Collimatrix

Hybrid warfare maskirovka!

@N-L-M and I discussed these crazy all-turret tanks. He pointed out that this is basically how a lot of backhoes are configured. I agree that it would basically require electrical or hydraulic drive. I don't understand why you would want to make a tank this way, but Xoon may have some crazy ideas.

I can do two better: https://patents.google.com/patent/US35600A/en https://patents.google.com/patent/US3216423A/en

You're right, my bad. But with NLM's clarification about only the steel part of the reactive armor array contributing to the K2, then it's actually only about 103mm. As soon as we know the formula for K1 we can figure out what the highest ratio of cosine(theta)/K1 is. That should give us the best efficiency. EDIT: for instance, the ratio of the secant of 80 degrees over the secant of 70 degrees is 1.96. Eyeballing the K1 chart, the effect at those slopes is about 3.5 and 2 respectively. 3.5/2 is only 1.75, so the increase in the effectiveness of the array is not offset by the increase in areal density. EDIT EDIT: That's the reciprocal of the cosine of the Greek letter theta, not the act of attempting to take out a loan from the Dianetic People's Bank by having your thetan co-sign.

Indeed, Ian G. Crouch. I remember looking into explosion welding and being surprised how simple it is.

I'm... not following. The 60mm/160mm tandem ATGM has 360mm penetration primary. Light NERA at 10 degrees is about 3.5 K1 coefficient, so that drops to 102mm penetration. K2 is 18*1.5/cos(10 degrees), or about 27.4mm, so there is 75mm residual pen after the first light NERA casette. Also, I think you'd get murdered on the above-line-of-sight requirement because the missile would hit the top of the array and bypass the first reactive armor casette entirely.

Hazell 2016 and Crouch 2017. They note that laminated steel armor that's assembled by explosive welding actually works better than roll bonded because the bond between the two plates is more robust (though there are caveats WRT residual stress). Unless N-L-M says otherwise explicitly, I don't think you can use laminated steel structures. Hand-wave it as the Californians not having sufficient industrial capacity to mass-produce such materials or something.

It's from 2016. Different steel hardnesses can definitely be joined by explosive welding or by roll bonding, and dissimilar metals can be joined with explosive welding. Not all combinations of dissimilar metals work, but a lot do. No, what I'm objecting to is the idea that putting a high hardness plate up against an RHA plate without welding them along the face where they contact will work. That very explicitly does not work well. The synergistic effect would be quite small.

I think holoween and Toxn have basically the right idea. If you have an array of reactive elements, the reduction is going to be of the form K1^N where K1 is your coefficient from the curve and N is the number of reactive elements. And if I remember anything from those finance courses that I never actually took, it's that compound interest is the most powerful force in the universe, and you get a lot more mileage from ABX by making X bigger than you do from worrying about A or B. At least if you aren't concerned overmuch about thickness. Toxn's array of 10 light NERA at 64 degrees is going to be like, 850mm thick, which is doable for turret front protection, but maybe a bit much for the sides. Maybe figuring out a workable frontal protection scheme is actually the easy part.

My books on armor technology explicitly say the opposite.

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.

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.

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

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. 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: 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.

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?

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.

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.

I'm not sure how you get 1.85 for the Leo 1. This picture shows that the Leo 2 clearly has a longer total aspect ratio than the Leo 1. But this picture: 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.

OK, I have further questions: 1) What is the actual penetration of the ATGM and RPG threats? It looks like it got truncated in the spreadsheet. Edit: NVM, I see that this information is in the OP. The RPG is 250mm and then 500mm penetration and the ATGM is 360mm and then 960mm penetration. Goddamn but that's mean. 2) How exactly do the .50 cal SLAP, DPICM and 155mm HE threats work? 3) How do tandem warheads interact with NERA? If the precursor warhead penetrates into a NERA element, is that element considered "expended?"

OK, I am doing some basic derived-spec number crunching based on the requirements thus far: The widest possible tracks are tracks that stretch out all the way to the very edges of the vehicle, or the 4m maximum. The track center to track center distance is the width between the track edges minus the track width (unless you're using asymmetrical tracks... which you probably shouldn't). If we go with 800mm wide tracks (tiger combat tracks were 725mm) at maximum width, the target 1.5 length to width contact ratio gives us 7.68 square meters of contact area. With the maximum weight of 120 tonnes, that comes to a Nominal Ground Pressure (NGP) of 153 kN/M2. The ground pressure requirements are specced in Mean Maximum Pressure (MMP), which is about 1.8x-3x NGP, depending on details of road wheel and track configuration. But even with that lower bound (which would almost certainly require interleaved road wheels), that's well above the threshold requirement. If we bump it up to meter wide tracks (that's like, fucking twice as wide as most tanks have) and the threshold track contact ratio, that gives us 10.8 square meters of contact, which means an NGP of 109 kN/M2, which is a bit high, but is within the bounds of sanity. But then we're only allowed four pieces of side skirt armor, and they need to pack on to the vehicle in such a way that they don't violate the height or width requirements. So, Conclusion Number One: It's actually very hard to max out the weight requirement without maxing out the ground pressure requirement first. If you go for a max-weight vehicle, get ready to use some shenanigans like hugenormous side skirts, or transportketten, or extra road wheels that are lifted above the ground so that they don't count for the contact length but do count for the ground pressure (TOG II did this). Next, I took a look at the protection of the Cascadian Entity's Norman MBT. The reference protection is given as 60mm of HHA (how do the infidels have better armor science than Scientologists?! We're really good at science! It's in the name!), a 20mm air gap, and then 200mm of RHA. So, working backwards, 60mm HHA definitely counts as thick enough to invoke the spaced armor rules. So we have main armor (subtractive), air gap (multiplicative), and HHA (subtractive). The air gap is 200mm, which gives it an exponent of 2 against the base protection of 1.05 for KE threats, which means it blunts KE threats to down to 90.7% effectiveness. Multiply the recipricol of that by 200mm, and we get 220.5mm, and add 120mm (60mm *2 because it's HHA), and we get a final protection of 340.5mm vs KE and 362mm vs CE. For KE, the Californian gun technology sounded slightly better than the U-5TS. So, something along the lines of early 2A46 ammo should do the trick. So, basically a gun along the lines of an L11 or Soviet 125mm firing fairly primitive APFSDS should meet the requirement. For CE, this is easy-peasy. If the Californian gun-fired heat can penetrate 5 charge calibers, 362mm can be poked with a 72.4mm charge. Accounting for shell wall thickness, something like a 20 pounder (84mm) firing HEAT should kill the Norman just fine. You know, right up until they rush ERA kits to the front. Conclusion Number Two: It's way easier to meet the lethality requirements with a HEAT-firing weapon than it is with an APFSDS-firing weapon, provided that the Cascadian Entity doesn't slap reactive armor on their tanks to make themselves overnight immune to them. If you want to be a total memelord, you could arm your tank with a KwK 36... that fires HEAT-FS rounds.

The Cascadian entity can make thicker HHA than we can, have tungsten monobloc darts, and are putting the finishing touches on beam riding atgms? Well, fuck.

Cell D33 of the specs xls, the text is cut off. What is the frontal armor array of the upgraded Norman supposed to be?

I just found this good breakdown: It gives a really good summary of how this went off the rails.

HIC looks like a basically traditional, frontal-arc focused spec against a variety of threat types including KE and CE. LIC looks like concerns about being ambushed from potentially any angle by RPG-toting Deseret insurgents.

We're using metric tons, right?