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peadar1987

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About peadar1987

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    Senior Rocket Scientist

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  1. Aye, but what a nozzle will do is focus the plasma, so more of the energy is directed along the thrust vector instead of escaping radially into space.
  2. As far as I'm aware the N1's odd shape was because the tanks were spherical, as opposed to cylindrical, as the USSR didn't have the required materials knowledge to produce sufficiently strong cylinders. The big taper in each stage was a consequence of having two spheres of different sizes to hold fuel and oxidiser.
  3. Okay, that all makes sense. But it still seems like an engineering problem (smaller than, say, producing grams of positrons), so I still think it's strange they're so settled on high-Z materials for the concept designs. @kerbiloid, the thrust vector is still going to be normal to the pusher plate, whether it's curved or not. Any off-axis thrust will be cancelled out if the plate remains symmetric.
  4. But what would be the advantage of using tungsten as the ablative material rather than carbon? A back-of-the-envelope calculation tells me that the halving thickness of carbon would be 10 times that of tungsten, but carbon has about 1/10th the density of tungsten. The overall mass of ablative material needed to absorb a given fraction of the X-ray flux is the same, but the tungsten has an atomic mass number 15 times that of carbon, so ablating carbon should give, all other things being equal, 15 times the exhaust velocity. Am I missing something here?
  5. So we all know antimatter is the most energy-dense fuel known to humankind. However, it is expensive to produce and difficult to store. One of the proposed drive concepts is a "Positron Ablation Engine", which tries to mitigate this by using positrons as the fuel. They're cheaper to produce than anything containing antiprotons, and they're easier to store, as they're charged and you can use a magnetic trap. The problem with positrons is when they annihilate, they release gamma rays, which are hard to redirect to produce thrust. A positron ablation engine (http://www.projectrho.c
  6. I've seen it on my drysuit before, I didn't know it had a name, thanks!
  7. Yeah, I guess the way I'd do it would be: -High strength tarp. -Epoxy to hab canvas to form a seal. -Sew through the overlapped area to take the load. -Epoxy a set of skinny patches over the sewed areas to seal off the needle holes. With the right materials, adhesive and contact area, the epoxy could maybe do the job all on its own (it's pretty powerful stuff, coming from someone who has accidentally epoxied his shoe to the floor :S )
  8. It's a 1 bar pressure difference across a 2mm hole, I'd say a few layers of duck tape would be plenty to seal it for now before they can get a patch epoxied on.
  9. It's a British English thing. Turtles live in the sea, tortoises live on the land. In American English they're all just called turtles.
  10. The Royal Palace of Nitori was lavish to the point of being vulgar, the perfect location for another drinks-reception-come-press-conference. Set on an ancient volcanic plug at the heart of the city of the same name, it towered above the narrow streets and townhouses of the old walled city, and the apartment blocks of the lower classes surrounding that. Jadra pulled up in the courtyard in a brand new, cherry red sportscar, gifted to her after her successful mission to space. At first she had tried to turn it down, embarrassed. It was then explained to her that the car wasn't for her benefit, it
  11. I'm more concerned about the fact that they seem to be using solar panels as structural elements
  12. It seems pretty unlikely, there are plenty of Pluto-like objects out there, and their composition seems pretty different to that of Uranus.
  13. This happened quite a lot on older aircraft carriers (back when planes had lower stall speeds). An aircraft carrier steaming at 25 knots into a 40 knot headwind could have a plane land pretty much vertically, level with the deck (although I've read some pretty hairy accounts of the effects of waves on this equation!)
  14. Wasn't there some anime about a Japanese space programme consisting of teenagers, because they were lighter? Get your dry mass down with female cosmonauts
  15. All casino games are "rigged" to a certain extent. There's always a house edge, play enough games and the laws of probability say the house is going to come out on top. The only measure of control you have is when to leave the game. Cruising riverboats take this away from you.
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