Aerospace companies are investing in the development of larger jet engines to meet the evolving demands of the aviation industry. Gone are the days when large aircraft were designed with four engines, with rising fuel costs and sustainability drives pushing the industry towards twinjet planes. This shift began in earnest with the release of the Boeing 777, which is powered by some of the largest commercial jet engines ever conceived, most notably the General Electric GE90.
But this requires engines to be more powerful than ever before. 
Boeing and GE once again collaborated on the Boeing 777X, the updated series of the 777 family scheduled to enter service in 2027, which will be powered by the monstrous GE9X engine. When it enters service, it will be the largest commercial jet engine ever, but it won’t stay that way if Rolls-Royce’s UltraFan concept becomes a reality. The UltraFan is RR’s new engine blueprint that could be the answer for future widebody and narrowbody commercial aircraft, delivering state-of-the-art engine technology for the next generation of aircraft.
Rolls-Royce UltraFan Development Continues
With a fan diameter of 140 inches, Rolls-Royce’s UltraFan concept promises to take jet engine scale to the next level. Although still in the demonstrator phase, Rolls-Royce sees UltraFan as its next-generation line of engines that can be scaled up or down depending on the size of the aircraft. The company began assembly of its first UltraFan demonstrator in 2021 at its DemoWorks facility in Derby before subsequently subjecting it to rigorous ground testing for around two years.
It will implement a very high bypass ratio of up to 15:1 to maximize efficiency and reduce noise emissions. In comparison, the GE9X powering the upcoming 777X has a bypass ratio of 10:1, which was itself already a step up from in-service jet engines. Not only will the UltraFan technology be scalable – meaning it could be applied to commercial jets of various sizes – but some of its innovations could also be transferred onto existing in-service engines to deliver key efficiency upgrades.
Other features of the next-generation engine include its geared architecture, carbon-titanium fan blades and composite casing to shed weight without compromising on structural integrity. Rolls-Royce claims the UltraFan could deliver up to 25% improvements in fuel burn compared to its Trent 700, and it has also been designed to run on up to 100% sustainable aviation fuels (SAF) as the industry strives to meet strict environmental targets. As per Rolls-Royce,
“UltraFan features a new engine core architecture and lean-burn combustion system which will contribute to improved fuel burn efficiency and lower emissions, along with a carbon titanium fan blade system and composite casing, which reduce weight. The engine also introduces a geared design to deliver efficient power at high-bypass ratios.”
Widebody And Narrowbody Versions
Rolls-Royce sees a viable market for the UltraFan across both future widebody and narrowbody aircraft designs, particularly with single-aisle jets now flying for longer than ever before. By 2028, RR expects to have a demonstrator for both engine types, which have been named the UltraFan 30 and UltraFan 80, setting the stage for a new era of commercial jet engines.
The UltraFan 80 is the widebody variant and will entail a redesign of RR’s current demonstrator. The company concluded ground testing on its original demonstrator in 2023, but plans on resuming tests by the end of the year. As for the narrowbody UltraFan 30, the enginemaker plans to build this demonstrator and have it up and running before 2029.
|
UltraFan Variant |
Approx. Thrust |
Fan Diameter |
Aircraft Type |
|---|---|---|---|
|
UltraFan 30 |
30,000–45,000 lbf |
90 inches |
Narrowbody |
|
UltraFan 80 |
80,000–100,000 lb |
140 inches |
Widebody |
With a thrust rating likely above 30,000 lbf, the UltraFan 30 will likely have a fan diameter of around 90 inches, while the UltraFan 80 is likely to be around 140 inches. This is a big deal for Rolls-Royce, with the enginemaker currently developing engines exclusively for widebody planes. These two engines will be built with significant commonality, helping future operators to minimize maintenance and supply chain costs.
When Might We See The UltraFan In Service?
