Kal
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Everything posted by Kal
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So if proposed tank uses russian 57mm autocannon, ke is 1,425,000j, exit velocity 1000m/a To balance force on vehicle allows HEAT 91mm At 940m/s 105 mm at 760m/s 125 mm at 660m/s 160 mm at 500m/s Seeing how easy it is to defeat smaller HEAT warheads, the complementary cannon is either the 160 mm at 500m/s. (Is is similar ratio to BMP 3 guns) or just go with the 90mm and make that an auto cannon also.
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BMP 3 30mm 2a72 has ke about 180,000j, exit velocity about 960-1120m/s 100mm 2a70 has ke about. 480,000 to 840,000j, exit velocity 250-350m/s Resolve for different durations, turns out that the 30mm and 100mm have same force on vehicle structure, but the 100mm has a longer duration. Hmmmm
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Magnesium alloy is generally better for welding than aluminium. But Aluminium makes better sheet and plate than Magnesium. But Magnesium makes better castings than Aluminum. So while Magnesium is better for welding than Aluminum, much less welding is used with Magnesium because its generally a casting anyway. Magnesium is sweet for castings, but its just not worth it for sheet or plate work. The alloy i would suggest is ZE41, popular from late 1940s to late 1960s. https://www.slideshare.net/mobile/GkhanBier/mg-alloys-in-industry
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How do you manage deltic starts/restarts?
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Mg Hull casting including glass inserts and 25mm textolite liner. 12.7 tonne Armour packages 11 tonne Frontal arc 60/160 resistant Side 50/150 resistant. Limited 60/160 area Turret incomplete Roof nera/era still to optimise
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Target is can i reduce weight down to low enough that 2 rolls K60 motors will suffice.
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Reduced front armour weight to 2.9 tonne per m2 with fuel. And 2.5 tonne per m2 without fuel. Defeats 360/960 CE, but only defeats about 800mm KE (depending on fuel). Glacis top protection is still crazy high, but thats inevitable with ricochet angle plate sheathed with reactive armour.
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There were lessons why Merkava have front engines. Merkava front engine layout works because High Intensity Combat included having infiltrated, tens of thousands Egyptian soldiers with ATGM shooting the sides of the tanks. On Israeli territory. Merkava front engine layout works because High Intensity Combat included having a last stand all out battle against hordes of Syrian tanks until ammo gets rationed down to 1 round per tank. Re stocking tanks in action, at the front, under fire is needed. Rear entry is safest for manual reloading. This is neither Nato nor warsaw pact expection of high intensity combat. Classic cold war armour is very face first. Rear engine pushes the parts of the tank that needs protection forward, thus reducing the length of side hull armour to defeat. Less armour to sides allow more amour to front. More armour to front was expected to be superior tank.
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Wow, a deltic. And i thought going with twin 5TD, L60 , K60 design was adventurous. Do tell, how big are your fuel tanks gonna be?
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I just want to confirm. If i model the fuel cells as a stack of jerry cans between 2 bulkheads. That when full, it is only 'Mass efficiency vs RHA of 1.3 vs CE, 1 vs KE. Thickness efficiency vs RHA of 0.14 vs CE, 0.1 vs KE. Density-0.82g/cm^3.' ie no space multipler effects. and when empty, the space effects can be in full force. 'Reduces penetration by a factor of 1.1 vs CE or 1.05 vs KE for every 10 cm air gap.'
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Im also treating polycarbonate as selfsupporting diesel. Is that ok or can you give values for that. The polycarbonate is mostly just a placeholder for replacement with interface defeat voodoo prior to combat Scrap that, I'll treat all that polycarbonate etc as ' Assorted stowage/systems Mass efficiency vs RHA- 1 vs CE, 0.8 vs KE.'
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thats fine. Interface defeat is not that simple to model. Also My ulterior motive for all the magnesium is that it would be most suitable for a 1970s tank to use for incorporating alumina LIBA (1990s concept) into the stucture of the tank itself. Fused quartz would also be compatible with that manufacture method. Which couldv'e been used in 1950s or 1960s if anyone had tried. Can I do that under the rules or is it no go? Of the 4 bulkheads, 3 are suitable and 1 is not, for cast in situ quartz LIBA. I would also use it for sides and rear but not the roof or floor.
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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.
