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AHHans

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Everything posted by AHHans

  1. Well, that is fairly straight-forward to answer. The first rule is: try not to have to do that! Seriously: inclination changes are *bleep*ing expensive so if there's another way to get to your target then choose that. But if you actually have to do that: inclination changes are cheapest when done at at low orbital velocities, i.e. at large distances to the central body. So if you are in a low circular orbit and want to change into another circular orbit at the same distance then it might be better to first change your orbit into an elliptical orbit with a fairly high apoapsis - and that apoapsis being at the AN or DN with your target orbit- change your inclination there, and then change your elliptical orbit back into a circular orbit. [After re-reading your question:] If your question is how to set up a maneuver nodes for large inclination changes, then you probably didn't consider that strong radial maneuvers will change your orbital energy, i.e. increase you AP and/or PE. So to keep radius of your orbit constant you need to add a retrograde component to you maneuver. (It's easy to see when you want to change your inclination by 180deg. Then you stay in the same orbital plane but want to go "backwards".) If you want to launch into a specific high-inclination orbit around Kerbin then it's best not to first launch into an equatorial orbit but directly launch into a matching orbit. For that you have to launch when the KSC is in the orbital plane of the target, i.e. launch at the correct time. (Which is what a launch window is.) So go to the map screen and advance time until the KSC is directly below the track of the target orbit. Remember if that launch window means that you need to launch to the north or to the south (You wouldn't be the first one to get that wrong!), and estimate the angle to the equator (or the NS direction) that the target orbit makes. Once you fixed the time and direction of the launch, you can launch into the predicted direction. You are unlikely to get it perfect directly from launch, but you should be much closer so that matching the orbits should be simple.
  2. Do you have a source for that? But otherwise you are right: I don't actually know!
  3. They are hotter and need to pump more volume, so I guess(!) that they tend to be louder than water cooled reactors. But I don't know what the major cause for noise is in dolphin reactors.
  4. You can switch the overlay on and off in that tab. Did you switch it off by chance? Edit: The switching is done by clicking on the "ore" line in the tab.
  5. Yes, but not nuclear powered. From the linked article: Another "interesting" textbite: I translate that to: "We couldn't do that if we would have to ask the people living in that state."
  6. The last section of the Wikipedia article about that incident made me think that it should be mandatory for employers to pay for life insurance for their workers. So that dependents are cared for in case something happens, and to motivate the employers to increase workplace safety.
  7. You forgot: Forum thread here, and actual paper here. (SCNR! ) I don't want to re-read the paper, but I got the impression that the mylar was expected to be coated with a conductor, e.g. gold or aluminum. That way you have a nice, low resistance path for the initial current to travel and the vaporize the coated mylar, to form the plasma for the 70 MA to travel trough.
  8. Why not make the stack out of infinitesimal thin pancakes, give it a decent nozzle, and call it a SRB?
  9. Indeed! Not that I know of. [...] O.K. I wasn't aware of how good a moderator carbon actually is, it's second only to heavy water (deuterium oxide). Other materials - e.g. pure oxygen, pure deuterium, or carbon-dioxide - would have similarly good scattering to capture ratios but lack in density. Yes, which is why MSRs are one of the few designs where I believe the "inherent safety" claims of their proponents. Another one would be an accelerator driven design: i.e. a subcritical core that is kept running by constantly adding neutrons from a spallation source.
  10. Hmmm... Considering that the German Wikipedia claims that TIGRA reactors of 20 kW power were (are?) on offer, I'd say that there's only a financial lower limit on a power reactor size. I.e. building any kind of nuclear reactor will involve significant costs so that doing so just to generate a few tens of kW of electricity or heat just isn't worth it. I don't think nuclear will ever be "scalable" in the sense that you have one design that you can just scale up or down to match the power required for your application. But it is scalable in the sense that you can get reactors from tens of kW to a few GW. Thermodynamic efficiency mostly depends on the input temperature of the thermodynamic cycle. (Because the lower temperature is usually close to surrounding air / water temperature.) But with nuclear the fuel is so cheap that the thermodynamic efficiency doesn't matter much. Nuclear power plants usually run at a low thermodynamic efficiency compared to e.g. coal power plants. My guess is that this is in order to increase the margin of safety: a leak in a pressure vessel in a nuclear PP is a much bigger problem than in a coal PP. I think the main reason why nuclear PPs are relatively large is because with the current designs it doesn't cost much more to build a 4 GWthermal reactor than to build a 0.5 GWthermal reactor.
