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jf0

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Everything posted by jf0

  1. Of course only English speaking countries use amber, it's an English word! But really only in traffic light standards or when talking about petrified tree sap! Where I am from the law *specifically* states that yellow (or amber) traffic light means you must stop unless it is unsafe to do so. So If a policeman sees you passing a yellow and judges that it was in fact safe to stop, they could potentially give you a fine for disobeying a traffic light.
  2. Well we usually assume under 'normal' conditions that we have the axiom of choice. This allows us to prove there are unmeasurable sets (and to make the pieces for banach-tarski balls). The point of the video is that your everyday intuition about measure (length, area volume etc) and 'continuum' type sets (real numbers, euclidean space etc) can't be combined without causing conflict (some sets might change their volume if you rotate or translate them for example). Axiom of choice lets you explicitly narrow down some examples (like banach-tarski). without it you can't say such things happen.
  3. With latest version, I have a ship with a 1.25 fairing closed on top, I went to launch pad, and before launch opened the settings menu with esc, adjusted the music volume and returned to the game, and the fairing had dissapeared. I tried again and it is 100% repeatable. The fairing wont dissapear just through entering the settings menu, it *only happens after changing the music volume*. I'm sorry if this sounds like the ramblings of a mad man but it is repeatable. Any ideas?
  4. I started a complete fresh game in a newly downloaded 1.2, every thing works fine. I rarely use any mods, and all I wanted was real plume. I added real plume, ow I can't right click anything in EVA, can't right click about half of anything any other time, after eva and entering the pod once the hatch becomes permentantly 'obstructed', the staging ui in the VAB goes insane regularly. Anyone else have similar issues, any idea how to fix? I just want stock plus real plume, that's it!
  5. I am from Australia and my native language is English. I can emphatically say that a couple is almost always taken to be a small, perhaps indefinite, amount of more than 1. "I'll have to think about it for a couple of minutes" "He saw me a couple of times." Almost never does it mean 'exactly two' except in the context of a married couple for example. in regular conversation it would usually be taken to be 2, 3 or 4. In the context of "a couple of minutes" even 15 would not be unreasonable. I now live in a country where the native language is not English, and those here that
  6. The paper claims Isp from 225 upto 260, but it also contains several editing errors and liberal use of the trademark 'TM' symbol, which to me gives it the appearance of nonsense (but thats just me....)
  7. Well, apparently the cargo bay is 4.6 x 18m (I'll assume that means 4.6 x 4.6 x 18m), so it has a volume of 380000 L. Going by the capacity and volume of the external tank which is about 553000L of LOX + 1500000 L LH2, with masses of 629000kg and 106000kg, the combined 'density' of LH2 and LOX propellent in the correct ratio is about 0.36 kg/L, so lets say you could get about 133000kg of propellent in the cargo bay. according to this http://bado-shanai.net/Speculative%20Engineering/SESpShMainEngine.htm the ssme uses 466.3 kg/s of propellent, so with three engines firing it would burn for about
  8. The irrationality has nothing to do with the decimal (or any other) representation. It is to do with the fact that it is not equal to any rational number. You define rational numbers without even talking about 'base' anything.
  9. I'm no expert on parachutes, but I would guess they wouldn't give a soft enough landing on solid terrain. But you could always add some kind of squishy inflatable landing bag. But maybe by this point it is getting just as complicated as doing a powered landing with the rocket.
  10. This page http://orbitalaspirations.blogspot.it/2011/10/japanese-lambda-4s-launcher.html says: "... is, to date, the smallest ground based launch vehicle to place a satellite into orbit..." If that is true, I feel like it would be very very difficult and unlikely that a "hobbyist" beat this, even tehough it is 1970s tech. according to this also http://www.isas.jaxa.jp/e/enterp/rockets/vehicles/l-4s/ you can see the mass at ignition and burn out for each stage, the mass ratio and specific impulse, for those interested. I would make a guess that solid rockets are us
  11. "Hydrogen can be stored in a metallic state" in the same sense that you can supply the worlds electricity by running hamsters in wheels, or that I can make an integrated circuit at home using a microwave oven, or I could get rich recovering gold from seawater as a hobby. In principle, yes, hydrogen is thought to have a metallic phase ... at several hundred gigapascals of pressure.
  12. Under 10t is feasible, this one took 26kg to orbit https://en.wikipedia.org/wiki/Lambda_4S
  13. The specific impulse will be very low because the specific heat of water is much much lower that the heat of combustion of, say, kerosene. Hot liquid water can hold something like 5J/g/K of energy (so cooling it from say 300 C to 0C as it expands in the nozzel could give you, say, 1500J per gram of water . The heat of combustion of kerosene is about 50000 J per gram! Very rough numbers but good enough to make a rough estimate: heat capacity changes with temperature... and ok not considering the mass of oxygen to burn the kero, but lets say chop it in half, kerosense/oxygen still gives nearly 2
  14. It's Spanish not Portuguese! The video description says (the speech in the video is just someone reading this text): "Scientists manage to capture an image of Schrodinger's Cat An international group of physicists have shown for the first time images taken with a camera without using a real object. Experts say that the idea can be useful in medicine. In their experiment, the scientists from Viena and New York used a laser and a stencil of a cat. The scientists did not choose the stencil of the cat by chance (however it could have been any other object), But because this alu
  15. This all comes about because of the idea that KSP 'is a game not a simulator', so I imagine it went something like this: Oh we think a real sized Earth/Kerbin would be too difficult/not fun/whatever for a game, so we'll make it 1/6th the size. But for simplicity, we'll keep gravity at 9.8m/s^2. Now there is a problem: that 'simplicity' implies that kerbin is super dense. Oh no matter we'll just make fuel heavier, part heavier too. Oh now our eninge isp and thrust numbers cant match up to real life, so we need to change those too. But now something else is broken, so we need to deviate there fr
  16. Of course you can, and in fact isn't that what I said: The OPs point was, I think, a frame where all other frames are at rest. This does not exist because surely given any coordinate system you can always easily find 'another' that is in relative motion. also a side note: also we should start being more specific about the correct use and meaning of 'coordinate system', 'object', 'point', 'reference frame'...