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Oops, my light NERA ERA array kinda defeated 360/960 shaped charge. It starts with light NERA at same slant as upper glacis at 8 degrees. Then 2 small rhomboid light ERA at 30 degree. Then a trailing second shot through light NERA at 8 degrees again. Starting was just projecting roof line down. Nb this is after some frontal protection against autocannon
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On an equal weight, bending basis, Mg is about 205% the stiffness of steel vs Al which is about 166% the stiffness of steel. But the Mg fragments burn, whereas the Al fragments dont. Its probable that 1% pb would be added for nuclear radiation scenario, this would actually improve damping propertics and thus the ballistic backing ability of the Mg. With appropiate design a Mg hull floor would have great blast resistance. Being that a little curvature would add massive blast resistance. Given that is 100mm thick anyway. But the main reason, Mg is easy for casting. 1 piece cast hulls are quick and easy, gravity sand casting will do.
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Proposed tank design has dual Kharkov engines at back, so a hit to one will not necessarily disable the other. But wow, 1500mm of space does wonders to CE. I would wager that its a lot quicker to replace a motor (kept as a field spare) than to rewire/rehose a fighting compartment. And probably cheaper too. In the automotive world a car's wiring harness is a higher cost item than the engine, its probably the same in tanks also. This is a 1960s tank, not a 1940s tank.
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Question re spaced armour and engines A compartment for an engine is 1500mm, kharkov 5TD For a nominal 1000mm CE the calcs are 1500/100 = 15 1000/(1.1 to power 15) = 240mm CE So, as long as precursor charge is already dealt with, the engine bay reduces CE by 75%. Hmmm, rear of my tank may be tougher than the front?
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Thats fine, i dont have a military background so dont trust anything i write. But review this doc. https://www.researchgate.net/publication/242230270_MULTIPLE_CROSSWISE_ORIENTATED_NERA-PANELS_AGAINST_SHAPED_CHARGE_WARHEADS When i backcalculate the Various k1s for their nera (after including a 390- 490mm space effect) i got First nera k1 = 3.3 Standard Follow up nera k1 = 1.1 Alternate follow up nera k1 = 1.6 That was for a 3/5/3 nera Anyway, point is that the norman turret upgrade is a good example of how to make these calcs work. Outer layer is ERA, on a vertical surface, chevron stye. Inner layer is NERA with a horzontal aspect to its lay. NERA calcs are for the optimal single nera cassette that gets stacked to maintain coverage.
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Sweet
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What acceleration is permissible to consider a heat warhead as 6 diameters effective? Vs the acceleration to consider a heat warhead as 5 diameters effective. I want to use rpg 29 warhead at less than double its acceleration (currently 40% more acceleration). its still low pressure. Can i assume i can retain its penetration? This is in a BMP 3 style turret.
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Problem is not the calcs, problem is that k1 value drastically reduces on parallel follow on NERA. So yes, your CE is fantasy. 2nd and 4th nera layer can be ignored. And rotate the 3rd nera layer if you don't want to ignore it either. I also think your first air gap is off.
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During 1960s Dow's magnesium from seawater extraction plants in Texas had about 100,000 tonnes capacity annually. Up from 50,000 circa 1941. Can we use magnesium? Early BMPs were magnesium. I would approximate keeping equal mass efficiency between cast Mg and wrought Al.
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https://www.armyrecognition.com/weapons_defence_industry_military_technology_uk/china_has_developed_first_unmanned_main_battle_tank_mbt_type_59.html M113, type 59. In future t72 Anything which has the special quality of being surplus available in quantity. Hulls are a big cost for these, why not reuse a known vehicle, complete with existing logistics?
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What would create a weight limit, but not a ground pressure limit. Presumably, in use, is ground pressure limited, which is compensated by increasing track length. Presumably, in transit, is weight limited, but transport vehicles also get upgraded, and so too does rail lines. Russia's china to europe rail line is now a major line, providing faster movement than sea, and cheaper movement than air. I would expect ease of tranport east and west has improved for russia's military.
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The Centre of Gravity for the T14 turret must be fore of the turret ring? Would that be the case for other russian tanks? Its likely that western tank's turret's centre of gravity is circumcised by the turret ring. This should affect the ease with which to obtain adequate longevity from interface between turret and hull. Perhaps it ok with 125mm t14 turret but not with 152mm t14 turret. Thus needing a new turret for 152mm.
