The race to field reusable hypersonic aircraft got a whole lot hotter last month, with GE Aerospace announcing a breakthrough in high-speed jet engine design that could potentially allow conventional aircraft to fly at speeds that exceed Mach 10.
According to GE’s press release, the company recently demonstrated “what is believed to be a world-first hypersonic dual-mode ramjet (DMRJ) rig test with rotating detonation combustion (RDC) in a supersonic flow stream.” This means leveraging rotating detonation combustion – a far more efficient means of power production – within a dual-mode ramjet (also sometimes called a dual-mode scramjet). Ramjets and scramjets are air-breathing jet engines that don’t function well at low speeds, but can power an aircraft or weapon from around Mach 3 up to Mach 5 and well beyond.
This would be a significant development toward producing dual-mode ramjet/scramjets with far greater range, but could represent an even bigger breakthrough if combined with a similarly Rotating Detonation Combustion-equipped turbofan engine in what’s commonly called a turbine-based combined cycle (TBCC) propulsion system. And those wheels are already turning. GE first acknowledged that it was working with the Defense Advanced Research Projects Agency (DARPA) and the Air Force Research Lab (AFRL) on an RDC-equipped TBCC engine in June of this year.
“GE engineers are now testing the transition mode at high-supersonic speeds as thrust transitions from the RDE-equipped turbine and the dual-mode ramjet/scramjet,” GE Aerospace Military Engines CEO Amy Gowder told Aviation Week.
This TBCC engine would combine four different types of air-breathing jet engine technologies into a single combined system that would allow an aircraft to take off and land under conventional turbofan power, while also achieving hypersonic speeds under scramjet power during sustained flight – a concept that has been proposed by at least three other firms before.
But GE’s design is the first to incorporate Rotating Detonation Combustion, which could make such an engine far more compact and efficient than previous efforts, potentially resulting in a much more practical approach to hypersonic flight.
A working TBCC engine has long been seen as the Holy Grail for reusable hypersonic aircraft, as the exotic propulsion systems powering today’s hypersonic weapons can’t function at low enough speeds needed to land aircraft, making them single-use.
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