 As an example, the intakes on the B-70 Valkyrie had an external compression ratio (cr) at M3 of 3.5 and internal cr about 6.6, followed by subsonic diffusion.The Lockheed SR-71 Blackbird and XB-70 Valkyrie had well-publicised unstart behaviour.Other aircraft that have flown with internal compression include the Vought F-8 Crusader III, the SSM-N-9 Regulus II cruise missile and the B-1 Lancer.