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Epsilon Moonshade posted:Has anyone actually tried making something float just by making a vacuum in it? I'm sure somebody's thought of it in a sciencey way, but, like I said, we just don't have strong and light enough stuff to make an inverse balloon. We've got vacuum chambers solved but they're too heavy to fly with current materials. The hydrogen/helium/hot air is structural in regular balloons, and they had ... a few problems enclosing those with aluminum girders past a certain size, as I mentioned above. Apparently the only last-generation Zeppelin to not meet a bad end and be just peacefully sent to the scrappers was Hindenberg's sister Graf Zeppelin II, which had a reduced flying schedule/skeleton crew after the other ship of the class, y'know, burned like a goddamn cutting torch in front of cameras and a live radio reporter. When we do figure out vacuum chambers light enough to fly, the first one to let go is going to make the Hindenberg fire look like a toy. But the other way around, of course.
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Jun 2, 2018 00:03
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Bad Angus! Bad!
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Epsilon Moonshade posted:Okay, this makes a whole lot of sense, but I'd never have thought of it myself. What's lighter than nothing? I seem to recall reading somewhere that someone did the math and there are no known materials that have the strength-to-weight ratio required for the job. Even a "balloon" (rigid shell, more like) made of diamond would have to be heavier than its own buoyancy to not implode from sea-level atmospheric pressure. Maybe someday, though, with like a nanotube geodesic dome supporting a graphene skin or something.
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Jun 2, 2018 00:05
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Epsilon Moonshade posted:Okay, this makes a whole lot of sense, but I'd never have thought of it myself. What's lighter than nothing? Yes, but it's just a materials problem. Air at STP is about 1.3 grams per liter. If you want your vacuum balloon to float at STP conditions, then whatever you build it out of has to be lighter than 1.3 grams per liter of volume, and strong enough to withstand 14.7 psi * the surface area of your balloon. As you get higher, atmospheric pressure declines, so the force you need to withstand gets smaller, but atmospheric density declines so your buoyant force also declines. Even diamond isn't going to work. Chillbro Baggins posted:When we do figure out vacuum chambers light enough to fly, the first one to let go is going to make the Hindenberg fire look like a toy. But the other way around, of course. Not really, vacuum doesn't really doesn't get you much. 1.3 grams of lifting force per liter of vacuum balloon, compared to 1.21 grams of lifting force per liter of hydrogen balloon or 1.121 per liter of helium balloon. There's only so much lighter you can get than helium, and even "nothing" isn't much heavier.
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Jun 2, 2018 00:10
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If you're comfortable shifting the goalposts a whole bunch, one could say that a submarine is essentially a vacuum balloon for the medium it travels in
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Jun 2, 2018 01:19
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Phy posted:a submarine is essentially a vacuum balloon for the medium it travels in A much denser medium than air. And yeah there is that pesky problem that airships, even theoretical ones with infinite-strength, zero-weight skins kinda have a much lower hard limit of buoyancy than anything in water, the latter of which can be made of steel (or titanium if you're fancy and Cold War Russia, bringing us back to if not dangerous chemistry, at least fun metallurgy, the dangerous chemistry was in the torpedo propellants) heavy as you need it to be as long as you can pump enough air into the tanks to offset the weight. In air, that idea no work so good. The problem is making a thing that can take 15psi pushing in and be light enough to float in air. Edit ... could you make a steel hull big enough to make a vacuum Zeppelin? There's gotta be some point at which ... I know it's impractically gigantic, but does the math work out at any size? Chillbro Baggins has a new favorite as of 02:00 on Jun 2, 2018 |
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Jun 2, 2018 01:44
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https://www.youtube.com/watch?v=JsoE4F2Pb20&t=140s https://i.imgur.com/VYXxNGv.gifv
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Jun 2, 2018 03:44
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According to Wisconsin law regarding toxic chemicals:quote:(j) 1. "Toxic substance" means any substance or mixture containing a substance regulated by the federal occupational safety and health administration under title 29 of the code of federal regulations part 1910, subpart z, which is introduced by an employer to be used, studied or produced in the workplace.
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Jun 2, 2018 05:17
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iospace posted:According to Wisconsin law regarding toxic chemicals: loving lutefisk lobby and their unfair regulatory carveouts! 
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Jun 2, 2018 05:38
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iospace posted:According to Wisconsin law regarding toxic chemicals: What purity of lutefisk is required? Can I profitably cut my toxic chemicals with just enough to make transport easier?
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Jun 2, 2018 06:41
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Sagebrush posted:Maybe someday, though, with like a nanotube geodesic dome supporting a graphene skin or something. Weren't they a thing in The Diamond Age?
