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Xoon last won the day on September 21 2016

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About Xoon

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  1. How long is the education in the US? Here it is 3 years in police college. 5 for a master. We haven't had armed police until recently (because of the homegrown terrorism and the terrorist threat abroad). Crime is very low here in Norway, to the point where criminals traveling from abroad is a bigger problem where I live.
  2. General news thread

    Very interesting sense of fashion, dressed up for a peaceful protest here: And what flag is that? The emblem looks like anonymous, but the brown and black part is weird.
  3. I created this topic for sharing, learning and discussing electric motors and their associated systems. First thing I want to discuss is cooling systems for EV electric motors. To get the most power out of the motor you can simply overvolt the motor, since more current=more power, this however decreases the lifespan of the motor. The reason why is because electric motors have magnet wire isolation rate to last 20 000 hours at their rated temperature. Let's take the cheapest type, which is usually rated at 150 degrees Celsius. Let's say it operates at 150 degrees, and you overvolt it and increase the temperature to 160 degrees, you have now halved the life of the motor to 10 000 hours. Increase it to 170 degrees and it halves again to 5 000 hours, and this continues to the motor burns. How do you counter this? You can wind the motor with thicker wires, which creates less resistance, and less heat, but this also hurts the power density of the motor, since thinner wires can be more compact. Thinner wires also increase the amount of turns you can do per pole, increasing the power. You can have the case be a heatsink, though this gets to ridicules levels quickly, making the motor extremely heavy. We have for example a 5hp motor at 140kg, a complete no-go for EVs. You can use a higher grade isolation, being rated as high as 500 degrees Celsius in some cases. The issue here? Higher cost and a thicker wire for the same resistance. It also has some implications. If you are using a PM motor you have magnets inside, which demagnetize at a certain temperature. You want PMs for compact motors, and the stronger the better. Neodymium magnets are the strongest, but they also demagnetize at 60-80 degrees Celsius, which means that having higher grade wire does not really do anything. You can of course use weaker ferrite magnets that work up to 250 degrees C, but then you lose power density. If you are a incredibly rich person that wants to make his own toy you can use sliver, which weights less, has less resistance and conducts heat better, at about 77 times the price, compared to copper. Now lastly the best solution in my opinion is cooling. This can be done in two different ways, air cooling and liquid cooling. Air cooling requires the motor to have a lot of surface area, be open and therefor not water or dust proof and to have a powerful fan blowing over it, a bigger fan, means a more cool motor. This however, is about as effective as in cars. Now lets get to the point. Liquid cooling. There are several approaches, we can give the motor a water jacket, and simply pump the water through it. We can have channels than run through the stator and rotor. Or we can (simplified) fill the motor with transmission oil, like they did in the Toyata Prius. Here the rotor circulates the oil as far as I have understood. The method I prefer is using channels that run through the stator, closely touching the wingdings. This is simply because copper is good at conducting heat, while steel is not. Though, I have no idea to circulate cooling fluid through the rotor. Which brings me to my question. How do you circulate the coolant? I was thinking about putting a pump right on the axle. This seemed like the good idea, until I realized that the electric motor also has to spin in the other direction, which would make all the coolant flow in the other direction too. I guess you can use a valve system to make sure it always flows one direction, but then you need a bidirectional pump which is not as efficient. Alternatively, you can use this: Does anyone have a better idea of how to solve this? And how to cool the rotor? Also, would it be possible to use a vortex tube to cool the air before it passes through the radiator?
  4. When it comes to the salmon migration, it should not really pose a problem. Just look to Norway. If it was really a big problem, we would not have such a huge fishing industry (In comparison to other sectors in the country.
  5. Nuclear power seems like the best bet here.
  6. Again, this is why hydropower is so damn good. Use whatever renewable you want, and supplement the rest with hydropower, and when you have excess, pump the water up in the dams again.
  7. I find it funny how solar and wind is the most popular renewable energies in media. First of all, even if we could be make perfect solar panels, they would still be too unreliable because of weather. Really sucks when your city breaks down because of a cloudy day isn't it? You know what the best part is? My bloody country is trying to build out solar power, the got damn hydropower king, with 90% hydropower. Just looking at a solar map shows how ludicrously stupid this is. All this because we built a few gas powerplant/refineries in case we need urgently more power. We are also building out windpower here, because a damn makes our valleys look too ugly, ironic isn't it?: Honestly, solar is very good in a private or individual setting, but it is bloody useless in a national sense unless your country is located in the optimal solar locations. Same goes for windpower, it varies widely, and has to break to avoid the generator from overloading in strong winds. Both need a energy storage medium to be effective, like , I don't know, hydropower! Funny isn't it? Or you can supplement it with fossil fuels or nuclear power. I honestly only see a future in hyrdopower because of its ability to store potential energy, and thermal power since it is pretty much constant. Supplement this with nuclear power and you pretty much has the cleanest possible power generation. You could of course exploit local geography with solar, wind or tidal current power. But they will never become mainstream. I really love the irony of the transport sector too. Regular folks has to be taxed for fuel and the cars has to be efficient and media panics about emissions. But in comparison to the shipping industry, the worlds car pollution is a drop in the ocean.
  8. General news thread

    In Norway a new government has been chosen, the Right-Progressive-Christian-Left coalition won. This means the Right party will lead Norway for 4 more years. Fun fact, a communist party named Red got 2,6% of the votes.
  9. General cars and vehicles thread.

    We completely lack any form of aircraft industry, maybe a few repair shops, but those are far and few in between. Forsvaret does not sell plane parts, at most a tracked vehicles, but usually a old car or truck or parts for them. We tend to recycle a lot, which makes it hard to even find good scrapyards, and our low population does not help. (About a 30. times smaller than the US).
  10. AFV Engines

    Because optimally, the VSD (speed controller) should be right next to the motor or a part of the motor housing. This leaves no space for cables.
  11. AFV Engines

    Only places I find aluminum useful would be for the motor casings and the cables between the Generator, battery, and controller.
  12. General cars and vehicles thread.

    We lack all of those in my country as far as I am aware, especially where I live. We don't have any aircraft industry, and only two small airline companies. Those two and the military are the only ones with jets. Could be tricky . I guess I would have to import then. I live 8000km from Tucson, so that would be pretty hard. I am thinking about just modding the crap out of a weaker electric motor, liquid cool and overvolt the crap out of it. Maybe change the frame.
  13. General cars and vehicles thread.

    Now, where do I find a gas turbine starter?
  14. CV-90, why so much love ?

    I did not know this, always great to learn new things from you. I am sadly not a very good at Norwegian history. I spoke with a actual historian awhile back who talked about the cooperation between the countries. We also tried to unify defense and such with Denmark and Sweden. This did not get anywhere however because of political pressure from the US and the Soviet Union. Instead Norway and Denmark joined NATO. It was also attempted again to unify the Scandinavian countries later, but this deal got killed by Denmark and Sweden joining the EU. Norwegian history, or Scandinavian history is very hard is since it is a pain in the ass with a lot of propaganda and romanticism. As far as I understand it is not nearly as deep as with Germany, it is mostly to save money on procurement. It's all about politics. And right now it is a mess. It was sarcastic. But I believe every choice should be properly bashed, the more popular the more bashing needed. Even the Swedes realized this, hence the SEP program. Though, Norway will most likely use the CV90 for a long time, just like the M113.