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Ardennes posted:The West is going to have to put in more quarters we're printing them as fast as we can
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Feb 25, 2022 02:29
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| # ¿ May 12, 2024 14:34 |
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atelier morgan posted:fissionable materials have a critical mass; that is, there is a theoretical minimum mass of material that needs to be present to make it go from sitting there menacingly to exploding, even if it is 100% purity in a perfect sphere You can design a nuclear weapon with considerably less than 10 kg of Pu-239. The 10kg figure is a very basic estimate: 1.) It is the "bare sphere" critical mass, meaning there is no neutron reflector around the fissile material: any neutrons which escape the assembly are lost. A neutron reflector can reduce the critical mass to less than half that of the bare sphere critical mass. 2.) It assumes density at standard atmospheric pressure. The entire point of an implosion assembly is to convert a subcritical mass into a critical one by virtue of compression. The critical mass (or any reactivity parameter) scales approximately as 1/C^2, where C is the density ratio (although, for reflected systems the scaling exponent is a bit lower than 2, since the reflector material is generally not compressed to the same ratio as the core). Practical compression systems, where the mass of high explosive is kept to within an order of magnitude or two of the fissile mass, can achieve density ratios of around 1.5-2.0 . The absolute limit for shock compression by high explosive is probably around ~2. So the amount of Pu-239 needed to make a bomb go bang is substantially less than 10 kg. It is relatively easy to design weapons with 4-5 kg (an often published figure for many American fission triggers). It should be quite possible to design a weapon with even 2 kg, if the implosion system is good and a suitable reflector is used. The absolute minimum amount of plutonium needed to make a bomb is probably between 1-2 kg. Tritium boosting would ensure that the efficiency of even such a small weapon could still be good. Such a minimum size fission stage may not be optimal for efficiently driving the 2nd stage of a thermonuclear weapon. The size of the required high explosive drivers and reflector may also increase total weight over a system using modestly more fissile mass. That may be why actual weapons seem to use larger than the minimum required fissile mass.
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Jul 19, 2022 22:41
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Also if I were in charge of Iran's nuclear weapons program, I would: 1.) Clandestinely develop a robust, tritium boosted implosion system designed for ~1.5-3.0 kg of reactor grade plutonium. "Weapons grade" plutonium isn't needed and doesn't significantly change the critical mass requirements, it's just that reactor grade plutonium has some heat dissipation, radiation, and background neutron issues. These are all irrelevant in a small, boosted weapon, though. This system could be tested without any fissile material to the point of being assured of its reliability. The needed amounts of reactor grade plutonium for several bombs could be recovered by small-scale and difficult to detect chemical reprocessing of small amount of reactor fuel over the course of a decade or so. 2.) Use the above in a conservatively designed 2-stage pseudo Teller-Ulam (really just "Ulam") design where on the order of 10 kg of moderately enriched uranium are compressed by the trigger in #1, possibly with tritium boosting in the secondary as well. The compression achieved by even a lovely radiation implosion device would be more than enough to fission the enriched (but not weapons grade) uranium, and such a two step weapon would be much easier to design than an actual thermonuclear bomb while easily achieving yields in the 20-100 kT range. All the major difficulties of a thermonuclear design (reaching the required pressures in the fussion fuel without excessive pre-heating, achieving ignition in the compressed secondary, optimal size and composition of the high-Z radiation tamper...) are eliminated and even the dumbest, ultra-conservative design will easily achieve sufficient compression to fission the enriched uranium. The above would be a very effective demonstrator weapon, could be practically deliverable, and could make use of small amounts of clandestinely produced reactor grade Pu and large amounts of enriched but not weapons grade uranium. It would also be a convenient test platform and starting point for a thermonuclear weapon. Anyway that's my ted talk
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Jul 19, 2022 23:04
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lollontee posted:tritium boosting, as in a fusion second stage? dont those take up a huge amount of space tho? No you just put like 2 grams of tritium-deuterium gas right inside the fission core. As soon as your fission assembly begins to go critical (even at the poo poo-tier fizzle stage), it generates more than enough heat to cause a decent number of fusion reactions in the boost gas. This produces a large number of energetic neutrons, which "help along" the fission reactor much faster than would occur if it were limited to the neutrons produced only by its own fission. As the fissioning continues, more heat, more fusion, more neutrons, and so on. So a small amount of tritium (deuterium doesn't count since its so cheap) greatly increases the efficiency of the fission bomb, and also simplifies its design in many ways
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Jul 19, 2022 23:08
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atelier morgan posted:tritium boosting etc would make the boom more efficient not less, though oh whoops i thought we were just talking about minimizing fissile material not minimizing yield.
