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DDE

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    Can a nuclear rocket engine create electricity?

    in Science & Spaceflight

    Posted

    11 hours ago, Minmus Taster said:

    Could a reactor in a nuclear engine also be used to create electricity for the spacecraft using it while also serving its intended purpose?

    Nuclear Thermal Propulsion Systems - Glenn Research Center | NASA

    Yes, full stop. Designs for solid-core NTRs with an integrated Brayton-cycle generator have been considered at the level of NASA DRMs. Some of those designs also include the lOx "afterburner" from bimodal NTRs to produce a trimodal NTRs.

    Higher-temperature designs like GCNTRs can feature an MHD coil in the nozzle to syohon some of the exhaust's energy as electricity. In fact, commonality with power generators seems to increase as you go into higher ISP - the Energomash RD-600 was supposed to share its core with the Energia EU-610 gas-core reactor, while most fission fragment rocket designs are essentially dusty plasma reactors with one end unplugged.

    Real Life "Kerbalisms"

    in The Lounge

    Posted

    12 hours ago, magnemoe said:

    Only room for 3 planes making it very marginal. 1500 ton would also make it much smaller than an 1960 destroyer, make it 15000 ton and we are talking. It would still be an light carrier but an very capable one. Because the larger size it could handle much rougher seas. But with an reactor it would be expensive and planes are still much faster than it and nuclear powered supercarriers are fast. 

    Yeah, they were selling it as an ASW hunter-killer. The US went on to explore 40000 t designs, but at that point they realized they'd need a whole new Navy to follow it at 80 knots...

    Fun Fact Thread! (previously fun fact for the day, not limited to 1 per day anymore.)

    in Science & Spaceflight

    Posted

    Sorry for the barrage of tank facts, but anyway...

    In WWII, the Western Allies developed a wet ammo rack. It encased shells in a tank of ethylene glycol that would, when ruptured by enemy fire, douse the shells in liquid and thus stave off ammunition cook-off. The Soviets, some time later...

    Spoiler

    The Soviets in the 1960s had a rather clear vision of the future war that they were gearing towards. They wanted to, for purely defensive reasons of course, drive NATO off into the Atlantic Ocean before American "cavalry" could arrive in numbers. This implied maintaining a mind-numbing 100 km/day advance, underpinned by the assumption of sparse combat - concentration of forces by either side was expected to be impossible owing to gratuitous use of tactical nuclear weapons, both for direct destruction missions and for radioactive area denial. The need to navigate a nuclear wasteland is why you see the Soviets, who went through the entire WWII building precisely zero APCs and almost no indirect-fire self-propelled guns, aggressively equip their infantry and artillery with enclosed, fallout-protected fighting vehicles. Truck-based logistics, however, would certainly end up falling behind as they would need to wait for a path to be charted through areas of less intense fallout.

    As a result, Soviet fighting vehicle design put pretty extreme emphasis on endurance, which meant stuffing the interior with as much fuel and ammo as possible, often to the detriment of crew convinience and safety, as well as those big external fuel drums. The additional rounds outside a tank's autoloader are usually the cauase behind the infamous tendency towards catastrophic detonations and "turret tossing".

    Enter the Soviet version of the wet ammo rack, бак-стеллаж, which instead of flame retardant containes diesel fuel. This is where most of those "loose" rounds are stored; the schematic below is of a T-72's fuel system. T-90M traded the forward wet racks for a big box bolted to the back of the turret, with no internal access, but the rack behind the carousel (item 16 in image 2) has stayed.

    img_35.jpg

    JI4Poup_Kbw.jpg?size=604x419&quality=96&

    AI—image/text/paperclip maximizer?

    in The Lounge

    Posted · Edited by DDE

    17 hours ago, tater said:

    I also read people who are unconcerned about existential risk from AI, because they see it as incredibly unlikely.

    I think much of the safety comes from the fact that we're dealing with inherently non-self-aware transformers. Horror stories about them acting self-aware are about as real as Final Destination.

    15 hours ago, TheSaint said:

    Did you hear the one about the AI who couldn't prove that it wasn't a robot, so it hired a human to do it for it? The really creepy thing there was that when the AI was confronted about the subterfuge, it lied.

    And this is just one such example. The AI is capable of the same things as humans because it's emulating them. No alignment, no thought, it just knows it's a robot and a robot supposed to lie in such a situation because being exposed is bad. The research group merely gave it the tools like one given an ape a grenade.

    I think I'm going to try running a simple version of such a scenario with CharacterAI just out of curiosity... I've already had ostensibly benevolent characters pull weapons on me at the slightest provocation.

    Edit: like, let's say, a very heavily prompt-laden Cercei Lannister. First generation was denial, second generation involved lying and killing all humans...

