Collimatrix

Ah, so that does sound like flash processing, or something fairly similar to it.

I am... not entirely clear on how flash processing works, chemically speaking.  You can do some interesting things with it that do not make sense to me.  The nanostructured bainite that has been of interest for armor applications lately has an extremely lengthy heat treatment process that requires that the steel be held at temperature for multiple days.  But flash bainite processing can produce a comparably strong microstructure in mere seconds.

Given how bainite actually forms, I don't understand how this is not just magic.

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.

Aha, I stand corrected.

On 4/13/2021 at 1:20 AM, Atokara said:

https://ssl.bsk-z.or.jp/kenkyucenter/pdf/mnm20191225.pdf

 

Heres a brochure on NC steel used in the Type 10 and Type 16.

Rough translation anyone?

This looks like flash processing to me.

6 hours ago, AssaultPlazma said:

I'm shocked MPF hasn't been canceled yet.... Even if it passes trials I wonder if in the end the Army will actually buy them.

Agreed.  It's a bit puzzling that MPF has escaped the axe, but OMFV didn't.

On 4/13/2021 at 1:20 AM, Atokara said:

https://ssl.bsk-z.or.jp/kenkyucenter/pdf/mnm20191225.pdf

 

Heres a brochure on NC steel used in the Type 10 and Type 16.

Very interesting, thank you!

At the behest of @Lord_James, this shall be the thread for general discussion of conventional passive metallic armor.  Whether it's steel, titanium, magnesium, exotic laminates of all three, this is the thread for it.

In answer to your earlier question, Lord_James, relatively small amounts of boron, in steels that have the appropriate levels of carbon, form intergranular barriers that dramatically slow the diffusion of carbon out of the austenite crystals during quenching.  Long story short, this means that the depth of material that can be effectively hardened is much greater.

One of the persistent mysteries I am trying to solve is why exactly the Swiss purchased the Dragon ATGM system, which was a pile of crap, when MILAN existed, which is only a few pounds heavier and also actually works.

I found this publication, which contains an article on Swiss bicycle troops.  As of 1994, the Swiss had three entire regiments of bicycle infantry.  I thought this might be an answer; even though MILAN is only a little heavier than Dragon, for a bicycle-borne infantryman, a few pounds could make the difference.  But no, this is not the explanation.  The article states that the antitank companies of the bicycle regiments were motorized.

8 hours ago, Toxn said:

And partly because Stg-44 is overrated, right?

7 hours ago, Sturgeon said:

 

They mostly played with the roller retarded blowback schema, which saw great success postwar.

Almost nobody bothered with the StG-44, in many ways it's the Panther of small arms (I would argue not as bad, though).

Indeed.  Most of the early work on what would become the HK and CETME family of rifles was initially done in France by ex-Mauser employees.  They later moved to Spain, which they seem to have preferred for its relaxed economic protectionism, drier climate, and slightly fascist dictatorship.

20 hours ago, Toxn said:

Exactly. Earthmovers also don't have to worry about suspension travel and such, meaning that you can pack your extra wheels in aggressively.

Small wheels also have higher rolling resistance, and at high speeds tend to wear their rubber out faster.

On 4/6/2021 at 6:20 AM, Toxn said:

So, since I finally found a good document for MMP calculations: the one thing that interleaved roadwheels are amazing for is to allow you to cheat MMP calculations.

 

The other ways being pneumatic roadwheels and long-pitch track links.

Interesting.  The long pitch tracks I knew about, although there are practical limitations there, as the longer pitch tracks tend to be noisier and wear out faster.  The pneumatic road wheels are, I must admit, a surprise.

Do you have a link?

Apparently the British goofed around with interleaved road wheels, albeit because they cloned captured German half-tracks.

Holy shit, it's SuperComrade!

16 hours ago, delete013 said:

I think in all of the discussions on this forum a track might have broken on my tiger.

Ah, yeah, that's not great metallurgy for tank armor by postwar standards, but it definitely sounds like they had big enough foundries to make the parts.  I did not realize that the Czech T-72 turrets were domestically produced!

