Eurocopter tames the whirl

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The prime technology thrust at Eurocopter continues to be the development of a rotating helicopter system that delivers less vibration, less noise and improved performance. The ultimate goal is to replace the complicated swashplate at the heart of the rotor control system with actively controlled individual blades.

Although the company has been a leader in taming the vagaries of vertical flight - Eurocopter led the industry with the first rigid rotor hub and all-composite blades in 1967, the first bearingless main rotor in 1988, and the first fly-by-wire helicopter, the NH90, in 1997 - its latest efforts will push its technological prowess to the limit.

"Rotor dynamics continue to be one of our greatest challenges," says Yves Favennec, Eurocopter vice-president of research and technology.

Like its counterparts, Eurocopter has been working on active blade technology for years, sharing the work between its French and German partners.

In 2005 it became the first manufacturer to test a rotor system with piezoelectrically actuated flaps attached to the rotor trailing edges, functioning initially with open loop software, then closed loop.

"We saw a significant improvement in noise and vibration," says Favennec.

"We're also working on a blade with a continuously moving trailing edge, again using piezo-electric actuators."

In the cabin, vibration improvements are aimed at giving passengers the same experience as they have on fixed-wing jets.

"The future of helicopters is to be able to use them like small airliners into city centres," says Favennec.

"We're looking at giving passengers a 'flying carpet' level of comfort."

A range of activities, including passive active damping, are under way to achieve 0.1g vibration levels, many of which have already been spun off into existing types.

Computer simulation plays a vital part in improving understanding, explains Favennec, not only in visualising airflows around the rotor system, but in areas such as the main rotor gearbox, where it is now possible to simulate the stresses and loads on individual pinions.

"If we can test a new pinion design without having to manufacture it we save a lot of time and money. We're making real progress in this area," he says.

Another major theme is to develop all-weather capability of the helicopter, and while the technology to do so exists, the European regulatory framework does not.

"The traffic rules in Europe do not reflect the state of technology," says Favennec.

"We're pushing the national and European authorities to allow instrument flight rules flights and to provide specific IFR routes for helicopters like in the USA."

As such, Eurocopter is heading the helicopter industry's contribution to the Eurocontrol Optimal programme, which is looking at changing the procedures for fixed and rotary-wing approach and landing. In June it will use an EC155 to demonstrate a Category 1 IFR landing at Toulouse airport using the Egnos wide area augmentation system. Later in the year it will perform an IFR landing on top of a roof in Lausanne, Switzerland as part of Eurocontrol's Giant programme, which is investigating the use of GNSS systems for approach and landing.

In the realm of next generation technologies, Eurocopter continues to research tiltrotors and is now concentrating on the four-year Nicetrip (novel innovative competitive effect tiltrotor integrated project) effort being run by the European Commission under its sixth framework research programme.

Eurocopter is working with Agusta on the programme, which will lead to windtunnel testing of a one-fourth scale mock-up.

"We have to ensure all of the aerodynamic problems are solved," says Favennec. He admits Europe is lagging behind the USA in tiltrotor research, "but we didn't have a government-funded V-22 programme to pay for it", he adds

"The future of helicopters is to be able to use them like small airliners into city centres" Yves Favennec, Eurocopter vVP of research & technology.