Collimatrix

So, for the record, this is how Obus-G works:

See those little ports at the back end of the shell?  Those let in propellant gas to the inside of the shell, which then vents out the ports in the front and through the gap between the nose fuze and the shell body.  The inner HEAT warhead is "floating" on the high-propellant gas that gets vented inside the shell.

On 4/22/2019 at 10:49 PM, AssaultPlazma said:

Abrams Driver then Gunner* 

 

Anyway once after we returned from Kuwait and not to long after we gotten our tanks back from the boat/train we had to loan out some of ours to another unit conducting training. So after like a week of so the guys return the tank claiming the turret was traversing on its own with zero human input whatsoever. So one day the mechanics tell us to go ahead and startup this particular tank and move it forward (so the turret can be freely moved without hitting other parked tanks). They specifically told us not to worry about the turret because its hydraulic line had been completely disconnected and that there was no way it could move unless manually.

 

I hop in and startup and I swear that thing made the freakiest engine startup noises I'd ever heard. Sure enough a couple of moments later with my head out cause I was open hatch in the seat the freakin turret starts traversing on its own! Needless to say I immediately ducked my head and dropped the seat and did an emergency shut off of the engine. Even if I hadn't have ducked I would have been fine since it was parked with 2 tanks on either side and once the gun tube hit the adjacent tanks bore evacuator it stopped it in its tracks anyway. No one got hurt but the tank next to it had to get a replacement bore evacuator though lol......

I stand corrected.

So what exactly causes the turret to swing around on its own like that?  That sounds... bad.

I am curious if this ammo is isolated as well.  But I propose that isolated ammunition stowage doesn't make as much difference in a hull rack as it does in a turret bustle.

With a turret bustle like on the Abrams, the ammo is behind the crew and the blast door is between the crew and the ammo.  In order for the blow-off panels to do their magic and vent the overpressure of the burning ammunition propellant to the outside, those blast doors need to be both closed and intact.

This is actually fairly likely in the case of the Abrams, because within the arc of the most likely lines of fire, it is probable that a round could go through the bustle but not penetrate the crew compartment and the blast door.  The residual penetration of the threat round would exit the back of the turret.  The rounds would then cook off, but the crew would remain alive.

But with a hull rack, the blast doors are going to need to be between the turret ring and the rack, and there will need to be a firewall between the driver and the ammo.  There aren't that many angles where a round can penetrate the hull rack from a frontal hit but not penetrate the blast doors.  Unless of course the round has exactly enough penetration to get through the hull armor and the ammo compartment, but it craps out before penetrating the blast door.

So, an isolated hull rack is good because it protect the ammo from cooking off in case of, say, a fuel or lubricant fire (or at least it means the ammo takes longer to cook off), but I don't know that it helps that much against incoming fire.

I've also seen pictures of a stack thin Al alloy plates that were glued together compared to a monolithic plate of the same composition.  The monolithic plate sheered, the layered one did not.  There are a few ways to skin this particular cat.

On 4/24/2019 at 9:54 PM, EnsignExpendable said:

Interesting I don't recall ever seeing one with a coax MG.

On 4/24/2019 at 10:55 PM, Scolopax said:

Seconded

Per this site, the STUG IIIs only started sporting coaxial MGs in 1944.

1 hour ago, AssaultPlazma said:

Anyone got a good picture of a StuG that was fitted with a coaxial machine gun? 

With

Without

That's for the cast mantlet.  I know there are supposed to be box mantlets with and without the coax as well, but I'm not sure what the box mantlets with the coax look like.  I also have no idea how the coax mount looks from the inside.

Three videos on techniques for adjusting the harmonics of an AR-15 barrel:
 

The techniques discussed are:

1)  Adjusting the orientation of the flash hider in order to find the harmonic sweet spot
2)  Tightening the barrel to the receiver (apparently this is covered in an American Gunsmith article in depth)
3)  Adjusting the torque on the barrel nut
4)  Applying a small amount of pressure on the bottom of the barrel via a set screw in a NM-style float tube
5)  Adding an adjustable harmonic mass (similar to the Browning BOSS system), outside the context of NM
 

17 hours ago, Alzoc said:

 

Just a plain old bump sign.

I guess that mean that yours is different in the US?

We have these:

2 hours ago, Kal said:

hull armour

Nose 189mm CE, 125mm KE includes bulkhead 1

Fuel tank 120mm CE, 103mm KE includes bulkhead 2

NERA ERA array

Horizontal Nera at 82

Vertical lefthand Era at 60

Vertical righthand ERA at 60

Horizontal NERA at 82 contines

Includes bulkhead 3 

Final armour, ceramic dwell package

193mm CE, 132mm KE

Includes bulkhead 4

 

Each bulkhead is 100mm Structual Cast Magnesium followed by 25mm textolite (as spall liner/fire resistence).   Bulkheads take up 30% of volume but maybe 10% of protection, 20% of weight

 

I have used interface defeat / dwell structures (shock wave attenuator, confinement, buffer/shear support, weak layer, ceramic, base ) twice but left the KE and CE as given for borosilicate.  Against steel, borosilicate glass can provide some dwell protection but doubtful against tungsten etc.   Is mullite an acceptable choice for 1961? its roughly halfway between quartz and alumina and is basically just high quality porcelain.

