Guy Norris/SEATTLE
ROLLS-ROYCE HAS defined a thrust level of 423kN (95,000lb) for the next growth stage of the Trent 800 as the three Boeing 777 engine suppliers prepare for new battles over the proposed -300X A-market stretch.
R-R Trent director Phil Hopton says: "We have determined 95,000lb in consultation with Boeing." General Electric is considering a GE90 throttle push or derate from the 467kN version, to 423kN, while Pratt & Whitney is already embarked on a 436kN version of the PW4000, called the PW4098.
R-R says that the higher thrust levels will be achieved with adjustments to the high-pressure and intermediate-pressure turbines, plus additional changes to increase core flow. "The changes we're talking about are nothing drastic. They'll be material refinements, thermal barriers and cooling air. We'll also grow the annular area to increase flow through the core by about 3%," says Hopton.
Early work on the higher-thrust engine, the Trent 895, has already started, "because we could see that the stretch would happen. R-R expects to kick off a 15-month development programme in mid-1996, culminating in certification in September 1997."
Hopton says that further growth beyond 423kN will be possible without any increases to the diameter of the fan, which, at 2.79m, is already the smallest of the three engine choices on the 777. "The fan is big enough for 100,000lb and beyond, while the basic 800 core is capable of 102,000lb of thrust," he says. R-R says that thrust levels of more than 471kN during tests have already been demonstrated.
The first Trent-powered 777 is expected to be flown on 26 May, when the initial Cathay Pacific aircraft is due to begin flight tests. A 1,008-cycle extended-range twin-engine operations flight-test programme is expected to begin on a second Trent-powered 777 around mid- August. This is expected to be completed in late March, two months after certification and delivery, of the first aircraft to Cathay Pacific.
Initial Trent 800s will be derated in service to thrusts between 333kN and 374kN, but will be the first 777 engine to be cleared for flight at 400kN.
Hopton admits that the Trent's fuel consumption is higher than that of either of its rivals, but he believes that lower installed weight and better performance-retention will more than compensate.
Source: Flight International
