AC GiantDad

54 minutes ago, VPZ said:

 

I'm talking about the exhaust on the chassis. 

the thing just above the 5th skirt panel? That's part of the NBC system

a reason that isn't a shitpost

On 5/18/2019 at 9:50 AM, heretic88 said:

Yes, that was the 3BM36 "Kamerger". Almost no info available. What is known that is was accepted in service in 1988, and it was part of the same development programme as the 3BM32 "Vant" for 125mm guns.

I meant the US Army developed their own as a test round to predict future threats, or it might have been an American 105mm round test fired at expected 115mm velocities

15 hours ago, heretic88 said:

I always find this "protection against 115mm" funny. What kind of 115mm? Penetration was ranging from around 220-240mm (3BM4) to probably more than 400 (3BM36). In 1978 3BM28 entered service, with DU core...

Afaik the Army made a 115mm DU monobloc round that was used for testing, no idea on the performance but I'm pretty sure someone here does

8 hours ago, Renegade334 said:

Wasn't the HAP armor previously described as steel-encased NERA arrays with DU backplates or interstitial DU meshing? Can't remember which piece of literature mentioned it or somewhat alluded to it (maybe DOE, not certain).

The only description I've seen of it that's verifiable is in the NRC license application, where it's described as "depleted Uranium encased in steel" and that says very little about the setup. I have a personal hypothesis on how it's set up, like several others, but it's purely conjecture.

On 4/7/2019 at 9:13 AM, Wiedzmin said:

DM13 same shitty round, have some report about it i think. need a lot of time to find it...

not really, DM13 uses a better penetrator slug made of WHA instead of WC and DM13 has a significantly better construction than BM-15/22, rather than simply having a slug that sits inside the nose of the penetrator body, the slug extends through the length of the penetrator body, meaning that it's less vulnerable to the shear stresses found at high obliquities. It's the same reason M735 and XM578E1 perform better at these high obliquities as well

You know, at this point, I've become convinced what the russians should have done is just taken the Object 187 hull and mated it with the Black Eagle turret or something. The Armata has been a comedy of errors, almost like a symbol of the government that spawned it really

the question I've got is what armor package they'll have. After all the NRC licensure process is rather long and tedious, will they use WHA as a uranium substitute like I've heard Australia did(don't quote me on that because I'm not sure) will they have a similar package to the Arab tanks or do you think they actually went through the whole NRC process

@SH_MM If I had to guess, maybe it's kind of like why Uranium alloys won out in the US for penetrators? Abundance and ease of manufacturing. Staballoys are easier to extrude and turn on a lathe than Tungsten alloys, they can also be drawn and cold rolled with less difficulty. WC and WHAs are often both sintered into a near-net shape because of the difficulty of machining them. Comparing between Oak Ridge's guide to machining depleted uranium and Midwest Tungsten Service's machining guide for their MT series heavy alloys, with a density of 17 g/cm³, the tungsten alloy requires a higher spindle speed, a slower feed rate and a slightly shallower depth of cut on roughing. In the worst case for both metals (slowest spindle speed, slowest feed rate, shallowest cut depth), you can turn tungsten at about half the rate of Uranium on a lathe.

1" Uranium bar Roughing: 573 RPM, 0.012"/rev feed, 0.050" cut depth = 1.080 in³/min metal removal rate

1" WHA bar Roughing: 764 RPM, 0.008"/rev feed, 0.030" cut depth = 0.576 in³/min metal removal

WHA lets you go significantly faster than uranium on finishing however, again comparing the worst case scenarios for both metals we get

1" Uranium bar Finishing: 1050.423 RPM, 0.002"/rev feed, 0.002" cut depth=0.013 in³/min metal removal

1" WHA bar Finishing: 954.930 RPM, 0.004"/rev feed, 0.010" cut depth=0.120 in³/min metal removal

This is why WHA penetrators are manufactured as close to the finished shape as possible while Uranium penetrators can afford to be further off from the complete shape.

Tungsten Carbide is an absolute bitch to machine too, requiring specialized inserts like Polycrystalline Cubic Boron Nitride and cutting rates during roughing that approach the finishing speeds of Uranium

There is also another difference between the two materials that's worth noting, how they interact with the actual cutting tool. Uranium is frequently compared to austenitic steel in Oak Ridge's literature, described as being susceptible to work hardening and built up edges. Tungsten on the other hand varies between class 4 alloys which behave like a highly abrasive version of grey iron with a risk of chip hammering, to the less dense class 1 and class 2 alloys whose behavior is closer to Uranium.

On 12/27/2018 at 2:19 PM, Liberator said:

  Reveal hidden contents

 

What's the source of the accompanying photo often used to verify this diagram anyways? Every time I try to reverse search it I hit a wall because it's either a recent post saying 'this is real M829' and not sourcing the image or diagram or it's on a bunch of Chinese language message boards which lead to me hitting a wall because unfortunately I can't read Chinese.

Asking because this lack of traceability makes me wonder about how correct this depiction of the 829 penetrator is. Especially considering that the cutaways/mockups of 829 series penetrators that this is often used as a counter-argument to are from General Dynamics/ATK, the manufacturers of the 829 series

Update: found source for M774 shape and the diagram, M774 shape is from from Aerojet Corporation promotional material regarding DU penetrators,

The diagram is from "FINITE ELEMENT MODELS TO PREDICT THE STRUCTURAI RESPONSE OF 120-mm SABOT/RODS DURING LAUNCH" by D.A Rabern and K.A Bannister

However the diagram is left un-sourced in the document and also provides no lead on the photo's origin