Competition: Tank Design 2239

[N-L-M]

Absolutely. The best description I've seen was by someone on this site, who described a tank as a "reverse TARDIS, much smaller on the inside". Even just an open museum or gate guard/monument, where you can climb in, gives you a useful scale. Everything inside a tank is harder, sharper and stronger than you. You are always the squishiest component, which has to squeeze out of the way of the bigger stuff in there. Proper systems integration and adequate volume allocation make the difference between sharp corner hell and a comfy (if tight) working space.

[Sturgeon]

240mm of heat pen may not be enough for your wasp to kill this roach, @Toxn

 

[Collimatrix]

The TL:DR of this 1950s report on spaced armor and other sources I've read is:

 

 

APCR: Totally fucked by even small stand-off plates parallel to the main armor in hasty add-on packages.  Most APCR projectiles had too brittle a core to deal with anything but homogenous armor.

HEAT:  Early HEAT was adversely affected by spaced armor, but by early 1950s level of HEAT projectile optimization it almost ignored it, or even got a slight penetration boost vs spaced armor.  Arrays of many thin plates were modestly more effective vs. HEAT.

APDS:  Adversely affected by spaced armor, but far less than APCR thanks to sheathe designs that protected the core from shattering.

APFSDS:  Early APFSDS was fucked by spaced armor quite badly, but metallurgical improvements meant that later rounds largely ignored it.

APCBC:  Effects heavily dependent on the optimization of the spaced armor array and quality of the rounds.  Well-constructed APCBC is actually more effective against simple spaced armor arrays than against homogeneous plate.  Poorly constructed APCBC suffers against simple stand-off plates almost to the extent that APCR does.  Geometrically well-optimized arrays are moderately more effective on a weight basis against APCBC than homogeneous plate.

[Sturgeon]

Upgraded M15E3 Roach:

 

 

You've got to ask yourself one question: 'Do I feel lucky?' Well do ya, punk?

[Sturgeon]

Fully upgraded Roach:

 

 

152mm high velocity main gun (with 8 degrees depression), stereo rangefinders, spaced armor array on turret, 1" thick side skirts. Uprated 750 hp engine.

 

A little over 42t all-up.

 

Peekaboo!

 

 

[Toxn]

7 hours ago, Sturgeon said:

240mm of heat pen may not be enough for your wasp to kill this roach, @Toxn

 

Ah, but that isn't even the 120mm gun's final form. 240mm is from WW2-era HEAT.

[Toxn]

1 hour ago, Sturgeon said:

Fully upgraded Roach:

 

 

152mm high velocity main gun (with 8 degrees depression), stereo rangefinders, spaced armor array on turret, 1" thick side skirts. Uprated 750 hp engine.

 

A little over 42t all-up.

 

Peekaboo!

 

 

How big is that thing? Because a big, high-velocity gun and a rangefinder are going to need an appropriately vast turret volume. Especially if you're going for substantial levels of depression.

[N-L-M]

7 hours ago, Collimatrix said:

APFSDS:  Early APFSDS was fucked by spaced armor quite badly, but metallurgical improvements meant that later rounds largely ignored it.

Soviet-style APFSDS (small WC core, large steel body) suffered almost as bad as APCR. Later versions (with the core in the base, not the nose) were a bit better. Sheathed tungsten alloy and monobloc tungsten alloy penetrators were largely immune to the worst effects of spaced armor.

[Sturgeon]

59 minutes ago, Toxn said:

How big is that thing? Because a big, high-velocity gun and a rangefinder are going to need an appropriately vast turret volume. Especially if you're going for substantial levels of depression.

 

T-55 sized. It works, don't worry.

[Sturgeon]

1 hour ago, Toxn said:

Ah, but that isn't even the 120mm gun's final form. 240mm is from WW2-era HEAT.

 

I can't wait for you to shoot it at my ERA array!

[Toxn]

1 hour ago, Sturgeon said:

 

T-55 sized. It works, don't worry.

Good job!

[Toxn]

1 hour ago, Sturgeon said:

 

I can't wait for you to shoot it at my ERA array!

This is getting homoerotic fast 

 

Oh well, guess I'd better upfun to 155mm...

[Sturgeon]

Roach basic (top) and fully upgraded (bottom).

 

[Belesarius]

55 minutes ago, Sturgeon said:

Roach basic (top) and fully upgraded (bottom).