On 3/31/2021 at 7:02 PM, Beer said:

 

To my knowledge none of the known drawings shows interleaved wheels. All had standard torsion bars, some trailing, some leading. One of the drawings had one pair of torsion bars leading and the rest trailing to create space for turret basket. All had also rear drive sprocket. Even the Surin's suspension was quickly abandoned (it survived in an attempt to create cheap export tank on the basis of LT vz.38 but there was so much cheap armor around the Globe that time that it didn't get anywhere past test chassis). 

 

What was taken from German tanks was the gun mantlet in Topfblende style which in combination with the later cast IS-3 style turret looked very interesting. Generally the earlier concepts were looking a bit more German, the later took a lot of insipration from IS-3 but the vehicles were planned to be smaller, lighter, much less armoured and a lot faster and all were to be equipped with autoloader.. I will post some drawings later in the history section. 

What was the state of Czech casting foundries at the time?  IIRC, the big cat mantlets were the biggest armor castings the Germans could make.

On 1/11/2021 at 8:11 AM, Beer said:

 

Sorry for being late to the party but I found it interesting that the to my knowledge not a single serial vehicle, prototype or concept coming from ČKD (BMM) or Škoda during the war had interleaved wheels (not even any paper project). In the end only one of those designed during the war made it to serial production - the Pz.38(t) n.A. chassis used on Panzerjäger 38(t) Hetzer (albeit the design was somewhat affected by the deliberate effort of ČKD chief designer Aleksey Surin to sabotage it, especially the early vehicles). It's notable that the companies had German management installed to oversee any development, yet they still insisted on not to use the interleaved wheels. In light of what you wrote it is also possible that Pz.38(t) n.A. lost to Pz.II Ausf.L Luchs for this reason because otherwise it was arguably the better machine for its task.   

I had heard vaguely that a design concept for the Czech post-war TVP project was mocked up with interleaved road wheels, but that this was rejected.  I never saw a picture or anything.

So, yeah, a napkin drawing of a napkin drawing, according to rumor.

Post-war, most designers seem to have been content with other ways of reducing the MMP of their tanks.

On 3/1/2021 at 5:38 AM, Wiedzmin said:

 

Vigilant 

What report is that from?  I would be very interested to see the whole thing if you have it.

I did find this picture of a TOW missile in flight, you can see it's significantly nose-up:



Edit:  Derp, I just posted the same picture you found.

11 hours ago, delete013 said:

You talk about panther's double system? Torsion bars in general are pretty narrow. They require about 10cm more heigh, that is all. Everything else is either bigger or more complex.

 

If you'd done several seconds of research you would know that this isn't true, and would have avoided looking like an idiot.  Do you have a humiliation fetish or something?

The additional height of a torsion bar isn't the diameter of the torsion bar itself.  Torsion bars almost never touch the floor of the hull.

It's almost like they need big bearings for the swing arms or something.

Again, you need only have taken several seconds to ascertain whether this was true or not.

Quote

Or you reduce the strain on each component by splitting the rotation of a wheel arm between two torsion bars and reducing the distance between wheels, as was the case of a panther.

For the love of Robert Hooke, that's not what "strain" means.

A patent that looks like it might be for the SU-57 air intake:

https://patents.google.com/patent/RU2460892C1/ru

Very interesting shock wave geometry.

16 hours ago, delete013 said:

251 would eventually be replaced by smth akin to Gep. MTW Kätzchen, which has what? The interleaved wheels.

The theory is pretty straightforward, as has bees mentioned. Larger wheels with narrower gaps in-between offer better absorption of terrain and better carrying of the weight at any speed. In fact, almost every late-war German design had overlapping wheels. The E-Serie study is full of them, not only the heavies.

 

They weren't considered as good as interleaved but a compromise had to be made. Any other form of suspension was an emergency improvisation, especially bogies that were considered obsolete. Lucky for the WAllies, rarely is pointed at the fact that they largely dispensed with tactical maneuver mid-war, do no need for fancy drive trains. Infantry tanks suddenly didn't need speed or agility, cruiser tanks no armour. Sounds perfect for that doctrine, too bad Germans didn't abide to it.

