The latest attempt to go past Mach 5 with the X51A has finished badly again, as a broken fin caused the missile to lose control before its air-breathing "scramjet'" motor could even kick in. It happened just after the booster rocket phase, which accelerates the craft to at least Mach 4, a high enough velocity for the hypersonic scramjet to work. The craft ended up in the Pacific shortly afterwards instead, and this lates
