Of the potential volume of a liquid fueled rocket's propellant tank, how much of that volume is actually dedicated to propellants (since ullage is needed because of pressurization, boiloff, etc.)?

Particularly, I'm looking for this measure with respect to the following fuels

  • RP-1,
  • LOX, and
  • LH2 fuels.

Note the gaseous hydrogen in the Ariane 5 EPC: that's the ullage space I'm asking about.


1 Answer 1


This report has the ullage volume of the LOX tank on the X-34 at 6%, and RP-1 at 0.5 to 1.5%.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

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