wumpus

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About wumpus

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  1. That should be easy to find, just find a bunch of space glowing due to all the matter/anti-matter annihilation going on (hint: we don't know of any. We'd expect huge areas if there were galaxies of anti-matter, but there aren't. You think you'd find small areas of anti-iron, but I've never heard of any. When I first heard of Orion (probably from Carl Sagan's Cosmos), I've always heard an "can achieve .1c" with no explanation of 30000000m/s delta-v. Going by the 12,000s assumption, I'm seeing a wet/dry ratio in the googol (>10100) range. The pusher plate and spring system should account for a large proportion of an Orion. Well, at least until you load it up with a few googol nukes.
  2. The rocket equation depends on the conservation of momentum. In a NPP, this breaks down into two parts: the pusher plate conserving the momentum of the blast it is hit with, and the pusher plate and rest of the rocket conserving momentum as the pusher plate is pushed back toward the rocket and then pushed back to the initial position. I'm not really sure if it still holds (it probably should, as the pusher plate forms an elastic body. But I'm not sure I can justify the same assumptions as a rocket).
  3. Does this happen when people move to NYC (or Europe) and don't need a car for several years and then start driving again later? I think that this should be a common enough experience. I tried to google if having a gap in insurance caused painful rate hikes but only saw hits for "gap insurance". "Won't save everybody" and "won't save a significant number of people" are two different things. By the time my father hit 80 it was obviously time to hang up the keys, but he lives in North Carolina so there really aren't other options. He's had at least one crash thanks to driving though a red light... I'd really like to know why everything has to be mandatory or prohibited. Presumably regulatory capture means that once a business is allowed to sell something, they want 100% market share.
  4. I remember a discussion on USENET back when China launched its first taikonaut back in 2003. Somebody categorically denied that this could possibly result in a space race, but I suggested confirming that with India (I don't think anyone believed that any other nation felt a need to prove themselves this way). Oddly enough, both SpaceX and ULA are "racing" to be the first commercial vessel to bring astronauts to the ISS. Winner gets to keep the flag that the last Shuttle brought. Of course this largely rests on NASA letting one of them launch first (plus, of course actually bringing them to the ISS). But nobody expects to see either of these expand their military via winning. Anyone who heard Sputnik's distinctive "beep" knew they were in range of Soviet nuclear missiles. Without understanding this, you can't understand a "space race" Musk has stated that he feels he is competing with the Chinese to pioneer space (and presumably Mars). But a "space race" is all about PR (listen to why JFK "choose to go to the Moon" if you have any doubts https://www.youtube.com/watch?v=kwFvJog2dMw Bezos appears to feel a rivalry with Musk (see the "welcome to the club" tweet exchange), but that hardly is a "space race". Also anyone trying to break into the small sat market has to compete with Rocket Lab. This isn't a "space race", but a bog standard "price and reliability" commercial market. Being first helps, but also lets others see your mistakes. That's all well and good, but the only reason NASA had the money to go to the moon was to prove the point. Go listen to Kennedy speech1: he explicitly says that we choose to go to the Moon to prove that the American way of life allows us to meet challenges that Communism couldn't. That was the entire reason for Apollo. Certainly NASA had a roadmap before that, but it was mostly torn up and replaced with this awesome goal. And the JFK roadmap more or less stopped after we "bring them home again". Once Apollo 11 landed, that goal was complete and there were other places that Nixon desperately wanted to spend tax dollars. The Viet Nam war was obvious, and Nixon (and presumably the American public) saw Apollo as a Kennedy victory, something Nixon didn't want to pay for2. Note that the Saturn V didn't quite die with the Moon program. Skylab was launched on one of them, and both manned Skylab missions and Apollo-Soyez launched on Saturn 1B rockets. Then it died. And part of the reason it was "dead dead" instead of "mostly dead" was that the only way it was getting funding was to just go to the Moon. The thing was never documented enough to build on its own (probably standard procedure for government contracts, to protect the contract) and required extensive machinist notes on the blueprints to complete (although presumably if you wanted to build one badly enough, enough machinists could learn how to build one after a few tries. A F1-B was printed/built well enough to test fire for SLS). Another issue was that by 1980 or so we couldn't launch the remaining Saturn V if we wanted to: the countdown routine wasn't documented enough and the original technicians weren't all available or capable of doing it. Note that this doesn't confirm the "NASA destroyed the plans" myth. In complex systems, there's a lot of specific know how to get the job done that for various reasons isn't entered into configuration management (probably because there's no system for the machinist to submit them. Just the engineers. Also don't ever believe that all redlines are fully captured. Not on a 6 million pound behemoth). So we have 99% of the plans. Which was enough to base a modified F1-B and testfire the thing, but don't try to "build to print" an entire Saturn V. 1. My speakers aren't working, so I can't confirm that includes the right parts of the speech. 2. This is 50 years old, and hopefully falls under "history" and not "politics".