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Jul 19, 2022 23:10
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lollontee posted:just by virtue of adding lots of neutrons to the mix??? huh, alright, 1-proton, two-neutron, make interesting. how do you make that stable chemically tho? just react the fissile metal with tritium? I think the usual practice is to have a cavity in the core (making the fissile material a shell rather than a sphere is beneficial for compression anyway) and to inject tritium from a reservoir during arming, since otherwise hydrogen gas diffuses into and out of everything. You could use tritiated + deuterated lithium too, but tritium has a short enough half life that it needs to be periodically replaced anyway, and that's much easier if it's in an external reservoir.
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Jul 19, 2022 23:32
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mawarannahr posted:seems extremely unlikely that Man and Nature would perfectly align so that a round number like 10 kg would be the official number where it blows up. also seems extremely unlikely there would happen to be exactly one isotope that can support a fission chain reaction while also being stable enough to persist in earth's crust but here we are.
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Jul 20, 2022 00:17
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There is reasonably good data about things like fission, scattering, and absorption cross sections for Pu-239, since those are important for nuclear reactor design and control, and the data isn't hard to obtain experimentally or theoretically. A lot of things can be arrived at theoretically with very good accuracy, or will be very similar to uranium. Opacity data at extremely high temperatures, or basically any equation of state data in the ultra high pressure / high temperature regime, tends to be classified and hard to get at. Probably the only secret information that is relevant to calculating the critical mass are some peculiarities about solid state phase transitions in plutonium and Pu-Ga alloys at high pressures. And that stuff isn't really important unless you are trying to really minimize your implosion system. Also, it can probably be computed theoretically with pretty good accuracy. Fission bombs aren't very complicated and there are no important secrets left. Hard part is really just getting the material, and even then only because it's so capital, labor, and energy intensive.
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Jul 20, 2022 01:18
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Filthy Hans posted:apart from grift, I don't see the point of lighter tanks, the Abrams is 70 tons partially because it carries enough armor and equipment to stop man-portable antitank weapons Infantry needs to be mechanized wherever it's possible, and a big, direct-fire cannon is a useful weapon that can't really be replaced by anything else. So, you need a system that 1.) has a big cannon on a turret, and 2.) drives around at some reasonable speed in varied terrain. That's what tanks are for. The armor is really just there because it can be. The fact that you can accomplish #1 and #2 while offering pretty outstanding crew protection (better than what they can have under just about any other circumstances) just turns tanks from good into great. There is a maximum weight that a tank can have before it becomes useless, and 70 tons is right around the limit. There is only so much protection that can be afforded to a 70 ton tank, and that degree of protection generally precludes reliably surviving hits from modern anti-tank weapons to anything but the front. So, every now and again someone raises the question of whether you really need to bother with all that armor, or if it's better to have a tank that weighs half as much, still protects against most weapons and artillery, but just doesn't try to eat an APFSDS or Konkurs to the face and survive. Maybe, the best way to protect the tank is to just know the dispositions of enemy forces, stay at a reasonable range, and be protected by other friendly assets like short range air defense systems and infantry... The answer over the ages has been a resounding "meh". The bottom line is that if your logistics can support the heavier tank, and it is physically able to cross bridges, the lighter tank won't really do anything better, and will do some things worse. The light tank may be cheaper, but who cares? Tanks are cheap in general. "bluh buh what about airlifting" never really matters since these stupid loving wars never work out to be the lightning fast combined arms maneuver exercises they are imagined as, and always devolve into chaotic shitpits for, by, and of morons. Morbus has issued a correction as of 22:47 on Sep 16, 2022 |
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Sep 16, 2022 22:37
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Frosted Flake posted:Mortars are supposed to be “the Infantry’s Artillery” and lighter and cheaper (and therefore simpler) than the lightest and cheapest guns of the same calibre. Ah, but putting a 120mm mortar on a stryker platform *is* lighter and cheaper than putting a 155mm howitzer on a tracked vehicle! So actually it makes perfect sense
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Sep 22, 2022 03:53
