-The HyFly is a hypersonic engine running as "scramjet" for testing Mach 3 to 4 speeds but programed to reach Mach 6 under the FASTT (Freeflight Atmospheric Scramjet Test Technique) program.

-The Hy-Fly is a current project that is rather within the Boeing-Rocketdyne Division.

"Boeing Hy-Fly on bench"

"Boeing HyFly cutaway"

"Boeing HyFly, artist impression"