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ATW Daily News

Rolls-Royce: Open rotor 'is real'; Pratt pushes geared turbofan

Friday May 29, 2009

Rolls-Royce expressed confidence this week that the open rotor concept can be viable, asserting that it will "comfortably meet Stage 4 noise requirements."

Speaking in Washington at the Eco-Aviation conference presented by ATW and Leeham Co., Strategic Marketing Manager-Future Programs Paul Randall said the open rotor is "the true game-changer" and could provide a 25%-30% fuel efficiency gain over turbofans powering narrowbodies today and be 10%-15% more fuel efficient than advanced turbofans that may come on line in the next decade. "Now the open rotor has moved from being a physics problem to an engineering problem," he said. "It is real and it is being realized."

He conceded that there is still a "long way to go" in developing the concept and acknowledged that "the biggest risk. . .is noise," adding, "we are coming into a period where we may have to prioritize [regarding] noise and carbon dioxide emissions."

Randall emphasized that while Rolls continues "to invest in a portfolio of technologies" including the open rotor, it is wary of moving forward with a formal program until the US and other governments establish CO2 standards for aircraft engines. "We will make the big investments when the requirements become clear," he said.

CFM International also is exploring the open rotor but has said it has not figured out yet how to mitigate its considerable noise and the concept is not likely to have an application until the mid-2020s (ATWOnline, May 26).

Pratt & Whitney, on the other hand, is pushing the geared turbofan and is skeptical that the open rotor's noise problem ever can be resolved (ATWOnline, May 22). "It's not conceivable to me that we could introduce a noisy aircraft and continue to grow [airline traffic]," VP-Technology & Environment Alan Epstein told the Eco-Aviation attendees.

He said Pratt's PurePower PW1000G geared turbofan, set to enter service in 2013, will provide a12%-15% fuel efficiency gain over current turbofans and can be expected to add 1% in efficiency annually from 2013 owning to technology developments. "We see geared turbofan engines that [eventually will] have the same reduction in fuel burn as the open rotor with much less noise," he said.

by Aaron Karp

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