Green Solution

Team from MIT presents a green airplane that reduces fuel consumption by 70 per cent

A team led by Massachusetts Institute of Technology (MIT) has designed a green airplane that uses 70 per cent less fuel and reduces noise and emission of nitrogen oxides (NOx). The design was one of two that the team led by faculty from the Department of Aeronautics and Astronautics presented to the National Aeronautics and Space Administration (NASA) as part of a $2.1 million research contract to develop environmental and performance concepts that will help guide the agency’s aeronautics research in the next 25 years. Named “N+3” which denotes three generations beyond today’s commercial transport fleet, the research programme is aimed at identifying key technologies, such as advanced airframe configurations and propulsion systems, that will enable greener airplanes to take flight around 2035.

MIT was the only university to lead one of the six US teams that won contracts from NASA in October 2008. Four teams led by MIT, Boeing, GE Aviation and Northrop Grumman, studied concepts for subsonic commercial planes, while teams led by Boeing and Lockheed Martin studied concepts for supersonic commercial aircraft.

The MIT team met NASA’s challenge by developing two designs: the 180-passenger D “double bubble” series to replace the Boeing 737 class aircraft, currently used for domestic flights and the 350 passenger H “hybrid wing body” series to replace the 777 class aircraft now used for international flights. 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.

Not only does the D series meet NASA’s long-term fuel burn, emissions reduction and runway length objectives, it could also offer large benefits in the near future because the MIT team designed two versions: a higher technology version with 70 per cent fuel-burn reduction, and a version that could be built with conventional aluminium and current jet technology that would burn 50 per cent less fuel and might be more attractive as a lower risk, near-term alternative.