The test flight of two small electric aircrafts earlier this month across the English Channel has got us wondering about when we'll get to ride in one of these clean, green planes.

While it may be a while before we board a cross-country electric flight, a short hop to the islands off Cape Cod may be more realistic. Engineers at NASA are working with Barnstable, Mass.,-based Cape Air to develop an Cessna 402 9-passenger electric airplane suitable for the short hops to the islands of Nantucket and Martha’s Vineyard, a flight of less than an hour from airports in New York or Massachusetts.

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NASA officials say they still have a way to go however before they start selling tickets. They are working on a prototype at the Armstrong Flight Research Center at Edwards Air Force Base. It’s a strange-looking device that resembles the old-fashioned flying wing developed after World War II. A row of electric motors line the front-edge of the wing, providing lift power.

“We can make the wing smaller and more aerodynamically efficient,” said Matt Redifer, chief engineer for NASA’s Scalable Convergent Electronic Propulsion Technology Operations Research (SCEPTOR) project. “We then use motors across the leading edge as a lift device and you get a much larger benefit from electrifying the aircraft.”

The wing is a testbed for a bigger prototype aircraft. Redifer and his colleagues are transforming an existing aircraft into an new electric one, using an Italian-made twin-engine, four-passenger Tecnam P2006T.

“We are looking at the whole system, instead of just replacing engines with electric motors, we are looking at a design that couples electric propulsion with a redesign of the wing.”

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Using multiple motors on the wing gives more efficient lift and propulsion, he said. The NASA project is currently testing the new wing design mounted on top of a big truck that is driving around the dry lakebed near Edwards AFB, the same areas where the space shuttle used to land.

In contrast, the Airbus E-Fan that made the Channel crossing on July 9 was a single-seat aircraft. The push for electric drive propulsion is coming from aircraft manufacturers who anticipate more rules cutting back on carbon pollution from jet aircraft.

The HEIST truck was driven at speeds up to 70 miles per hour across a dry lakebed at Edwards Air Force Base, Calif., providing researchers with valuable data.NASA/Tom Tschida

The Environmental Protection Agency said in June that carbon emissions by airlines contribute to climate change, and new regulations could be ready by 2017. The European Union has started charging some airlines for CO2 emissions.

NASA’s research could pave the way, according to Redifer, and its aircraft is scheduled to be ready for flight testing in 18 months.

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“What we are looking at with this four passenger aircraft, expecting anywhere form 800 pounds of batteries with takeoff weight of 3000 pounds,” he said. “That gives us enough range to prove that we can get this five times energy reduction (over existing jet propulsion).”

Redifer and others admit that the big issue to overcome for electric airplanes, just like electric cars, is battery life.

Aircraft fuel is more efficient since the airplane gets lighter over time as the gas is burned. Electric airplanes will have to haul around large packs of lithium iron batteries, a scenario that has caused aircraft fires in the past and led to warnings by the FAA.

“The idea of an electric plane is attractive,” said John Hansman, director of the International Center for Air Transportation at the Massachusetts Institute of Technology. “But electric cars can only go a couple hundred miles, and electric planes will have about same range as electric cars."

Hansman and others foresee an electric hybrid drive using a small amount of fuel to generate electricity that powers the electric motors. This, coupled with the steady improvements in battery technology could lead to a real change in transportation, according to Brian German, associate professor of aerospace engineering at Georgia Tech.

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In the long run, the combination of electric propulsion and automatic flight controls and self-guided navigation will make flying an aircraft much cheaper and easier. Call it the Uber of airplanes.

“With new technology, the cost drops out the bottom and maybe we open new markets,” German said. “If you can reduce the pilot workload and degree of training with autonomy, then you open the possibility for on-demand aviation. The airplane flies to the airport and picks you up and takes you somewhere.”