  5. Was the plan to not fill them in peacetime? Or more realistically, outside of an active warzone or otherwise likely to come down on enemy territory? Or was it more of a pain to have non-permenantly sealed hypergolics that the techs would have to drain and refuel?
  6. This surprised me, as the R-7 uses kerosene and LOX not vodka and LOX. But those engines otherwise look suspiciously like A-4 engines, including turbopumps driven by hydrogen peroxide. And as far as I can tell, doesn't have an additional stage, although the Vostok appears to have yet another A-4 on top of the previous 5 A-4s.
  7. Soyuz first flew in 1966, and has 1700+ flights. Boeing 737 first flew (commercially) in 1968, although Boeing appears to be breaking that classic design. The goal for Starship is to be like Soyuz, and if success blocks the next generation then so be it. Perhaps Elon will simply design another, or simply go and do something else.
  8. No love for abysall lurker? These might be obsolete now (they were all done with pre 1.0 installations), but the missions were amazing... https://www.youtube.com/user/ablu444 Another great one who stopped recording is Bob Fitch. His "Project Alexandria" (a recreation of space from 0-1969 in RSS) was amazing. I think his Apollo 11 was far too much work for the views (go watch it, it's great) and he stopped soon afterwards. https://www.youtube.com/watch?v=SZeoHfONUxA&list=PLBhKowDYZ822XxTabtoYup81ZLsrgA4be Scott Manley doesn't claim to be the best pilot in KSP (and then lands extremely long rockets on their exhaust bell on the Mun, without them falling over). I didn't know why until I checked out Abysal lurker and others... He certainly knows his orbital mechanics and space history, and especially keeps the patter on such subjects going during the tedium between burns (which makes his videos so great).
  9. Especially before the "moar boosters" pack, I'd often build larger rockets with multiple kickback stages. I also remember that was the favorite strategy for low cost to orbit with expendable boosters (a forum competition). One strategy I used for a long time was to have a pair of boosters to one side, and connect all other boosters to that stage. This was more important with hammers (and somewhat with thumpers) as the cost of the decouplers was often more than the booster. With the current options, it makes more sense to go simply use larger engines (and even more huge boosters) rather than adding more boosters.
  10. I can't tell if the Popular Mechanics ships carry jet or propeller aircraft. It might have worked for propeller craft, but there really isn't any reason to build a carrier that can't carry MiGs. I heard that during the early part of the Iraq War, the US parked an empty carrier in the Indian Ocean. Perhaps they later replaced it with a similar sized container ship (especially during an economic downturn), but it was effectively a "floating base". Just make sure you haven't deployed on while fighting an enemy with an effective navy (read: has submarines).
  11. I'm going to have to study that slide deck, if only for all the other information for air-breathers it appeared to have (mostly trajectory analysis). If you want one of these, I'd start with an air-augmented rocket. Even side boosters can justify work learning how to build intakes that work on at least one mode of the multitude of modes that NTR requires. By the time you can build the intakes, perhaps nuclear power won't be quite so demonized.
  12. On the reusability of lunar rockets (taken from the Solar metro map the Kerbal metro map was based on)... Sealevel - LEO: 9400 m/s - presumably reusable (although I don't think Falcon 9 reuses parts that supply more than 3000m/s, and the shuttle probably reused engines that provided less overall relative thrust) LEO - LLO: ~4000 m/s reusable if and only if you aerobrake on Earth, you almost certainly leave the craft in orbit, and you resupply the propellant (and everything else you need) in orbit. LLO - Lunar Surface - LLO: ~3500m/s and would be left in Lunar orbit (presumably not docked to any space tollbooth). All the propellant issues from LEO-LLO, plus the need to haul them to LLO (ions might come in handy, as long as none of the fuel is cryogenic). Note that if you *are* using ions to haul non-cryogenic propellant to the Moon, it might also make sense to build a fuel-depot in an elliptical Earth orbit with ~1500m/s delta-v. This will require a two more trips through the Van Allen belts, but it greatly reduces the mass of fuel needed. But it also is more than a bit silly just for getting to the Moon. If the Chinese (trying to stay on topic) do this, I'd expect they are doing so with their sights clearly set on leaving the Earth's sphere of influence.
  13. I'll have to read it again. I was going to make a comment about obeying the rocket equation, but I'm not sure it has to (it gets its momentum a bit differently). PS: the book is by George Dyson, the late Freeman's son. Highly recommended. https://www.goodreads.com/book/show/21243.Project_Orion
  14. When they needed a crash deep dive to test *everything* and found a show stopper mid-flight does not bode well. Certainly the vast majority will be minor. It is how many that endanger the crew & mission and how likely they are to occur is the big deal. I suspect they knew they had lousy tests, designed to meet contract requirements. That they found real problems with real tests that quickly shows that they need to do the whole thing over again with real testing. Of course, the fact that in the end the crew would have survived implies that it probably isn't all that bad (not Apollo 1 or Soyuz 1), but still needs some real testing and a lot of fixes.