NASA-MIT 'greener' airplane could use 70% less fuel

MIT lobbies for its new plane design -- will NASA take it forward?
Written by Deborah Gage, Contributor

MIT has presented NASA with two new airplane designs as part of a $2.1 million research contract to create more environmentally friendly planes. NASA wants planes that are quieter and can take off from shorter runways. It also wants planes' emissions of greenhouse gasses (nitrous oxide) cut by 75 percent.

The first design, called the "D" or "double bubble," would use 70 percent less fuel than a Boeing 737, according to MIT. Note the long, skinny wings and the small tail.

Although the plane would fly 10 percent more slowly than a 737, it has a wider body, so passengers should be able to get in and out of the plane faster and maybe shave a few minutes off flight time, MIT hopes.

From MIT:

"The engineers conceived of the D series by reconfiguring the tube-and-wing structure. Instead of using a single fuselage cylinder, they used two partial cylinders placed side by side to create a wider structure whose cross-section resembles two soap bubbles joined together. They also moved the engines from the usual wing-mounted locations to the rear of the fuselage. Unlike the engines on most transport aircraft that take in the high-speed, undisturbed air flow, the D-series engines take in slower moving air that is present in the wake of the fuselage. Known as the Boundary Layer Ingestion (BLI), this technique allows the engines to use less fuel for the same amount of thrust, although the design has several practical drawbacks, such as creating more engine stress."

The other design, the H, would replace the Boeing 777 for international flights. It's closer in design to current planes and would burn 50 percent less fuel.

Again, from MIT:

"...a larger design is needed for this plane to carry more passengers over longer distances. The MIT team designed a triangular-shaped hybrid wing body aircraft that blends a wider fuselage with the wings for improved aerodyamics.  The large center body creates a forward lift that eliminates the need for a tail to balance the aircraft.

The large structure also allows engineers to explore different propulsion architectures for the plane, such as a distributed system of multiple smaller engines. Although the H series meets NASA’s emissions-reduction and runway-length goals, the researchers said they will continue to improve the design to meet more of NASA’s objectives."

Plane designs can't get too far ahead of today's planes because current airports have to be able to accommodate them, although the FAA's Carl Burleson says that even the Double Bubble shouldn't require any redesigning of airport gates.

MIT's team is competing against teams from Boeing, GE Aviation and Northrop Grumman, which also worked on subsonic commercial jet designs. Boeing and Lockheed-Martin, meanwhile, have designed supersonic commercial jets.

NASA will pick two of the six teams to move forward, probably within the next few months. The agency is looking far ahead -- these planes won't be ready to fly until 2035. By that time, says MIT's chief designer, Professor Ed Greitzer, air traffic will have doubled.

This post was originally published on Smartplanet.com

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