shynung

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About shynung

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    Propellant Alchemist

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  1. Vouching for this combo too, for the same reasons. Might also upgrade to methane/peroxide if ISRU capability is considered, just need to have a stock of catalysts (2-ethylanthraquinone and palladium) accessible.
  2. RCS and OMS generally used hypergolics because the engines that use them can be throttled very far down, and can start and stop nearly instantly, which is critical for controlling spacecraft orientation. Using propellants that need external ignition systems may introduce delays into the operation of the RCS/OMS that degrades the craft's orientation capability.
  3. If two supersonic planes pass each other too closely (i.e. plane A goes north, B goes south, 100 m distance at closest approach), would the pilots hear each other's sonic booms? Would the planes sustain damage from such an encounter?
  4. Which is why I intended this kind of thing to be a strap-on booster rather than the core - they're meant to be jettisoned pretty early on. They'd be using gas-generator cycle engines, sacrificing some specific impulse for pure TWR. Well, yeah. We can make the wings wet, though that would make them thicker, creating additional drag. OTOH, I'm also thinking of a blended wing-body rather than a winged-tube booster. Almost all of the internal volume could be used for propellant, plenty of space in the back for mounting several engines side-by-side, without sacrificing effective wing area. Of course, the additional drag is still there, plus the manufacturing costs would be much higher due to the complicated shape.
  5. Glide back, so the booster can use every last drop of propellant to push the main stack. The wings and landing gear would be sized for an empty booster, and it would have no parachutes or wheel brakes - just a tail hook, to stop it Navy-style.
  6. This, with strap-on kerolox boosters that glide back to the launch site.
  7. Not if you can pulse it like a TRIGA reactor. No, I'm not talking about the infamous Orion.
  8. Yep. It'll be handy if the mission is stuck with low-performance engines like hypergolics, but that's about it. It's basically an extreme form of staging. I'm taking the scenario depicted in your second paragraph, with the added tidbit that the vehicle can be controlled remotely. Hence, the rescue vehicle can launch with empty seats, so we can safely assume there will be enough seats for the rescued crew. Also, I vouch for the practice of keeping a second, unmanned vehicle ready on the pad whenever a crewed launch is underway, especially if abort-to-ISS is unfeasible. If the crewed vehicle cannot return to earth after reaching orbit, the second unmanned vehicle would launch a rescue mission. I'm thinking of a two-type vehicle with a cargo and crew variant, but sharing most of the propulsion hardware. Downmass capability is not something that we have a lot of currently, and it can be useful for dropping massive cargo in Lunar or Mars missions.
  9. Agreed. Although... This is still kind of possible. Barely, but can be a viable choice if payload mass must be conserved at all costs. I'm going under the assumption that the crew cabin ejects only during launch and ascent, so I'd leave most of the ECLSS on the upper stage, leaving just enough oxygen in the cabin for post-abort EDL, and waiting for the rescue crew. The heatshield would then be scaled for, at most, LEO reentry. All that is to shave mass in order to lighten the crew cabin's post-abort landing system (I'm assuming a Soyuz-style parachute-and-landing-solid-rockets), so that the landing system's mass can be minimized. Basically, in an aborted launch before reaching orbit, only the crew cabin returns, the rest of the rocket is written off. If anything bad happens to the upper stage after the vehicle reaches orbit that warrants aborting the mission, a better course of action would be to send an empty, unmanned vehicle, dock the new vehicle with the damaged one, transfer the crew to the new vehicle, use the new vehicle's engine to deorbit both vehicles, then land the new vehicle while dumping the damaged one towards the ocean.
  10. I don't see much advantage in making them reenter together if the upper stage and crew vehicle can reenter independently. The crew cabin can be designed to be detached from the upper stage for emergencies, then have a launch abort tower stuck on top.
  11. Isn't that essentially the Apollo missions' configuration when going from Earth orbit to Lunar orbit? Rocket stage, lander, crew capsule? Not to say this isn't complicated. but it's not that complicated. Though, I tend to agree with the idea that combining the upper stage and the payload/crew module, a la ITS, is a better configuration.
  12. I'm proud to say that I didn't use any guides or YouTube videos to get to orbit. Staging, however, didn't occur to me until much, much later. My earlier rockets were all enormous SSTOs with pitiful mass ratios.
  13. NASA Mars Reconnaissance Orbiter mission used an aerocapture maneuver. This reduced the fuel needed for Mars orbit insertion by half.
  14. I see. Guess we'll need a few more decades for a deflatable module, then. I'd suggest using an aeroshell designed like a wingless Space Shuttle Orbiter, with cargo doors enclosing an unpressurized cargo bay, and a heatshield on the other side. The inflatable/deflatable module is connected to a rigid pressurized module by a swinging joint - to inflate the module, the joint swings the module out of the cargo bay (still attached to the rigid module via a pressurized tunnel/walkway), then inflate after the module is clear of the cargo bay. Stowing the module would be the opposite - deflate, swing-in, the close the cargo bay doors.
  15. You can get around this by having a deflatable expandable module, and a rigid flight deck. Just before aerobraking, the crew goes to the flight deck and strap themselves, while the expandable module retracts (care must be taken to not leave free-floating items that may damage the module). IDK if the BEAM module can be deflated and neatly folded after deployment, though. Might need some more development on that front.