Sn10's nose, complete with its newly installed flaps, has been moved into the High Bay where it's expected that it will be mated to the rest of Sn10 at any time.
And Elon's gone crazy again. (From watching Boston Dynamics dancing robots apparently.) He writes:
"We're going to try to catch the Super Heavy Booster with the launch tower arm, using the grid fins to take the load."
https://twitter.com/elonmusk/status/1344327757916868608
Viv asks whether he's playing Kerbal, the Real World Edition.
Elon says
"Saves mass & cost of legs & enables immediate repositioning of booster on to launch mount - ready to refly in under an hour."
https://twitter.com/elonmusk/status/1344342598694047744
Lots of skepticism about this. Frankly it sounds crazy. But Elon has a proven track record of successfully doing crazy things so you can't dismiss it.
Then Tim Dodd asked about the Sn8 header tank problems and whether the changes to Sn9 were hardware or software changes. Then Tim asked whether the headers are back pressurized with gaseous CH4 and GOX. Elon chose to answer the second part.
"Sn9 will press CH4 header tank with helium. Long-term solution is under debate. not clear what is lightest/simplest."
If they've gone to helium, that answers the first part of Tim's question too, since it presumably will require plumbing mods, not just software.
https://twitter.com/elonmusk/status/1344344855237992448
Some of the engineers think that what happened in Sn8's CH4 header was something called 'ullage collapse'. It's the counter-intuitive idea that stirring the contents of a partially full tank of cryogenic fluid reduces pressure rather than increases it. And Sn9's radical pitch up flip maneuver obviously sloshed the contents of the fuel header. I'd never heard of ullage collapse until today, but below is an explanation of the phenomenon in cryogenic liquid hydrogen tanks, though I assume that the principles should be the same for liquid methane. Elon suggests that using helium to maintain pressure is just a temporary expedient until a better permanent fix comes along, presumably employing autogeneous pressurization from engine bleeds which is the long-term plan (not without its own challenges though).
Amazing how much information the engineers can squeeze out of a little off-hand twitter post.
https://hydrogen.wsu.edu/2015/03/19/expl...-collapse/
And Elon's gone crazy again. (From watching Boston Dynamics dancing robots apparently.) He writes:
"We're going to try to catch the Super Heavy Booster with the launch tower arm, using the grid fins to take the load."
https://twitter.com/elonmusk/status/1344327757916868608
Viv asks whether he's playing Kerbal, the Real World Edition.
Elon says
"Saves mass & cost of legs & enables immediate repositioning of booster on to launch mount - ready to refly in under an hour."
https://twitter.com/elonmusk/status/1344342598694047744
Lots of skepticism about this. Frankly it sounds crazy. But Elon has a proven track record of successfully doing crazy things so you can't dismiss it.
Then Tim Dodd asked about the Sn8 header tank problems and whether the changes to Sn9 were hardware or software changes. Then Tim asked whether the headers are back pressurized with gaseous CH4 and GOX. Elon chose to answer the second part.
"Sn9 will press CH4 header tank with helium. Long-term solution is under debate. not clear what is lightest/simplest."
If they've gone to helium, that answers the first part of Tim's question too, since it presumably will require plumbing mods, not just software.
https://twitter.com/elonmusk/status/1344344855237992448
Some of the engineers think that what happened in Sn8's CH4 header was something called 'ullage collapse'. It's the counter-intuitive idea that stirring the contents of a partially full tank of cryogenic fluid reduces pressure rather than increases it. And Sn9's radical pitch up flip maneuver obviously sloshed the contents of the fuel header. I'd never heard of ullage collapse until today, but below is an explanation of the phenomenon in cryogenic liquid hydrogen tanks, though I assume that the principles should be the same for liquid methane. Elon suggests that using helium to maintain pressure is just a temporary expedient until a better permanent fix comes along, presumably employing autogeneous pressurization from engine bleeds which is the long-term plan (not without its own challenges though).
Amazing how much information the engineers can squeeze out of a little off-hand twitter post.
https://hydrogen.wsu.edu/2015/03/19/expl...-collapse/