“Rolls-Royce’s UltraFan Revolutionizes High-Power Aircraft Engines”

2023-05-20 06:17:00

As the big comeback of the Paris Air Show approaches, aircraft manufacturers, engine manufacturers and equipment manufacturers are sharpening their weapons. Although no new large-scale program is expected from the main players in the sector, this will not prevent them from highlighting the various progress made. The British engine manufacturer Rolls-Royce will undoubtedly focus on its UltraFan concept which has just had its first ground tests.

A demonstrator of this new generation engine has thus run on the giant Testbed-80 test bench, inaugurated in 2021 in its stronghold of Derby (United Kingdom). This first test campaign comes after several months of waiting, or even more. The first tests were initially planned for 2022. Anyway, this step represents an important step for Rolls-Royce. After relying for more than 50 years on the concept of the triple spool engine, designed with the RB211 (which powered the Boeing 747, among others) and then developed across the entire Trent range, the British engine manufacturer has taken a step forward by testing for the first time a new architecture for high power engines.

Developed through its Advance3 program, this central architecture is distinguished by the addition of a power transmission box (power gearbox or PGB) and the use of three independent shafts allowing the different motor modules to rotate at different speeds. This makes it possible to optimize the speed of rotation of these modules and to reduce the number of elements (in particular the low pressure turbine at the engine outlet). Described as the most powerful gearbox in the world of aeronautics, the PGB of the Ultrafan demonstrator developed a record power of 64 MW during the tests. Other innovations are also integrated, with new composite materials with ceramic matrix (CMC) or carbon-titanium for the crankcase and the blades, or an optimized combustion system ALECSys (Advanced Low Emission Combustion System).

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Turning the Trent page

The Ultrafan should allow Rolls-Royce to prepare its future programs for medium to high power engines (from 25,000 to 100,000 pounds of thrust) and in particular the replacement of the Trent family. The Ultrafan thus offers a fuel consumption saving of 25% compared to the first generation of Trent engines, and 10% compared to the latest versions such as the Trent XWB which equips the A350. The Trent family also equips the Boeing 787 and the Airbus A330 NEO. Some of these technologies should also make it possible to improve the current engines of the Trent family.

If the gain seems limited compared to what a disruptive concept like CFM’s Rise project can offer (Open Rotor fan or unducted fan), of the order of 20%, this remains substantial, particularly in the long-haul segment. In addition, Rolls-Royce announces 100% compatibility with Sustainable Aviation Fuels (SAF) which represent the only means of massive decarbonization for transcontinental flights. Tests of the demonstrator have so far only been carried out with SAF.

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Find altitude

The development of a new range of engines is essential for Rolls-Royce’s civil aeronautical activities. The engine manufacturer is certainly present on the A350 (exclusively) and the 787, but it is not on the 777X (re-engined version of the 777) under development. Similarly, it withdrew from the engine segment for medium-haul aircraft, leaving the field open to CFM International (a joint venture between Safran and GE Aerospace) and Pratt & Whitney to power the Boeing 737 MAX and Airbus A320 NEO. However, this one is the most dynamic today and by far. In addition to the phenomenal number of engines sold – several tens of thousands of copies – it offers a fantastic financial windfall to engine manufacturers with the associated service contracts for the maintenance and upkeep of this equipment.

Rolls-Royce must therefore not miss the mark in the event of the launch of a new aircraft program by the end of the decade. And with Ultrafan, the band doesn’t want to close any doors. If this engine seems more intended to equip long-haul aircraft in view of its performance, its wide power range should allow the British engine manufacturer to position itself with more modest aircraft. A version with 25,000 pounds of thrust can thus be used to power replacements for the A320 NEO and 737 MAX.