The “Project Firefly,” an all-electric helicopter technology demonstrator has been unveiled by Sikorsky Innovations at the Experimental Aircraft Association (EAA) AirVenture exhibition. The Project Firefly is based on an S-300C light helicopter and equipped with a 190-horsepower electric motor replacing the standard piston-engine and lithium ion battery packs added to either side of the cabin that will keep the electric motor up and running, resulting in a much more efficient system. The first flight is expected later this year.
The demonstrator contains a new digital motor controller and next generation cockpit display along with the electric motor and battery packs. The German Gaia produced the lithium-ion batteries, whose total capacity is 48.1 kWh, enough for a flight of approximately 15 minutes. Californian firm U.S. Hybrid from California built 190 hp (142 kW) motor. The changes in an electric helicopter technology are an additional 40 horsepower, constant operation at 3200 RPM and forced air cooling as opposed to water cooling.
German manufacturer GAIA’s battery pack consists of 300 cells, 150 in every bay, with an energy density of 0.13 kW per kilogram. Temperature for left and right battery packs, flight time remaining and voltage, which is shown on an interactive LCD monitor are included inside, real-time aircraft information. The electric helicopter show huge improvements in efficiency. Heat loss, where the electrical system loses just 15 percent compared to 73.4 percent on the 76D according, is the other notable comparison.
The demonstrator has an expected flight time of 15 minutes but as battery technologies get better, this will improve exponentially. The problem is that these batteries are non-rechargeable, but research and development of rechargeable versions is ongoing.
Sikorsky’s head of research and engineering Mark Wilner says rising fuel costs are starting to threaten the role helicopters play in many fields, making research into alternate fuels essential. Vice President, Sikorsky Research & Engineering, Mark Miller said, “Through the electrical conversion, propulsion efficiency of the aircraft has been increased roughly 300 percent from baseline,” and “Electric propulsion also inherently simplifies the complexity of the propulsion system by reducing the quantity of moving parts, increasing reliability while reducing direct operating costs.”
Lauder sees lithium air batteries as one of the most promising of these developing technologies. “Lithium air batteries would be lighter (because they have no anode) and provide nine times the energy density of the current batteries, enabling three hour flights and rivaling combustion engines.”
Features of the “Firefly” include:
- All-electric drive system
- Automated monitoring and alert technologies
- Safe and efficient high-density energy storage system
- Next generation cockpit displays
Sikorsky electric helicopter specifications:
- Max Gross weight – 2,150 lb
- Power 190 hp (142 kW) Permanent Magnet electric motor
- Forced Air Cooling
- Endurance – 15 min
- Lithium Ion Battery – 45 Ah, 3.6 V, 3 cells in Parallel = 135 Ah, 100 set in series = 360 V
- Max Velocity – 79 kt
- System Efficiency – 79 % (Cruise), 91 % (Max Power efficiency)