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Jun 2, 2018 08:14
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Sagebrush posted:I seem to recall reading somewhere that someone did the math and there are no known materials that have the strength-to-weight ratio required for the job. Even a "balloon" (rigid shell, more like) made of diamond would have to be heavier than its own buoyancy to not implode from sea-level atmospheric pressure. I remember back in the late 90s when carbon fiber was just beginning to be a thing, one of the guys in the SunRacer project at our college made a tetrahedron out of thin CF panels. There was a schraeder valve in one panel and sticky tape on the edges. He could vacuum the thing down and it would float to the ceiling, hit something, and pop with a fairly tremendous bang and the panels would tumble to the ground. It didn't shoot to the ceiling like a helium baloon would, but it still floated up. I may be slightly misremembering about the valve; I just remember he had to hold the pump hose against one side of one panel until the vacuum was pretty good.
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Jun 2, 2018 11:36
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Re: vacuum airships, they've been an idea since the 1600s but as people have pointed out the material problems are...big I do know that the DARPA project WALRUS (a proposed idea for a larger-than-a-modern-supercarrier military transport airship) wanted to use 'vacuum spheres' which could be filled with air as part of its ballast system, that might have been just a crazy dream for writing checks for materials research though. The project was cancelled, before 2008 I think Chillbro Baggins posted:I'm sure somebody's thought of it in a sciencey way, but, like I said, we just don't have strong and light enough stuff to make an inverse balloon. We've got vacuum chambers solved but they're too heavy to fly with current materials. The hydrogen/helium/hot air is structural in regular balloons, and they had ... a few problems enclosing those with aluminum girders past a certain size, as I mentioned above. Apparently the only last-generation Zeppelin to not meet a bad end and be just peacefully sent to the scrappers was Hindenberg's sister Graf Zeppelin II, which had a reduced flying schedule/skeleton crew after the other ship of the class, y'know, burned like a goddamn cutting torch in front of cameras and a live radio reporter. I have such sights to show you  This list is the latter part of BIG AIRSHIP (1920-1940). All non-blimps are counted, if they flew at least once after 1920. Decommissioned: British R100: (airliner, kinda sad, showed promise and worked well, took a flight to Montreal and back) R32: (a wooden frame military design, just squeaked in to 'flying in 1920') R33: (Military, sister ship to R34, this one lasted till 1928) R36: (a military turned passenger airship, not successful, never actually flew passengers, was damaged in an accident, then stored, then refurbished for a flight to Egypt. Calculated then showed R36 couldn't fly in tropical weather, and she was scrapped) R80: (attempt at a commercial design that failed, only used briefly by American crews for training before R38 disaster.) Germany Germany had quite a few Zeppelins at the end of World War 1, but was forbidden by the Versailles treaty from having them. These were either given to Allied Powers, including Belgium and Japan, or scuttled. AFAIK the only military airship to fly with a non German crew was: L 72: one of three souped-up height climbers with six engines and extra displacement. Was taken by the French and renamed Dixmude (see below.) Graf Zeppelin: (Sister to USS Los Angles, arguably most successful hydrogen airship, grounded after the Hindenburg explosion) Graf Zeppelin II: (Sister to Hindenburg, flew some propaganda and spy missions for the Nazis, decommissioned when war started, last hydrogen airship) French Nordstern: Sister to Bodensee, passenger airship. Operated by the French as a airliner for a year between South France and Algeria, then switched to military service patrolling the Mediterranean, serving four years Italian Bodensee: A civilian airliner made by Zeppelin, operated a passenger service in autumn 1919, war repo'd to Italy where it made one long flight in Italian service before being scrapped Norge: (after the first flight over the North Pole and the first flight across the Arctic, in Alaska) Omnia Dir: Small Experimental, fate unknown USA O-1: (small semi-rigid built by Italy, used for training in early 1920s, retired) USS Los Angeles: built by Zeppelin, only American rigid airship to retire Wrecked: British R101: Crashed then burned while on flight to India, 48 of 54 passengers and crew killed. R34: Military airship, first aircraft to fly across the Atlantic and Return only a few weeks after Alcock and Brown's historic flight from Butt's farm, NL to Galway, Ireland. Flew into a hillside, survived, flew back to its hanger in Yorkshire, could not be brought into shed due to high winds, had to be tied down outside, took further damage during the night, judged a write-off. (0 dead) R38/ZR-1: completed to sell to the US Navy, exploded over Hull due to a structural failure. 