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InigoMontoya

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Everything posted by InigoMontoya

  1. The problem with that idea is "conservation of mass". To pull air out of a mine shaft you have to put some other air *into* the mine shaft. How are you going to do that? It's not a trivial problem.
  2. For those who've never been around honest to goodness shrapnel... It's sharp. Walking around a site full of shrapnel is like walking around a site covered in broken knife blades... So even if the foamglas were to leave a few sharp edges, that's nothing we're not used to dealing with. However, if it's properties are like pumice, it's probably a no go.... Pumice has amazing properties when it comes to blast wave dampening.
  3. We've actually looked into this. The sand is a no go. What you see as "better protection for the blow up" translates to defeating the purpose of the test. Any insulation that provides significant....resistance... is bad. The whole point is to see how much damage the items of interest will cause. Mitigating that damage with a layer of sand means that you no longer know the answer to the question you're asking. Clay pellets... Interesting. I'll have to look into that. And the box is certainly single use 99% of the time. Detonations are pretty violent, after all. Very interesting. I'll have to look into that as well!
  4. And yet, with all those Billions at his disposal, Gates has done nothing to make the scheme a reality. 'Just cause the simulations say it will work - and I've no doubt it would if you could get the resources - doesn't mean it's actually doable. Why isn't it doable? Because you can't get the resources. They simply do not exist.
  5. You just don't seem to be grasping the size of the problem. Using the prior analysis as a template.... Google sayeth that a typical thunderstorm releases approximately 10e15 Joules of energy. Mind you, we're talking about a garden variety thunderstorm and not a full on tropical storm. But hey, you don't seem to be grasping the scope of the problem so we'll roll with it.... I recall that it takes 333.6 kJ to melt a kg of ice. 1*10^15 / 333.6*10^3 = 3*10^9 kg of ice required. Or would you prefer to see it written as 3,000,000 metric tons of ice? That's definitely better than the hurricane, but it would still require 44,000 Boeing 747s to haul your ice load... Which is only about 30X as many 747s as has ever been built. Remember, this is for a storm system way smaller than anything that resembles a named storm. How many such storms do we have per year? We made it to Sandy this year so that's 18... I say again: You do not seem to grasp the scale of the problem.
  6. Have you bothered to calculate how much ice we're talking about yet? edit: OK, I'm bored.... A quick google tells me that the average hurricane releases 52*10^18 J of energy per day (most of which is released as heat when water condenses). If I say that the hurricane lasts 7 days, that's 364*10^18 J of energy that we need to absorb. Ah, heck... We'll be nice and assume that you only need to absorb HALF of that to prevent the hurricane (let it just stay a tropical storm). OK, so we need to absorb 182*10^18 J of heat energy. Another quick google tells me that it takes 333.6 kJ to melt a kg of ice. 182*10^18 / 333.6*10^3 = 545*10^12 kg of ice required. Or would you prefer to see it written as 545,000,000,000 metric tons of ice? A cubic meter of ice weighs in at roughly 900 kg. Thus, we're talking about 606*10^9 cubic meters of ice. For comparisons sake, that's only 242,000 times the volume of the Great Pyramid at Giza. Or if you prefer, a slab of ice 10 meters thick and 278 km in diameter. All that to stop ONE hurricane. What do we have... half a dozen hurricanes per year? So tell me.... Who's back yard did you want to put this ice house in?
  7. Not only that, but to create all that ice, you've to release a crapload of heat somewhere else... Which is no doubt going to come with it's own "unintended consequences."
  8. I seem to recall reading an article a few years back wherein the idea was discussed that it was technically feasible to steer a hurricane via selective cloud seeding. No, you couldn't stop it or reduce it's impact, but you could get it to hit an uninhabited stretch of beech 100 miles to the East rather than New Orleans. HOWEVER.... ....No one will endeavor to do such because there is no such thing as "uninhabited". If you cause the hurricane to hit a comparatively uninhabited area that it would not have otherwise hit and someone dies... Congratulations, the family has the grounds for one hell of a lawsuit. After all, you took action to knowingly steer a hurricane in their direction that resulted in the deaths of their loved ones. Alternatively, what happens if you try to steer a hurricane, things go badly, and you have it pull a Sandy/Katrina? In short, the lawyers would have an absolute field day. Thus, nobody with any sense wants to get into that game. It's just not worth it from a personal liability perspective. As an aside: I want to see the 500 mile wide sheet of plywood. It wouldn't stop a hurricane, but it sure would be a sight!
  9. different agencies have different methods, but for us... The inner shell of the oven is sheet metal and resistive heating elements are epoxied to the metal. The whole mess is then wrapped with insulation. As for the bury the whole mess idea, that's prohibited. Part of the data package at the end of the day is fragment mapping. The powers that be want to see how far debris gets thrown. If you bury it, it won't be thrown very far.
  10. Don't have a pic of the particular design that we use, but you can get the general idea from.... http://www.dtic.mil/ndia/2009insensitive/2Againes.pdf Looks for the part about "slow cook off" testing. ...looks like they use a different insulation though. Something white. Hmmm.... Wonder what it is?? May not matter as it too looks fibrous (mineral wool?). Additional note: Our ovens tend to be significantly larger than the one pictured. Still, the idea is there.
