PARIS – Airbus and Boeing are each helping to test a radical new engine design with an open fan being developed by CFM International, making it a prime candidate to power the next generation of all new aircraft in the mid to late 2030s.
The new engine with a huge open fan would change the look of airplanes and significantly reduce the CO2 emissions of the next generation of new jets.
Dave Calhoun, Boeing CEO, said this month, “There’s no denying the emissions and efficiency gains you’re getting as a result.”
Airbus Chief Technology Officer Sabine Klauke said in Paris on Friday that the European manufacturer plans to test the open-fan aspect of the CFM concept on one of its A380 superjumbo jets around mid-decade.
Around that time, Boeing will be testing another aspect of the CFM design — a hybrid electric fuel-economy capability — on a Saab 340 turboprop.
GE and French engine manufacturer Safran, who form the 50:50 CFM joint venture, are already building and testing hardware components.
“It’s not on paper anymore. It’s real,” said Mohamed Ali, vice president of engineering at GE Aerospace, in Paris.
At a briefing Monday at the GE Chalet at the Paris Air Show, Ali gave an impassioned pitch for his team’s new design.
“We believe that today’s engine architecture is underperforming in terms of the ability to achieve significant improvements in fuel burnability,” he said.
But Ali said removing the nacelle that encases the engine on today’s jets allows for a much larger fan at the front to produce much more thrust and far better fuel efficiency that “can’t be matched any other way.”
“Honestly, it’s not fair to the planet, the environment, or the industry to leave that on the table,” Ali concluded.
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Leaves changing inclination, wings closing
CFM has dubbed its new engine design project “Revolutionary Innovation for Sustainable Engines” (RISE).
The open front fan is just the most visible part of a number of revolutionary changes the company is researching for the engine.
The fan is certainly impressive on a half-size model on display in the GE Chalet.
This engine is designed for a single-aisle aircraft like the 737 MAX, but the fan blades will be about as long as those on the GE-9X engine that will power Boeing’s massive 777X widebody jet.
That translates to a diameter of about 11 feet, almost double the diameter of the 737 MAX’s LEAP engine.
The blades can be moved to change their pitch and adjust airflow, as can a set of fixed blades just behind the fan. These vanes are designed to direct and smooth the airflow to prevent it from being blown away from the engine.
With today’s engines, when the pilot brakes on landing, a complex mechanism called thrust reversers is activated in the engine, blocking reverse airflow and slowing the aircraft.
There is no reverse thrust on the RISE. The fixed blades behind the fan can change their pitch so that they almost approach each other, blocking airflow and acting as a brake.
Christopher Lorence, chief engineer at GE Aerospace, said eliminating the heavy nacelle and internal thrust reverser saves about a ton of weight on each engine.
A series of design changes, not just a big fan
Another striking aspect of the RISE concept, besides the huge fan, is the tiny engine core. This is the part of the engine where air is drawn in, compressed, ignited and blown out to the rear.
The size of the core in the RISE is similar to that of a small business jet engine.
Ali said GE and Safran used an advanced supercomputer to design every aspect of the jet, including the advanced materials and additive manufacturing processes used to create intricate internal nozzles and cooling paths within the core.
“We are the only non-governmental organization using this most powerful supercomputer in the world,” he said. “We used that to design the fan. We also use it to design many aspects of the core.”
And CFM is also trying to make the engine hybrid-electric.
In today’s aircraft like the 787 Dreamliner, the fan spinning the central shaft generates electricity that is used to power various systems on the aircraft. With the RISE, this current is also used at times to turn the shaft.
When a hybrid electric car runs on electricity, it doesn’t use gas. For an aircraft, this is a new concept in fuel efficiency.
Both Airbus and Boeing seemed confident in the engine’s promise. Every aspect and component must now be tested before a full line of engines is deployed in 2028 to prove the concept delivers on that promise.
If that’s the case, Airbus and Boeing may be faced with choosing between two very different engine types when building their next all-new aircraft.
Will they choose this revolutionary ASCENT? Or will they opt for Pratt & Whitney’s more conventional architecture, with likely less improvement in fuel economy?
If Boeing chooses the former, they will have to significantly redesign the airframe to accommodate the huge fan.
Stan Deal, CEO of Boeing Commercial Airplanes, said in Paris Boeing will remain open-minded and that the more conventional engine “probably poses less technical risk compared to RISE.”
“Let me tell you, GE has technologically superior engines, we’ve seen that throughout history,” Deal added.
GE’s Ali believes the pressure on aviation to address climate change and cut emissions more drastically means it’s time for a revolution.