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Frosted Flake posted:My read is that this was political manoeuvring to preserve the relevance of the USMC, but it’s not a serious doctrine, for the reasons you outlined. It maintains the budget, in the same way the attempts to rebrand the USMC as urban warfare specialists from 2003-10 did. They were able to trade on Fallujah for a long time in Washington, but it lead to things like the M27 replacing the M249 SAW in the rifle section as the 249 was “too heavy to carry in Fallujah”. The M27 came about mostly from the M249 being a stupid heavy piece of poo poo. It weighs nearly twice as much as an RPK, about the same as a PKM (!) and nearly as much as an M240 in some configurations. There is also the problem that the entire concept of a light machinegun firing an intermediate cartridge optimized for rifles is a compromise that arguably undermines the most important part of an infantry squad. If for some reason you can't bring or don't actually need an M240, you are arguably not that much worse off just giving everyone or a few people an M27 and calling it a day. The solution was always to just make a better light machinegun. The M250, against all odds, actually seems to have produced a pretty excellent result in that regard, but by insisting that the machinegun and rifles must use the same cartridge, the accompanying M5 rifle is hilariously overweight (potentially heavier than the aformentioned RPK, lmao). Morbus has issued a correction as of 01:57 on Oct 5, 2022 |
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Oct 5, 2022 01:51
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Frosted Flake posted:It seems like a lot of work just to go back to the C2, BAR, Bren, and forget the reason the FN MAG and Minimi were acquired in the first place. Yes they are heavy. Fine but if your light squad-organic M249 weighs the same as a loving PKM what exactly have you accomplished? It's not OK for infantry equipment to be egregiously heavier than it needs to be.
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Oct 5, 2022 02:29
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ModernMajorGeneral posted:https://www.heritage.org/press/heritage-foundation-releases-2023-index-us-military-strength-gives-us-military-first-ever 
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Oct 20, 2022 04:44
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Danann posted:https://twitter.com/zhao_dashuai/status/1590326304007933954 hey what if we use aircraft to drop self-propelled flying machines that steer themselves to a target then explode. someone quick file a patent
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Nov 11, 2022 22:56
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Lostconfused posted:I guess everyone forgot about Australia, but there's some choice quotes here. I thought the whole AUKUS deal was that there would be a technology transfer and Austrailia would build the submarines in Austrailia. Due to the entirely foreseeable difficulties with that plan, arising from Austrailia's unique position of being Austrailia, there has been some talk about just building the first one in the US. This guy just seems to be saying they aren't gonna do that, but they may "lend" a largely American crewed sub as a stopgap. AFAIK that is entirely consistent with the original agreement...it never made any sense to interrupt the US Navy's own deliveries to just give one to another country.
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Dec 7, 2022 19:39
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The Oldest Man posted:*watching maybe the best air assault force in the world get bodied by a bunch of draftees and shoved off their objective with heavy losses thanks to "concentration of force, logistics, and artillery don't stop existing because you came in a helicopter"* Agreed. You need to arrive in a rocket https://www.nationaldefensemagazine.org/articles/2021/8/13/space-force-dreams-of-using-rockets-to-supply-warfighters
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Aug 15, 2023 21:38
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Votskomit posted:Are the ruling class people really dumber than before? age-related cognitive decline is real, and strong, and my friend
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Oct 27, 2023 19:58
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Lpzie posted:MELT YOUR GUNS , FORGE SHOVELS
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Oct 28, 2023 00:47
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poisonpill posted:pay more? esprit d’corp? all impossible in modern America, apparently If you gave every single person in US active military service $1.2 million cash dollars right now, it would cost about the same as the F-35 program, lol.
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Nov 2, 2023 18:44
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Frosted Flake posted:Yeah, I had a meeting on the ramjet thing and I'm curious who planted the story, since the technology has never worked, base bleed and RA shells already exist (and are already marginal in both utility and use), and basically there's no reason for it to be fielded - corps artillery range with less firepower than regular munitions is almost negatively useful, and the range and warhead requirements are already met by MRLS, the precision fires and range requirements are met by Airpower, and I suppose MRLS. Even overlooking all that, supposing you did want a gun-fired solution, there is no reason whatsoever for it to be employed by 155mm guns as opposed to 175mm or 203mm Corps/Army artillery calibre - because they may as well have the payload to be useful. Considering the specialization of the mission, the narrow scenarios where they would be usefully employed, and the expense, there's no reason why this would be a field artillery mission, and therefore field artillery calibre. The mission is to make money.
