A monster plane deserves a monster engine.
With a composite fan more than 11 feet in diameter tucked inside a 14-and-a-half foot nacelle, General Electric's GE9X is the biggest jet engine in the world. It will be used to power the new Boeing 777X long-range wide-body airliners currently under development. GE has been testing the GE9X around the clock and around the world as the the engine enters the final phases of FAA certification. Now GE is gearing up for the next step: flight.
A GE9X was recently mounted in the number 2 position on the left wing of GE's 747-400 flying testbed, as . Although the GE9X will be used on twin-engine 777s, testing it on a four-engine 747 allows GE to evaluate the GE9X alongside established engines (CF6-80C2s) that have known performance envelopes and can serve as a control group of sorts.
GE released a photo of the GE9X mounted on the 747 (above). You can clearly see how the engine manufacturer had to shift the engine forward and up slightly above the wing's leading edge to provide enough ground clearance for the tremendous high-bypass turbofan. The GE9X is supported by a 19-foot custom strut adaptor to angle the engine up 5 degrees more than the three other engines on the flying testbed. Even then, there is only about a foot and a half of ground clearance below the hulking GE9X.
GE says ground clearance for the GE9X will be a concern mostly for ground operations rather than takeoff and landing. Just like with GE90 testing, used on previous versions of the 777, the fact that the aircraft's wings bow upward during landing is expected to give any aircraft with GE9X engines plenty of clearance to safely land. GE also removed six-foot wing extensions on the 747-400 to reduce the wingspan to a little over 195 feet, stiffening the wing to accommodate the weight of the large engine.
The engine mounted on the 747 flying testbed is the fourth of the program. GE plans to ship two engines to Boeing to be used on the first 777X next year, and Boeing hopes to flight test the 777-9, the first aircraft in the 777X program, in early 2019.
The initial GE9X, known as the first engine to test (FETT), was fired up for the first time in March 2016. That engine is now being used to prepare GE Aviation's ice testing facility in Winnipeg, Canada, for future GE9X testing. The second engine of the program is being prepared for the official FAA 150-hour block test slated for 2018, a robust performance test that will require GE to run the GE9X up to triple red-line conditions, meaning maximum fan speed, maximum core speed, and maximum exhaust temperature. A third engine is to undergo crosswind testing at GE's testing ground in Peebles, Ohio.
It won't be long now until the GE9X officially becomes the largest jet engine ever to fly.