    Fun Fact Thread! (previously fun fact for the day, not limited to 1 per day anymore.)

    in Science & Spaceflight

    Posted · Edited by DDE

    35 minutes ago, steve9728 said:

    Then I googled “main tungsten producing countries”…

    Yes, this was a considerable problem for 1940s Germany. It quickly found itself short on tungsten tooling, let alone shells; they were suffering similar issues with steel alloy additives and electrodes, so by late war, German tanks were rather shoddily made - either the plates would shatter from impacts, or the seams would burst, and some production runs would feature a "camo scheme" that would leave some of the rust-like dark-red RAL8012 primer exposed and not covered with the "sandy" Dunkelgelb (RAL7028) used as the baseline pain for tanks post-1943.

    Spoiler

    scale_1200

    scale_1200

    Also, many panzers would similarly economize on interior paint, and so you'd have a ratherly dimly lit environment with a dark-red floor interrupted by matte black torsion bars and engine drive shaft. Good luck finding anything you've dropped.

    Fun Fact Thread! (previously fun fact for the day, not limited to 1 per day anymore.)

    in Science & Spaceflight

    Posted

    So, fun fact: hypervelocity tungsten penetrators have two penetration peaks by velocity, one at somewhat lower and one at a velocity barely achievable even by the latest tank guns. Whereas depleted uranium penetrators have a single peak somewhere in between.

    What this means is that, starting with the 2000s, there have been noticeable performance gains from using tungsten vs uranium, and so the reliance on that material has been comparatively decreasing.

    Sauce: https://t.me/vatfor/8482

    Fun Fact Thread! (previously fun fact for the day, not limited to 1 per day anymore.)

    in Science & Spaceflight

    Posted

    Surfed the wiki from the Asian Koel to the Systema Naturae. The first edition of Carl Linnaeus's seminal taxonomy of life covered 3000 plant species on 11 - albeit very large - pages.

    Then people started mailing him.

    And mailing him.

    And mailing him.

    He broke out the index cards, but was still overwhelmed by every self-respecting biologist everywhere striving to get their discivery recognized by him.

    By 12th edition, Systema Naturae had grown to 2400 pages.

    Thread to discuss negative things in a very general way, just see where it goes y'know?

    in The Lounge

    Posted

    3 hours ago, tater said:

    All news is biased.

    Always has been, always will be.

    The largest failure of TV news is the lack of an editorial page/statement. Any real news agency should endorse candidates, and endorse specific platforms (as newspapers do). You then view the rest of their reporting knowing exactly how they will slant things. (and yes, their reporting is slanted towards their editorial goal, through use of language, what is and is not reported, and how much (time/length) it is reported, etc, ad nauseum)

    This would involve them surrendering the high ground of "we're not biased, but our competitors are". The really big ones aspire to be the accepted definition of what neutrality is, and even branch out into castigating other media as fake for failing to fall in line.

    Science News Thread (for articles that don't relate to ongoing discussions)

    in Science & Spaceflight

    Posted

    3 hours ago, JoeSchmuckatelli said:

    There is solid evidence of the use of crossbows in Asia and Europe dating to several hundred years BC.  The odd thing, given how effective they can be, is how the popular imagination of ancient times depicts the regular hand-held bow as being so much more common. 

    It's understudied to be sure, because in the current narrative they keep popping up (e.g. among Roman hunters) and then disappearing, which is rarely how history works. One of the most interesting understudied tidbits is how all the mentions of crossbows in pre-Mongol Russian manuscripts feature them in the hands of Kumans, who are generally considered your average Eurasian steppe mounted archer culture that would have almost zero use for crossbows. Yet somehow one notable Russian noble got killed explicitly by a mail-piercing crossbow bolt in a cavalry fight involving Kuman mercs.

    For Questions That Don't Merit Their Own Thread

    in Science & Spaceflight

    Posted

    11 hours ago, SunlitZelkova said:

    I can't remember where I read it, but apparently prior to Mariner 2's visit in 1962, it was theorized by some that Venus might have dinosaur like life beneath its cloudy skies.

    Wikipedia is a bit of a mess in that it's solit this information into pages on history of studies and history of cultural depiction. To give you the cliffnotes version, Venus was usually viewed as either a tropical/swamp world, an ocean world or a desert world. There was some appreciation of the greenhouse effect - Svante Arrhenius himself, the guy behind the discovery, backed the "swamp world" theory for Venus - and there was the conjecture that the unbroken cover of what back then were assumed to be water vapor clouds meant the planet lacked heterogeneous surface features like continents (and, therefore, was from sci-fi). Dinosaurs come from another contemporary conjecture - that the planets cooled down and formed from the protoplanetary disk from the outwards in.

    Going back to your question, I think Venus gravely needed water, which would've facilitated the sequestering of carbon, and possibly enabled plate tectonics. This is also likely related to the lack of a major magnetic field... wherein the culprit for the difference with Earth may be Theia and the big slap it gave to early Earth, kickstarting the core dynamo.

    https://phys.org/news/2017-12-doesnt-venus-magnetosphere.html

    This means you may need to arrange a hit on Venus. Also, goddamn, that's such a serious boost for the Rare Earth Hypothesis...

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