As part of its €1.6 billion ($2.2 billion) Clean Sky joint technology initiative, Europe is undertaking a number of projects toward the development of more-electric helicopters. A March call for proposal noted that “a primary objective of the Green Rotorcraft integrated technology demonstrator (ITD) is the removal of hydraulics from all rotorcraft systems.” To that end, several projects are looking at technology demonstrators for electrically powered pieces of equipment.
One €1 million ($1.4 million) topic is devoted to electric motors powering landing-gear wheels on the ground, a propulsion method that would avoid spinning the rotor just for taxiing. The electric motors are expected to yield benefits in noise, fuel consumption and ground personnel safety. Requirements for the project are an 11-knot maximum ground speed, an average speed of five knots and taxiing time of 10 minutes. The demonstration’s results are expected to be delivered in October 2013 and should assess the system’s integration on a medium twin (six tons, 13,000 pounds).
Another topic under study is an electric rotor brake to replace current hydraulic brakes that dissipate the main rotor’s kinetic energy as waste heat. An electric brake would be able to recover part of that energy. Among the specifications, the electric brake must be able to stop the rotor in 20 seconds. The two-year project represents an investment of €700,000 ($980,000).
Finally, another project seeks to demonstrate a high-voltage, rapid charge/discharge, electric energy storage system. It should store at least tota six kWh and be able to release 0.6 kWh in 20 to 50 seconds. The two-year project will cost €450,000.
The Green Rotorcraft ITD accounts for 10 percent of Clean Sky’s budget. It involves Eurocopter and AgustaWestland, among other companies and research organizations. The Clean Sky public-private partnership is to end in 2017, by which time the European Commission and the industry will have each spent €800 million ($950 million), in cash and in kind, respectively.