Rolls-Royce is making final preparations to start testing its new “Advance 3” engine core, meant to form the basis of its future large powerplants. Testing will take place using a hybrid engine based on a combination of the Trent XWB-84 fan system and Trent 1000 low pressure turbine. Rolls says it designed the Advance 3 to establish a new “scaleable” architecture.
Assembly of the first Advance 3 engine core started last month and “is progressing well” at the company’s Bristol facility in the UK; the company will move the core to its main base in Derby, England, to start testing in mid-2017.
Unveiled in 2014, the Advance program will also play a part in future UltraFan (including possible Open Rotor) applications. Meanwhile, testing of the first prototype Power Gear Box (PGB), which Rolls describes as “the world’s most powerful aerospace gearbox” capable of producing up to 100,000 horsepower, has neared completion at the UK-based company’s German facility in Dahlewitz, near Berlin. The three-foot-diameter PGB, along with a range of other new technology including a new lean-burn combustor, will allow 20-percent efficiency improvements within a conventional engine layout and a 25-percent improvement in an UltraFan, the later iteration of the architecture. Although the company has not identified the first application, Rolls expects to ready Advance for entry into service in some form by 2020 and in an UltraFan engine by 2025. It hopes that the PGB could use engine oil for simplicity but said it would not rule out the need to use a different oil in the final design, given the extreme challenge such a gearbox presents. “It needs to be able to operate on a hot summer’s day in the Middle East,” Mike Whitehead, chief engineer and head of the UltraFan program, told journalists during a press visit to Dahlewitz in late March.
Phil Curnock, chief engineer of civil aerospace strategy and future programs, added that finding a first application depends on aircraft manufacturers’ requirements, and no company has issued an RFP yet. He explained that Rolls designed the architecture to be as mature as possible ahead of the identification of an application, allowing for a shorter development time for the final production engines.
The gearbox uses five planetary gears and allows for a slower fan but a core that can operate at higher, more optimal speeds. (The ratio equals 4:1 with identically sized sun gear and planets.) The outer gear, also known as the ring gear, will not move relative to the engine. Friedrichshafen, Germany-based ATT (Aerospace Transmission Technologies), a joint venture Rolls formed with Liebherr especially to develop the PGB, has performed much of the development.
The fan under development for Advance is made of carbon/titanium (CTi); Rolls has already gone through four generations of blade and more than 50 birdstrike tests. It has also completed a flight-test campaign in Tucson, Arizona. Current testing takes the blade beyond 120 inches in diameter, aimed at developing a mature fan technology for mating with the core and PGB at Derby.
Curnock said UltraFan also remains “on track” for demonstrator concept freeze “later this year,” while schedules call for the start of flight testing in 2021 and the possibility of first application entry-into-service around 2025.
He also described technology development efforts at Rolls-Royce for possible future aircraft that could include hybrid-electric aircraft, embedded propulsion systems and possible distributed propulsion using electric motors. A new Rolls-Royce/Airbus-backed Aerospace Integration Research Centre (AIRC) opened at Cranfield University in England on January 24 to encourage a more “collaborative approach” with airframers to define possible future airframe/engine configurations, Curnock said.