NASA X-43 mach 7

[Robotic Pope]

It was fast huh? hard to imagine that kind of speed. I think that tv programe you watched must be old though because the X-43 did finaly get a record of mach 9.8.

By the way, the current Boeing scramjet test aircraft, X-51, first flown last year goes mach 6 but it can go for much longer burns, it has the record at 140 seconds compared to the X-41's 12 seconds on its record speed flight.