The Present and how we got here.
According to Rob Coppinger of flightglobal.com, the future of general aviation is electric.
He argues that advances in power cells and lithium batteries, coupled with increased efficiencies and new control systems for small electric motors, have made it possible for light sport aircraft to be powered entirely without fuel, noise or emissions.
The idea of electric aircraft is not new. John Monnett and Peter Buck of Sonex Aircraft sketched out the necessary hardware and electronic controls in 1994, even before he started Sonex, the granddaddy of kit-built planes. Sonex has progressed along a path charted as their e-Initiative since their inception. Sonex chief designer Peter Buck helped develop the Monerai sailplane and the Moni motorglider. He created the plans for the Sonex, Waiex, and Xenos — Sonex’s product line of kit aircraft.
Monnett is now offering two ways to go electric. One is a kit plane with battery power-pack and rotary electric engine. The other is a retro-fit kit he displayed at EAA in 2007 consisting of a Sonex Waiex motor glider with a proof-of-concept prototype electric powerplant (AeroConversion engine, controls and lightweight batteries) installed in it.
Over the course of the last few five years, several aircraft have had their debuts as experimental, uncertified LSAs. Yuneec Aircraft of China displayed the Yuneec International E430 in 2009. It is a two seat, V tailed, composite aircraft. The plane is being marketed in the US as a kit built aircraft, complete with powerplant.
Also in 2009 Flightstar Sportplanes debuted the Flightstar Spyder ultralight, designed by Tom Peghiny of South Woodstock, Connecticut, USA also using a powerplant by Yuneec.
Another line of attack on the piston engine has been followed by glider pilots, seeking to have a totally noiseless experience, including take-off and landing. On 2006, Randal Fishman converted a powered hang-glider, replacing its small gas engine (used only for take-off) with a battery and an electric motor.
The all electric glider has come a long way quickly, because the engine is only needed for launch and landing, and the propeller operates as a windmill to crank energy to its batteries during controlled dives. This extends the total flight duration considerably.
Self-launched gliders have existed for decades, using small combustion engines for take off. The Lange Aviation Antares 20E debuted in 2005. In 2010, the Lange Antares 20E became available with a 42-kW electric motor and SAFT VL 41M lithium-ion batteries. On a single charge it is capable of taking off and soaring to 3,000 meters, though the same amount of energy could also be used for multiple launches to a lower altitude, or for range-extension during a mostly unpowered flight. The variety of purposes served by the Antares 20 point out that electric planes are more versatile than most combustion models. The Antares 20E is thought to be the first fully certified and commercially produced electric plane. Over 50 had been built and more will be available during 2011 as production ramps up.
Other aircraft have come from Pipistrel, led by Slovenian master designer Ivo Boscarol. They have a line of light sport aviation craft (electric and combustion) and a new line of gliders.
Electric Aircraft Corporation is an all American outfit that does ONLY electric aircraft – paragliders, Light Sport Aircraft and a new even lighter and more versatile LSA (Electraflyer). Their website declares, “The technology of electric motors and high capacity batteries has finally reached the level of development where pure electric flight is now possible. Electric Aircraft Corporation now makes this dream a reality!”
RANS’ website describes the veteran firm this way, “Established in 1974 on the plains of western Kansas to build Sailtrikes, RANS has evolved into a world leader in the ever growing recumbent bike and kit plane industries. Setting the standard of innovation in these exciting fields, RANS uses cutting edge technology to produce safe, high quality aircraft & bicycles.” Along the way, the firm designed the Coyote as a certified light aircraft, long before the category or concept of Light Sport Aircraft became official jargon.
Where to Next?
Coppinger predicts that many current producers of LSAs will market conversion kits to adapt the current fleet of combustion models to electric versions.
The planes described here vary tremendously in the size, efficiency and operating times of their powerplants. Some are built for speed, others for duration of flight, and others for attainable altitude. With the power-to-weight ratio of batteries constantly growing and the design of more efficient rotary engines, both new planes and retrofit packages will improve the capabilities of electric engines. This increases the versatility of these craft with each advance.
There is tremendous upside for electric aircraft, for several reasons. As the earth-friendly lifestyle movement takes aim at the emissions of the general aviation fleet, both all-electric and hybrid models will evolve. We’ve already mentioned it adds to the aesthetics of LSA and glider flights by eliminating noise pollution and combustion emissions. Some commentators have suggested that small jets, and eventually large ones, will have electric motors for take off and landing to reduce noise and pollution at commercial airports, while retaining the large jet turbines for long range high altitude and high speed travel between airfields.
Radical new designs for aircraft flight control systems will improve efficiency (See the May 17 entry of this blog at www.AeroInnovate.org on the European SmartFIsh design).
The Fuel-less Aircraft
The European Solar Impulse consortium is flight testing an enormous plane with the wings of a 747 covered with solar power cells. (See the May 3 entry of this blog at www.AeroInnovate.org on the European Solar Impulse consortium). They are in the middle of flight testing, and will attempt the first fuel-less global circumnavigation next year. The solar cells recharge the batteries during daylight and the plane flies through the night on this stored energy. Four power plants provide the thrust while the long wings make the plane an efficient glider. Hydrogen fuel cells have been suggested as an add-on to a battery-powered system or a solar-powered system.
