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Flashman

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Everything posted by Flashman

  1. But it would be an efficiency issue if you can be comfortable at 19C with 30% humidity rather than 21C with 0% humidity. Then the question would be whether it costs more to maintain 30% humidity vs 2C more temperature differential with the outside walls. However, yes you can go off the other way, 80% humidity at 19C would probably tend more towards "clammy".
  2. Those pink skinned primate things that typically inhabit your typical dwelling, lose heat through evaporation of water from the skin. Since the purpose of wastefully heating this volume of air is to keep the naked primates cozy, then increasing humidity will decrease the rate at which water can be lost from their skin, thus reducing the rate of heat loss, thus making them more comfortable.
  3. So umm, you wouldn't get anywhere by centrifuging water at 1C would you? Thermal diffusion still too great?
  4. Depends how impatient you are too, the longer you wait, the more charge you get, but it never quite gets full. Like if you cross half the room, then cross half the distance remaining, then half that, then half that... you never actually get to the other wall.
  5. Hi folks, I need (I think) some zinc oxide in a hurry, I've got zinc, I can get 3% peroxide solution, how effective would that be in oxidizing zinc? Is it a grind the zinc into it and come back next week kind of thing, or needs heat, or fairly rapid at room temperature, or even not worth bothering with with that low a concentration of peroxide? Is it likely to make a precipitate that can easily be retrieved with a coffee filter or will it be too fine? Then because I only have a small strip of pure zinc, and disemboweling batteries is messy, how rapidly would 3% solution, hot or cold
  6. It's important to realise that any ideas you might get for small scale models may not scale up. There's potential problems with mixing up fuels or reactants for example, where the amount of heat generated in a reaction can easily be dissipated from teaspoon quantities, but where mixing large amounts would boil buckets full or prematurely explode. You get any issues with incorrect reaction speed, due to propellant grain size or quality, nozzle blockage, self confinement, etc you've just taken out a city block, and they probably won't find enough of you to bury.
  7. Take one balloon, one nozzle made from a pen cap, and one plastic toy car, tape balloon to nozzle, tape nozzle to back of car, inflate balloon, enjoy.... Because I can't for the life of me imagine that you'd consider messing with the 100lb or so of highly dangerous chemicals it would take to push a real car with absolutely no experience in propellants.
  8. Benzene, no, but a shot of mineral oil to move it all through probably works good.
  9. Interesting stuff. I had a bee in my butt a while back about trying to use a thermite for making a ceramic, I can't recall exactly where I was going, hope I scribbled it on an envelope somewhere.
  10. I might have gone home, ate half a loaf of burnt toast, then put myself on 1000mg vitamin C 3 times a day... that'd take care of a lot of potentials.
  11. Thanks for pointing that out, I'm not particularly worried about corrosion at the moment. This will be something of a proof of concept thing. Not quite sure but I think the alloy involved might have a small fraction in it already. I'm reading about zincate baths to prep the aluminum, but I would rather steer clear of zinc because it has effects on the process I'm trying to achieve with the copper. The copper is required as a catalyst. The part will see heat up to around 150C but normally about 100C. I'm thinking the zinc will migrate to the surface, which would be bad, and any porosity of
  12. Thanks, I wanted to anodize something else, but been hitting a brick wall locally for getting sulphuric acid, well as battery acid anyway. I wouldn't like to think of trying to plate on top of anodizing, even if it wasn't sealed, I'd be thinking the tubes would plug early, and you wouldn't get anything like a plating on it. If I just wanted it copper colored it would probably be a better way to go. I need the copper for it's chemical properties rather than it's appearance.
  13. Whoops, you're right, not thinking rigorously, had a glitch in my mental free body diagram. Maybe should have said, the resultant displacement towards the center of mass is dependent on the velocity. At classical velocities the force remains the same, independent of the velocity.
  14. I was thinking azeotrope, and looked it up, for which I've got 35.35% as the magic number. Maybe it doesn't take long to boil down to that?
  15. Classically, the force is gonna be the same however fast it's moving, however the resultant acceleration actually affecting it would change according to it's velocity component at right angles to the gravitational force.
  16. Howdy good folks, I've gotten myself into a bit of a conundrum. I need some copper plating on an aluminum alloy surface. My chemistry is about 20 years rusty, but I understand this is meant to be "difficult" to "unpossible" with a simple CuSO4 electroplating setup. However, I remember achieving a reasonable plating on aluminum before, many years back, when I was a kid with a model train transformer and a bag of CuSO4... So, been looking around here and on the rest of the net for tips... it occurs to me that I could use some method not regarded as commercially viable, either due
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