An experimental Eurocopter BK-117 with a prototype electrical blade-flap rotor control system has made its maiden flight from the company’s Donauwörth site.

BK117 Big

The blade-flap control system is designed to reduce noise caused by rotor tip vortices and the vibration experienced by passengers.

The control system uses three flap modules at the trailing edges of the rotor blades. The flaps are moved 15-40 times a second by piezoceramic actuators, integrated into the blades, which respond to voltages by changing their length.

“The demonstration system has yet to be miniaturised and optimised for commercial use,” says Eurocopter aeromechanics and flight control programme manager Valentin Kloppel.

The movement of the flaps up to 40 times a second helps to mitigate the blade slap noise associated with descending helicopters. Their use can lower the overall noise level by up to 6dBA.

The control system’s development is being sponsored by the German ministry of economics and labour in co-operation with the German Aerospace Agency, Eurocopter Deutschland, EADS’s corporate research centre and EADS shareholder DaimlerChrysler.

Source: Flight International