UK-based industrial technology group Rolls-Royce announced on Wednesday that the prototype power gearbox (PGB) for its new-generation UltraFan jet engine had set a new world aerospace power record. The record was set in the group’s dedicated PGB test facility, in Dahlewitz, near Berlin, in Germany.

In the record-setting test, the PGB reached 64 MW (87 000 hp). This was enough to power a city the size of Bath, in the UK (which has a population of roughly 89 000). Meanwhile, construction of the PGB for the demonstration UltraFan engine (designated UF001) is continuing, with delivery scheduled for later this year.

“Reaching this record is another great achievement that showcases the performance and durability of this key component for our UltraFan programme,” highlighted Rolls-Royce PGB sub-system executive Dr Holger Klinger. “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.”

To date, the testing of the prototype PGB has been focused on validation, reliability and endurance. These tests started in 2017 and the prototype has so far accumulated in excess of 650 hours of testing. And not only has it been subjected to high power tests, it has also been tested on the Dahlewitz Attitude Rig, which simulates the conditions that the PGB would experience on the wing of a flying aircraft, during various flight phases, including take-off, climb, banking and descent.

The PGB is ‘planetary’ gearbox, with each of its ‘planets’ being able to hold the force of a Rolls-Royce Trent XWB engine – at full throttle. Two Trent XWBs power Airbus’ A350 XWB wide-body airliner. The PGB is so designed that the turbine at the rear of the UltraFan engine will be able to run at very high speed while the fan at the front of the engine will run at a lower speed. This will make the engine very fuel efficient.

Rolls-Royce is developing the UltraFan because gas turbine engines are going to be needed to power long-range aircraft for many years to come. But these engines will have to become more sustainable, to meet carbon emission reduction targets. The first test run of the demonstration UltraFan engine will, in fact, be conducted using 100% sustainable aviation fuel (SAF). But, in the short term, SAFs will be more expensive that conventional jet fuels, so the increased efficiency of the UltraFan will reduce the costs to airlines of switching to SAFs. The UltraFan is planned to be 25% more fuel efficient than the first generation of the company’s Trent engines.