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4 hours ago, DIADES said:

The rule of thumb 1.5 is just that, a rule of thumb.  It dates to the 50s and there was work in the 80s that continued to advocate it in public domain material.  It is the outcome of a calculation that has several simple parameters.  The most critical of these relate to the structural limits of the soil/sand whatever that the vehicle is maneuvering on.  The magic number can go a high as 3 depending on the soil data used.  Does not correlate well with experiment and the experiments are limited to very hard flat ground.  I reckon the professionals have their own metrics.  I calculate LEO 1 to be 1.85 - comfortably over the 1.5 limit.  I don't recall the users complaining about LEO1 maneuverability!  Recent publications also show that number of road wheels has an effect.  More road wheels = better theoretical maneuverability.  Track tension also important, lower is better.

 

 

I'm not sure how you get 1.85 for the Leo 1.

 

lxp2rfA.png

 

This picture shows that the Leo 2 clearly has a longer total aspect ratio than the Leo 1.

 

But this picture:

Na7ukev.png

 

shows that the ratio of contact length to track center length is only 1.62 for the Leo 2.

 

 

I do buy that more road wheels would affect maneuverability.  More road wheels reduces MMP, and the lower the MMP, the lower the penetration of the tracks into the soil.  The less the tracks sink into the soil, the less soil they have to shift sideways when the tank turns.

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OK, some initial goofing with the armor system:

 

 

Because Scientologists can't weld worth a damn, they are really short on options for armor with good thickness efficiency.  Now, granted, Sea Org-spec HHA is pretty great fucking stuff, and it's noticeably better than actual 1960s HHA.  It's comparable to top of the line 2019 HHA, actually.  But they can't weld it, they can't make it thicker than 1.7 inches, and they can't laminate or explosively bond it to make double or triple hardness steel.

 

This means that their armor arrays are going to be þikcqqqq.

 

3Yi3iQg.png

 

 

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30 minutes ago, Xoon said:

What is the minimum amount of crew required? 

0.

General rule of thumb- if it isn't deliberately written down in the introductory post or appendices, it is not limited and you may use your design sense as you see fit. Your choices will be judged in the context of the alternatives proposed by the other competitors.

The DPRC is accepting of diversity in the design of tanks as it is in many other fields.

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9 hours ago, Collimatrix said:

 

 

I'm not sure how you get 1.85 for the Leo 1.

 

shows that the ratio of contact length to track center length is only 1.62 for the Leo 2.

 

It turns out I thought I was looking at at what I had searched for rather than what was delivered.  The data I used was for LEO 2 and found in Armour, Nov, Dec 1976.  Actually for a LEO2 proto and it differs slightly from your better looking data.  It gives track on ground length as 5,030mm rather than the 4,733mm in your data.  Track width was 630 rather than your 635.  Track centres at 2,710mm rather than your 2,785mm (hard to read that one?).  Other primary dimensions agree.   Interesting - the track on ground length in your image is actually centre to centre of first and last road wheel.  True track on ground will be longer but not by a lot.

 

Anyway!  My point was and is that 1.5 is not a limit as such so if designs are presented that exceed this metric, knowingly, then they may well be valid.

 

 

 

 

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What are our holdings in Colorado and Nevada?

 

Particularly, do we have access to the Henderson and Climax Molybdenum mines in Colorado, or the Mount Hope, Nevada; Lucky Jack, Colorado; or Rico Deposit, Colorado molybdenum deposits?

 

Additionally, how is the tungsten being assayed for use in armor piercing projectiles?

 

 

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8 hours ago, Xoon said:

What is the minimum amount of crew required? 

At least two LGBTQQIP2SAA and/or racial minorities

1 hour ago, A. T. Mahan said:

What are our holdings in Colorado and Nevada?

 

Particularly, do we have access to the Henderson and Climax Molybdenum mines in Colorado, or the Mount Hope, Nevada; Lucky Jack, Colorado; or Rico Deposit, Colorado molybdenum deposits?

 

Additionally, how is the tungsten being assayed for use in armor piercing projectiles?

 

 

 

I am interested in your participation Citizen Mahan, I have read your file and you are under suspicion of the heresy of believing that that Xenu brought humans to Earth on Boeing 707s rather than the one true DC-8. 

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1 hour ago, A. T. Mahan said:

molybdenum deposits?

 

Additionally, how is the tungsten being assayed for use in armor piercing projectiles?

