Collimatrix

So I've seen this image used a whole lot across the internet as an estimate for the proportions of DM53 and I thought I would do my own measurements on it to see how things line up.
 
Disclaimer: I am merely providing my own interpretation of the measurements using the same methodology as whoever originally posted the image. Pixel measuring is an inherently inaccurate measurement tool and very subjective especially on blurry images such as this as people will have different opinions on which pixels can be considered part of the rod and which cannot. I accounted for pixel bleed as best I could by ignoring the softer and less consistent outlines where it was applicable. I do not consider my measurements any more correct and encourage other people to do their own measurements to compare to as well. In the image M829A3 and DM53 are not scaled exactly the same, there is a few px difference, so the ratios for both OP and my measurements will vary between the rounds.
 
Both DM53 and M829A3 don't have any officially published lengths, so people have gone to pixel measuring as a way to get estimates.
 
I started with M829A3 first by taking the pixel ratio for OPs estimate of 930mm. At 696px long this gave a ratio of 1.3362. The sabot diameter is always 119.9mm which makes it an excellent scaling tool which is what I used for my measurements(here I rounded it up to an even 120mm for simplicity sake). At 90px wide the ratio I got was 1.333 repeating. At a 0.003 difference OP did a good job measuring 829A3 imo as my ratio gave me a total length of the projectile of 928mm, only a 2mm or less than 2 pixel difference in our measurements. For all intents and purposes I consider M829A3's measurements accurate as can be estimated using this method.
 
Now onto DM53. Using OPs estimate of 760mm that gives us a ratio of 1.381818. Going off of the sabot which is 88px wide, I get a ratio of 1.3636 repeating. Now the difference here is a bit bigger (10mm or just over 7 pixels difference which I consider far outside the margin of error of 1-2pixels from M829A3) and when applying my ratio to the 550px long rod I get to total length of exactly 750mm. I actually found that OPs measurements for the diameter of DM53 lined up pretty well with mine just being a 1mm difference, but that is understandable due to the smaller pixel count of the diameter.
 
My last issue is with how OP measured the depth that the actual penetrating rod goes into the fin section. The pic of M829A3 is a proper cross section and we can see exactly where the rod ends so there is no estimates there, however the DM53 pic isn't a cross section and OP has given his own estimate of where he thinks it might end. To find a more accurate (but not exact) estimate in the ball park of where it might end I utilized the ratio of fin length to depth that the rod goes into that section. Here I also brought in a diagram of Type 10 APFSDS and I will explain why later.
 
M829A3 has 125mm long fins based on my measurements, 28mm or 22% of that length is overlapped by the penetrating rod.
DM53 has 110mm long fins based on my measurement and OPs estimate puts his estimate of where the rod might end at a depth of 54mm or just shy of 50%
 
Here I brought in a diagram of Type 10 APFSDS, because despite how secretive the Japanese are about their military equipment, we know quite a bit on this round. I used it as a control value to compare my estimates of M829A3 and DM53.
At 748mm long for the projectile and 350 pixels across I got a ratio of 2.13714. With the sabot at 56 pixels in diameter applying my ratio gives 119.6mm which is well within the margin of error (which is expected as we already know the measurements).
 
Now that we know the Type 10 diagram is accurate we can go back to the fins. Type 10 has 117mm long fins and a 32mm rod depth into the fin section which gives a 27% overlap (M829A3: 22%, OP's estimate DM53: 50%). And that is where my issue lies. I went ahead and gave DM53 the same overlap as Type 10 at 27% as M829A3 has a very different and longer fin design that pushes farther past the projectile body. 27% of 110mm gives 30mm and when measuring to the penetrator tip that OP estimated we get a 625mm penetrator length and an overall projectile length of 750mm for DM53.
 
Let me know if I screwed up anywhere.

K1s and K1E1s of the 5th Infantry Division conducting training at the Darakdae Training Center.
 

 

No, maraging steels require a pretty good amount of alloying elements, usually (a whole metric buttload of) nickel, cobalt and molybdenum, and then a dash of something strange like titanium or aluminum which forms the small, dispersed intermetallic inclusions that form during the final heat treatment.

Yes.  Generally speaking, bainitic steels are fairly cheap, at least in terms of the raw materials.  I can't speak for how much the exotic heat-treatment processes needed to create them drive the cost.
 
The martensitic transformation is a diffusionless transformation.  In fact, not only is it diffusionless, but it works substantially better and easier the less diffusion there is.  For this reason, fairly expensive alloying elements like molybdenum and chromium are added to (among other things) prevent the diffusion of carbon out of the austenite crystals during quenching.

The bainitic transformation is the opposite; it's a reconstructive, diffusion transformation.  So, for the most part and with a few exceptions, all the fancy and expensive alloying elements dramatically slow down the bainitic transformation.



