GE Aviation has disclosed initial details of the 18,000-lb.-thrust Affinity powerplant, which is the first supersonic engine ever to be developed for a business jet, and the first designed to meet Stage 5 noise limits. 

Combining military supersonic design features with the high-pressure (HP) core of the CFM56, the twin-spool engine merges a relatively large core and medium bypass ratio to enable supersonic cruise with acceptable environmental and range performance. 

The Affinity is configured with a two-stage fan, a nine-stage HP compressor, a single-stage HP turbine and a two-stage low-pressure turbine. Distinguished externally by an extended, low-drag spinner and a set of fixed inlet guide vanes with movable flaps, the low-pressure system comprises two stages of wide-chord, integrally bladed – or blisked – titanium fan blades. 

The aft end of the engine incorporates a sophisticated exhaust mixer resembling the ceramic matrix composite-made design used in GE’s Passport. The annular combustor is designed for supercruising (the term describes sustained supersonic performance without afterburner), while the HP turbine and stator are protected by an advanced thermal barrier coating. To reduce cross-sectional area, the engine is contained in a slimline carbon-fiber casing.

The engine will be controlled throughout a broad flight envelope of up to 60,000 ft. by a next-generation full authority digital engine control (FADEC). GE says the engine is designed to “enable efficient supersonic flight over water and efficient subsonic flight over land, without requiring modifications to existing compliance regulations.”

“We chose ‘Affinity’ because the name reflects the engine’s class and the harmonious assemblage of GE Aviation’s commercial, non-civil and business aviation propulsion technologies to bring a true step change in commercial supersonic propulsion,” says Brad Mottier, GE vice president and general manager for business and general aviation and integrated services.

“It is designed for both supersonic flight over water and efficient subsonic flight over land, and therefore does not require modifications to the existing compliance regulations. That’s a very important point. When people think of supersonic they think it’s going to be noisy and have emissions, and that there’s not going to be a viable business case. But working with Aerion and Lockheed Martin collectively we have threaded that needle – which I think is pretty amazing.”

The Affinity is “a medium-bypass engine. It’s not a turbojet, it’s not a fighter engine and it’s not like the engines that were on Concorde. It’s a hybrid between an airline engine and a fighter engine,” he adds. It also represents the first of a family. “We don’t view this as one application. It’s a class of engines. We are building a technology suite so we can add additional engines,” says Mottier.