44 of 49 killed. French Dixmude: Exploded near Sicily, all 52 people onboard killed German Hindenburg: Sister to Graf Zeppelin II. Exploded while docking in New Jersey, cause controversial, IMO most likely cause sabotage. Wreck ended BIG AIRSHIP era. Death toll: of the 36 passengers and 61 crewmen, 13 passengers and 22 crewmen died plus one guy on the ground crew. (97 total onboard, 35 shipboard deaths.) Italy Italia: Imagine an airship crash combining with a polar expedition disaster and that's Italia in a nutshell. Built for arctic exploring and first flying in 1924, Italia crashed in May 1928 during an Arctic expedition into arctic pack ice, dumping the gondola and the people inside (and one fox terrier) onto the ice. The dog and eight survivors were left on the ice, with one person killed. With the gondola and all those people now no longer onboard, the airship took off again. As the envelope drifted away, the Chief Engineer had the presence of mind to start hucking stuff out of the airship for the people now on the ice. He and five others would disappear with most of Italia, never to be seen again. Death toll is difficult to figure - 7 died - eventually - from the initial accident, and then there was those ugly cannibalism charges... (the dog survived to be rescued) Soviet SSSR-V6 OSOAVIAKhIM: A passenger airship designed by Italian Norge/Italia designer Umberto Nobile, this design flew for several years in the mid-1930s USSR. Beat an endurance record for constant flight set by Graf Zeppelin. Participating in an arctic rescue mission in 1938, she lumbered into a hill at night and burned. 19 onboard, 13 killed. USA Roma: A hydrogen using semi-rigid built by Italy and brought to the United States. During a test flight its rudder failed, and Roma drifted into high voltage power lines and for some reason exploded. 34 killed, 8 injured, 3 escaped unharmed. The first "worst air disaster in US history." After this, all American LTA craft used helium. USS Shenandoah: Designed partially by copying the design of a height climber Zeppelin, she was the first USN rigid airship. First transcontinental aircraft flight over the USA. Destroyed in 1925 in a thunderstorm. 29 survivors, 14 deaths. USS Akron: Sister ship to Macon, flying aircraft carrier. Destroyed in a thunderstorm off of New Jersey, 73 out of 76 killed, all time worst Airship disaster. Deaths caused mainly by lack of lifeboats, life jackets. USS Macon: Much longer flying sister ship to the Akron. Broke up off of Big Sur California in a thunderstorm after high winds caused a partial structural failure in the tail that both airships shared. Thanks to lessons learned by wreck of the Akron, 64 out of the 66 aboard survived, with two dead. One airman jumping from the airship too early, and the other swam back to the airship wreck after escaping to get personal effects. The last airships, Hindenburg and Graf Zeppelin II, and the Akron and the Macon, are the largest flying objects ever constructed. Akron displaced 7,401,260 cu ft (209,580.3 m3) and was 785 ft (239.3 m) long; Graf Zeppelin II displaced 200,000 m3 (7,100,000 cu ft), and was 245 m (803 ft 10 in) long. She had a payload capacity of 232,000 kg (511,000 lb). Also, writing this, made me realize that is a fair number of deaths Nebakenezzer has a new favorite as of 18:48 on Jun 2, 2018 |
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Jun 2, 2018 15:29
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babyeatingpsychopath posted:I remember back in the late 90s when carbon fiber was just beginning to be a thing, one of the guys in the SunRacer project at our college made a tetrahedron out of thin CF panels. There was a schraeder valve in one panel and sticky tape on the edges. He could vacuum the thing down and it would float to the ceiling, hit something, and pop with a fairly tremendous bang and the panels would tumble to the ground. It didn't shoot to the ceiling like a helium baloon would, but it still floated up. Are you sure he wasn’t filling it with helium instead of vacuuming the air out? Because there’s no way carbon fiber panels and sticky tape are either going to be strong or sealed enough hold a vacuum or be light enough to float even if filled with vacuum. A tetrahedron is also by far a worse case than a sphere because of all the stress concentrations.
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Jun 2, 2018 15:57
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If you want to get a feel for the forces involved in a vacuum, try to pull the lid off a partially-evacuated vacuum chamber. A small one with a 24 cm / 10" diameter lid takes over 5 kN / 1000 pounds of force to pull free with a full vacuum. Even if you only remove 1/4 of the air, you're going to have an immensely difficult time pulling that lid off. Now imagine a much larger object trying to hold in a vacuum, and remember that the force scales with area. Edit: The obvious solution is to replace the atmosphere with sulfur hexafluoride. Cichlidae has a new favorite as of 17:57 on Jun 2, 2018 |
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Jun 2, 2018 17:51
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Or, y'know, just look at those collapsing pressure vessels upthread. That is some violent poo poo.
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Jun 2, 2018 17:54
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Obviously you just have to put in enough vacuum to keep the balloon taut 
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Jun 2, 2018 19:16
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Thanks to the zeppelin effort-posts I did some looking and the USS Akron was designed to be a flying aircraft carrier. Looking at pictures of it, I can't see any launch/landing areas, so how the gently caress did this glorious scifi monstrosity loving work?
