Inside the UltraFan: How Rolls-Royce is rewriting the rules of jet propulsion
The Rolls-Royce UltraFan is the world’s largest technology demonstrator jet engine. It is designed to test a range of new technologies for next-generation jet engines. The UltraFan has a massive fan diameter of 3.5 meters (140 inches), larger than the world’s most powerful jet engine, the GE9X (3.4 meters, 134 inches).
The company aims to test thrust performance and propulsive efficiency over a range of 25,000 to 110,000 bf thrust. The UltraFan promises greater fuel efficiency than existing engines, lower carbon emissions, and compatibility with alternative fuels.
Redefining propulsive efficiency through the design
The propulsive efficiency of a turbofan engine depends on various factors, the most important of which is bypass ratio. It is the ratio of the airflow entering the engine core to the airflow bypassing through the secondary duct.
With the ultra-large fan and a compact core, Rolls-Royce is set to hit a home run with the demonstrator design. A unique combination of carbon/titanium fan blades and a new engine core architecture will maximise fuel burn efficiency while reducing emissions.
The UltraFan design benefits from advanced manufacturing and material technologies. Additive Layer Manufacturing (ALM) techniques are used to produce major components of the engine. Such 3D techniques allow building of industrial objectives in successive layers using digital models.
Unlike traditional subtractive technologies that relied on grinding and machining of metal blocks, the ALM method reduces material waste and allows the creation of intricate designs. The technique also minimises component weight while increasing the accuracy and precision of complex parts.
The UltraFan’s Power Gearbox also holds a world record
The Ultrafan is a geared design featuring the world’s most powerful accessory gearbox, termed Power Gearbox (PGB). In 2021, UltraFan’s PGB set a world record by reaching 64 megawatts (87,000 horsepower) during a test in the company’s facility in Dahlewitz, Germany. Enough to power a small city, the Power Gearbox demonstrated sheer performance and durability – the two parameters essential for next-generation engines.
Dr. Holger Klinger, the subsystem executive of PGB at Rolls-Royce, stated,
“Reaching this record is another great achievement that showcases the performance and durability of this key component for our UltraFan programme. The power gearbox technology is central to the success of the next generation of Rolls-Royce jet engines, and I’m proud to see us pushing the engineering boundaries again.”
Apart from power, endurance, and reliability validation, the PGB demonstrated successful testing on the Altitude Rig, simulating different phases of flight.
First successful tests of the UltraFan
In November 2023, Rolls-Royce completed the first successful tests of its UltraFan demonstrator engine to maximum power. The manufacturer conducted the tests at its Testbed 80 facility in Derby, UK. The first tests were conducted using 100% Sustainable Aviation Fuel (SAF), demonstrating strong compatibility with alternative fuels. Rolls-Royce stated that the tests were in line with expectations and that several futuristic technologies were tested during the run.
The CEO of Rolls-Royce, Tufan Erginbilgic, states,
“Hitting full power with our UltraFan demonstrator sends a strong message that we are leading the way in the transition to more efficient and sustainable aviation. This fantastic milestone puts us in a strong position to support the plans of our customers as they develop the next generation of super-efficient aircraft.”
The Rolls-Royce UltraFan demonstrator is scalable to both widebody and narrowbody aircraft. Rolls-Royce states that commercial versions of the type may emerge in the early 2030s. The technologies built on the UltraFan enable 25% greater fuel efficiency than first-generation Trent engines, and 10% greater efficiency over the Trent XWB engine.