Reaction begins testing Mach 4 jet engine upgrades for US Air Force
The UK's Reaction Engines has started a new test campaign to greatly expand the envelope on its high-mach propulsion technology, hoping to prove it can upgrade current jet engines to be capable of working from takeoff speeds up to Mach 4 and beyond. The new tests are being done in conjunction with the US Department of Defense and Air Force Research Laboratory, as part of a Foreign Comparative Testing program that the US military uses to identify high-TRL (Technology Readiness Level) technologies that could "rapidly and…