All RISE for Increasing Focus on Durability

As the CFM RISE (Revolutionary Innovation for Sustainable Engines) program progresses toward its inaugural technology demonstrator, program partners are confident that the innovative open-fan design is achieving milestones set out at the beginning of the decade. However, while the experimental architecture is on track to deliver fuel-efficiency gains of at least 20%, this target is also being augmented by a more prominent focus on durability.

“If there’s anything we’ve learned over the last years, it’s that durability matters as much as, if not more than, fuel efficiency,” GE Aerospace v-p for future of flight Arjan Hegeman explained during a recent media briefing. The RISE initiative—first unveiled in 2021 by partners GE and Safran—initially prioritized unlocking fuel-burn benefits. Although Hegeman acknowledged that the industry will need to make ultimate trade-offs between durability and performance expectations, he is nevertheless confident that RISE can deliver “revolutionary improvements in both.”

“The overall deliverable for the operator is not fuel efficiency: that’s how the [high-bypass turbofan] CFM LEAP and [Pratt & Whitney] GTF were done. The overall deliverable for the operator is the cost of ownership,” he continued. Both of these commercial narrowbody engines have faced notable reliability challenges in recent years, with the higher demands made of inherent architectural limitations contributing to time off-wing.

Crucially, RISE’s architecture is key to unlocking what Hegeman termed “a whole new system that is neither propulsive efficiency nor thermal efficiency, [but which] enables a new era of overall engine optimization.” Turbofans are physically restricted in size by their casings, limiting their bypass ratios, and a larger surface area diminishes overall propulsive efficiency returns. However, while the CFM56 and GTF have bypass ratios of around six and 11, respectively, RISE’s technology demonstrator is aiming for a figure above 60.

Alongside air drawn into the RISE powerplant’s fan and engine, a third stream—part of the adaptive bypass system—can be regulated to change the open fan’s bypass ratio during flight. This optimized efficiency will be enabled by a hybrid-electric system combined with a smaller engine core. Unlike previous counter-rotating second-stage fan concepts explored over recent decades, RISE’s static second stage will help simplify the system while retaining efficiency.

While narrowbody turbofan blades typically spin at over 2,000 rpm, RISE’s will spin at less than half of that. Durability expectations are also being supported by Dowty Propellers, leveraging the GE subsidiary’s 40-plus years of composite blade experience. From its first fully composite propeller blade—which entered service in 1984 on the regional Saab 340—to high-intensity hovercraft applications, Dowty technical director Jonathan Chestney is confident the company can “address the challenges that are required to make [the RISE] model a reality in a few years.” While the RISE architecture will feature more blades than a legacy turboprop, and the overall blade shape may differ, Dowty says that the loads each one experiences are very comparable.

In 2025, project partner Airbus suggested that a fully functioning engine would be flight-tested on an A380 by the end of the decade. RISE partners are working closely with airframers to define the optimum installation of a potential follow-on commercial offering. Hegeman explained that the underwing configuration remains the most realistic option, whereas a fuselage-mounted open-fan engine would entail a significantly greater weight penalty given the requisite armored areas of reinforcement.

In addition to material expertise and manufacturing experience, Hegeman also cited advanced computational power as integral to the project’s progress. GE uses the Frontier supercomputer at Tennessee’s Oak Ridge National Laboratory for its simulations, able to process in days what may once have taken decades. According to Hegeman, GE is “leaning into” ways of working more analytically versus empirically. “What has really changed over the last six years is that RISE is no longer just maturing technologies for the future generation; it’s also maturing the next generation of engineers, and it’s maturing the next generation of tools that we’re going to be using when we’re executing these programs,” he concluded.