn't disturb the shot the bounce doesn't matter until the reload is finished.

[Lord_James]

I would suspect it has something to do with the recoil length and chamber pressure; the shorter recoil length being necessary to fit in the eastern-block turrets would produce a higher impulse, but I don’t really have any numbers, and I am too lazy right now to go look. 

[Korvette]

Fofanov says the 125mm's recoil length on the MBT's are at 310mm hard stop, Rh120 is at 500mm (I think, the brochure doc for the gun has really unusual english). But Russian MBT's also don't necessarily have 'strong' suspensions like the NATO mbts and are much lighter. So they dont have to give much care to ground pressure and track size due to their weight being 20+ tons less than the West. And just as said the K2's hydro suspension will help a bit with absorbing the force from firing, just like the Leclerc and admittedly CR2, though watching them fire with the additional weight packages makes them seem like unmovable bunkers instead of 'stable firing platforms'.

 

It really comes down to how heavy you are which makes it harder to push, how much is being absorbed and how stable you are. Russian tanks don't have a reason to care much for this since they're smaller, tighter, and lighter. Plus with a stabilized sight as with all modern vehicles have, you're not having your eyes forced off target for the next shot.

Edited April 16, 2021 by Korvette

[h44]

1 hour ago, Korvette said:

Fofanov says the 125mm's recoil length on the MBT's are at 310mm hard stop, Rh120 is at 500mm (I think, the brochure doc for the gun has really unusual english). But Russian MBT's also don't necessarily have 'strong' suspensions like the NATO mbts and are much lighter. So they dont have to give much care to ground pressure and track size due to their weight being 20+ tons more than the West. And just as said the K2's hydro suspension will help a bit with absorbing the force from firing, just like the Leclerc and admittedly CR2, though watching them fire with the additional weight packages makes them seem like unmovable bunkers instead of 'stable firing platforms'.

 

It really comes down to how heavy you are which makes it harder to push, how much is being absorbed and how stable you are. Russian tanks don't have a reason to care much for this since they're smaller, tighter, and lighter. Plus with a stabilized sight as with all modern vehicles have, you're not having your eyes forced off target for the next shot.

 

Very interesting thanks. Also interesting is according to this website, they mention that "US studies on the gun concluded it was overly complex and expensive by American engineering standards, so a version using fewer parts was developed (such as a new coilspring recoil system, instead of an hydraulic one, like on the Rheinmetall 120mm L44), and designated the 120mm M256 gun." I also vaguely remember looking at a picture on here that someone posted with a M256 gun taken apart and you can see the recoil system but I can't find it now.

[Atokara]

2 hours ago, Korvette said:

It really comes down to how heavy you are which makes it harder to push, how much is being absorbed and how stable you are. Russian tanks don't have a reason to care much for this since they're smaller, tighter, and lighter. Plus with a stabilized sight as with all modern vehicles have, you're not having your eyes forced off target for the next shot.

 

Simple size and weight shouldn't really be an excuse here seeing as the Type 10 is the lightest MBT with a standard chamber pressure that is 100 bar short of the 2A46M-5s maximum chamber pressure, while also having the smallest recoil impulse. That isn't to say that Russia NEEDS a better recoil system though. When you have 7+ seconds between firing and a completed reload cycle there isn't much point of having an immediate stable firing platform when you still need 5 more seconds to finish reloading. My point is just that Russia's recoil system is pretty substandard and being light isn't an excuse for that.

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11 hours ago, Collimatrix said:

The most effective way for light vehicles to deal with high trunnion loads from their cannons is to have very long recoil lengths for their cannons' recoil systems,

 

Japan went this route for the Type 16

https://www.youtube.com/watch?v=rDJPxZKXlcU&t=21s

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Although the Type 16 doesn't have active suspension like the MBTs it still has passive suspension for smoothening regular cross country driving as well as recoil impulses which allows for stuff like this. 

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While the Stryker which ironically has an active suspension system, lacks a proper passive one looks like this

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[Korvette]

3 minutes ago, Atokara said:

 

Simple size and weight shouldn't really be an excuse here seeing as the Type 10 is the lightest MBT with a standard chamber pressure that is 100 bar short of the 2A46M-5s maximum chamber pressure, while also having the smallest recoil impulse. That isn't to say that Russia NEEDS a better recoil system though. When you have 7+ seconds between firing and a completed reload cycle there isn't much point of having an immediate stable firing platform when you still need 5 more seconds to finish reloading. My point is just that Russia's recoil system is pretty substandard and being light isn't an excuse for that.

  Reveal hidden contents

 

 

 

Japan went this route for the Type 16

https://www.youtube.com/watch?v=rDJPxZKXlcU&t=21s

  Reveal hidden contents

 

Although the Type 16 doesn't have active suspension like the MBTs it still has passive suspension for smoothening regular cross country driving as well as recoil impulses which allows for stuff like this. 

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While the Stryker which ironically has an active suspension system, lacks a proper passive one looks like this

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I did also specifically state the amount being absorbed is also important.

[SH_MM]

13 hours ago, Korvette said:

Fofanov says the 125mm's recoil length on the MBT's are at 310mm hard stop, Rh120 is at 500mm (I think, the brochure doc for the gun has really unusual english).

 

The recoil length is 340 mm for the L/44 and L/55 guns with a hard stop at 380 mm. Only the L/47 LLR (light low-recoil) has a recoil length of 500 mm.

 

12 hours ago, h44 said:

I also vaguely remember looking at a picture on here that someone posted with a M256 gun taken apart and you can see the recoil system but I can't find it now

[Beer]

http://fofanov.armor.kiev.ua/Tanks/ARM/2a46.html

 

310 mm hard stop for 2A46 family but 700 mm for low-recoil variant 2A75 used in Sprut-SD/SDM. 

[Collimatrix]

Yes, typically light tanks or tank destroyers have special, longer recoil stroke variants of standard guns.  For an older example, the TAM had a special variant of the L7 which could accommodate a 540mm recoil stroke vice the standard 280mm.

[Korvette]

7 hours ago, SH_MM said:

 

The recoil length is 340 mm for the L/44 and L/55 guns with a hard stop at 380 mm. Only the L/47 LLR (light low-recoil) has a recoil length of 500 mm.

 

Okay thanks, I was reading off this where it said 'width of recoiling mass' which seemed off but sort of what I was trying to find.

[Stimpy75]

Bismarck wheeled Tank from behind

[Beer]

Photos from the military trials scrutineering of the three contenders for the Czech IFV tender. 

 

Interestingly the CV90 is on rubber tracks while the ohters on metalic ones. 

https://www.idnes.cz/zpravy/nato/bvp-obrana-metnar-havlicek-vlada-pasove-vozidla-armada-vybor.A210428_131259_zpr_nato_inc/foto/nahledy

[Serge]

CV90 is the lightest contender. 

[Stimpy75]

Jordanian Centauro 

[BaronTibere]

They really love that camo. I wish they didn't.

[Beer]

On 4/28/2021 at 7:45 PM, Beer said:

Photos from the military trials scrutineering of the three contenders for the Czech IFV tender. 

 

Interestingly the CV90 is on rubber tracks while the ohters on metalic ones. 

https://www.idnes.cz/zpravy/nato/bvp-obrana-metnar-havlicek-vlada-pasove-vozidla-armada-vybor.A210428_131259_zpr_nato_inc/foto/nahledy

 

Short video:

 

[Beer]

New video from Czech IFV military trials. Some speed driving.

 

[Beer]

New short video from the Czech trials. There isn't anything really interesting in the talk.