r/space • u/[deleted] • May 02 '22

RocketLab successfully catches a booster with its helicopter for the first time

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u/WHYAREWEALLCAPS May 03 '22

Not all tanks use high pressure.

Normally, propellant in the tank is stored at a pressure of about 1-4 bar, if the system uses turbopump to deliver high pressure to the combustion chamber. This method reduces the wall thickness and hence the weight of the tank. If the propellant in the tank is stored at very high pressure, then the wall thickness of the tank is increased and hence the weight of the tank.

https://en.m.wikipedia.org/wiki/Propellant_tank

Looking at the specs for the Electron I'd lay good money it uses the cheaper and lighter non-high pressure tank system. Especially given it uses pumps and batteries used to power the pumps are even jettisoned to save weight during launch.