In April 2007, Pratt & Whitney's X-1 JP-7-fueled demonstrator scramjet engine completed a simulated Mach 5 flight of the X-51A WaveRider -- officially known as the Scramjet Engine Demonstrator - WaveRider, or SED-WR -- at the NASA Langley Research Center in Hampton, Va. The demonstrator engine, which has fitted with full authority digital engine controls and a closed-loop thermal management system that uses the fuel itself as a coolant, was designated the SJX61-1. Credit: Pratt & Whitney Rocketdyne