  11. Well, the oven has to maintain temp for a few days so insulation that is on fire is probably a bad thing. Regarding the later suggestion of PU foam... Will PU take those temps? I didn't think it would. Fumes and such aren't a big deal as we're outside and no humans are within 1/2 mile of the oven while it is at temperature.
  12. We use faced rolls (I believe that's the correct term). I'm thinking ideally a replacement material would be in rigid sheets. I thought about mineral wool, but it doesn't look any better than fiberglass from a health perspective (don't breath it!).
  13. Situation: At the office we make disposable ovens. Temperature? Up to 500 F. Volume? It varies, but up to 60 ft^3. I say "disposable" because we use them to study the reaction of explosives to elevated temperature. Even under the best of circumstances, the ovens never get used twice. Oven construction is for the most part simple, but they are a pain in the arse to insulate. We have historically used fiberglass insulation like you'd put in your house, but it's itchy and difficult to control if the wind is blowing. We'd like something better. And so I wonder if anyone here has any words of wisdom.... Requirements: - Inexpensive. - Easy to work with. - Negligible health issues (respiratory, skin irritation, etc.). - Usable to 500 F. Thoughts?
  14. Do the wheels collapse under 1 G acceleration? No. Do your legs collapse under 1 G accleration? yes. When I speak of stabilization, I'm not talking about balance. I'm talking about structural integrity.
  15. In a word: Gravity. To walk, you must stabilize your entire body against the effects of gravity. To sit, you only have to stabilize your upper body. Your lower body no longer fights gravity. That means you aren't working as hard.
  16. Yup. In theory, a bike with regenerative braking (what you're talking about) could work, but I don't know that it would be worth it. Bikes are dominated by wind resistance and regenerative braking won't help that at all. Plain ol' Newtonian Physics and Thermodynamics. The Physics will give you the foundation to understand the Thermodynamics. The Thermodynamics are at the core of discussions such as this one. Note: Thermodynamics aren't just the study of heat flow. They're the study of energy flow.
  17. Read my lips: It won't work. It would actually be much more efficient for you to simply power the bike with a chain connected to the pedals and the hub (ie, like every other bike on Earth). Energy is energy. If you put 1000 Joules of energy into the pedals, the absolute maximum amount of energy you can ever get out of your system - no matter how it's arranged - is 1000 Joules. In reality, you'll always get less. So... you put 10000 Joules into the pedals. Using a traditional bike, you'll get on the order of 900 Joules at the bike's hub (the traditional chain/sprocket system is about 90% efficient). But what would you get out of your generator system? From the pedals to the gearbox, you'd get about 900 Joules (chain/sprocket system, just like to the wheels). From the gearbox to the generator you'd get about 810 Joules (I'm being nice; your stated gearbox design is grossly inefficient but I'm giving you the benefit of a doubt and giving you the same 90% as a simple chain/sprocket system). From the generator to the battery, I'll again be nice and give you 95% efficiency (it will really be less) which then allows you to store 770 Joules in your battery. From the battery to the motor in the bike's hub, we'll again give you 95%.... Giving you 731 Joules. You lost 169 Joules because you jumped through all sorts of crazy hoops to avoid simply pedaling your bike. And again, I'm being very nice with my numbers. The reality will probably be much worse. It. Won't. Work. At least, not the way you think it will. Your bike will move and all that... But it will suck.
  18. OK, half a mile is doable then. I just took you at your word when you said you were shooting potatoes.
  19. Yes. The "moving generator" charging faster than the energy used is otherwise known as a "perpetual motion machine" and violates the 2nd Law of Thermodynamics. In other words, it won't work the way you think it will.
  20. 1) OK, I'm not an RF guy. I wouldn't have the first clue. I asked because I know some folks who play around with the COTS stuff and could ask for recommendations. But if you want to build it yourself.... No clue! 2) I know a thing or twelve about potato guns ( ). One thing that most folks don't realize is that shooting a potato is a lot like throwing a feather. It doesn't matter how hard you throw it, it slows down quite quickly and doesn't end up going very far. Granted, a potato will go a lot further than a feather, but getting one to go half a mile is virtually unheard of (read: I've never heard of a *reliable* measurement indicating such ranges).
  21. A couple of thoughts.... 1) Are you building this as a project in and of itself or are you using this to further a larger project. More to the point, what you ask for is commercially available. Do you WANT to build one or were you just unaware that you could buy one? 2) Your potatoes aren't going as far as you think they are.
  22. Now you're on the right track but let's take that step just a little bit further.... Rather than turning on the generator when you're going downhill, just use it anytime you want to slow down. Congrats, that's called "regenerative braking" and it's why hybrid cars get good gas mileage in stop/go conditions.
  23. By the way... I meant to say it earlier but failed.... That's a sweet set up on your existing bike, Dr. J. Did you build it or buy a kit or...??
  24. If I remember correctly.... Power = Torque (N*m) * Angular Velocity (rad/s) So.... Power = (45.18 * 1.0) * (115/60 * 2 * pi) = 544 watts. I concur. edit: Note, however, that just because 544 watts is the power required to keep the turbine spinning, that does NOT mean that it has any relation to the energy stored in the rotational motion. That's a totally different entity (and has already been identified by Swansont).
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