Rolls-Royce is talking up the possibility of a new generation of turboprop-powered aircraft replacing a substantial proportion of today's narrowbody jets.
The manufacturer believes high oil prices are likely to drive airframers to sacrifice cruise speed for economics.
"The TP400 engine [for the Airbus A400M military transport] is a very efficient propulsion system," R-R director engineering and technology, Colin Smith, says. "There is a very sound argument to be made for the majority of the 150-seat market, which flies mostly for less than 1.5h [being turboprop-powered]...if somebody does want a high-efficiency turboprop then have we got one for you."
R-R civil aerospace president Mark King adds: "More and more manufacturers are looking at whether the bottom half of this market would be better addressed with turboprops."
The jet aircraft consigned large, 100-seat-plus turboprops such as the Lockheed Electra and Vickers Vanguard to the history books four decades ago. The largest turboprop airliners today seat no more than 80 passengers, although Bombardier is evaluating a stretched Q400 variant that could seat up to 100.
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King stresses that the engine-makers have yet to be asked by the airframers to satisfy a specific requirement: "All we know is that a lot of people who currently fly around in 150-seat aircraft will need transporting in the future. Is that going to be in a single-aisle or twin-aisle? There are plenty of persuasive arguments about what that will be.
"What is the range of this thing? A thousand miles [1,600km] or 3,000 miles leads to fundamentally different machines."
King stresses, however, that there remains great uncertainty about the timescale of when airframers will launch new programmes in the 150-seat class, and says the timing will in turn affect the technological solutions offered by engine-providers.
He says: "There are so many different things that affect the timescale. Open rotor is 2018 turboprop we are in the middle of advanced turbofan is just the typical engine development timescale."
Rolls-Royce will start running a new open-rotor engine test rig in the next couple of weeks, which it says will allow testing of units that "are not core size but are pretty big".
King adds: "The kind of open rotors that we are looking at are still quieter than today's aircraft. They are just not as quiet as they would be if you were to design solely for noise."
Source: Flight International
