>>12171849I wanna clear something up for all the anons out there, because I'm autistic enough to do the math and bring this knowledge to all of you.
We can roughly estimate the propellant mass of Starship by using known dimensions to estimate the internal volumes of the tanks, and if we assume a 90% fill ratio, we get about 1300 tons of methalox. We also know that Starship with full payload is gonna need at least about 6 km/s of delta V, yes? This is because of how much delta V the Booster can realistically supply while still being reusable. So Starship has 1300 tons of propellant and a delta V of ~6 km/s once dry, WITH payload. Working backwards, estimating an average Isp of 370 for the stage, I get a burnout mass of ~300 tons.
Basically, as long as SpaceX can build Starship and have its dry mass be 300 tons or less, it can get to orbit fully reusable. That requires a propellant mass fraction of 81.25%, which is easy to achieve even with reuse hardware installed, because methalox is rather dense. Once SpaceX has built a version of Starship that has this mass fraction, they can do reusable orbital flights and continue to improve the dry mass over time.
Literally any reduction in dry mass results in a 1:1 increase in payload. To achieve 150 tons payload to LEO, Starship needs a dry mass of 150 tons. That'd be a mass ratio of 90% propellant, more difficult but doable. Alternatively, they can just stretch every stage to increase wet mass, dry mass, and payload mass in proportion until the payload becomes equal to 150 tons.