1. Moly is available in sufficient quantities for steel alloys but not for other uses.

2. Tungsten supplies are limited and no more than 100g may be used per shot.

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1 hour ago, A. T. Mahan said:

I meant is it 100g of elemental tungsten, or 100g of a given tungsten alloy?

100g of elemental tungsten, to be used as seen fit (WC, WHA, or friends).

 

Assorted rare earth elements are not available for use other than in trace quantities as alloying materials or in limited electronics applications.

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17 hours ago, Collimatrix said:

 But they can't weld it, they can't make it thicker than 1.7 inches, and they can't laminate or explosively bond it to make double or triple hardness steel.

 

 

Just stack several HHA plates and encase them in RHA. You get whatever thickness you want.

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7 hours ago, holoween said:

 

Just stack several HHA plates and encase them in RHA. You get whatever thickness you want.

 

 

That would work!  The total array efficiency would be somewhat less efficient than pure HHA due to the RHA holding it together, but it would be admirably efficient overall, and certainly quite thin.

 

I was thinking of arrangements where steel armor of different hardnesses is laminated together (note: this is tricky to do).  An arrangement with a harder, more brittle steel as the strike face backed by a softer, tougher steel is more protective than the sum of those two plates on their own.  An arrangement with soft/hard/soft is better still.

 

Metallurgically trickier still are laminates with aluminum bonded to high hardness steel.  I haven't read much about them, except that they're supposed to be quite good, and also a bitch to make.

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I would just like to say that I am deeply offended by the fact that the ATGM arcs are wider in the LIC spec than the HIC spec.  Are you implying that the Cascadian government would supply Deseret with ATGMs?  Are you saying that the government of a developed, democratic republic would consider supplying advanced guided missile systems to a bunch of religious zealot insurgents just so screw over an opposing state?

 

That strategy would obviously backfire.  Who would be that stupid?

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OK, so I've had enough time to think about the armor system to have _somewhat_ cogent thoughts:

 

 

The 90mm HEAT rocket has 360mm of armor penetration.  I know a lot of you played World of Tanks, which had tanks with all-steel armor and penetration was calculated (more or less) as a function of LOS thickness of all steel armor.

 

360mm is a whole hell of a lot of penetration vs. all steel armor.

 

d3GrX8b.jpg

 

That will centerpunch a Chieftain through the thickest part of the glacis with about 85mm of penetration left over.  And that's on the best part of the Chieftain's armor, from head-on, and with one of the weaker threats in the specification inventory.  And that's on a fairly heavy tank.

 

The next temptation is to thin down the steel armor to the structural minimum, and use the remaining weight on the armor with the best mass efficiency.

 

That doesn't work either.  The best passive material on the armor list against HEAT is the fused silica with a thickness efficiency of 1 and a mass efficiency of 3.5.  But that damn tandem-warhead ATGM has a combined penetration of 1320mm.

 

Once you add the underlying chassis and the confinement, you're looking at an armor package that's the better part of a meter and a half thick.  And if you look at the best estimates for actual MBT armor array thickness, they're not anywhere near that huge:

ZEnt4Wf.png

 

And the protection spec against the HEAT demands protection against a fairly wide arc.

 

The saving grace is that the reactive armor rules and the spaced armor rules are essentially multiplicative with the armor arrays underneath them.  The passive armor is all basically additive.

 

So, as an example, say we hang a 12.5mm thick HHA plate off of some sort of bracket, and then hang a light ERA panel 18mm away (N-L-M said he was going to change the ERA spacing rules to require 2x sandwich thickness spacing instead of 3x, and that he would add that as soon as he updates the secondary threat rules), and then slant it all at 60 degrees from the vertical, and then park it about four inches away from the main armor, then against the 90mm basic bitch rocket we have:

 

1)  RPG hits the high-hardness armor burster plate and explodes
2)  RPG penetrates the high hardness armor burster plate.  The LOS thickness is 25mm, and HHA has a TE of 2 against CE threats, so the jet loses 50mm of penetration, bringing it down to 310mm.

3)  RPG penetrates the ERA casette.  The K1 coefficient looks to be about 1.5 for 60 degrees off the vertical, and K2 works out to 36mm.  So the 310 pen is reduced down to 170mm.
4)  The jet from the RPG is traversing the 100mm offset between the ERA and the main armor.  The HHA burster plate is thick enough to invoke the spaced armor rules, and the 100mm gap reduces the penetration of the jet down to 155mm.