  11. As already mentioned may main issue with many new reactor design is that they use graphite as the moderator. And while graphite will not burn in normal circumstances, a nuclear reactor with a failed cooling system will get hot enough to ignite graphite if it comes into contact with air. (It will also react with water if the amount you pour onto it is insufficient to cool it down fast enough.) As a case in point please remember that a large amount of the radioactive contamination from the Chernobyl disaster was released because the graphite moderator was on fire, or the Windscale fire. So every new reactor design that plans to use graphite as moderator needs to address this issue in a satisfactory fashion. And, no, "we won't let oxygen get to our reactor core" is IMHO not satisfactory! AFAIK the German pebble-bed reactors - e.g. the THTR-300 - had a claimed security feature that at high temperatures the nuclear reaction is self limiting - although more through Doppler broadening than thermal expansion AFAIK - with the reactor core being able to withstand temperatures where the cooling trough radiation will keep the temperature stable. But I'm sure that didn't include oxygen (i.e. normal air) getting into the mix...
  12. Thanks! And maybe back to @JoeSchmuckatelli's unspoken original question: Helium diffusion out of a coolant loop of a nuclear reactor isn't going to be a contamination problem: that helium won't be radioactive because, well, helium isn't!
  13. AFAIK the latter. But that's mostly "I haven't heard anyone complaining about helium diffusing everywhere" and not "I know that helium is well behaved." My main issue with these concepts is that helium as coolant usually means graphite as moderator, which then can lead to problems if oxygen reaches an overheating reactor. [But if anyone wants to discuss that further then we should take that somewhere else.]
  14. Did you retract or break(!) an antenna on the rover? Is there still line-of-sight between the rover and the satellites? Did the satellites move farther away from the rover?
  15. That is what "partial probe control" means. You do not have commnet connection from the rover to the KSP, but to be nice to you the game gives you some control over the craft. (It's actually an option in the difficulty settings.) So as @jimmymcgoochie already wrote, you need a signal (== commnet connection) to drive the rover. If the rover indeed has connection to the relay satellite then it is possible that the satellite has no connection to the KSP.
  16. . o O ("When we win the football cup.") I hope the Germans didn't get too huffy about that. Germans are prone to use much worse "false friends", e.g. using "when" when they mean "if".
  17. The tricky part is figuring out the correct place for the PE: you want it to be at the place where you need it for the final escape burn. I don't have a good procedure to find that. Up to now I've essentially just "winged it".
  18. While what @steuben writes is correct as such, the actual differences that you see are not due to rounding errors but due to the difference between an instantaneous maneuver and a long burn. The prediction from the maneuver node is done with the assumption that the whole maneuver is applied to the trajectory as a single, instantaneous "kick". But in reality the burn takes some nonzero time, which results in a different orbit than the prediction. If the burn is short (a small fraction of the orbit) then the difference is also short, so that you may not notice it. But on long burns the difference becomes large: you not only wind up on a different trajectory than predicted but you also need more dV. To deal with this you can split your burn into multiple burns: to save dV you can split your burn over multiple orbits. Do one or more short burns at the PE until you are on an elliptical orbit close to the edge of the SOI (but still inside) and then do the final escape in one (probably longer) burn. Ta actually arrive at the target do what they also do in RL: make one or more correction burns somewhere during the transfer.
  19. Good point! But if that turns out to be an actual problem then just keep them heated.
  20. While you can split water into hydrogen and oxygen by simply heating it, I understood it that in steam plants you typically have the water reacting with some of the structural materials/metals (e.g. the zirconium of the nuclear fuel cladding). Oxidizing the metal and leaving hydrogen, which then tends to escape the steam system(*) and can form explosive mixtures with atmospheric oxygen. (*) Hydrogen considers steel piping more a strong suggestion and not an impenetrable barrier.
  21. I think the March 2022 (not '21) date is not because of the first orbital flight of starship, but that they expect to be ready for real live testing of their calibrated camera by then.
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