2
$\begingroup$

Starship's mass of propellant is 1.2 million kg, and Superheavy's is 3.4 million kg. How much of that is the liquid oxygen?

$\endgroup$
5
$\begingroup$

According to Wikipedia, the propellant mixture ratio for the Raptor is 3.55:1 (mixture ratios are conventionally given as oxidizer mass to fuel mass), so 78% of propellant mass is LOX.

It's unclear whether that mixture ratio is including methane that's going to go back to the tanks for pressurization, so I'm not sure if the propellant tankage matches that mixture ratio. If it does, that works out to around 930 tons of LOX for Starship and ~2600 tons of LOX for Superheavy.

$\endgroup$
6
  • 1
    $\begingroup$ Does Starship use autogenous pressurization? If so, is that the inlet or overboard mixture ratio? (I've no idea, honest questions.) $\endgroup$ Dec 17 '20 at 17:23
  • 1
    $\begingroup$ I believe it will be using autogenous pressurization; are you pointing out that some of the methane is going to go back to the tank as pressurization gas? I'll replace some significant figures with caveats. $\endgroup$ Dec 17 '20 at 17:28
  • 1
    $\begingroup$ It is supposed to use autogenous pressurization, but I believe at the moment, it still uses helium. The ultimate idea is to reduce the number of fluids required as much as possible, ideally down to only two. At the moment, there is still the cold-gas thrusters (to be replaced with to-be-developed Raptor-derived hot-gas RCS thrusters), the helium pressurization, and probably some other bits. $\endgroup$ Dec 17 '20 at 17:29
  • $\begingroup$ Meanwhile I found a Musk tweet saying Starship + Super Heavy propellant mass is 4800 tons (78% O2 & 22% CH4). $\endgroup$
    – Joe Jobs
    Dec 17 '20 at 17:42
  • 1
    $\begingroup$ 4600 = 4800 as far as I'm concerned, but it would be a good idea for you to link the source you used for the figures in your question. $\endgroup$ Dec 17 '20 at 19:49

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.