 

Total array is about 4.5 tonne per m2.  And fits within the 1.75m depth allotted to it (1.68m).

 

No way is turret anywhere as well armoured as hull.  But design is commander and driver in hull, gunner 1 and gunner 2 in turret.

This is a fascinating idea, but just to be clear, there's nothing in the armor calculation rules about additional protection gained by making the threat go through layers of alternating density.  I spoke with N-L-M about this, and he didn't see a way to include it without making the armor rules too complicated.

What the fuck is that nearest sign, land mines?

I do not recognize that weapon.

On 4/19/2019 at 2:49 PM, Ramlaen said:

 

This is happening at the same time that Boeing is insisting the V-280 is a mature product that should be taken seriously, yes?

And also at around the same time that serious problems with their airliners are being discovered, and all the while they can't do a fucking tanker right.

BOEING.

GET.

YOUR.

SHIT.

TOGETHER.

A nuclear-powered YB-49?  All it needs now is a chrome bumper, a blonde chick in a poodle skirt and a shirtless man being menaced by weasels to make it the most 1950s thing ever.

There has been a large explosion in Sri Lanka.

Looking forward to your pictures!

Sturgeon's House started with a community of people who played tank games.  At the time, most of us were playing World of Tanks, but I think there were a few Warthunder and even Steel Beasts players mixed in there too.  After nearly five years, we must be doing something right because we're still here, and because we've somehow picked up a number of members who work with, or have worked with tanks in real life.

I know that @AssaultPlazma served as an Abrams loader, @Merc 321 and @Meplat have helped maintain and restore privately-owned armor, and @Xlucine has volunteered in a tank museum.  I'm sure I'm missing several more!

So, what are your favorite personal tank stories?

On 3/27/2019 at 6:01 PM, Belesarius said:

https://mwi.usma.edu/lets-get-things-straight-nuclear-weapons/

 

Interesting article discussing nuclear war in todays context.  @Collimatrix , @LostCosmonaut, thoughts?

 

I think he has some right ideas, and some dubious ones.  The proposition that serious thinking about nuclear combat has atrophied strikes me as correct.  The idea that nuclear warfare does not really introduce an entirely quantitatively different level of devastation strikes me as plain fucking ignorant.  An all-out nuclear war between NATO and the USSR at their height would have left most of the population centers of Eurasia in rubble from nukes, the entire continental ecology unsuitable for agriculture for years since nerve agents kill insects, and the soils contaminated for who knows how long if the Soviets decided to get frisky with their weaponized anthrax stores.

He brings up the European powers' decision to go to war in 1914 as an example of state actors' willingness to risk destruction and brave the risks of war.  But none of the powers in 1914 foresaw the depth and breadth of the war.  They thought it would be a quick, relatively painless conflict and had no idea what they were risking.

On 4/12/2019 at 10:10 AM, skylancer-3441 said:

One could simply redefine allowed trafficability levels, while doing nothing about ground pressure, just making statements that it's worth the increase in survivability.
I mean - back in late 70s XM2 had ground pressure of about 0.5kgf/cm2, and now with Bradley M2A3 w/ BUSK its like what, more than 0.8? It was accompanied with change of Go/No-Go terrain in German Wet scenario from 98/2 percent to 92/8 percent, and they were ready for much worse - while looking for AMPV, US Army was ready to accept 85/15 percent.

Yikes!  That seems like asking for trouble from General Mud.

Cat Urbigkit sets the record straight on the realities of wolf reintroduction.

The hardest limit to these sorts of upgrades is the ground pressure.  Engines could be developed that are more powerful, but fit into the old engine bay (the original Leo 1 engine wasn't even turbocharged, so there's probably lots of room for improvement there).  New transmissions that can handle the power could reasonably be developed.  New torsion bars that can handle the weight could be installed.

But there's not really any practical way to make the track contact area bigger.

The Russian government has stooped to giving weapons to the Houthis, I see, by laundering them through the Saudi armed forces.

Do they have to fly a fighter jet down the trench to hit the reactor?

On 4/9/2019 at 12:43 PM, LoooSeR said:

   Apperently high quality assets can play a huge role in visuals. Vanila Unreal engine.

 

   Maybe we don't really NEED huge increases in computing power in short amount of time.

Yes and no, I think.  They are setting up these real-time, photorealistic scenes in situations where conventional rasterization with shaders looks very good.  There aren't any shiny objects, there's nothing transparent, and the lighting is fairly simple.

With that said, the ability of the new NVIDIA cards to do shiny reflections and raytracing is limited.  Most of their examples of how it makes a scene look better are very contrived.  Battlefield V with raytracing on looks not very different from Battlefield V without raytracing... because most of the graphics are conventionally rasterized!  Raytracing is still too computationally expensive to use much, so they only use it on certain lighting and reflection details.

The most convincing argument I have heard for full raytraced games is that it will make game development cheaper if it completely replaces rasterization.  The artists wouldn't need to do shader mapping (bump maps, etc); all that stuff would be built into the game engine.  But that sort of technology is still many years away, and I am not convinced that the cost of paying artists is a large factor in video game development costs and timelines as compared to, say, EA's incompetence and greed.