Trying for hypersonic

X-51A WaveRider test set

This week, a B-52 will drop an experimental unmanned aircraft that will - hopefully - operate for a record 5 minutes on the power of a scramjet engine. The Supersonic Combustion Ramjet is intended to allow for missiles and aircraft to travel at X-15 type speeds of 3,600 mph in the atmosphere, at altitudes up to 70,000 feet.  Most jet engines, even on supersonic aircraft, keep the airstream flowing through the combustion chamber subsonic.  Trying to sustain combustion in a supersonic airstream is a goal engineers have pursued for over 50 years.  Today, flight by flight, albeit with plenty of failures along the way, they are getting closer.