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A flying Prius? Electric plane takes NASA efficiency award

A flying Prius? Electric plane takes NASA efficiency award

What gets better MPG than a Prius and flies? The Taurus G4, of course. It is the recent winner of the CAFE Green Flight Challenge, sponsored by Google and administered by NASA.

The first place prize of $1.35 million went to Taurus G4 creators of State College, Pa. Their craft flew at an equivalent fuel efficiency of 403 passenger miles/gal. at a 107 mph. (Taurus G4 carried two pilots and two sacks of concrete representing two additional passengers.) This beats the EPA-rated fuel efficiency of a Prius which comes in at 50 mpg at 55 mph, resulting in only 200 passenger miles/gal. assuming all the seats are occupied.

The plane holds four seats and is powered by a 145-kW (about 200 hp) brushless electric motor driving a two-blade propeller. The electric motor mounts on a spar between the plane's twin-fuselages. The plane’s wingspan is about 75 ft.

The parent company, Pipistrel d.o.o Ajdovščina, was established in 1987 as the first private aircraft producer in the former Yugoslavia. It started out making ultralights and gliders. The company has invested almost €500,000 (about $379,000) in the Taurus G4, but not just for the NASA competition. It sees the G4 as a testbed for upcoming technology, including a new model called the Panthera. The first Panthera will carry a conventional gasoline engine and will be capable of taking 4 people over 1,000 miles at 200 knots. The second generation expected in 2013 will use the same electric motor and battery management technology as found in the competition aircraft. The electric motors will handle takeoff and landing and the well-known Rotax 914 engine will keep the plane cruising at altitude. Pipistrel says eventually a completely battery-powered version of the Panthera will be released.

The second place finisher, the eGenius aircraft, shares a lot of parts in common with the Pipistrel Taurus. The wings were manufactured by Pipistrel as were the fuselage forward of the leading edge. The plane also carried an electric motor but was originally designed to run with hydrogen and was converted to electric. The electric motor sits on the leading edge of the vertical stabilizer. eGenius, of Ramona, Calif., picked up $120,000 in second place prize money for its efforts.

Jack Langelaan, team leader for the Pipistrel-USA team, is an aerospace engineering professor at Penn State. He says Penn State’s Dept. of Meteorology provided high resolution wind field predictions over the competition area, and grad students there wrote flight planning software and generating the flight plans used in the competition. During the first three laps of the miles per gallon flight on Tuesday, September 27 the actual energy consumption was within 1% of that predicted by the flight plan, says Langelaan.

More info: Pipistrel,

NASA Green Aviation Prize page,

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