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chilehed

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Everything posted by chilehed

  1. chilehed

    gas mixing?

    Even if you didn't shake the container at all, each specie would diffuse throughout the volume so that they would end up fully mixed. Left alone, they will remain fully mixed.
  2. chilehed

    Nitro Kits

    During WWII a lot of testing was done with a variety of oxygen-carrying agents. O2 caused lots of problems with detonation, which in retrospect isn't surprising. Nitrous oxide is a great compromise between storage density, container mass, cost, and ease of transport. BTW, "nitro" is nitromethane, not nitrous oxide. Which reminds me of a drag car running in the blown alcohol class in Florida during the early '80's. The guy took advantage of a rule that let you run naturally aspirated using nitro and nitrous. Man, that thing hauled a**.
  3. chilehed

    gyro madness

    I'm not qualified to answer, but as far as I know they all use fixed-pitch blades.
  4. chilehed

    gyro madness

    Naah, you're just making it harder than it is. As the prop in the back pushes the 'copter forward, the wind drag from the overhead rotor causes the 'copter to tilt back a bit. When that happens the rotor begins to spin like a pinwheel in the wind, and its resistance against the air lifts the 'copter off of the ground.
  5. I want to make a cabinet in which to grow orchids, and need a control system for lighting, temperature and humidity. I have an old laptop and a basic understanding of coding and control system theory. I'm handy with a soldering gun, and if I can find a circuit diagram I'm sure I'd be able to fabricate a humidistat. I could physically connect a t-couple and such to a port, but I have absolutely no idea how to get the controller to look at the port so it can process the signals. Can anyone recommend a resource that explains how one goes about all of this? I'm sure that it would be easier to buy a system from someone, but I'm strapped for cash and if I can learn this I have a few more projects that I could work on (like controlled barbeque smoker). Thanks.
  6. chilehed

    Quad Turbo

    The first thing you should know is that you'd better have a LOT of spare cash to blow. You'll need it. This is a very difficult project, but I think it could be done. The dynamics of exhaust flow are such that banks of three cylinders per turbo are ideal. Sizing the turbos won't be any more complicated than for a twin-turbo application, each turbo just handles less flow. It will be a nightmare dealing with the plumbing and the heat radiating from the exhaust system. Unless you have a strong engineering background, a lot of practical experience desining multi-turbo systems, or have hit the lottery, I'd leave this idea alone.
  7. You have a number of good answers, but I don't think anyone's mentioned this one. The power output of an internal combution engine is a function of the rate at which it burns fuel. Spinning the engine faster increases the airflow rate, which means more power. So, other things being equal, a 2.0L engine spinning at 20k RPM will make about the same power as an 8.0L engine spinning at 5k RPM. One problem with rotary engines has to do with the fact that the combustion chamber is swept over a large surface area during the cycle, which increases heat losses during combustion and thus reduces efficiency.
  8. Already done. I'm looking for confirmation that I got the right results.
  9. The problem I'm having is that I can't find any information whatsoever about what radiant intensity coresponds to what magnitude. I have a light meter that I use to measure the lighting in parking lots and such. The meter has a built-in filter that weights the results for frequency so that the meter returns the same value regardless of spectrum, as long as the human eye would perceive the same illuminance. It's essentially the same thing as a dBA measurement in sound intensity, and I'm wondering about the same kind of thing for the apparent magnitude of stars.
  10. I don't understand. There's a conversion from watts/m^2 sound pressure to dB, why can't there be a conversion from footcandles to apparent magnitude? Sems to me that an object is determined to hava a brightness of zero magnitude because of the amount of light falling on a meter. That gives a certain number of foot candles - so how many footcandles corresponds to zero magnutude?
  11. I kinda' miss the days when you could flip the channels by jingling your keys at the tv....
  12. There were some turbine locomitives made in the U.S. back in the '70's, but they were so loud that their use was restricted to remote locations. They were abandoned after a few years.
  13. Another question about my kid; he's trying to get a collection of all the elements he can wants me to grab him a piece of tungsten welding rod. It's alloyed with 2% thorium, and I'm wondering how much risk of radiation exposure there is. My gut feeling is "not much", since he's not going to be sleeping with it and OSHA hasn't pulled it from the workplace. If it were mine I'd think nothing of it, but it's my kids'.... Thanks.
  14. Wouldn't be the first time... Thanks, guys. Sounds pretty much like I thought, except I thought that Pu had a much longer half-life.
  15. Or is it just that they don't occur in our solar system? We make them in reactors, and if stars are just big energetic reactors...? I can understand how we'd not be able to find the short half-life stuff even if it had originally been around, but that doesn't explain the absence of plutonium in nature. My kid's getting to where his questions go beyond my mechanical engineering background as well as anything I recall reading in the past. He's also wondering: if you got shocked by a charge of protons, would it feel like an electric shock? I told him my guess is that if you could get some at a low enough energy it might, but free protons take a bit of energy to make so as a practical matter if you got zapped by them and could feel it then you'd be dead pretty quickly. Thoughts? Thanks.
  16. Have you gone to your instructor after class and asked for help? I've always found that face-to-face exchanges work better, and on top of it he'll like that you're interested.
  17. I'm not sure this is the same as the Rutan idea you cite. I'm picturing two airfoils tied together and operating in airstreams of different velocities. The craft is traveling at a speed between those of the two airstreams, which means that the airfoils are oriented in different directions. Sounds crazy, but I don't see any obvious reason why it in principle couldn't work. I agree that even if it works it's not likely to ever be of much commercial significance.
  18. It says nothing of the sort. The part you're missing is that the hydrogen fuel cell reaction is vastly more efficient than an IC engine, such that even when throwing away the heat value of the carbon you can still end up with more efficiency overall. Not if you're using fewer gallons per mile. Plus there are no NOx emissions and virtually no CO, unlike an IC engine.
  19. On-board reformers is another way. You can fuel up with hydrocarbons, strip the hydrogen out of the molecules (burning the carbon as the heat source for the reaction) and use it to run a fuel cell. You waste all of the heat from the combustion of the carbon because it's not moving you down the road, but the H2 fuel cell reaction is so efficient that you end up with a net improvement in miles per gallon.
  20. I'm not sure that those guys know what they're talking about. Like here: Hydrogen has an octane rating of about 130, which means it can handle compression ratios a lot higher than 9.5/1. Its high combustion rate is precisely one of the things that contributes to its octane rating. A high combustion rate results is less tendency to detonate or preignite, not more. One big issue with H2 is its low ignition energy, which makes it critical to manage hot spots in the combustion chamber. You can't do that merely by recalibrating the software unless you're willing to give up much of the potential efficiency improvement. The combustion characteristics of H2 are so different from hydrocarbons that you need engineer the engine differently from the start. IMO it's a dumb idea, if you want dual-fuel you'd be a lot smarter to go with natural gas.
  21. Wow! That's COOL! Let's see if I get how this works. Every time the wing passes from one layer to the next there's an abrupt increase in effective airspeed, which means there's an abrupt increase in lift. Because the path of the wing is circular, the component of increased lift acting perpendicular to the plane of the wing represents an increase in the centipetal acceleration of the craft, which necessarily means that the speed with respect to the center of the path increases. Am I getting it?
  22. Hey, another sick plant junkie! Sounds like a cool collection, I had no idea that there were such large carnovores, what genus? I got my first amorphophallus last year, and it seems to me that a plant whose flower smells like a dead animal would be the perfect foil for a collection of carnivores. Whadd'ya think?
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