RedKraken

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About RedKraken

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    Sr. Spacecraft Engineer

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  1. RedKraken

    Big Steel Rockets

    The BFR template is mostly done. Who will build the next big steel rocket after spacex?
  2. RedKraken

    SpaceX Discussion Thread

    Caffeine? or sleep? I have been following the hopper threads a bit too closely and i am starting to hallucinate. Hopper/starship updates is going to be like world cup finals that go all year... My hopper estimate was pretty crude. And it may not translate across to BFS/starship well at all. Hopefully we will find out in a month or two. i've got no idea how much propellant this contraption will carry.
  3. RedKraken

    SpaceX Discussion Thread

    wild guess for hopper dry mass : If they use all 5mm stainless @ 8000kg/m3, I get minimum 55 tonne for the steelwork we can see. Body is about 35t, legs 5t, leg fill (fins) maybe another 5t? Included is 5 tonnes of engines (3t) + plumbing, and 5 tonnes of bolted hexaweb.
  4. RedKraken

    SpaceX Discussion Thread

    Reading the active cooling re-entry (energy budget) threads on reddit and nsf. Lots of assumptions flying around. Plenty of uncertainty. Some folks think film cooling is a must. Other folks want to add convective cooling beforehand. Will be interested in seeing these ideas tighten up as the subject matter experts get involved. I wonder if a re-entry test unit could be back on the cards.. not the hopper...something orbital. Like the BFSmini but cheap and nasty. F9 upper stage, clad with stainless, cooling channels and vents, drag fins, stainless cap as fairing, methane thermos and pumps as payload, instrumented up. Push it out toward ~GTO for a high speed re-entry.. It doesn't have to survive, only the telemetry matters. A ~3.66m, 20t vehicle is not a 9m, 100t vehicle, but it might be a cheap way to get data before the first starship is built.. The mass budget could be something like 10t including a few tonnes of methane coolant. 5mm SS armour for S2 is about 6t (12m x 4m diameter).
  5. RedKraken

    SpaceX Discussion Thread

    I've seen rough estimates on reddit specify 5000kg methane over 200s for (earth?) reentry with most (80%) of the hot methane vented. If correct, this requires 25kg/s average pumped thru the windward skin. Peak might be a good deal more. A single raptor 2000kN/330s fuel turbopump moves about 130kg/s CH4. I assume you would have dedicated, redundant pumps for this. Not the raptor turbopumps.
  6. RedKraken

    Russian Launch and Mission Thread

    Soyuz at vostochny in 10min
  7. RedKraken

    SpaceX Discussion Thread

    Its a shame that the grand old men of soviet rocketry could not live to see what spacex is doing now. Korolev, Glushko, Mishin, Chertok and many others. I'd like to think they would have been thrilled. (Glushko may have been surprised (or maybe not) to find his engines powering american rockets.)
  8. RedKraken

    SpaceX Discussion Thread

    4:1 is stoichiometric by molar mass? raptor uses 3.6:1 .....fuel-rich for lower temperature combustion at the cost of a few seconds of isp. 3.6kg lox 1 kg methane. You can check the ratio against the fuel load for the BFS..... 240 tonnes methane, 860 tonnes lox. Ratio 3.583 Raptor at 2000kN/330s is burning about 600kg of propellant per second. Bulk methalox density is ~900kg/m3 when subcooled compared to ~1100kg/m3 for kerolox. All subcooled. lox is ~1230 kg/m3 @ 70K and methane is ~440 kg/m3 @ 96K tank volumes are split about 44% CH4 and 56 % LOX.
  9. RedKraken

    SpaceX Discussion Thread

    That place looks like jeb's junkyard.
  10. RedKraken

    SpaceX Discussion Thread

    Hopper mockup from https://twitter.com/martinengwicht? ..... found in NSF forums
  11. RedKraken

    SpaceX Discussion Thread

    an xkcd would be perfect..... or a reddit sales-weasel meme... ***slaps bfr roof*** "you can fit so many redesigns in this baby"
  12. RedKraken

    SpaceX Discussion Thread

    "need to use a Russian engine on Atlas, but that engine design is brilliant" ....brilliant, but heavy and much too expensive to expend.
  13. RedKraken

    SpaceX Discussion Thread

    ******Keep tweeting elon!******
  14. RedKraken

    SpaceX Discussion Thread

    Radically redesigned Raptor ...... crikey elon.....what have you done? Its a musk xmas twitter-storm. A surprise to be sure ...