Guy Norris/EAST HARTFORD
Pratt & Whitney has begun studies of an advanced-technology geared-fan engine in an initiative to re-enter the narrowbody market and challenge the dominance of CFM International.
The study outlines an initial series of engines for the 107-156kN (24,000-35,000lb)-thrust range, and is based around the use of geared-fan technology developed for the now-abandoned advanced-ducted-propulsor (ADP) programme. The fan would be driven by a derivative of the new PW6000 turbofan, the core of which is under test at P&W's East Hartford site in Connecticut.
As part of the studies, P&W has begun talks with Airbus Industrie to define the cost-saving target over current-technology engines such as the CFM56 and International Aero Engines V2500, in which it is a major partner. As well as having potential applications on the narrowbodied A320 and Boeing 737 families, the engine would also be suitable for an advanced version of the Airbus A340-300, now equipped with the CFM56.
Much of the savings would come from the low-noise operation of the geared fan, says P&W Large Commercial Engines planning director William Stromberg. "It will give the operator lower landing fees, direct routings with associated time savings and use of noise-preferred runways. The geared fan gives a noise benefit which would become a big operating cost benefit for the airlines," he explains.
P&W is serious about the study, despite the overwhelming market dominance of the CFM56, thanks mainly to its exclusivity on the Boeing 737 and, to a lesser extent, the success of the V2500. "We're forecasting between 14,000 and 15,000 aircraft deliveries over the next 20 years in the 90 seats and above category. Some 60% of those will be for narrowbodies, and that is 9,000 aircraft, of which only a small percentage are on order today. So there's a tremendous open market," says Stromberg. "The market has an appetite for an engine that could provide a significant reduction in operating costs, but it's got to be a game changer," he adds.
According to Bob Leduc, senior vice-president P&W programmes and services, the study engine would be aimed at a bypass ratio of between ten and 11, rather than the 13-plus of the ADP, which was aimed primarily at widebody applications. Unlike the ADP, the geared turbofan would not have the complication of variable-pitch fan blades and, for braking, would rely instead on a conventional thrust reverser. "This uses fewer composites, which allows us to catch up on operating costs. The gear reduces the fan-tip speed and lowers noise generation and, because of the higher bypass ratio, we get better fuel efficiency. If we could get it working, we would have a winner," he says.
Leduc cautions, however, that the study is in an early phase.
The gearbox, which was designed by Italian company Fiat for the ADP demonstrator with a rating of up to 29,800kW (40,000shp), is now considered a low-risk technology by P&W. The company recognises, however, that there may still be hurdles to overcome. "Gears are an added complexity," admits Leduc, who says that P&W is pushing it because of "the environmental concerns of the 21st century".
Source: Flight International
