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SN10
Has anyone heard anything about what caused the premature relaunch of
SN10. Relaunches are usually after much more than a few minutes or within a few seconds of landing (for the relaunches of the SN10 type leading to RUD). I'm wondering, will this lead to something like don't start servicing a Starship less than several hours after landing to let the engines cool down or what not. Or maybe it will lead to keep this valve closed after landing. If SpaceX ends up delaying servicing returning vehicles for several hours, it isn't really a big deal. But still, they seem to want to go for a very rapid turnaround, so if they could trim those several hours from the refurbishment time, it can make it even more cool. Alain Fournier |
#2
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SN10
On 3/25/2021 4:30 PM, Alain Fournier wrote:
Has anyone heard anything about what caused the premature relaunch of SN10. Relaunches are usually after much more than a few minutes or within a few seconds of landing (for the relaunches of the SN10 type leading to RUD). Nothing specific, but there was rampant speculation out there that either a connection line or the main propellant methane tank itself became damaged because of the hard landing causing an uncontrolled methane leak that eventually accumulated enough around the damaged rocket that was set off by an extant fire that started on the way back down prior to landing and was never completely extinguished. The root cause of that fire also remains a mystery. Another line of speculation thought that perhaps the tank let go due to structure failure first *before* the explosion that was subsequent. As for the cause of the hard landing itself, Elon has tweeted about that, you can read the whole thing he https://www.teslarati.com/spacex-sta...ion-explained/ Several design changes in the works for SN11. I suspect a total re-think of the helium pressurization setup for the header tanks. Perhaps some new form of autogenous pressurization, along the lines of a cascade dual pressurization scheme, whereby the header tanks are placed under higher pressure than before from the engines and then that is used to prevent ullage slosh, while the engines are off during the belly flop. Not sure why Elon went the helium route in the first place on SN9/SN10. It's going to be more complex in some ways than the helium scheme but hopefully and somewhat un-intuitively more reliable. I'm wondering, will this lead to something like don't start servicing a Starship less than several hours after landing to let the engines cool down or what not. Or maybe it will lead to keep this valve closed after landing. Some have speculated on flaring the methane after landing. Which would look incredibly cool (I mean hot, heh). When I was a kid, seeing the verniers firing on the old Atlas was one of the coolest (hotest?) features of an Atlas launch in my opinion at the time: https://i1.wp.com/everydayastronaut....-Thrusters.jpg Having the methane flared off would look similar, but on an otherwise stationary Starship. If SpaceX ends up delaying servicing returning vehicles for several hours, it isn't really a big deal. But still, they seem to want to go for a very rapid turnaround, so if they could trim those several hours from the refurbishment time, it can make it even more cool. Flaring off the methane would be even more hot. :-) Might be not only the quickest way to depress the tanks but also the safest! Methane wants to misbehave a bit after agitation. Not as bad as hydrogen, but he's not trying to land a hydrogen rocket. Dave |
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SN10
David Spain pounded on thar keyboard to tell us
Several design changes in the works for SN11. SN11? Probably not any major change. SN15 is supposed to be the 1.1 release. I suspect a total re-think of the helium pressurization setup for the header tanks. Perhaps some new form of autogenous pressurization, along the lines of a cascade dual pressurization scheme, whereby the header tanks are placed under higher pressure than before from the engines and then that is used to prevent ullage slosh, while the engines are off during the belly flop. Not sure why Elon went the helium route in the first place on SN9/SN10. It's going to be more complex in some ways than the helium scheme but hopefully and somewhat un-intuitively more reliable. It was a quick fix to the low header pressure problem of SN8, of course. And it wasn't so supposed to be the permanent fix, so SN15 could be a *revised* autogenous pressurization scheme; after all, they've had 3 months to do fresh engineering. /dps -- "This is all very fine, but let us not be carried away be excitement, but ask calmly, how does this person feel about in in his cooler moments next day, with six or seven thousand feet of snow and stuff on top of him?" _Roughing It_, Mark Twain. |
#4
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SN10
On Thursday, March 25, 2021 at 4:30:44 PM UTC-4, Alain Fournier wrote:
Has anyone heard anything about what caused the premature relaunch of SN10. Relaunches are usually after much more than a few minutes or within a few seconds of landing (for the relaunches of the SN10 type leading to RUD). I'm wondering, will this lead to something like don't start servicing a Starship less than several hours after landing to let the engines cool down or what not. Or maybe it will lead to keep this valve closed after landing. If SpaceX ends up delaying servicing returning vehicles for several hours, it isn't really a big deal. But still, they seem to want to go for a very rapid turnaround, so if they could trim those several hours from the refurbishment time, it can make it even more cool. Alain Fournier I have always wondered. variable temperatures and fuel line diameters can cause a vapor lock in the fuel system. This is fairly common in small aircraft engines. But the existence of this lock does not exclude its application to rocket engines. This dynamic at liquid O2 temperatures has been tested? This can result in rocket detonation? |
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