Rolls-Royce Prepares New Engine Variants for Boeing, Airbus
As Rolls-Royce (Booth N23) prepares to begin a two-year development and testing phase for the latest Trent engine–the Model 1000-TEN, designed to power Boeing’s stretched 787-10 large twin-aisle twinjet–it has completed three full demonstrators and is building a fourth that will be used in a 500 flight-cycle trial. The first development engine is planned to begin tests before April and formal certification is due to be achieved in the second half of next year.
The engines are being assembled using hardware from other Trent variants but each unit also features new technologies being developed for the new model.
Trent 1000 (T1000) chief project engineer Jeremy Hughes confirmed that, although destined for the 787-10, the variant will, in fact, enter service first on the smaller 787-8 and -9 models by mid-2016, before the heavier, double-stretched target model begins operation about two years later. At the beginning of this year, six airlines were operating about 90 T1000s, a number that is expected to double during 2014 as Boeing works to fulfill orders for some 460 Trent-powered 787s.
Apart from the test engine earmarked for the 500-cycle test, the other three demonstrators each employ planned new T1000-TEN technologies, according to Hughes. These will ensure that the 78,000-pound-thrust design incorporates “all the lessons learned” from other Trent variants in service, including advanced seals, fan case dressings (to reduce weight and complexity), materials and disc architecture.
In addition to an upgraded compression system, Trent XWB technology contributing to the -TEN is said to have provided a “significant improvement” in engine performance. The complete cyclic testing will be used to prove enhanced cooling available with the new high-pressure turbine (HPT) disc.
The new RR engine’s physical hardware characteristics introduce knowledge gained from earlier variants. This includes:
– A new “rising line” intermediate pressure compressor using Trent XWB technology;
– A new HPT, with a full-face cover plate in front of the HPT disc, expected to offer longer life and to permit through-life improvements;
– A modulated HP air system that reduces “parasitical” flow, helping to improve fuel burn efficiency and also improving performance retention through maintenance of seal margins;
– A new, more efficient HP compressor previously demonstrated on the New Aero-engine Core (NEWAC) concepts program and the Trent XWB; and
– New lighter, more efficient bladed discs (“blisks”), again using Trent XWB technology.
The UK manufacturer is reporting ever-increasing efficiency with successive Trent engine models and upgrades, with the new -TEN claimed to offer 2 percent better specific fuel consumption (SFC) than the T1000 with performance improvement package C (Pack C)–the current build standard–which, in turn, is said to have been a 1-percent improvement over earlier Pack B units.
Overall, RR claims the T1000 design provides the best “lifetime SFC” for 787 operators on “average” range flights. It says the engine is well ahead at the 500- to 1,000-nm sectors that characterise distances flown by launch customer All Nippon Airways on the Japanese carrier’s domestic routes, said Hughes.
RR expects to fit a T1000-TEN to the company’s Boeing 747 flying testbed for flight trials, with Boeing’s own flight testing slated for sometime after mid-2015, about 12 months after formal ground tests are scheduled to begin.
Last month, T1000 engine experience from about 35,000 passenger services amounted to some 175,000 flying hours and around 70,000 flight cycles, said Hughes. The fleet leader engine had logged 5,268 hours in 2,023 cycles and overall despatch reliability was put at 99.96 percent.
Another family member has exhibited 99.9 percent reliability, according to RR fleet programs customer marketing head Peter Johnston. This is the Trent 700 (T700), the most popular of the manufacturer’s widebody aircraft engines, which powers 70 percent of Airbus A330 operations. Since November’s Dubai Airshow, the engine manufacturer has confirmed planned development of a T700 Regional that will be “perfectly matched” to the A330 Regional (A330R) variant now being offered to airlines. The new variant will be optimized for the lighter aircraft at less than the 72,000 pounds thrust of the standard A330. It will be interchangeable with the basic engine, which RR says could be converted to the Regional specification.
T700 Regionals will incorporate technologies already developed for enhanced performance (EP) and EP2 upgrades for the main fleet (with the latter becoming the production build standard after about mid-2015). The T700R will operate at lower engine speeds and temperatures throughout the operating spectrum, leading to expected lower maintenance costs.
Johnston said the T700R would be available to A330 operators not flying the A330R. He also said that, unlike the A330R, most of the current fleet is not being used to operate short ranges all of the time. The official would not discuss engine price, but said that RR is in the business of “selling thrust.”
The manufacturer sees Asia as an important market for the new airframe and engine variants. China was “obviously the first thought,” given that country’s high market share, according to Johnston. He said that RR would “push [the T700R] very hard” for short-range operators in North Asia, as well as in Southeast Asia and India.
The T700 EP2 has “cleared the engine approval system” and is expected to enter service in 2015, about two years after introduction of the initial EP upgrade. While the earlier enhancement had involved modified compressor rotor blades, the new improvement features three-dimensional stators and other minor changes to both the intermediate- and high-pressure compressors that together are claimed to offer a further one-half of one percent SFC benefit, compared with the T700 EPs.
This gain is expected to double with the simultaneous introduction of better nozzle guide vane sealing and improved “aero standard [anti] flutter bridge” in the low-pressure turbine. RR claims that introduction of T700 EP2 modification is worth $200,000 a year per aircraft to operators.
Having entered service in 1995, T700 engines today power some 560 aircraft flying with more than 60 operators. The engine has logged more than 25 million flying hours and more than six million cycles.