Edgy new blades ease Eurocopter noise footprint

HAI Convention News » 2010
February 20, 2010, 2:53 PM

New technology is a main focus of Eurocopter at Heli-Expo 2010. At its booth (No. 3128) the company is showing rotor blade technologies designed to reduce noise and vibration, and an avionics technology that promises to improve pilot situational awareness and safety.

Eurocopter’s Blue Edge is a passive system that features a redesigned main rotor blade that uses a double-swept shape to reduce the noise generated by blade-vortex interactions (BVI), which occur when blade-tip vortices interact with the rotor blades. A five-blade Blue Edge main rotor has logged more than 75 hours on an EC155 testbed, demonstrating a noise reduction of three to four decibels. Eurocopter says it is ready to move Blue Edge into “serial applications.”

Yves Favennec, vice president of Eurocopter research and innovation, said Blue Edge was optimized to a fixed angle of descent, but is less expensive to maintain than active systems. “It is not aimed at decreasing vibration, only noise,” Favennec said.

Separately, Eurocopter’s Blue Pulse is an active system that the company says can achieve a significant reduction in noise and vibration. Blue Pulse uses a piezo-active rotor control system designed to reduce noise levels generated by BVI. The system also promises to reduce vibration within the airframe, increase passenger comfort and extend the service life of sensitive components, such as avionics, but will not extend the life of the blades themselves. 

Blue Pulse uses three flap modules located at the trailing edge of each rotor blade. The piezoelectric actuators move the rotor flaps 15 to 40 times per second in order to completely neutralize the familiar “slap” sound that is typically associated with helicopters during descent. Blue Pulse has been flying since 2005 and produces a measured nose reduction of up to five decibels on an EC145.

Favennec said Blue Pulse is “adaptable to all angles of descent. It is both dealing with the vibration and the noise. This system eliminates the normal passive anti-vibration systems in a normal helicopter so that overall the weight is the same.”

“We’ve flown it a lot,” he said, “and we have another campaign scheduled as soon as we get the blades back [to France from Heli-Expo].”

Favennec said Eurocopter was pursuing both systems because of their differing price points–the Blue Edge system is less expensive–to give customers a choice. Blue Pulse requires power and a computer and is more complicated, he said.

Favennec stressed that both systems remain under development and that decisions on production and price have not been made, but that Eurocopter was very pleased with the results of the testing to date, particularly Blue Pulse, in achieving “jet-like vibration levels. It is very smooth,” he said. 

Thinking Like a Pilot
In addition to blades, Eurocopter continues to research the next generation of helicopter avionics and has what it considers an important development on display in a flight simulator in its booth at Heli-Expo. Eurocopter’s Pilas (Pilot Assistance System) cockpit demonstrator provides virtual synthetic vision and intelligence by automatically calculating and displaying routes that avoid obstacles, terrain, weather and other aircraft. The company thinks Pilas is ideally suited for the helicopter EMS and law enforcement markets. 

Stefan Maisch, project manager for mission systems and research at Eurocopter Deutschland, said Pilas is “programmed to think how a pilot would think during a mission.” When slaved to a tracking and message system, such as OuterLink, “The assistance actually begins before the mission,” Maisch said, explaining that as soon as the helicopter is switched on, the Pilas system takes a destination sent to it by OuterLink and “is immediately calculating the first leg of the route, and the route is safe. It is calculated against obstacles and terrain from a database, weather and traffic.” Maisch said the database would also contain published and private approaches.

The system is dynamic and continually monitors the recommended route in flight for changes such as VFR traffic conflicts and can recalculate the route as required.  Eurocopter first flew the system in 2008 on an EC145 and has accumulated approximately 30 hours of test flying on the system to date.

Eurocopter has programmed a variety of missions and routes into the Pilas simulator here, including a few in the Bavarian Alps. Maisch said parts of the Pilas system could be certified within five years.

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