P&W’s Geared Turbofan – right engine, right time?

Having just spent two days at Pratt & Whitney’s Connecticut facilities, some of the company’s fervour for the Geared Turbofan appears to have rubbed off on me. With oil at $110 at barrel and jet fuel at $2.70 a gallon, an engine that promises to reduce aircraft fuel burn by 12%, and noise and emissions by 50%, seems to make a lot of sense.

And those figures are for the GTF at entry into service in 2013. Pratt is promising to continue reducing fuel burn by 1% a year, for a 20% reduction by 2020 – with consequent reductions in carbon dioxide emissions. Conventional turbofans will keep getting better too, but Pratt believes the physics of its geared-fan architecture give the GTF a 6% advantage the others can’t catch up with.

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Where’s the catch? Well there is the gearbox. But, having seen it, I’m inclined to believe Pratt’s claims that it has mastered and matured the technology. For a 30,000shp gearbox, it’s small – about 18in diameter and weighing around 200lb – and simple. Then there’s the torture chamber Pratt has constructed to test the gearbox to its limits, and beyond – like 2.5 times the maximum misalignment caused by gyroscopic forces on the fan during take-off rotation.

Airbus and Boeing are interested, Pratt says, but they are waiting until the company flight tests its GTF demonstrator. Flights on the company’s Boeing 747SP engine testbed are planned to begin in late June/early July. By then the GTF could have been formally launched on the Mitsubishi Regional Jet, and perhaps Bombardier’s CSeries.

Up till now, airline interest in new engines has been about dramatically reducing their carbon emissions. That has encouraged Airbus and Boeing to consider holding off and waiting for new technology to mature, like open rotors. But with oil prices soaring, fuel burn may take the lead, and airlines may start demanding action sooner rather than later. That would appear to put Pratt and its GTF in pole position.

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