Hydraulics are not dead, declares Safran

Paris Air Show » 2009
June 14, 2009, 1:44 AM

More electric systems are gaining ground aboard new aircraft but they will not force hydraulics out in the near or even mid term, according to Alain Coutrot, Safran’s deputy director for research and technology. Moreover, he said, depending on the size of the aircraft, electric power addresses different needs.

“In 30 years from now, we will still have some hydraulic power aboard aircraft,” Coutrot predicted. This could be local power, such as electro-hydraulic actuators, which generate hydraulic power from a local tank and do not rely on ducts that supply fluid all over the aircraft.

“The bigger the aircraft, the more power you need. In that instance, going more electric helps cutting fuel burn,” Coutrot said. Overall system optimization is a major benefit. For example, generators can be more properly sized. They usually are oversized to cope with peaks that happen rarely. And you have to add an oversized hydraulic generator to an oversized pneumatic generator, and so forth. It is better having a single kind of power. And electric generators better cope with peak demand.
For the next generation of narrowbodies–namely the successors of the Boeing 737 and the Airbus A320–Safran is already working intensively on such optimization.
On smaller aircraft, the benefit is rather in maintenance costs, Coutrot asserted. For Falcon business jets, Dassault is thus studying how to get rid of hydraulics, even in powering control surfaces. The current fly-by-wire concept involves flight controls, not the actuation of ailerons and rudder.

Here at the Paris Air Show, Dassault will host a conference on the topic on Thursday morning in Chalet A320. Visitors can attend by registering with exhibitor AS Tech (Hall 3 Stand A81).

The 787, for which Boeing has touted a much more electric architecture, was to make its first flight two years ago, but it still has to do so. Coutrot confirmed Safran’s electric brake has been available since the initial date.

The trend is still relatively hazy. For example, Airbus’s A350 will enter into service after the 787 (according to current schedules) but will be less electric. Its engines will supply bleed air for some systems, while Boeing has even electrified pressurization. In regional jets, the in-development Sukhoi Superjet has a conventional architecture, Coutrot admitted.

Clean Sky, a major private-public research initiative in Europe, does cover more electric architectures. “Part of Clean Sky will be a demonstrator made of several interconnected pieces of equipment and a generator,” Coutrot said. The so-called copper bird will be an upgrade of one created for a previous European research program, called Power Optimized Aircraft. It will run at Safran’s Hispano-Suiza labs in Colombes, near Paris. 

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