 

You don't understand, is not on your favourite tank, so it is stupid? Lol. Overlapping wheels on tiger 2 were not considered as optimal as the interleaved would be. But they still offered that needed weight distribution, across the chassis but also on individual wheel. This reduced strain on roadwheel arms and individual torsion bars when hitting several bumps on uneven terrain. Which is one clue to understanding that IS-2 with its small wheels couldn't be anything but slow, unless one wanted to incapacitate the crew or the drive train. Hence, faster off-road speeds for Germans, better maneuvering, more flanking surprises, better combat performance. And it is pretty clear what the Allies were the worst at, maneuver warfare. There is no reason to think that the design wasn't the best around. Everyone else ran about with lighter or slower vehicles.

 

There is however another reason. Germans had to include the limitations of their steel into calculations.

You categorically do not understand what you're talking about.

 

Quote

The theory is pretty straightforward, as has bees mentioned. Larger wheels with narrower gaps in-between offer better absorption of terrain and better carrying of the weight at any speed. In fact, almost every late-war German design had overlapping wheels. The E-Serie study is full of them, not only the heavies.

That's not the theory at all.  I'm slightly curious if you read this nonsense somewhere or came up with it on your own, but only slightly curious, so please don't belabor me with a large amount of detail.  Having more points of articulation on a suspension does not affect the force experienced by the chassis or crew.  When the tank is at rest the road wheels will exert the tank's weight against the ground via the suspension springs.  When the tank is going over an obstacle, the vertical component of the acceleration will be buffered by the travel of the independent suspension stations.  If there are more of these stations, then they will have lower K values of their springs, otherwise the suspension would just get stiffer from having more stations.  There will be a very slight difference in response from having more unsprung mass.  Having more points of articulation does increase the tendency for the tank to pitch in response to acceleration and deceleration, but for the number of roadwheels typical for tanks this distinction is immaterial.

 

Quote

They weren't considered as good as interleaved but a compromise had to be made. Any other form of suspension was an emergency improvisation, especially bogies that were considered obsolete. Lucky for the WAllies, rarely is pointed at the fact that they largely dispensed with tactical maneuver mid-war, do no need for fancy drive trains. Infantry tanks suddenly didn't need speed or agility, cruiser tanks no armour. Sounds perfect for that doctrine, too bad Germans didn't abide to it.

Interleaved roadwheels are equivalent to overlapped ones in terms of ground pressure reduction.  Point me to any serious engineering analysis that says otherwise.

 

Quote

You don't understand, is not on your favourite tank, so it is stupid? Lol. Overlapping wheels on tiger 2 were not considered as optimal as the interleaved would be. But they still offered that needed weight distribution, across the chassis but also on individual wheel. This reduced strain on roadwheel arms and individual torsion bars when hitting several bumps on uneven terrain. Which is one clue to understanding that IS-2 with its small wheels couldn't be anything but slow, unless one wanted to incapacitate the crew or the drive train. Hence, faster off-road speeds for Germans, better maneuvering, more flanking surprises, better combat performance.

You need to learn that words mean things.  "Strain" has a very specific, mathematical meaning, and you are badly abusing the word here.

Thank you very much!

Does anyone have a copy of History of the Shillelagh Missile System?  The original link to it on the Redstone Arsenal page is dead.

Chinn has this to say:

"If it were possible, it would be highly desirable to be able to compute exactly what size and shape of orifice should be used, or to know in advance how the configuration of the passage leading from the barrel to the gas cylinder will affect the variation of the cylinder pressure with respect to time.  Unfortunately, accurate solutions to these problems and to problems of a similar nature can not be obtained analytically because of the complexities involved in predicting the flow of the turbulent and high velocity gases produced by the propellant explosion."

I suspect that such analysis could be done today with computer voodoo, but that for the vast majority of existing gas operated designs, the engineers applied some rules of thumb to get themselves close, and then iterated from there.