Eurocopter Reveals Hybrid-Helo Flight Trials

Eurocopter is finishing up flight trials of a hybrid helicopter concept that should aid pilots during autorotation and, potentially, ease regulatory concerns about single-engine helicopter operations.

Eurocopter has quietly been working on the technology that adds an electric motor and power supply to an AS350, with flight trials underway at its Marignane headquarters in southern France since July. Flight test personnel had enough confidence in the system to begin autorotation trials on the first flight, says Eurocopter’s technical director, Jean-Michel Billig.

The motor, which is powered by a chargeable lithium ion polymer battery, automatically kicks in when the turbine fails to minimize the loss of rotor speed. “It gives the pilot some time to react and keep control of the helicopter,” Billig says.

A second power input comes just before landing. The overall goal is to relieve pilot stress during the two most critical periods of an autorotation.

Eurocopter officials are guarded about elements of the technology, including the exact weight of the motor and the power output it can provide. Billig says it is adequate to assure safe touchdown and keep control of the horizontal speed and rate of descent.

With the basic technology demonstrated, much of the focus now is on whether the system can be engineered to be viable in a commercial operational setting. That means improving production maturity of the hybrid system, bringing the motor and battery weight down, and determining whether the supply chain is adequate for a commercial offering. Billig is optimistic that those boxes will be checked off in the coming months and that Eurocopter can then take a decision of how, when and on what rotorcraft the technology can be introduced. “It is not a matter of years,” he asserts.

But long-term, Eurocopter has ambitions beyond just aiding safety. Further evolutions of the hybrid technology could allow the electric motor to kick in at certain points in flight to reduce fuel burn and, consequently, carbon dioxide output, effectively performing some of the functions of a hybrid system now seen on cars.

The focus is squarely on single-engine helicopters, for Eurocopter the EC120, AS350, EC135. One goal is to also give regulators a greater comfort factor with single-engine helicopters, to expand their commercial appeal.