The USAF keeps pushing forward the race towards cleaner skies-and leaner warmachine and potential global mayhem costs-moving from pure oil-derived fuel to a mixture between oil and synthetic fuel. The new benchmark is not a B1 bomber, which they already put through its paces using a similar mix, but a fighter jet: They broke the Mach 2 barrier using the new fuel mix in an F-15, which according to the Air Force is a crucial step:

They are much higher performance and a much more demanding environment. That was just another risk reduction step to prove the aircraft was not leaking fuel and the engines were behaving nominally. We asked them [the pilots] point-blank if they noticed any difference in performance and they said it was a "non-event". In other words, they couldn't tell the difference. The aircraft behaved the same.

The test this time started with a 50-minute ground test, pushing the engines to full afterburner. In the flight, the pilots put the F-15 to Mach 2.2, approximately 1,450mph. Hopefully, this experiments will also change the civilian airline industry, all in the name of costs and a cool looking environmentally-friendly brochure. [Defense Tech]