Jeremy Monnett shows off the electric motor and mount employed in a proof-of-concept Waiex airframe to demonstrate the potential of compact electric power and advanced-technology batteries. Photo by Dave Higdon

With the price of oil rising faster than an F-15 in an unrestricted climb and the potential for $6 per gallon self-serve avgas a real possibility, alternate ways of powering aircraft, ways that require much less fossil fuel, are going to be important to the future of sport aviation.

On Tuesday, Sonex Aircraft LLC took the wraps off its previously secret e-Flight initiative.

"This is an exciting announcement and one that you are really going to appreciate," EAA President Tom Poberezny said at the beginning of the press conference. He added, "It addresses the grass-roots research that is important to the integrity of EAA and the homebuilt movement. More importantly, it is growing aviation by making it more economical."

The most visible aspect of e-Flight right now is a Sonex Waiex airframe equipped with a proof-of-concept prototype electric powerplant. The aircraft, which is expected to fly later this year, will be used to further develop the motor, along with the requisite control systems, charging systems, and of course, battery systems.

"It was [apparent] that once we started down this path to developing an alternative power source for the airplane, that we had to do it in very specific steps," John Monnett, Sonex founder and president, said when he introduced the electric plane. "The whole object of [the proof-of-concept] is to come up with a powerplant

that is equivalent in weight and in power to our AeroVee-powered Sonex and Waiex [models]."

Monnett went on to add the sole mission of the airplane displayed here is to develop the technologies that will ultimately result in production systems. The test-bed airplane is also expected to test other, as yet unspecified, electric power sources.

The prototype powerplant uses brushless, cobalt motor technology and, according to AeroConversions, is the most powerful, lightest weight, and efficient motor of the type ever produced. It was developed with the help of Bob Boucher of Astro Flight Inc. Astro Flight is a major producer of electric radio-controlled model motors.

The 200-amp motor is 90 percent efficient and operates on 270 volts of direct current electricity, as advertised by the Waiex’s tail number, N270DC.

According to Pete Buck, Sonex’s chief engineer, the motor was manufactured in-house. He added that Sonex expects to construct virtually all of the components of the future production systems themselves. Production systems, unlike the current AeroVee engine, likely will not be offered as kits, due to the critical tolerances and potential dangers with some of the electrical components.

Monnett pointed out that a couple of technologies are key to making electric flight a reality. Of course, powerful and light batteries are a must, but a motor controller capable of managing the high power involved also is required. A charging system, capable of replenishing the batteries in a reasonable amount of time, is another must. Sonex is developing both technologies.

Target flight duration for the proof-of-concept airplane is 25 minutes to 45 minutes. Production systems are expected to allow for one-hour flights. Buck says an hour’s endurance is difficult right now but ultimately is very possible as both the system and the available technologies are further developed.

In addition to the electric Waiex, Sonex’s e-Flight initiative also involves two other aspects: the practical use of ethanol fuels in the AeroConversions AeroVee 2.0 engine and developing other enhancements to the AeroVee, improving its already-impressive efficiency.

Sonex partnered with Wisconsin-based Renew Fuel Stations, a distributor of E85, a blend of up to 85 percent ethanol and 15 percent gasoline, to develop an AeroVee engine configuration that can use the fuel. Renew’s interest in the project is expansion of the market for ethanol fuels. Testing is under way right now.

The idea of electric flight is not new to Sonex. It dates back to 1994 when Monnett and Buck looked into the possibility of building an electric plane specifically for the purpose of establishing speed records for a new class of aircraft. Although the project was deemed to be practical, Sonex put the project aside to further develop its current set of kit airplanes and to support their customers. The company is committed to completing the effort this time, though Monnett stated firmly that the e-Flight program will never detract from Sonex’s commitment to its customers.

Sonex is financing the entire effort itself.

Once production systems are available, Sonex plans to make them available to the experimental market for installation on other airframes.

Sonex will present a forum on the e-Flight project Wednesday at 11:00 a.m. in Forum Building 11. More information about the project is available on the web at www.AeroConversions.com/E-Flight.