 

And just to keep things simple, let's say we have a 155mm LOS steel chassis plate to soak up this hit.

 

That array comes to 370mm LOS thickness (25mm HHA, 90mm for ERA plus spacing, 100mm air gap, 155mm steel structure underneath it all), but it's protecting the same as 360mm of steel and only weighing 53% as much.  So that's a TE of .97 and an ME of 1.86.  For an extremely simple and clearly un-optimized armor array.  The ME would go down a bit once we add proper mounts for the HHA and ERA, but the bottom line is that this is much lighter than steel, and much smaller than the equivalent textolite protection.  On top of that, it is an imminently practical array.  The ERA is protected by the HHA, so it can't get popped by machine gun fire or scraped off by the tank running into things.

 

Now, this array only provides 255mm against KE.  But you get the idea.  Reactive armor FTW.

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1 minute ago, Toxn said:

So my first pass at optimisation revealed something fascinating.

 

Basically solver decided that light ERA and light NERA are the way to go. Intriguingly, however, it decided that the ERA layer works best when completely flat...

 

Did you double check whether you were measuring angle from the vertical or angle from the horizontal?

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7 minutes ago, Collimatrix said:

 

Did you double check whether you were measuring angle from the vertical or angle from the horizontal?

Yup.

 

Solver decided that it wanted two-ish layers of light ERA (I forgot to force it to use whole numbers) on the flat, and 10-ish layers of light NERA at 64' from the vertical (ie: alpha is 26).

 

The result, when draped over a flat RHA base with the bare minimum thickness (45mm) is a 1-metre deep array that will stop both the highest KE and CE threats and has a total areal density of ~5 tonnes per square metre. Which is amazing given that an equivalent RHA armour plate would be ~10 tonnes per square metre.

 

I don't think I've reached a perfect solution here, but I suspect that when I do it will involve the same components in differing configurations.

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Oh, yeah, @N-L-M mentioned that he wanted to clarify that the explosive filler of ERA has a density of 1.5 gm/cm^3.

 

Which means that light ERA has a density of 5.7 gm/cm^3, or 7.41 gm/cm^3 after you account for brackets.  Which means that flat light ERA has a mass efficiency of 2.1 thanks to the K2 rules!

Dang, you're on to something there.

 

Now, watch all the submissions resemble those Azov Brigade creations covered in several tons of layered explosives.

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10 minutes ago, Collimatrix said:

Oh, yeah, @N-L-M mentioned that he wanted to clarify that the explosive filler of ERA has a density of 1.5 gm/cm^3.

 

Which means that light ERA has a density of 5.7 gm/cm^3, or 7.41 gm/cm^3 after you account for brackets.  Which means that flat light ERA has a mass efficiency of 2.1 thanks to the K2 rules!

Dang, you're on to something there.

 

Now, watch all the submissions resemble those Azov Brigade creations covered in several tons of layered explosives.

The perfect Californian tank is impenetrable to all attacks, but occasionally detonates when left in the sun for too long...

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7 minutes ago, Collimatrix said:

Each flat light ERA casette provides 36mm RHAE of protection, but they need to be spaced 36mm apart from each other.  So, the TE isn't all that great.

Yeah, on that note I'm not sure why solver decided on the particular ratios of light ERA and light NERA that it did.

 

Trying to force it to go for thinner arrays just results in failures to solve, and minimising thickness instead of mass results in nearly the same array but with a 10cm air gap shoved in.

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3 hours ago, Collimatrix said:

 

 

That would work!  The total array efficiency would be somewhat less efficient than pure HHA due to the RHA holding it together, but it would be admirably efficient overall, and certainly quite thin.

 

I was thinking of arrangements where steel armor of different hardnesses is laminated together (note: this is tricky to do).  An arrangement with a harder, more brittle steel as the strike face backed by a softer, tougher steel is more protective than the sum of those two plates on their own.  An arrangement with soft/hard/soft is better still.

 

Metallurgically trickier still are laminates with aluminum bonded to high hardness steel.  I haven't read much about them, except that they're supposed to be quite good, and also a bitch to make.

 

@N-L-M, is laminated armor available in DPRC? 

 

I dont think I’ve seen anything on the process for laminating armor plates, though I do know Hot Isostatic Pressing can laminate different metals together, albeit it takes a while. 

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