Edit:  I suppose there are some other advantages as well.  Quenching and tempering to form a traditional martensitic microstructure can cause significant distortion of the metal.  Not only does plunging hot metal into oil or water potentially cause it to warp, but there's actually a small (but incredibly rapid) volume change associated with the martensitic transformation.  In fact, this is why katanas aren't straight.
 
I don't think that the bainitic transformations are anything like as sensitive to part thickness and geometry as quench and temper heat treatments can be either.

It uses a mix of medium and high frequency induction heating. With the device they patented, they are able to treat sections of steel up to 3m in length (which is a pretty big deal since it's usually hard to get NC steel plates that large). Talks about the quenching liquid and cooling rate to prevent cracking, but doens't mention which liquid was used, but does mention that Matensite does form in the cooling process. Talks about maintaining the correct space between the induction heater and steel plate and methodology to maintain that distance despite possible warpage from the heating process. Talks about how their methodology allows for the treatment of much thicker plates than what was normally possible before.
 
Basically they use a combination of medium and high frequency induction to allow for better heat treatment deeper into the steel (prior to this methodology single frequency induction was primary a surface treatment and didn't penetrate and heat treat the center of the steel). While the coil is moving around and heating the plate they dump an unknown liquid onto the surface at varying temperatures appropriate to the stage to quench the metal before it is once again passed over by the coil. The rapid heating and quenching at varying temperatures allows for better crystal structure formation as only certain crystal structures form under certain temperatures and conditions so the changing variables allows for more even and diverse crystal formation. Another effect of multiple treatments in rapid succession is that the grains constantly form, break apart then reform smaller each time which allows for the extremely small grain structure required of NC steel.
 
Video showing what induction heat treatment is like
 

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.

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.

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.

Thank you for the feedback. I used a variety of sources, including Nexter/GIAT drawings of a Leclerc UAE hybrid and plenty of reference images to generate the models:
 
 
As well as image references and Dark Labor's work:
 
 

https://www.serdp-estcp.org/content/download/34366/332230/file/WP-200805-FR.pdf
 
Demonstration of Tungsten Nanocomposite Alternatives to Depleted Uranium in Anti-Armor Penetrators
 
A more recent comparison of DU and WA penetrator performance.

https://ssl.bsk-z.or.jp/kenkyucenter/pdf/mnm20191225.pdf
 
Heres a brochure on NC steel used in the Type 10 and Type 16.

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.

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.

Factory new UAZs were received by separatists. Kornet launcher on some of them.

 
 

https://helda.helsinki.fi/bitstream/handle/1975/8020/ECO031.pdf;jsessionid=1D4F492F19FEAAE2F3ECAA7A5A2BEF66?sequence=3
 
A paper outlining a bunch of methods for calculating tire/track pressure on soil. This includes the original MMP formulas.

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

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

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.

Already before WW2 Czechoslovak industry rutinely produced heavy extremely thick armoured cast pieces, especially observation cupolas and firing posts for the fortifications. To my knowledge at least three companies were supplying them in hundreds (Steel works in Vítkovice, Třinec and Škoda in Plzeň). They had a lot of experience from working on armoured parts for Austro-Hungarian fortresses and navy (basically all heavy machinery of A-H Empire was enherited by Czechoslovakia). 
 
The mass-produced armoured cupolas for Czechoslovak interwar fortiffication had 150-300 mm thickness (per object resistance class), the weight was 20-65,5 tons (300 mm heavy cupola for twin-HMG). They were later largely removed and reused on Atlantic wall by the Germans. 
 
Due to Münich treaty this thing was never installed but parts were built by Škoda including at least one turret. The Armor of the turret was 300-350 mm, the fixed armor around the turret is 175-450 mm thick. The weight is roughly 120 tons for the retractable turret and 180 tons for the surrounding armor (there are two full-size semi-automatic 105 mm howitzers inside hence why the size). 
 

Source of the pixture is book of Eduard Stehlík: Lexikon tvrzí československého opevnění z let 1935–1938
 
 
Here is something from a recent research done with one of one of the cupolas produced in Třinec in 1937 (200 mm thickness): 
Chemical: C 0,28; Mn 1,15; Si 0,44; P 0,026; S 0,023; Cr 0,35; Cu 0,27; Al 0,01 
Ferrite-pearlite structure with measured hardness 177 HV 30 which shall be equivalent to 169 HB, i.e. rather soft. It is not much known about the original requirements, incomplete sources say the steel had to have tensile strength between 550-700 MPa and ductility 14-17%. Based on that the steel used on this cupola was probably close to the lower strength limit. 
 
Source is here.
 
 
Anyway starting with early 50' the new armory in Martin, Slovakia was producing quality cas turrets for T-34/85 and later T-55 and T-72 in thousands. 

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

 

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.

 

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

 


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