Rolls-Royce is developing the UltraFan as its engine blueprint for the future, so we are still many years away from seeing it on a commercial jet. The company has not reached any agreement to power an upcoming aircraft series, but has its eye on both widebody and narrowbody platforms in the 2030s. The UltraFan was originally envisioned for long-haul widebodies — with RR seeing it as a replacement for its Trent XWB and Trent 1000 range — but could be scaled down for narrowbodies too.
As explained by RR, the engine will hopefully be available to the market in the 2030s as determined “by airframer requirements and market demand.” We know that Airbus is working on a next-generation narrowbody design, and such a platform would be ideal for a lower-thrust version of the UltraFan. Boeing has long been mulling over a new midsize aircraft (NMA) design too, but had previously earmarked turbofan engines from Pratt & Whitney or General Electric as its powerplant of choice.
As for potential widebody platforms, the UltraFan could find its way onto a future model of the A350 family, given the success of its XWB engines. Whether a re-engined version of the current A350 or a clean-sheet addition to the family, the UltraFan would work on both. Although Airbus is considering another stretched version of the A350 — dubbed the A350-2000 — it has no plans for a next-generation upgrade to the A350 family.
The GE9X Will Debut Soon
The UltraFan will have serious competition in terms of power and size if and when it enters the market. The GE9X is set to be the largest commercial jet in service within the next couple of years, possessing a fan diameter of 134 inches and rated at 110,000 lbf of thrust. This isn’t quite as powerful as the GE90-115B (115,000 lbf), although the GE9X has broken records in testing after achieving over 134,000 lbf.
According to GE, the GE9X will deliver a 10% improvement in fuel burn compared to the GE90-115B, as well as a reduction in noise emissions of 10%. It achieves its exceptional performance through several innovations, including ceramic matrix composites (CMCs), 16 fan blades, and a 10:1 bypass ratio. Its 27:1 compressor pressure ratio is also the highest-ever on a commercial jet engine, giving the 777X an enviable efficiency advantage over its predecessors.
|
Specification |
GE9X |
|---|---|
|
Fan Diameter |
134 inches (3.40 meters) |
|
Total Engine Diameter |
14.5 feet (4.42 meters) |
|
Total Length |
13.5 feet (4.10 meters) |
|
Bypass Ratio |
10:1 |
|
Thrust Rating |
110,000 lbf (489 kN) |
|
Fan Blades |
16 composite blades |
As it stands, Boeing has penciled in a 2027 launch date for the 777X, having repeatedly pushed back this timeline due to various certification hurdles. When it first announced the 777X program back in 2013, Boeing was aiming for a 2020 entry-to-service date, but this is now likely to occur in early 2027. German carrier Lufthansa will be the launch customer for the 777X, which has secured almost 500 orders for its two passenger variants, the 777-8 and 777-9.
Open-Fan Technology Promise
Rolls-Royce’s UltraFan is not the only large jet engine project in the works today. RR’s industry rivals are also hard at work developing larger engines to meet the changing needs of the industry. One concept that looks set to play a key role in developing larger and more powerful engines is open fan architecture, which the UltraFan may eventually integrate in the future. This design entails the engine fan blades being partially or fully exposed, as opposed to being contained within a nacelle.
CFM International has its RISE (Revolutionary Innovation for Sustainable Engines) program to develop a successor to its LEAP turbofan family. With an estimated fan diameter of up to 140 inches, RISE will be an open fan design that could achieve up to 20% lower fuel consumption. As of 2025, CFM has completed over 200 tests on its RISE concept, including wind tunnel testing on a 1:5 scale model. RISE is primarily targeting narrowbody models of the future, but its technology has the potential to scale up to larger long-haul aircraft.
Open fan engines are still under active development, with the first models likely to enter the market sometime in the 2030s. The open fan design will ultimately allow for larger fan diameters to improve fuel burn, further driving down operational costs for airlines. Additionally, the design can dampen noise emissions by reducing tip vortices, helping operators meet tighter noise regulations. With the industry working hard to achieve lower emissions in the coming decades, advanced engine technology will play a key role in helping airlines meet these targets.
