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Nuevo posted:I cannot even begin to comprehend where a myth like that would even start to come from. Interpreting correlation as causation. "I stored these car batteries on the floor in my freezing garage all winter and never topped them up, and now they're dead! It must be something to do with the floor!"
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Sep 29, 2016 05:52
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Nuevo posted:I cannot even begin to comprehend where a myth like that would even start to come from. Ufer grounds is my guess.
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Sep 29, 2016 05:56
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VectorSigma posted:there's a pretty persistent myth that storing car batteries on concrete will destroy its ability to hold a charge. You can store them on concrete, as long as they're under a pyramidal shape.
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Sep 29, 2016 05:57
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iirc back in the dayyyyyyy battery cases were made out of some stupid creosote and cardboard thing or some similarly hilariously late 19th century answer, and there actually was a bit of dissipation through the case. that also hasn't been valid for at least eighty years though
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Sep 29, 2016 06:06
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Not sure but don't a lot of batteries dislike cold temperatures, and the concrete usually being cold would cause people to extrapolate that concrete = cold, cold = bad for battery, concrete = bad for battery? Not my belief, just channeling the inner idiot.
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Sep 29, 2016 09:07
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It becomes an issue when its an extreme cold or heat, or a rapid change in temps. Extreme cold is a fun issue since you will have fewer cranking amps available the colder it gets. If you look on a battery, you will see a bunch of numbers all over it, but one is labeled CCA. This is the battery's cold cranking amp rating, taken at 0° F/-18° C. CA are cranking amps, which are measured at 32° F/0° C, along with MCA or Marine Cranking Amps. Edit: The rapid change in temps part is why parts stores, dealerships and independant mechanics see a spike in customers coming in for batteries during early spring and late fall and will offer deals on batteries at that time. Elmnt80 fucked around with this message at 09:21 on Sep 29, 2016 |
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Sep 29, 2016 09:18
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https://www.youtube.com/watch?v=QiN9M0ahfmM
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Sep 29, 2016 12:44
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Saw a very OSHA thing yesterday when I was out and about. A guy was trying to screw in something that was slightly above his reach so he took a hand truck, put it upside down, leaned it against the wall and was using it as a stepladder.
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Sep 29, 2016 13:32
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KiteAuraan posted:It of course, doesn't work, which is why Qin Shi Huang Di, First Emperor of China is dead now, rather than Lo Pan'ing us all to this day. Indeed!
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Sep 29, 2016 14:09
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Wasabi the J posted:How many times do we have to rehash the fact that elemental Mercury isn't that loving dangerous unless your drinking it? Deteriorata posted:In this case it is accurate, because elemental mercury is not absorbed very efficiently, if at all, and passes through you fast enough that you don't get much of a dose from it. The main avenue of absorption of elemental mercury is through inhaling its vapor. It's not like it's Dimethyl Mercury. 
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Sep 29, 2016 15:22
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The Sausages posted:It's not like it's Dimethyl Mercury. For those who don't know much about chemistry: seeing a naming format of number prefix-methyl metal/cation is code for "I (probably) want to kill you."
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Sep 29, 2016 15:34
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quote:In 1972, a 28-year-old chemist in Czechoslovakia had suffered the same symptoms as Wetterhahn after synthesizing 6 kg of the compound. Jesus Christ, what do you need 6 kg of one of the strongest known neurotoxins with almost no applications for?
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Sep 29, 2016 15:35
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i was once told i was not allowed to store dead lead-acid batteries next to fresh ones because 'the charge would even out' and drain the full ones 
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Sep 29, 2016 15:56
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Nuevo posted:I cannot even begin to comprehend where a myth like that would even start to come from. Well, it's on the ground, see? So it's grounded and everyone knows grounded batteries lose their charge. Duh.
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Sep 29, 2016 16:01
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Captain Foo posted:i was once told i was not allowed to store dead lead-acid batteries next to fresh ones because 'the charge would even out' and drain the full ones https://youtu.be/brdmnUBAS00
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Sep 29, 2016 16:11
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The Sausages posted:It's not like it's Dimethyl Mercury. well that bummed me out for the day.
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Sep 29, 2016 16:20
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http://i.imgur.com/2CqyyzE.gifv
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Sep 29, 2016 17:18
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Seems like nowadays you could add a quadrotor to the basket and guide the basket to the plane rather than the plane to the basket.
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Sep 29, 2016 17:30
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I hope these guys don't get in trouble for this. Only the Fun Police would arrest them. 
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Sep 29, 2016 17:34
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Ak Gara posted:Seems like nowadays you could add a quadrotor to the basket and guide the basket to the plane rather than the plane to the basket. I think for most tankers nowadays, the refueling boom is steered by someone in the tanker while the plane being refueled tries to hold formation.
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Sep 29, 2016 17:44
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McGavin posted:Jesus Christ, what do you need 6 kg of one of the strongest known neurotoxins with almost no applications for? No, seriously. John D. Clark posted:Phil Pomerantz, of BuWeps, wanted me to try dimethyl mercury, Hg(CH3)2, as a fuel. I suggested that it might be somewhat toxic and a bit dangerous to synthesize and handle, but he assured me that it was (a) very easy to put together, and (b) as harmless as mother's milk. John D. Clark posted:At NOTS, Dean Couch and D. G. Nyberg took over the job, and by March 1960 had completed their experiments. They used a 250- pound thrust RFNA-UDMH motor, and injected mercury through a tap in the chamber wall. And the thing did work. They used up to 31 volume percent of mercury in their runs, and found that at 20 percent they got a 40 percent increase in density impulse. (I had calculated 43.) As they were firing in the middle of the desert, they didn't bother with the scrubber. And they didn't poison a single rattlesnake. Technically, the system was a complete success. Practically—that was something else again. Source: https://library.sciencemadness.org/library/books/ignition.pdf
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Sep 29, 2016 17:59
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Rocket Science is all about finding the most stupidest compound you can and saying "Can I set it on fire?"
