Saw this on TV last night, dont know if its been done before but couldn't find it. Reaction Engines A2 - Wikipedia, the free encyclopedia Looking at the specifications it could be quite a Plane. snip "The vehicle is intended to have about 12,430 miles (20,000 km) range and good subsonic and supersonic fuel efficiency, thus avoiding the problems inherent in earlier supersonic aircraft. The top speed is projected to be Mach 5+. It calls for the use of liquid hydrogen as a fuel, which has twice the specific impulse of kerosene, and can be used to cool the vehicle and the air entering the engines via a precooler." With the increased range it would be able to avoid some of the problems encountered by Concord due to sonic boom problems by flying to & from Australia over the Arctic & Pacific!