  17. Surely not: if I come up with a coordinate system that is stationary relative to me, I can come up with infinitely many that are in motion relative to it. Ok sure; if you have a coordinate system that you call 'at rest' you can come up with infinitly many that have no realtive motion to it (simple example just shift the origin by any amount...), relativity or not. But that does not mean every thing is at rest relative to it, you can still come up also with infinitely many that are in motion relative to it ... maybe you meant something else could you explain?
  18. Imagine a pump where the arrow is, imagine the second tank is missing at first. The fuel exiting the pump pushes back on the pump with the same force the pump is pushing on the fuel (this is really just like how rockets produce force anyway, so we know that works...) so in this case there is definitely a force. When the second tank is there, initially the same force pushes back to the left on the full tank. When the liquid hits the opposite wall of the empty tank,or diffuses into any liquid already in the tank, it creates an equal force to the right, so in 'steady state' there is no net f
  19. For the angular momentum of the rocket plus fuel. If you had a circular pipe filled with fuel with a pump on it, floating in space and you turned the pump on so the fuel started circulating in the pipe, the whole contraption will start rotating in the opposite direction. Conservation of angular momentum is correct, but an even more obvious way to look at it is that the pump pushes on the fuel, and the fuel pushes back on the pump with the same force. If you had two fuel tanks say arranged 180 degrees apart around a rocket and you simply pumped fuel from one to another, fuel leving on
  20. A simple idea, no influence on game play except a little enjoyment: I'd love to be able to place flags, (or even other signs, text etc?) on my rockets in any position. Mainly I thought of this because 1) many parts that seem like they should have a flag, don't (all the fuel tanks for example) and almost without fail, the flag placement on the command pods is in a weird position: eg the 3-kerbal pod say you want to put 2 or 4 things symmetrically around it: in almost every postiion they interfere with something, the hatch, the windows, and of course the flag. If I could place the flag in any po
  21. For the boost into orbit, not at all. Computers fly a combination of preprogrammed trajectory and real time calculations. All major maneuvers and burns would be pre-planned and calculated, and even contingencies for use in an emergency. Even unplanned maneuvers would be calculated by computer. I'd say usually, the astronauts punch numbers into a computer which does the work. Softwier is right about the role of astronauts in apollo, but almost all of the actual 'flying' is done by computer. During the lunar landing, the computer controlled the de-orbit burn and attitude using its inertial navig
  22. This. This. This. add apoapsis, periapsis, time to each, etc to the staging view, fix the 'stage only' fuel calculation in the resources tab (I have never seen it give me the correct amount of fuel when I click the 'stage only button') and change the little roll/pitch/yaw input indicators under staging to show the roll/pitch/yaw RATES not the current vaule of the input! (This is really completely useless, I almost feel like it happened by mistake some one seeing a picture of a space craft control panel and seeing these little needle displays and not realising they actually should show ang
  23. I always thought this would be good, but definitely a configurable option. The way I imagined it is something like this: all parts, perhaps in the r&d menu or in the VAB would have a slider. When full, the part is very expensive, but very reliable, with minimum rare faliures that are not critical (example an engine could lose 50% of its thrust or shut down early, or a battery could lose some capacity/whatever)/ With the slider at minimum, the part is cheap BUT has a higher rate of faliure, and the faliures are more severe (structural faliure, explosion, gimbal stuck at full angle etc). Thi
  24. In light of the facts: 1) All rocket engines currently use fuel and oxidiser in the same ratio and all rocket tanks hold it in this ratio 2) There is only one type of fuel and oxidiser (and I think it has been said before that adding different kinds is out of the question) 3) Jets and the nuke use only liquid fuel 4) There is no tank in the stock that can hold only oxidiser 5) all 'rocket proellant' tanks (with a couple of bizzare excepetions) have the same full to empty mass ratio 5) fuel and oxidiser have the same density - therefor the center of mass of a single ta
  25. In real life most rocket propellants are liquids (or solids) which don't compress much, even under very high pressure. The reason liquid propellants are good is because they are dense without storing under pressure. High pressure means you need stronger and heavier tanks. This is why liquid oxygen,for example, is used in rockets rather than compressed oxygen gas. The density of some liquid propellants can be increased a tiny bit by (furthur) cooling and pressurising, but nowhere near doubling the density (which is what you get by clipping two tanks into each other)
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