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Sep 29, 2016 18:22
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Zopotantor posted:Rocket fuel. It's important to point out the the "agonized reappraisal" led them to use elemental mercury, not DMM, in that rocket test. The quoted sections by themselves could lead people to think they sprayed hundreds of pounds of DMM all over the landscape.
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Sep 29, 2016 18:27
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This seems like a good time to post nuclear rockets.
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Sep 29, 2016 18:29
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this should be the soundtrack https://www.youtube.com/watch?v=b4pSjzI8BSw
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Sep 29, 2016 18:42
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Zopotantor posted:Rocket fuel. In Czechoslovakia? Here's a link to the article about the dude's post-mortem, but it's behind a paywall so I can't access it. I do know that they tried using it as a fungicide on wheat seeds in Iraq, but made the seeds into bread instead of planting them and killed at least a hundred people.
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Sep 29, 2016 18:44
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Armacham posted:I think for most tankers nowadays, the refueling boom is steered by someone in the tanker while the plane being refueled tries to hold formation. USAF Tankers do this, as do a few other foreign air forces. Most people, including the US Navy, use probe and drogue, where the drogue just sort of dangles there, and it's on the refuelling pilot to make the connection. Ak Gara posted:Rocket Science is all about finding the most stupidest compound you can and saying "Can I set it on fire?" And then you learn about the wonderful world of hypergols, where you don't even need to ignite them. Just mix em, and they'll do the rest.
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Sep 29, 2016 18:50
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Yes, it's like a lava lamp.
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McGavin posted:I do know that they tried using it as a fungicide on wheat seeds in Iraq, but made the seeds into bread instead of planting them and killed at least a hundred people. more like at least a thousand https://en.wikipedia.org/wiki/1971_Iraq_poison_grain_disaster
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Sep 29, 2016 18:52
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PittTheElder posted:where the drogue just sort of dangles there, and it's on the refuelling pilot to make the connection. And the pilot discovers the ejection seat doesn't work and he has to remove the canopy and crawl out at several hundred knots. And then the pilot discovers the parachute doesn't open, so he has to fall several thousand meters into the sea. And then the pilot survives the impact - partly because he had his spleen removed a few years earlier. https://uss-la-ca135.org/60/1960Judkins-Knott.html
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Sep 29, 2016 19:05
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PittTheElder posted:And then you learn about the wonderful world of hypergols, where you don't even need to ignite them. Just mix em, and they'll do the rest. The world where godawful poo poo like FOOF and chlorine trifluoride were seriously considered as propellants.
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Sep 29, 2016 19:09
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PittTheElder posted:USAF Tankers do this, as do a few other foreign air forces. Most people, including the US Navy, use probe and drogue, where the drogue just sort of dangles there, and it's on the refuelling pilot to make the connection. A boom's advantage is that it can support a much higher flow rate, but the probe and drogue are more flexible; you can mount a drogue system even on small aircraft for buddy stores or you can mount several of them on large tankers so the tanker isn't limited to refueling just one plane at a time. So if you're like the USAF and your main thing during the development of aerial refueling was refueling big fuckoff bombers so they could go nuke the Soviet Union, you develop the boom system and you mostly stick with that. If you're like the USN and have no big fuckoff bombers to refuel, you do probe and drogue.
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Sep 29, 2016 19:22
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https://www.youtube.com/watch?v=Dl7tyF71zHA E: Apparently the video got taken down. It was a review of this thing: http://www.wickedlasers.com/laserdock E2: Now the video is back. Updated the link. This device seems somewhat off. The lack of FDA approval could be just red tape, but the "interlock" killed me. It's just a cheater to short the pins. I'd be interested in the safety systems in a "real" laser projection system. Guy Axlerod fucked around with this message at 22:53 on Sep 29, 2016 |
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Sep 29, 2016 19:25
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Today I saw a truck from a company that, according to their site, sells OSHA-related gear such as fire extinguishers, teaches workers about safety, and so on. Their biggest mystery to me is their logo. 
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Sep 29, 2016 19:25
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Carbon dioxide posted:Today I saw a truck from a company that, according to their site, sells OSHA-related gear such as fire extinguishers, teaches workers about safety, and so on. 
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Sep 29, 2016 19:26
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Carbon dioxide posted:Today I saw a truck from a company that, according to their site, sells OSHA-related gear such as fire extinguishers, teaches workers about safety, and so on.
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Sep 29, 2016 19:28
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Carbon dioxide posted:Today I saw a truck from a company that, according to their site, sells OSHA-related gear such as fire extinguishers, teaches workers about safety, and so on.
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Sep 29, 2016 19:40
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Guy Axlerod posted:https://www.youtube.com/watch?v=OdpO3wtQZ7I 
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Sep 29, 2016 20:06
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The video got taken down I guess. It was a review of this thing: http://www.wickedlasers.com/laserdock
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Sep 29, 2016 20:58
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Guy Axlerod posted:The video got taken down I guess. It was a review of this thing: http://www.wickedlasers.com/laserdock quote:----UPDATE--- The video is being re-uploaded on youtube - the original file became corrupted somehow. This will take a couple of hours.
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Sep 29, 2016 21:30
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OK here is the new video of the laser thing with a lovely "interlock" https://www.youtube.com/watch?v=Dl7tyF71zHA
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Sep 29, 2016 22:52
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