Rolls-Royce launched the Trent 900, its latest large turbofan, at September's Farnborough air show. The 356kN-thrust engine, a derivative of the Trent 800, which powers the Boeing 777, is being developed to power the proposed Boeing 747-500X/600X and Airbus A3XX ultra-high-capacity airliners.
The Trent 900 uses the same 2.8m-diameter fan, structure, systems and accessories as the Trent 800, with scaled-down intermediate-pressure (IP) and high-pressure (HP) compressors, a new five-stage low-pressure turbine, and "reduced-loading" IP and HP turbines. The first Trent 900 core is due to be run in January 1998, followed by the first full development engine the following September. Entry-into-service is projected for December 2000, on the 747-600X. Meanwhile, R-R appears to be accelerating studies of a "hybrid" derivative RB.211-524G/H engine, which would incorporate the core of the Trent 700, following encouraging results from initial tests. The hybrid is expected to offer a 2.5% reduction in fuel consumption and significantly improved reliability, compared with the -524G/H. The biggest benefit, to reliability is expected from the revised HP turbine design, which would be much less prone to vibration. The reduced vibration levels would result from the use of inclined root dampers at the base of the blades and redesigned nozzle guide vanes (NGV). Compared to the -524 family, which has 36 NGVs, the Trent core has 40. .
On the military side R-R is collaborating with its US subsidiary, Allison Engines, and General Electric to develop the YF120 engine for the US Joint Strike Fighter programme, competing against P&W, offering the F119. Separately, R-R and France's Snecma are carrying out research work into future military power plants on behalf of the French and UK governments, as part of studies into a Future Offensive Aircraft.
Source: Flight International
