Why the Time for Open Fan is Now

Why the Time for Open Fan is Now

The a-ha moment came around 2014. At the time I was leading GE Aviation’s advanced technology team, a group of technical engineers whose sole role is to test the boundaries of what’s possible. We were probing the possibilities of improving fuel efficiency with the goal to see how far we could push.

GE had designed and tested open fan designs dating back to the 1980s and we had advanced significantly on that work, but a counter-rotating fan was essentially a given to us at that point. That’s when one of the engineers asked, “Why does it have to counter-rotate? What if it’s single stage?”

It was like a lightbulb went off. One of those moments when you’ve worked on something for so long that you can’t see it any other way, and then someone did. It wasn’t just a breakthrough, it was radical. A single stage fan that wasn’t simply a propeller, but rather one set of rotating fan blades with the same speed and performance of a counter-rotating fan.

As chief engineer of GE Aviation and a GE engineer for the last 27 years, I’ve watched how we’ve incrementally improved fuel efficiency with each successive new commercial aircraft engine design. The LEAP engine*, introduced in 2016, is 15 percent more efficient than CFM56-5B and -7B engines. The GEnx engine is up to 15 percent more efficient than the CF6-80C2, and the GE9X engine has been designed to be up to 10% more efficient than the GE90-115B.

But the push for 20 percent greater fuel efficiency in one generation? That is something different. Engineers like big challenges, and this is certainly one of them.

To address this challenge, CFM International, our 50-50 joint company with Safran, announced the CFM RISE* (Revolutionary Innovation for Sustainable Engines) technology demonstration program back in June, targeting reduced fuel consumption and CO2 emissions by more than 20 percent compared to today’s most efficient engines.

Central to the program is state-of-the-art propulsive efficiency for the engine, including advancing the open fan architecture.

The path to 20% lower fuel consumption

In the past, when we’ve broached the open fan, it’s been in response to rising fuel prices. The technology foundation from our work in the 1970s with NASA’s Quiet Clean Short-Haul Experimental Engine (also known as QCSEE) and in the 1980s with the GE36 open fan is what we are building on today.

With the CFM RISE Program, our engineers are again pushing the limits to develop even more advanced technologies than we have before. What’s different this time is why. We are now at a point in the dialogue where fuel prices aren’t driving the discussion. Instead, we are putting all of our best technology on the table toward an even bigger, more impactful goal — reducing CO2 emissions to achieve a more sustainable aviation industry.

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