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About shynung

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    Propellant Alchemist

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  1. We need further research into human long-term space habitation systems, medical effects of being in reduced gravity for extended periods of time, closed-system LSS, maybe a medical hibernation system. Basically, anything that can keep us alive out there, far away from home. The "getting there" part, I think we can do by EOR-assembling a multistage expendable methalox transfer vehicle by 6-10 heavy-lifter launches, then stacking a two-stage Mars lander, inflatable hab section, and Earth reentry vehicle on the nose. Crew comes up separately after everything is assembled, then goes off to Mars after everything checks out fine.
  2. Ah, I see. I would suggest an identical stack, though. The original Energia stack is already a powerful machine.
  3. This is Energia II, a reusable booster made by strapping wings and landing gear to the same type of booster that once launched Buran to it's only flight. Most of the engine hardware is the same as the standard Energia and Zenit boosters, just stuck on winged tanks.
  4. Since we're talking about nuclear Earth-based SSTOs, I agree with @KerikBalm at their thread that the nuclear lightbulb is the way to go. Barring a pulsed-solid core rocket, it's one of the few reactors that can run hot enough for a sufficiently torch-like performance on almost all situations.
  5. Yeah, it's basically a whole other game. Not impossible, but pretty tricky. Even the HELIOS program whose picture I posted proposed launching it reeled-in, using a chemical booster. That kind of surprised me. 900 seconds is the typical NTR ISP. I was expecting higher ISP at lower TWR.
  6. Launching, I think. would be fine. It's like a plane towing a glider. Atmo entry, on the other hand, might by tricky; I'm thinking about reeling in the payload section at entry, then reeling it back out during descent and landing. Then, after payload section touches down, the engine section must maneuver to touch down a safe distance away. This is a pretty clever way to end up with an exhaust stream hotter than the reactor. It'd be somewhere between pure NTR and pure nuclear-electric rocket, in terms of ISP, I think.
  7. Well, that's the whole point. A pulsed reactor would try to heat propellant by neutron flux rather than through the reactor structure. Though, you can always tow the payload behind the rocket. Also solves the problem of getting stuff/people on and off the rocket, if using a flexible connector. Also worth considering that if propellant cost is less of a concern than reactor fuel, it's useful to have a nuclear rocket motor than has a variable Isp. This allows a lower-output reactor to have a useful TWR at the cost of propellant fraction, which can ultimately save on nuclear fuel costs.
  8. There's a concept for a pulsed NTR reactor here that can boost effective reactor power output by, obviously, pulsing the reactor. From Atomic Rockets section on it:
  9. I agree, that depends a lot on ship configuration. A winged ship can probably land with the propellant tanks still mostly full, but a Falcon-9-style rocket lander would need more propellant for EDL. Drop tanks would be appropriate for the latter. Also, is the setting's tech levels allow for atmospheric ISRU scoops? This is the kind of device that can take in the surrounding atmosphere and stores what it sucks into a propellant tank, to be used later on. That way, the ship can enter the atmosphere with mostly empty or half-filled tanks, fill them on the way down, and land with a mostly full tank. That same scoop can later top up the propellant tank as the ship ascends to orbit, effectively extending the dV capacity of the tank whenever it is flying in atmosphere.
  10. If we're talking about an orbit-based surface shuttle for tactical drops, I have an idea that just might work: drop tanks. Essentially, the ship has an internal tank and detachable external tanks. The external tanks carry the propellant for EDL, while the internal tank carry the propellant for STO flight. The ship would land on nearly-empty external tanks, deploy/pickup payload as necessary, and drop the empty external tanks before liftoff. If the EDL is aborted for any reason (ex: hot LZ), then the ship can just drop the external tanks in-flight, and still has enough dV to boost itself back to orbit right away.
  11. I think "craft" would make sense as a common word. We have such words as "watercraft", "aircraft", and "spacecraft". Not a linguist, so please don't quote me on that.
  12. For the actual chemists in this forum. Are common automobile gasoline suitable for engine regenerative cooling? I'm talking about piston engines, not rocket combustion chambers.
  13. One thing I'd always thought about cargo airships is that they can carry large pieces of cargo that can't be broken down into smaller things, and can also act as stable aerial platforms. This enables us, for instance, to carry fully-assembled wind turbines slung underneath right to their installation point, and lower it into position using airship-mounted winches, essentially using it as a gigantic aircrane. The other thing I can think about is that a cargo airship can be incredibly useful if we have a launch pad on a mountain. This vehicle can lift entire rocket stages, fully-assembled, right on top of the pad, and stack them into position.
  14. Kind of a nitpick here. Aviation turbofans derive most of their thrust from the fan, not the engine. On most common current-gen aviation turbojets, about 1/6 of the air entering the engine ever encounters the combustion chamber, while the rest goes straight to the exhaust nozzle; a bypass ratio of 5:1. Some newer engines such as some models of the PW1000G has bypass ratios that goes up to 12.5:1. That's how they get their efficiency: only a small amount of air entering the engine actually gets combusted, the rest is simply pushed backwards by a big fan. Power generating turbines differ from aviation ones, mostly because they don't have to bother with generating aerodynamic thrust and size/mass limitations, except maybe for ships. This is a steam turbine from power plant. High-pressure steam would enter from the middle, where the red-shirt person is standing, and exit through both axial ends. This reduces thrust loads on the bearings.
  15. LH2 for nozzle and chamber cooling. Hot LO2/GO2 in small cooling channels sounds like a disaster to me - it'd corrode everything frighteningly fast.