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Posts posted by RCgothic

  1. An interesting article. I think the biggest takeaway is the chief scientist at arecibo doesn't want to replace it like for like, but with a compact parabolic reflector array on a tiltable platform situated within the arecibo depression. It'd have twice the sky coverage (including visibility of the galactic core) and five times the radar power. Current estimate is under half a billion dollars.




  2. I agree with your analysis that a 1st stage for a rocket with half the payload of Falcon 9probably weighs about half as much, ~14t, and that six Rutherford's aren't going to cut it for a landing.

    Probably needs at least 9 auxiliary Rutherfords, (octoweb arrangement?) and they'd have to be firing on ascent so as not to be dead weight whilst retaining enough charge for a landing. Rutherfords are only 25cm across though, so it's easy to squeeze 9 into a 1.5m diameter, leaving a 1.5m wide annulus for the main engines.

    For a takeoff TWR of 1.5 Neutron would need ~4MN of thrust. Nine Rutherfords barely dent that. And it'll need four more engines more powerful than Merlin 1D. Or alternatively six 640kN engines.

    Feasible. 15 is a lot of engines for a first stage though.

  3. 24 minutes ago, JIMMY_the_DOG said:

    uhm no..? wouldnt it be sn12 next?

    As tater said, SN12, 13 and 14 were scrapped due to (as yet unknown) upgrades to SN15 and subsequent prototypes.

    (Landings excepted) testing has gone pretty smoothly so far, so it wouldn't be worth delaying flight experience with SN15-type prototypes in order to get more flight experience with SN8-type ones. Totally worth the manufacturing practice though.



  4. 7 hours ago, paul_c said:

    They need to get to grips with why the engine(s) seem to work fine on a test stand, but don't once attached to a spaceship and flown in the profile they have in mind for the thing. 

    That's why they fly.

    The only site at risk belongs to SpaceX, and the people who get the say on whether SpaceX can risk that site is SpaceX. The flights haven't come even close to risking anything else, and they're equipped with flight termination systems in the event that they might. And on the contrary, I don't think SpaceX is taking any reputational damage whatsoever from these flights. 

    I don't see why the FAA would have any more problem with SN10 than SN9 (or especially SN8).

  5. I've heard that advanced solids are pretty much locked in at this point, and that whenever they debut that will be block 2. It won't be as much of a performance increase as liquid boosters. Nowhere near 60t to TLI.

    I reckon it'd need a 5th RS25 and liquid boosters to hit that milestone. Might need to stretch the core further, and the boosters would probably be larger diameter as well which is all kinds of disaster for GSE compatibility.

  6. 7 minutes ago, sh1pman said:

    What if they needed to abort after lighting the SRBs? Can’t just shut them down. Did the Shuttle have launch clamps that could hold it on the pad with burning SRBs?

    I don't believe so. Once the SRBs are lit shuttle is departing or exploding no matter what.


    Edit: Yes, the hold down charges and SRB igniters were fired at the exact same time. The exhaust plume of the SRBs can boil steel, so nothing survives it for long. Ares 1-X torched a decent section of fixed service structure during its takeoff pad avoidance manoeuvre, not that it mattered as it was due to be demolished anyway.

  7. 6 minutes ago, tater said:


    Payload to GTO is 26.6t, and to Mars is 16.8t. TLI is in between.


    6 minutes ago, tater said:


    Yes, if the payload goes up on FH. If it goes up on two F9's, then that's 32t of spacecraft in LEO. 

    FH then goes up with nothing but a fairing and a basic docking target, the combined spacecraft autonomously docks to it, and 63t of fuel residuals sends 32t to the moon from LEO easy.


    I'd like sevenperforce but I'm out for today.

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