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Belesarius

We will build it for China! New Chinese 125mm tank gun handed over for testing.

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Liked the article for the most part, but they're wrong in the fact that all ZTZ-99s use two piece ammo, the A2 was upgraded to fire unitary ammo quite a bit ago and doesn't even use the same gun/autoloader as the ZTZ-96/Previous gen 99s. (It has an L/52 gun as opposed to L/48.)

 

Though damn, it sure as hell doesn't have a 1200mm length penetrator rod, that's goddamn massive.

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What enemy would make China need this gun?

It wouldn't be the Indian Army due to terrain and Vietnam doesn't have great armor either. Japan is a stretch. South Korea and U.S. Forces in SK seem likely but I know a country that just debuted a new tank and has a large border with China and is likely going to have diplomatic crises with China in the coming years over Central Asia.

Armata killer?

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What enemy would make China need this gun?

It wouldn't be the Indian Army due to terrain and Vietnam doesn't have great armor either. Japan is a stretch. South Korea and U.S. Forces in SK seem likely but I know a country that just debuted a new tank and has a large border with China and is likely going to have diplomatic crises with China in the coming years over Central Asia.

Armata killer?

 

It's not uncommon to test larger guns just as future proofing.

 

Hell, China has done it in the past with their 140mm high velocity gun, the USA, Germany, Switzerland, Sweden and probably some other western nations have also tried 140mm Guns, the USSR/Russia have tested 152mm in the past before. etc.

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I manage it would be more likely then the 140mm they tried in the past for a few reasons, either way, an APFSDS round made of DU with a potential length of 1000-1200mm, 30mm wide (the width of a half dollar piece quoted and also the width of the current unitary rod) and traveling at 2,000 m/s might be enough to give me an erection.

 

.....erm.... I mean.... *quickly disappears into bathroom*

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Memory serve me, ATK used to have that photo on their info PDF before their merger with OSC, they have a different one now but the text, font and color of the specs below are still the same.

 

http://www.orbitalatk.com/defense-systems/armament-systems/120mm/docs/M829A3_Fact_Sheet.pdf

 

New one is shittier. =/

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Comparative measurements of gun power are interesting, and deceptively complicated.

 

I'll have to put up a proper thread on it as soon as I know all the physics and math, or at least more of it, but basically:

 

 

-A gun is an internal combustion engine, only it spits its piston downrange at the enemy.

 

-Bore volume in a gun is analogous to displacement in an engine.  (Obligatory make fun of T___A moment)  The swept volume traversed by the projectile informs how powerful the gun is.

 

-Pressure is the other part of the equation.  By dimensional analysis, volume times pressure is work.  (Distance cubed times force divided by area is force times distance is work).  So, the integral of a pressure/distance plot multiplied by bore area would be work:

 

barrel5.jpg

(The jitteriness is caused by limitations in the sampling equipment.  The real curve is obviously smooth)

 

-Only this isn't true, because inside a gun, things are moving so quickly that Pascal's Law does not apply.  The work performed on the bullet is the integral of the distance/pressure curve times bore diameter of the pressure at the base of the projectile.  The pressure at the base of the projectile is lower than the pressure that the breech is containing, and these numbers diverge more as velocity goes up.  This is because there's a finite speed of sound in the propellant gas, and as the projectile moves faster and faster, it's outrunning some percentage of the propellant gas, which is thus not exerting pressure on it.

 

 

 

 

So, what does all this ugly math, thermodynamics and (shudder) fluid dynamics have to do with the power of tank guns?

 

At this point in the arms/armor race, APFSDS penetrators are the way to go for gun-launched anti-tank projectiles.  HEAT rounds of a given caliber can generally produce more penetration in RHA, but there are currently more effective countermeasures to HEAT ammunition than to APFSDS.  For best effectiveness, APFSDS needs to be very long and moving very fast.  So the gun had better have some oomph to it if it's going to fling a long enough penetrator fast enough to hurt enemy tanks.

 

Military Reform people (I'm thinking specifically of Blacktail Defense) love to obfuscate this facet of tank design and sign paeans about how wonderful the old L7 was, and how it's just shiny-technology-obsessed brasshat narcissist fucktards who insisted on overspecialized smoothbore 120mm that don't have the ammunition capacity or flexibility that the nonlinear modern battlefield requires.  Bullshit.  L7 was stretched to its absolute limits and kept in service far longer than it should have been.  125mm APFSDS couldn't touch a T-90 with Kontakt-5; what the hell would make anyone think that the piss-weak British rifled guns still had a place on a modern tank?

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