You do realise that a scramjet has a TWR of 2, no? That's less than what our NERVA has... The "OP-ness" is the one you want.EDIT: FFS, more than 5000 kN of thrust, come on, I don't think your scramjet weighs 250 tons. EDIT2: So you lower the threshold speed yet you don't lower the max speed, good one OP.