Officially announced at AirVenture 2010, Sikorsky’s Project Firefly sets out to demonstrate the feasibility and showcase the benefits of electrically powered helicopters.
The technology demonstrator is based on an S-300C light helicopter, with a 190-horsepower electric motor replacing the standard piston-engine and lithium ion battery packs added to either side of the cabin. The result is a significantly more efficient system that – although it’s expected to fall short of typical helicopter performance when the first flight takes place later this year – is just the tip of the iceberg for the new era of manned electric rotorcraft.
Along with the electric motor and battery packs, the demonstrator includes a new digital motor controller and next generation cockpit display. The drive train, rotors and flight controls from the S-300C have been retained and very little has been changed on the airframe, as the electric motor has been designed to pick up the same hard points as the piston engine it replaces.
The 190 hp (142 kW) motor built by Californian firm U.S. Hybrid from California is derived from a unit developed for ground based vehicles but, as Sikorsky’s Tim Lauder explained to Gizmag, it’s been specifically tailored for use in rotorcraft. These changes include an additional 40 horsepower, constant operation at 3200 RPM and forced air cooling as opposed to water cooling.
The battery pack from German manufacturer GAIA consists of 300 cells – 150 in each bay – with an energy density of 0.13 kW per kilogram.
Inside, real-time aircraft information including temperature for left and right battery packs, flight time remaining and voltage is shown on an interactive LCD monitor.