Last I heard from the hard science fiction people, such ramjets have an upper speed limit imposed by some sort of drag. Can't remember for certain... maybe Ato

Last I heard from the hard science fiction people, such ramjets have an upper speed limit imposed by some sort of drag. Can't remember for certain... maybe Atomic Rockets has something on them... yeah, http://www.projectrho.com/rocket/slowerlight.php#Bussard_Ramjet http://www.projectrho.com/rocket/slowerlight.php#Bussard_Ram... . They say 0.12c is the best speed for ramjets.