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[ TECHNOLOGY ]
important factors when evaluating the engine’s sembled to understand how all constituent parts performed during
overall performance. the tests. “In addition to checking out the demonstrator, the series
Open Rotor technology makes use of two of tests carried out at Istres was designed to validate the high-
counter-rotating, unshrouded fans and when value-added technology building blocks we developed, which will
the technology matures, engines using this be integrated in tomorrow’s engines,” says Jérôme Bonini, Vice
layout could deliver reductions in fuel con- President for R&T at Safran Aircraft Engines.
sumption and C02 emissions by 30 per cent
compared with engines such as the CFM 56 Interestingly, it appears that airframers are already looking at such
and 15 per cent as compared to the LEAP and technologies for the future. “The question is not ‘will we be seeing
GTF engines. propellers on our aircraft in the future?’ but rather ‘when will they
be back?” says Stéphane Viala, Senior Vice-President Engineering,
Open Rotor technology makes use of two ATR, who is also responsible for innovation at the regional aircraft
counter-rotating fans, one behind the other leader. “Of course, we’re looking closely into hybrid propulsion, but
as part of its structure and has no nacelle to with a more general approach, exploring the full range of options,
attenuate the noise generated by the rotating which means considering which technologies are available and
blades, in terms of acoustics. When integrated investigating their operational impacts, right down to their impacts
on an aircraft, an Open Rotor engine will be on infrastructure,” Viala explains.
about twice the diameter of current turbo-
fans, at nearly 4.50 meters (or about 15 feet). ATR certainly appears to be on the right track, when one consid-
Certification will also be a long and challenging ers the promise of open rotor engines. The airframer states that
route as a result of the brand-new architecture all plans to design new eco-responsible aircraft are now based
of such engines. on the use of propellers, starting with hybrid aircraft. “This is a
research field which is being closely monitored by ATR, world leader
The Open Rotor project was launched in in turboprops and regional aviation, along with all other aircraft
2008 and Safran has completed several mile- manufacturers… But it could well be that ATR is a step ahead of the
game, since it is one of the rare manufacturers to have continued to
give pride of place to propellers, while the majority pursued other
paths,’ Viala maintains.

stones since then, such as; wind tunnel tests
at ONERA, the French aerospace research
agency, assembly of a demonstrator in 2015
and a series of ground tests on the open-air
test rig at Istres (southern France) in May 2017,
with a new configuration of the Open Rotor
aircraft engine, with its two counter-rotating
fans and no thrust reversers. All test data was
analysed in 2018 and the demonstrator disas-

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