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Jun 2, 2018 20:04
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It just dragged a bunch of balloons behind it
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Jun 2, 2018 20:07
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Ravenfood posted:Thanks to the zeppelin effort-posts I did some looking and the USS Akron was designed to be a flying aircraft carrier. Looking at pictures of it, I can't see any launch/landing areas, so how the gently caress did this glorious scifi monstrosity loving work? A really goofy fishhook and trapeze system.
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Jun 2, 2018 20:08
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Midjack posted:A really goofy fishhook and trapeze system. https://www.youtube.com/watch?v=1FIm5qt5JrQ&hd=1
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Jun 2, 2018 20:16
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Ravenfood posted:Thanks to the zeppelin effort-posts I did some looking and the USS Akron was designed to be a flying aircraft carrier. Looking at pictures of it, I can't see any launch/landing areas, so how the gently caress did this glorious scifi monstrosity loving work? Trapezes. Not joking. Let this image be your spirit animal: 
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Jun 2, 2018 22:50
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Toast Museum posted:Obviously you just have to put in enough vacuum to keep the balloon taut This is how I would try faking it. Fill the tetrahedron with hydrogen at something less than atmospheric pressure: low enough to put some stress on the panels but nowhere near vacuum.
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Jun 3, 2018 02:36
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Remember how I posted that wonderful biochem known as prions? Well we started making synthetic ones. It's to allow for easier research and potential cures, sure, but gently caress PRIONS SO MUCH
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Jun 6, 2018 17:28
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iospace posted:Remember how I posted that wonderful biochem known as prions? Holy NOPE
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Jun 6, 2018 17:32
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Why would you do that? gently caress immortal prions forever.
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Jun 6, 2018 17:33
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iospace posted:Remember how I posted that wonderful biochem known as prions? Coming soon to a city near you! This is one of the less unlikely anthropogenic quick ends of the world.
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Jun 6, 2018 18:16
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I mean, they're already in the wild, at least they're contained here? I wouldn't want to work in that lab (or most pathology labs), but it's good that they're being studied. I am curious as to how containment and disinfection is done at this lab. Recommendations seem to be keeping the surfaces moist until disinfection, autoclaving and treating with 1N NaOH. Everywhere I looked also noted that disposable equipment should be preferred though, and that disinfection procedures are poorly controlled.
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Jun 6, 2018 18:51
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MrAptronym posted:I mean, they're already in the wild, at least they're contained here? I wouldn't want to work in that lab (or most pathology labs), but it's good that they're being studied. Lava would work I think.
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Jun 6, 2018 18:58
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Nuclear fire from orbit would be better
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Jun 6, 2018 21:11
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Hexenritter posted:Nuclear fire from orbit would be better
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Jun 6, 2018 22:15
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Hexenritter posted:Nuclear fire from orbit would be better Do the experiments IN orbit, transmit the data planetside, then nuke the orbital research station.
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Jun 6, 2018 22:29
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Dirt Road Junglist posted:Do the experiments IN orbit, transmit the data planetside, then nuke the orbital research station. Do a bi-elliptic transfer into the sun 
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Jun 6, 2018 22:33
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Guys the Expanse thread is in TVIV.
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Jun 6, 2018 22:39
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Autoclave the entire facility and everything inside it. Robots and disposable grad students are the only researchers allowed inside the facility.
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Jun 6, 2018 22:49
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Dirt Road Junglist posted:Do the experiments IN orbit, transmit the data planetside, then nuke the orbital research station. This is how you spread them along the planet.
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Jun 6, 2018 22:55
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Platystemon posted:disposable grad students Reduntant.
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Jun 6, 2018 23:00
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Hexenritter posted:Nuclear fire from orbit would be better 
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Jun 6, 2018 23:01
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I was at a nursing home helping my dad fill out a patient information sheet for an upcoming neurology exam, he was a tool & die maker in the 70s and 80s and when we got to the line where you list the significantly dangerous chemicals you've been exposed to we just both cracked up. He told me that they kept a big drum of "methyl" to wash their hands in at the end of every workday. I guessed it was methanol or methyl ethyl ketone, but he said that one day the owner brought in a drum of MEK and told them to start washing their hands with that instead because it was a little safer. I don't know what the first one was... "Is it safer to wash your hands in methanol or MEK?" is a helluva question.
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Jun 6, 2018 23:26
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Syd Midnight posted:"Is it safer to wash your hands in methanol or MEK?" Methanol, but only if you hit the bar afterwards.
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Jun 6, 2018 23:37
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I will never understand the fear of MEK. So far as organic solvents go it’s just about insert, the only reason it was restricted was because of air pollution concerns since it’s a VOC. It’s no worse than acetone biologically.
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Jun 7, 2018 02:33
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