/sci/ - Science & Math

>>10986268
>>10986219
that's definitive FUD. Cryogenic upper stages have similar risks to propellant transfer and old space has flown dozens of those. And hey, maybe instead of just straight up refueling two starships, why not do a smaller demo mission first to derisk things? Oh and the interesting thing is that propellant transfer actually turns out to be more difficult when you have smaller tanks:
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19840017685.pdf
>>10986651
>>improper ullage is an issue,
Ok I need to calm down here because I might have just turned into a ULA shill, but ULA seems to have demonstrated a means of dealing with this. They took a centaur and just spun it and it turns out that works. Pic related from here, which is ULA shilling propellant depots:
https://sciences.ucf.edu/class/wp-content/uploads/sites/58/2017/02/Propellant-Depots-IEEE-2011.pdf
>> preschoolers
the issue here is that preschoolers don't understand what resonance is and the system resonance frequency ends up being too goddamn low. But yeah, I'd expect any half competent aerospace company to avoid this.
>>10986745
>>is to mitigate for rough 90-95% of the risks and then sending/learning from real thing.
which you do by doing smaller tests first. Dumbass.
>> theorize their shit for few years
the theory isn't good
the theory says that unless you've got a computer that can simulate stuff down to individual atoms that you really need to test a small scale system and that propellant transfer to a smaller tank is harder than it is with bigger tanks. So because ULA demonstrated spinning rockets are an ok means of getting fluid where you want in microgravity, now the big issues are on the receiver side. An empty prop tank ain't gonna be cold, so you need to figure out how to cool it. This could get weird if we just inject fluid straight into a warm tank, because then you've got the leidenfrost effect in microgravity.