French engine manufacturer Snecma has revealed a concept engine for future single-aisle aircraft which could be in operation by 2015.

The engine as currently presented is in the form of a ducted contra-rotating propfan and is being studied by the newly created Aerospace Technologies division of Snecma parent Safran.

The design is completely different to that being pursued by Pratt & Whitney, which is working on a geared turbofan (GTF) to achieve the quantum leap in fuel burn that will be required of the next generation of aero-engines. The aim is to achieve a fuel burn reduction of at least 12% against the most efficient engines in service today along with a huge reduction in noise and emissions. P&W aims to fly a 30,000lb thrust GTF demonstrator in 2008 aboard a Boeing 747 flying testbed.

Snecma’s idea uses two contrarotating propfans to achieve the ultra-high bypass ratios necessary for efficient engines. An interesting element revealed in its concept is that the forward fan has fewer blades than the rear fan, an indication of the application of the latest three-dimensional design technology to increasing fan blade efficiency.


The contra-rotating fan idea harks back to the General Electric Unducted Fan tested aboard a McDonnell Douglas MD-81 testbed in the late 1980s, in which the fans were mounted at the rear of the aircraft. While the 25% reduction in fuel burn targets were met, the engine was too noisy and the unprotected fans considered unsuitable for modern aircraft.

GE Aviation and Snecma are partners in the CFM56 turbofan which powers A320s and Boeing 737s and both have designs for future single-aisle engines. Snecma, however, is the first to emerge with a visible concept.

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