 

Needs a log and external fuel drums.

 

[Donward]

20 minutes ago, Belesarius said:

Needs a log and external fuel drums.

 

 

It's a good thing the Pac NW has a strategic supply of LOG

[Zadlo]

My baby slowly starts to live - one of two versions of the light tank 

 

Length: 18' 6"

Width: 10'

Height: 5' 6 1/4" + 1' 6" ground clearance + currently unknown height of the turret

Engine: It is going to be 27L 340 - 410 HP (250 - 310 kW) V12 compact engine (Liberty L-12 derivative)

 

[Zadlo]

The another thing - quite short (2' of height) welded turret with two isolated ammo racks

 

[Toxn]

11 hours ago, Sturgeon said:

 

I can't wait for you to shoot it at my ERA array!

I've been meaning to address this, but isn't it also doing your heads in to put yourselves in the shoes of designers who know that ERA and NERA are easy to make and will help to counter HEAT rounds if/when processes are developed to make them better?

 

I imagine a sort of spy-v-spy situation forming; where you don't bother re-developing certain forms of armour because you know that your opponents know that an easy counter is on its way in a few years and so won't bother to develop the weapon the counter was meant to counter. So you both field APHE and RHA (but eventually with 3-axis stabilisers and laser rangefinders) for decades because it just isn't worth it to change over to HEAT-FS when it will be largely ineffective a month into the fight. And then everyone suddenly jumps to hypervelocity kinetic missiles all in one go because the tech base is finally there and that was the last thing to get fielded before the bombs fell.

[Toxn]

At least, that's what I figured happened here: decades of 10-tonne light tanks because you know that 20 and 30-tonne designs are worth 3 years of combat at most, then an immediate jump to MBT analogues once the metallurgical and automotive tech is available because you already know what the successful final form looks like.

[Sturgeon]

1 hour ago, Toxn said:

I've been meaning to address this, but isn't it also doing your heads in to put yourselves in the shoes of designers who know that ERA and NERA are easy to make and will help to counter HEAT rounds if/when processes are developed to make them better?

 

I imagine a sort of spy-v-spy situation forming; where you don't bother re-developing certain forms of armour because you know that your opponents know that an easy counter is on its way in a few years and so won't bother to develop the weapon the counter was meant to counter. So you both field APHE and RHA (but eventually with 3-axis stabilisers and laser rangefinders) for decades because it just isn't worth it to change over to HEAT-FS when it will be largely ineffective a month into the fight. And then everyone suddenly jumps to hypervelocity kinetic missiles all in one go because the tech base is finally there and that was the last thing to get fielded before the bombs fell.

 

Why do you think I came up with the 152mm high velocity gun?

[Toxn]

24 minutes ago, Sturgeon said:

 

Why do you think I came up with the 152mm high velocity gun?

Dick measuring and supreme confidence in your ability to do what the old Soviet designers couldn't?

[Sturgeon]

20 minutes ago, Toxn said:

Dick measuring and supreme confidence in your ability to do what the old Soviet designers couldn't?

 

...Correct.

[Belesarius]

50 minutes ago, Sturgeon said:

 

...Correct.

What would the ammo load out be for a 152mm gun?  Doesn't sound like you'd be able to fit that many rounds in.

 

[Sturgeon]

2 minutes ago, Belesarius said:

What would the ammo load out be for a 152mm gun?  Doesn't sound like you'd be able to fit that many rounds in.

 

 

I haven't really done the ammo racks for the 152mm, but you wouldn't be able to load that many. Probably 25 rounds or so.

[Toxn]

So to check the credentials of my 120mm L/35 gun, I came up with a poor mans APFSDS: a 20mm diameter, 1m long finned steel rod with a fixed 120mm aluminium sheath to locate it in the barrel properly (3kg all told). The muzzle energy was set to mimic the 122mm M-30 firing HE (21.7kg, 458 m/s), and longrods was used to calculate the penetration. This came out to nearly exactly 200mm. Velocity drop-off would be obscene given the aluminium sheath, but over a few hundred metres I don't think it would matter much.

 

All of which means that the XM16's gun, firing herpaderp cobbled-together APFSDS (edit: technically just APFS) with a (relatively) low powder load could still probably give trouble to anything that isn't the roach's stupid-thick turret front.