Leaps in battery efficiency and endurance are bringing practical electric flight ever closer, and Oshkosh-based Sonex Aircraft is at the lead of motor and controller development for fixed-wing aircraft.

Its Waiex kit aircraft is displayed all week at the EAA Welcome Center, showing off its 80 lithium power cells that produce 270 volts and 200 amps, what spokesperson Mark Schaible says is "A lot more voltage and amperage than anybody else who's flying right now with electric flight."

The prototype isn't flying yet, and no timetables are announced. Over the past 18 months the Sonex home at the east end of Wittman Field saw the birth of the AeroConversions E-Flight Electric Motor. A little larger than a coffee can, the 55 pound DC motor produces just less than 80 hp.

 Sonex electric engine

Why build their own from scratch? "Because a motor of this size and power and efficiency just didn't exist. The same goes for the controller," he says. "It's a 3-phase motor, so essentially you have three different channels switching on and off the different windings to propel the core." That's 3,200 switches each minute.

Detailed explanations are set for tomorrow at 11:30 am in Pavilion #11.

Sonex  president John Monnett will join officials of MG Consulting, ElectraFlyer, Pipistrel, and Omega Research for the Electric Aircraft Panel Discussion on Thursday, at 2:30 pm in Pavilion #7. Monnet will also speak that evening at 7:45 at Theater in the Woods.

Schaible says battery technology is being propelled so quickly by other fields that speed and range predictions of their aircraft can be regularly bumped upward.
Between 30 and 60 minutes of flight is the prediction now, though running at top speeds will drain the battery to 16 minutes of life. 

"This airframe, on 80 hp, can go 150 mph up at altitude and 130 mph at lower altitudes," says Schaible. But, he continues, the Waiex is not the ideal airframe. "We will sell this system for use in whatever you want to install it," he says. A Xenos motor glider could be approaching 80 minutes with today’s battery technology. Three to four years from now we could be talking 160 minutes, and that's not counting turning off the motor. It's a motor glider."

In March Boeing Phantom Works first flew a Dimona motor glider powered by batteries and two hydrogen fuel cells. The ultralight trike from Electraflyer Corp. is available for sale now and is giving demonstration flights through the week.

On April 28 at the CAFE Foundation 2008 Electric Aircraft Symposium on EAA announced a request to the FAA for regulatory exemptions to allow electric motors in ultralights and LSAs.

"The request for those specifications, combined with suggested language changes to remove exclusive references to reciprocating engines, would make electric motors legal for these aircraft," states Earl Lawrence, EAA's vice president of industry and regulatory affairs. EAA has also formed a task force to promote electric powerplants.
For ultralights, the request suggests weight limits of battery packs and for light sport aircraft it seeks adoption of ASTM standards for electric motors.

Electric-powered aircraft are currently legal in Europe. European Aviation Safety Agency officials say using the term "piston engines" in a recent rule proposal led to a quick and justified outcry, and "powerplants" will soon be the terminology.


Source: Flight International