3 ms·Another comment says that the paper cites 1000-1200 ISP that is simply HUGE.by tigershark 6y agoAnother comment says that the paper cites 1000-1200 ISP that is simply HUGE.baybal2 6y agoFor an air breathing engine? Not so much.valuearb 6y agoThe theoretical max ISP for Hydrogen rockets is only 530, so they are talking about using atmospheric oxygen.