The new aircraft will be a direct competitor to Lockheed martin's upcoming SR-72. ... Speaking to Aviation Week Aerospace Daily, Boeing's hypersonics chief described how Boeing was planning a two-step development process for the new war plane. The first stage would involve flight tests of an "F16-sized, single-engine" precursor vehicle that acts as a "proof of concept". The second stage is the creation of a "twin-engine, full-scale operational vehicle" that has roughly similar dimensions to the 107-foot-long SR-71. ... The speed of sound – or Mach 1 – is around 1235km/h. So hitting Mach 5 would mean the Son of Blackbird would have to...