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Nov 30, 2023 07:01
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The Oldest Man posted:im just going to tell you why you should watch this: this is a hundred million dollar condo skyscraper, in downtown san francisco that is sinking because it wasnt designed right, and that sinking was bad enough to cause panes of glass on the building facade to shatter and fall into the street in high winds But thaaaaat's my life!
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Jan 4, 2024 00:09
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Gresh posted:I don't know where to post this but Pakistan and Iran have both bombed each other in the last 24 hours lol it's more of a team-building missile exchange program
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Jan 18, 2024 05:42
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Cindy the SKULL posted:I think you're all seriously underestimating the ability of the modern imperial state for infiltration, suppression and cop-opting political organizations that would be able to offer an alternative to the ghouls in charge. It's not the 1960's anymore, you can't do any kind of political activity without agent provocateurs and cops tracking your every move, and building a lawfare case against your organization, which you have zero ability to prevent due to the incredible brutality of the police state, which you do not have the ability to match with counter-intelligence. you can actually just shoot them op
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Jan 25, 2024 16:28
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stephenthinkpad posted:Has anyone made a study on the phenomenon of using cheap civilian graded weapons to suck up the expensive and limited ammo of air defense system? Any serious plan to attack an IADS or carrier group or whatever includes 1.) lots of missiles 2.) lots of decoys 3.) having them all arrive in a short time to achieve saturation and let you be as economical as possible with 1 and 2 Even with 1960's technology, the cost of achieving this was much less than the value of ships you could sink. An exocet missile is like 200k. 2000 of them is 400 million, a bargain. The commodification of the electronics and sensors that made these weapons expensive only makes things worse. The idea that you can just park a vessel or whatever in range of an attacker and shoot down missiles all day has never been correct. The US just hasn't fought a real war in decades, so it's used to getting away with dumb poo poo.
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Jan 26, 2024 05:24
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The Oldest Man posted:a dji phantom with a firecracker goes off at the base's fence line lmao
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Jan 28, 2024 22:28
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Cerebral Bore posted:when you're wounded and left on afghanistan's plains lmao
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Jan 31, 2024 00:12
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Gripweed posted:It did occur to me recently that if anyone in government was smart or gave a poo poo, Let me stop you right there
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Feb 1, 2024 19:44
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unwantedplatypus posted:Mortars might be incredibly effective, but have you considered that it's hard to make a grift out of a tube with a spring? Don't worry, grift is In Everything We Do(tm) https://www.gd-ots.com/munitions/mortars-and-mortar-components/81mm-rcgm/
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Feb 28, 2024 00:45
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DJJIB-DJDCT posted:It can't be that they're running out of infantry weapons, right? Because those should be the easiest to manufacture, and I would imagine there are war stores of M240s and leftover M60s to last until the end of time. "It can't be that they're running out of 155mm shells, right? Because those should be the easiest to manufacture"
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Feb 28, 2024 00:51
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The Oldest Man posted:[screaming internally]  Me, very neoliberally: "the second picture. that is the better one"
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Feb 28, 2024 01:32
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gradenko_2000 posted:https://twitter.com/PantexPlant/status/1762662630026567754 NOW WERE TALKIN
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Feb 28, 2024 05:20
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Orange Devil posted:Hey if we're asking that question we can also ask "why would China invade Taiwan?". We're in RAND lala-land here, I'm just wondering what scenario's these idiots are actually gaming out. They always seem to suppose a Chinese invasion when that's not at all necessary? The salient features of most analyses, wargames, etc. are: -Any surface vessels in the general area are going to have a bad time -China can probably interdict shipping to Taiwan indefinitely, so don't count on being able to resupply them by sea Now, the obvious conclusion from #1 and #2 is that, yes, if China wanted to exert pressure on Taiwan they could just blockade them and the US couldn't really do much about it. If anyone wasn't convinced of this before, I think operation pRoSpErItY gUaRdIaN should have set them straight. However, every RANDbrain just jumps from here to "well, that means amphibious landing craft are gonna get hosed, so China would not be very successful at a ground invasion as long we can count on the Taiwanese fighting fanatically and the US flushing half its navy and aircraft down the toilet". Which is probably true, but seems like it misses the point.
