Aircraft

Pratt & Whitney aims to begin testing a demonstrator GTF geared turbofan engine within four years, incorporating new technologies designed to head off any threat from rival engine manufacturers in the battle to power the single-aisle replacements from Airbus and Boeing.

This proposed "advanced GTF" will deliver up to 10% more efficiency that the current engine, giving it at least a 20% advantage over today's engines.

Speaking at an event in Toulouse to officially mark the end of the current GTF demonstrator's flight-test campaign on Airbus's A340-600 flying testbed, P&W vice-president next-generation product family Bob Saia says that the engine maker has identified its "next step of technology features" and expects to begin testing advanced concepts on a demonstrator by 2013.

"The GTF that enters service in 2013 is in the 12-15% [lower fuel burn range than current engines] and we'd like to improve fuel consumption by another 8-10%, so we'd be looking at a total of around 20%," he says.

© Pratt & Whitney

The areas being examined "touch all aspects of the engine - for example aerodynamics, lightweight materials, improving the thermal efficiency of the core, and more temperature-capable material", he says. "We want to make the fan bigger and increase the gear ratio from 3:1 on the current GTF to 4:1 or 5:1 to increase propulsive efficiency."

Saia says that P&W launched the programme in mid-2008 and aims to start laboratory and windtunnel testing some of the features in 2010, ahead of flying a full-scale demonstrator in "late 2012-13". He says this timetable will enable P&W "to have the advanced GTF available in the 2017-2019 timeframe, depending upon when those aircraft will be looking for new powerplants".

Although the advanced GTF is aimed at the expected single-aisle replacement aircraft from Airbus and Boeing, Saia says that P&W has had no discussions with either company about operating a joint flight-test programme with the demonstrator.

While the current GTF demonstrator uses the core of the existing PW6000 engine, Saia says the advanced-GTF demonstrator will adopt the core from one of the production PW1000G GTF engines being developed for the Bombardier CSeries and Mitsubishi MRJ regional jet - possibly with advanced technology incorporated. He adds the aim is to enable as much of the technology to be developed for the advanced GTF transferrable to the first-generation PW1000G GTFs.

"Through all the work that we do on the fundamentals of the engine to improve efficiency we will introduce new designs that will go as a minimum on new-production engines, so it's conceivable that a good proportion of the advanced GTF improvements will be available [to the CSeries/MRJ]," says Saia. "Whether they're retrofittable to the existing engines will be a function of how or when we introduce those designs."