3 ms·
The issues are: a) boil-off (others have addressed that elsewhere in this these threads), and b) transfer in zero G (something close to an inertial frame of ref
by cryptonector 3y ago
The issues are: a) boil-off (others have addressed that elsewhere in this these threads), and b) transfer in zero G (something close to an inertial frame of reference). (b) is hard because bubbles of gas form randomly as you drain one tank, so the pump can't work very well. Bubbles of gas are not a problem for rockets normally because they either are always under acceleration (so the gas floats to the top of the tank, while the outputs are at the bottom) or because they have small and full tanks that SpaceX calls "header tanks" to make engine start possible which then resolves the gas bubbles problem in the larger non-full tanks.
- avmich 3y agoIt's possible to avoid creation of the bubbles in the first place though. Some tanks could use pistons, and some - flexible membranes between displacing gas and the liquid fuel. Or tanks could be flexible themselves, squeezing the fuel out when their volume decreases and when being fueled, increasing their volume. If bubbles appear, it's possible to liquify them back. Increase of pressure with possible decrease in temperature (active cooling) could help. This is an old problem, with quite a few ideas how to solve, some of those ideas even tried in practice.
- cryptonector 3y agoRetrofitting such things into Starship sounds difficult.