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Mar 1, 2024 01:24
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Zodium posted:scandinavian countries are a type of barnacle that grows on empires lol
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Mar 2, 2024 00:31
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DJJIB-DJDCT posted:I was just reading a paper on airborne ASW these days, and discovered that, other than the Russians and Chinese putting SAMs on the masts or periscopes or whatever, no submarines today have a defence against aircraft. Oh, they have thought about it. And the answer they came up with is the same answer they always come up with: enemy aircraft will not be able to conduct ASW operations because the US will have uncontested air superiority in all places at all times Other than that, ASW operations by aircraft do take time and it's not that easy to find a modern submarine. To really have a good shot, you need a relatively dense array of hydrophones/sonobuoys with a direct sound propagation path to the submarine, and this is hard to accomplish unless you already have it's location pretty well narrowed down Every now and again you do read some poo poo about active ASW countermeasures, including attempts to spoof or jam sonobuoys (either acoustically or their RF communications). I don't know if any such systems have ever been actuallydeployed, but they are at least plausible. At the end of the day, people have been developing ASW systems for decades but there haven't been any large scale anti-submarine engagements or really any substantial naval battles at all to truly test them. My general opinion is that regardless of how effective these systems are, the idea of a submarine as a super-expensive, undetectable, unattritable asset is not tenable. In any large scale naval battle, submarines are going to sink lots of ships, and lots of submarines are going to sink.
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Mar 2, 2024 01:10
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Justin Tyme posted:I don't understand the "aha! We will turn the A-10 into a drone!" concept because I dont think (&I could be wrong here) the cost of training a pilot is more than fuel and maintenance, plus you still need to train a pilot, they just sit on their rear end on a terminal instead of a cockpit. I guess robots don't need to maintain flight hours? It's not just the cost but the time & flight hours, and this is especially an issue with the US/NATO air forces that rely on multi-role aircraft without a lot of GCI where pilots are expected to do everything. Even if the airframes were attritable (they are not lol), and even if there was the production capacity to keep up with missile/bomb expenditures (lmao), the current US model of pilot training is arguably incompatible with a real, sustained war.
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Mar 8, 2024 01:31
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Tempora Mutantur posted:given the speed and range they operate at, how's guidance on hypersonics supposed to even work? Hypersonic weapons (as usually described) are mostly used against fixed targets or ships, and the terminal closure rate in those cases is actually not faster than what is common for many air-air or surface-air missiles. Even at mach 4, you've got 3-4 seconds to make adjustments once the target is clearly resolvable to a vis/IR camera, and longer than that for radar terminal guidance. The missile only moves about 1 meter per millisecond, so the speed of the computers and sensors is not really a problem. Having a very well characterized flight model and control system is the "hard" part, and even then you can do pretty well with simple on-off actuators and bang bang control If you are relying entirely on GPS/INS things can be harder and depend on the quality of your position data, but for something as expensive as a hypersonic glide vehicle or ballistic missile, almost everyone uses vis/IR or radar terminal guidance because why wouldn't you? They are cheap and reliable.
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Mar 18, 2024 18:59
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The Oldest Man posted:https://breakingdefense.com/2024/03/towed-artillery-has-reached-end-of-the-effectiveness-army-four-star-declares/?amp=1 *me, after watching the ukraine/russia war intently for the last 2 years* "you know, we'd really better get to work on self-propelled, autonomous 58mm robot cannons for use by special operators in entry operations"
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Mar 28, 2024 05:26
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zetamind2000 posted:the Germans were brilliant in all things military (even if they didn't win many wars)"
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Apr 2, 2024 20:14
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rudecyrus posted:why is vietnam pro-us its what they call a power move
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Apr 2, 2024 21:52
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Ignore_Me posted:no I think some people are pressured by their parents to enlist or are doing so out of some form of punishment or other, and they don’t otherwise actually want to enlist of their own volition so they sabotage a test that is incredibly easy to sabotage It is not credible for someone to fail the ASVAB unless they are profoundly stupid, or have some kind of serious mental disability. If any halfway normal person scores "far below" the minimum eligibility requirement, it was almost certainly intentional
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Apr 3, 2024 02:48
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