SEATTLE - At over 10 feet in diameter, the original GE90 engine developed for the first Boeing 777-200 in the 1990s was the world's largest jet engine. Now, larger version holds that title aboard the extended range 777-300. However, the new GE9X is in development for the Boeing 777X and that fan diameter goes beyond 11 feet and has at least 102-thousand pounds of thrust. Each.
Across the street from Boeing field, General Electric engineers and technicians are busy at work inside Boeing's Low Speed Aeroacoustic Lab. It's one of only a handful of labs around the world that study engine and aircraft noise. It has a large open-section wind tunnel that blows air past large scale engine models to listen for noise levels coming off of fan blades and other parts.
The lab, which is lined with precision microphones, can simulate how that noise would be heard around airports. The engine fan system currently being tested is about one-fifth of the size of a full size engines. The idea is to make the GE9X even quieter than the GE90, boosting the engine into what's called "stage five," which is dramatically quieter than so called stage one engines from the early days of the jet age.
"We can actually scale them up to full scale predictions if we have a winning design for the 9X program," said Tony Opalski, GE's lead test engineer for the GE9X.
GE is testing three types of fan blades in the tunnel, considered so secret they would only allow us to film the blade tip while the engine was stopped.
The testing started in late January and is scheduled to run until October. Most of the crew, which fluctuates between five and 10 people, are based at GE's Aviation Division outside of Cincinnati, Ohio.
Opalski said the testing is a series of structured building blocks that lead up to that final configuration that will include the engine nacelle, or covering that most people see surrounding the engine when they visit the airport or fly.
But the testing isn't just about making things quieter; it's about making the engine more fuel efficient, producing fewer emissions.
"Economics to airlines is all about fuel burn," said Chuck Johnson, GE Aviation's program lead for the 9X. "We're committing to a 10 percent fuel burn improvement on the GE9X."
The GE9X is also expected to push the envelope of other technologies including CMC or ceramic matrix composites, stronger and lighter than metal and used in high heat applications inside the engine's core where temperatures reach levels where even the toughest metals can melt.
There is a lot of work to go. Testing is expected to start in 2016 in preparation for FAA certification before going to Boeing for test flights of the 777X starting in 2018. The first delivery of the 777X to airlines expected in 2020.