Fly the Eco-Friendly Skies: Airplanes That Would Use 70 Percent Less Fuel Than Current Models

MIT's D "double bubble" series design concept is based on a modified "tube-and-wing" structure that has a very wide fuselage to provide extra lift.
The aircraft would be used for domestic flights to carry 180 passengers in a coach cabin roomier than that of a Boeing 737-800

ScienceDaily (May 19, 2010) — In what could set the stage for a fundamental shift in commercial aviation, an MIT-led team has designed a green airplane that is estimated to use 70 percent less fuel than current planes while also reducing noise and emission of nitrogen oxides (NOx).

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http://www.sciencedaily.com/releases/2010/05/100517162834.htm