Competition: Tank Design 2239

[ApplesauceBandit]

4 hours ago, Lord_James said:

pretty much done with the hull for now, gonna move on to the turret. 

 

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center of gravity included, haven't calculated mass yet (will probably edit it in). 

 

 

 

Edit: Mass= 14 metric tons (13.92), I was expecting more  

material= high strength, low alloy steel (7.850 g/cm³), so thoroughly average steel (the color is rubber green, cause @ApplesauceBandit already took the rusty red I wanted ) 

 

Feel free to use the red, it's just a placeholder color since I'm too lazy to figure out how they changed lighting in 3ds max 2018 and me just defaulting back to that clay mode is easier.

[Lord_James]

ok, so I fudged up the turret a little bit... and I have to start over, tomorrow. BUT, I did get the shells done!! 

 

I present to you, the 94/74mm Shot Mk-1 APCNR: 

 

Spoiler

 

755mm long complete round (11.4kg without propellant [and steel body]... as I don't know how much propellant I need, yet) 

94x275mm squeezebore projectile (7.63kg with steel body, 5.84kg with aluminum body... dont know which to choose) 

50x200mm Tungsten Carbide penetrating slug (4.88kg) 

 

 

Hopefully I can get the gun and turret done tomorrow. 

[Sturgeon]

1 hour ago, Lord_James said:

ok, so I fudged up the turret a little bit... and I have to start over, tomorrow. BUT, I did get the shells done!! 

 

I present to you, the 94/74mm Shot Mk-1 APCNR: 

 

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755mm long complete round (11.4kg without propellant [and steel body]... as I don't know how much propellant I need, yet) 

94x275mm squeezebore projectile (7.63kg with steel body, 5.84kg with aluminum body... dont know which to choose) 

50x200mm Tungsten Carbide penetrating slug (4.88kg) 

 

 

Hopefully I can get the gun and turret done tomorrow. 

 

Pick the aluminum body. Steel is way too heavy, and unnecessary. Historical US APCR (I know yours is squeezebore, but it doesn't matter really) used aluminum bodies, and Cascadia has its own domestic source of aluminum (otherwise you'd have to switch to steel due to wartime shortages, with a resulting change of trajectory and sights - it'd be a mess). So just use aluminum.

[Sturgeon]

So my tank is a tad overweight. Current loaded weight estimates put it at 50.7 tonnes, giving it a curb weight of almost 48 tonnes. However, my tank also has an exceptional armor coefficient of 55% (which isn't surprising, @Collimatrix, as I was taking more than a few cues from the IS-3 in the hull design), and dropping that to a still extremely respectable 52.5% brings the tank's curb weight to right about 45 tonnes. I won't be modifying my model's armor layout (because lol effort), but I will be including mass and approximate armor figures for the "lightened" hull version which will be pretty accurate.

 

I like the heavy version, myself, but I do understand the original requirements necessitate a 45 tonne maximum so we'll work within that.

[Sturgeon]

These are as close as I can get them right now:

 

Armor mass: 33,774 kg

Engine and transmission mass: 2,750 kg

Gun mass: 1,150 kg

Suspension mass: 4,751 kg

Tracks mass: 

Ammo mass: 1,109 kg

Fuel mass: 1,086 kg

Track link mass (steel): 34.7 kg

Track link mass (aluminum): 27.2 kg

No. of tracks: Approx. 160

Tracks mass (steel): 5,552 kg

Tracks mass (aluminum): 4,352 kg

Tank curb mass (steel tracks): 49.5 t

Tank curb mass (aluminum tracks): 48.3 t

Tank gross mass (steel tracks): 51.7 t

Tank gross mass (aluminum tracks): 50.5 t

 

one fat boi

[Sturgeon]

Assuming I need to drop 4500 kg of armor, that means I would need to decrease hull armor thickness on the glacis (top and bottom) by 6.5 inches to drop that much. The glacis is only 4.4 inches thick...

 

Serendipitously, I discovered that I can adjust my glacis thickness at will without breaking the model, which allowed me to test a 3" (top and bottom) glacis version. This saved me 900 kg, which is nice but not enough. I may have to compromise the turret... But I am betting that won't be easy.

[Toxn]

16 minutes ago, Sturgeon said:

Assuming I need to drop 4500 kg of armor, that means I would need to decrease hull armor thickness on the glacis (top and bottom) by 6.5 inches to drop that much. The glacis is only 4.4 inches thick...

 

Serendipitously, I discovered that I can adjust my glacis thickness at will without breaking the model, which allowed me to test a 3" (top and bottom) glacis version. This saved me 900 kg, which is nice but not enough. I may have to compromise the turret... But I am betting that won't be easy.

It's really more efficient (from a weight saving standpoint, at least) to thin side armour, roof armour and floor armour. Much more volume removed for an incremental loss of protection.

[Toxn]

@Sturgeon Just eyeballing your model, it looks like a 65mm glacis (raked back at what looks like 60') is about the minimum required to keep out the Californian long 70s that will be one of the most common threats. So I'd put that as a hard floor.

 

Edit: I'd also say that side armour around the crew compartment should be about the same to keep present-gen 70s out across a decent arc.

[Toxn]

On a side note: I seriously cosidered a quasi all-or-nothing armour scheme where the front and side crew compartment is 25mm, but the turret has over 100mm LOS all around (going up to 150mm on the front) and the turret basket is made from a 75mm casting. Everywhere else gets 10mm.

 

This is also called the "fok julle drivers" scheme.

