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  1. It cost ~$300 million to develop Falcon 9 (v1.0). It cost over a billion to develop Falcon Heavy. I doubt they want to do that again. But I can't help but think that it needs two RTLS air-augmented boosters and a "Starship inspired" center booster that goes to the maximum delta-v/height possible that can land without ceramic tiles. I'd think they already go that high/fast with superheavy, but it still seems so low I can't believe it. Note that I'm quite aware that developing such a rocket makes zero sense *now*, but the way SpaceX moves, they might well have reduced enough costs elsewhere to make this needed by the time it could be done if you started now. It would take a long time to develop (also taking their time should ease the cost a bit, but that isn't Elon's style).
  2. First, put any propellant/fuel between the engine and the crew compartment. Any other gases, water, whatever as hydrogen isn't going to be all that effective in blocking radiation no matter how many kgs you have. Second, I've often suggested that simply jettisoning the fuel rods after a single use could easily be the way to go, especially at first. Mostly so you don't have to cool the reactor by running propellant through it (thus killing Isp), but also so most of your radioactive mass no longer threatens the crew. I neither have the data, nor have the skills to crunch it for this type of thing to say it would absolutely be better, but suspect it should definitely be on the table when considering a crewed nuclear vessel (possibly even an uncrewed vessel that starts and stops the engine a lot).
  3. Makes the kick feel better when you don't have to cough up millions to do it. Yeah, that makes sense. So if separation failed, the press could go on and on about how the peculiar shape of the rocket lead to the death of all aboard (although I'd suspect the center of mass difference would make it unlikely to be aerodynamically stable even with a constant diameter rocket).
  4. The only reason to design it that way would be in case of a failed separation. I can't think of *any* rocket (crewed or not) that failed due to a separation, so they wouldn't design it that way. But if separation failed, and wasn't a complete surprise to Blue Origin (probably only possible if they were trying something new like Spacex and pneumatic separation), then I'd expect the booster to handle the landing with capsule. I don't think Blue Honeywell has tried anything new.
  5. The electrical (US) world is blessed with metric. Only issue is that often printed circuit boards (and components) are in inches and mils (.001 inches). I've often been thankful that I don't have to deal with 12 1/2 Franklins to the Edison for current or such.
  6. I'd like to assume that booster landed where it was supposed to, and that it has a margin to land the capsule on top of it. Having the booster fall off much later than expected (i.e. too late for the parachutes) would be a huge problem, but if the parachutes don't pull it off the booster, I don't know what will.
  7. I have to wonder just how many of these questions wouldn't be needed if somebody sat down and played KSP until they could reach another planet. This one might be an edge case, as KSP has a limited range of nuclear rockets (the only one included matches the only one ever test fired) and you might not realize that the Isp of NTR/Water < hydrolox (for virtually all cases). But a surprisingly large number would, especially the orbital mechanics ones. Anything regarding TSTO might require the realism overhaul mod, but I'd recommend that for anyone who needs correcting on "things KSP doesn't cover/covers badly".
  8. There was a Scott Manley video where he was talking with his brother. His brother does (or did however long ago it was published) a lot of producing thin films. He kept talking about "mils" and I was never sure if he meant milimeters or dealt enough with the American market to be talking about US "mils" which are mili-inches. I'm pretty sure he meant mm.
  9. They don't. They just use fancy names as a way to gatekeep projects that people haven't sweated blood over out of consideration. And a clever name is a shortcut to showing that. Check the names out of funded mid-cost projects (not Senate Launch System). They all have terribly clever names. And I'd expect committee members don't want people to think they don't know the difference between Greek and Latin, and otherwise not be impressed by the name. There are a ton of potential projects out there and the committees have to dump nearly all of them and then pour through a short list for projects they are going to fund. Don't expect this one to get on the short list. Basic rule of science, if it isn't funded it doesn't happen. And space takes a *lot* of funding, so it takes a lot more convincing to get people to hand over the money.
  10. When you see a massive correlation between clever names and funding, it becomes harder and harder to believe that. No funding, no project. Simple as that.
  11. "Nuclear reactor power plus airbreathing rocketry" with ... water? [snip] Launched from the sea: The whole idea is to use a huge rocket and reduce infrastructure costs, this helps in launching the rare huge rocket (see Sealaunch). Nuclear rocket: high-cost, likely requires a high cadence. Only reason not to use ground launch is nuclearphobia. Nuclear thermal rockets heat the propellant and expel it out the back. There is essentially no reason not to use all water or all air. And if you do use water (I think that's the right choice), make sure you purify it (probably reverse osmosis) before heating to rocket exhaust temps in your heating chamber. Assuming stage 1 is nuclear, the big issue is getting enough thrust to get in space. Almost certainly not going to happen, but if you want a spaceplane this is the easiest way to justify it (you never need thrust > weight). Assuming stage 1 is nuclear, there is no reason to drop the first stage. Just switch "fuel" tanks to hydrogen and use that for your "second stage" to orbit (or beyond). And while cracking water to hydrogen is inefficient, if you happen to have your nuclear reactor nearby *and* a strong hydrogen "fuel" tank handy cracking the water wouldn't be all that dumb (although you might eventually want turn around times high enough to crack the stuff at your launch base instead of waiting to refuel while doing the ISRU thing on Earth). Isp of NTR/water is going to be lower than a SSME (same exhaust, and SSMEs and any reactor would melt running at the temperature of a SSME combustion chamber), but NTR/H2 was achieving 800s in the early 1970s and should get a bit higher.
  12. Have you *seen* just how clever the names are that get funded? Note how our own forum member's project Osiris Rex manages to fit a perfect acronym. It seems to be one of those things that imply you put some real effort into the proposal, so the committee actually looks at your proposal.
  13. The pendulum fallacy relies on that if the rocket is free to rotate, then it doesn't matter where the exhaust is as long as it is inline with the center of mass. Once you add wheels (which provide a fulcrum for the exhaust to torque around), you are in a different case and rocket placement matters. But where you don't want to be is on the skateboard.
  14. Mixing Greek/Roman naming? BAD. Poseidon/Odysseus or Neptune/Ulysses, pick one. It doesn't help that the whole Odyssey existed thanks to Poseidon granting his son Polyphemus's prayer to curse Odysseus and prevent him from getting home. Maybe they can use Pentium processors for computing power.
  15. When working with rocketry/fireworks, the goal is to be as far away as possible while the rocket is burning. This violates that basic principle.
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