In the meantime work on 5m composite tank is ongoing.
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View attachment 67942
This carbon fiber based composite material has density of 1.7g/cm³, aluminium alloy has a density of 2.8g/cm³, aluminium–lithium alloy has a density of 2.7g/cm³. This material is also 8 times stronger than aluminium alloy and 6 times stronger than aluminium–lithium alloy.
Composite material liquid oxygen tank is 30% lighter than metal tank and has the potential to reduce overall rocket cost by upto 25%.