[N-L-M]

3 minutes ago, Toxn said:

On a side note: I seriously cosidered a quasi all-or-nothing armour scheme where the front and side crew compartment is 25mm, but the turret has over 100mm LOS all around (going up to 150mm on the front) and the turret basket is made from a 75mm casting. Everywhere else gets 10mm.

I too had considered that, the problem is the sheer proliferation of fiddycals and HE frag means that on the whole you're increasing your vulnerability by focusing too much on the high-end threat.

[Toxn]

16 minutes ago, N-L-M said:

I too had considered that, the problem is the sheer proliferation of fiddycals and HE frag means that on the whole you're increasing your vulnerability by focusing too much on the high-end threat.

I actually couldn't remember why I didn't bother with it in the end (jank ideas appeal to me), so I ran the numbers.

 

On my design it cuts the weight down to... 42 tonnes unstowed.

 

[N-L-M]

1 minute ago, Toxn said:

42 tonnes unstowed.

 

I can see why that would be a problem, yes.

[Sturgeon]

OK, looks like the lightweight turret cuts about another 670kg. My turret side armor (which is at a 0 deg angle from the front) was excessive so I cut it down from 3" to 2". I also fixed all the fuckery that was going on with the fillets on my turret so now it's a much nicer and healthier model overall. 

 

That puts my curb mass at 46.7 t with aluminum tracks. Getting there.

[Sturgeon]

Another 270kg cut out by reducing the thickness of the turret floor to half an inch. Pretty sure they don't need so much steel there... Right?

[Sturgeon]

Holyfuckingshit no wonder. I just realized my side hull armor is three inches sloped at thirty degrees. I mean that's awesome, but... Probably unnecessary for a 45t tank

[Toxn]

8 minutes ago, Sturgeon said:

Holyfuckingshit no wonder. I just realized my side hull armor is three inches sloped at thirty degrees. I mean that's awesome, but... Probably unnecessary for a 45t tank

From the vertical? Yeah, you could cut it down to 60mm then, if you want to keep current Californian 70mm guns out at any range. Maybe 55mm, if you want to keep them out at battle ranges.

[Sturgeon]

4 hours ago, Toxn said:

From the vertical? Yeah, you could cut it down to 60mm then, if you want to keep current Californian 70mm guns out at any range. Maybe 55mm, if you want to keep them out at battle ranges.

 

I cut the sides down to 2" (same thickness as a Centurion - at a greater angle - , I figure that's good enough since there are 1" thick side skirts). That cut the weight of the tank by almost three tonnes, and I am now down to a very healthy 43.6 t curb weight with aluminum tracks (44.8 t with steel tracks). WHEW!

[Toxn]

3 minutes ago, Sturgeon said:

 

I cut the sides down to 2" (same thickness as a Centurion - at a greater angle - , I figure that's good enough since there are 1" thick side skirts). That cut the weight of the tank by almost three tonnes, and I am now down to a very healthy 43.8 t curb weight with aluminum tracks (44.8 t with steel tracks). WHEW!

With the skirts that's very respectable indeed. You could cut those down to 15mm and still be okay.

 

Just to demonstrate: a 50mm side angled at 30' from the vertical, plus a 25mm skirt angled at 0', gets you ~115mm LOS thickness at the end of your 45' arc. At 30' that soars to ~165mm. This means that your tank's side armour is essentially immune to present-gen guns in the 30' arc, and is well-protected against the most common next-gen threat in the 45' arc.

[N-L-M]

22 minutes ago, Toxn said:

With the skirts that's very respectable indeed. You could cut those down to 15mm and still be okay.

 

Just to demonstrate: a 50mm side angled at 30' from the vertical, plus a 25mm skirt angled at 0', gets you ~115mm LOS thickness at the end of your 45' arc. At 30' that soars to ~165mm. This means that your tank's side armour is essentially immune to present-gen guns in the 30' arc, and is well-protected against the most common next-gen threat in the 45' arc.

It's even better than that- at 30', you have, for 600mm wide tracks, 1200mm of air between your first layer and the hull. The first layer sets off fuzes and damages projectiles, they then have 1.2m to destabilize and break up before hitting the main armor, making your main armor more effective.

[Toxn]

Just now, N-L-M said:

It's even better than that- at 30', you have, for 600mm wide tracks, 1200mm of air between your first layer and the hull. The first layer sets off fuzes and damages projectiles, they then have 1.2m to destabilize and break up before hitting the main armor, making your main armor more effective.

Definitely, and slope effectiveness against AP is more than just LOS thickness. I'm just giving the most conservative case here.

[N-L-M]

I haven't modeled the sideskirts yet, but my design rather heavily relies on those effects.

[N-L-M]

Springs and sprocket are now a thing:

The springs were mostly eyeballed, and they just barely clear the hull and wheels. This is why the Merkava has such narrow wheels, otherwise the tank gets really wide really fast. Width over the sprockets is barely under the limit.
The intended wheel vertical movement is +300/-100 mm. Ground clearance is 500mm with tracks (to be installed). return rollers also to be installed.

[Sturgeon]

Reminds me of the T-44, which coming from me is a compliment.

Can you export your springs as sldprt files? I, uh, may want to poach them.

[N-L-M]

4 minutes ago, Sturgeon said:

Reminds me of the T-44, which coming from me is quite a compliment.

Can you export your springs as sldprt files? I, uh, may want to poach them.

A quick googling says that Solidworks can import ProEngineer/Creo files, so how do you want it sent?

[Sturgeon]

1 minute ago, N-L-M said:

A quick googling says that Solidworks can import ProEngineer/Creo files, so how do you want it sent?

 

IGES or SLDPRT, preferably.

 

Email or dropbox is fine.