Scientists unveil plans for eco-friendly plane

Plans for a silent, energy-efficient plane which could take to the sky in less than 25 years' time were unveiled this afternoon by scientists.
On a typical flight the plane, which has been designed by scientists from Cambridge University and the Massachusetts Institute of Technology (MIT), will achieve the same kind of fuel efficiency as a Toyota Prius.
The scientists behind the plane, currently known as SAX-40 (Silent Aircraft eXperimental), are Professor Edward M Greitzer from MIT and Professor Ann P Dowling of Cambridge University, the lead researchers on the Silent Aircraft Initiative.


This is a collaboration between scientists and partners including BAA, Rolls-Royce and Boeing set up to develop "a conceptual design for an aircraft whose noise was almost imperceptible outside the perimeter of an airfield in an urban environment".
However, the design of the aircraft, which appears to have a single wing structure, rather than a separate body and wings, also has the potential to be up to 25% more fuel-efficient than a standard plane.
The scientists predicted the plane could achieve 124 passenger miles per gallon of fuel, compared with a Toyota Prius, which can achieve 120 passenger miles per gallon when carrying two people.
The 787 Dreamliner, a fuel-efficient airliner being developed by Boeing for delivery in 2008, is expected to achieve 100 passenger miles per gallon on a typical flight.
The quirky shape of the SAX-40 is designed to allow a slower approach and takeoff, which reduces noise. The flaps and hinged rear sections, which are found on standard aircraft wings and are a major source of airframe noise when a plane is taking off and landing, have also been eliminated from the new design, and engines have been mounted on the top of the aircraft, which will screen much of the noise from the ground.
A variable-size jet nozzle allows slower jet propulsion during takeoff and landing and efficient cruising at higher speeds.
"Public concern about noise is a major constraint on expansion of aircraft operations," explained Prof Greitzer, professor of aeronautics and astronautics at MIT.
"The 'silent aircraft' can help address this concern and thus aid in meeting the increasing passenger demand for air transport."
He said the researchers were hoping to turn their design into a reality by 2030, but building the propulsion system would be a key challenge.
"The propulsion system, with engines embedded in the fuselage, is different than for traditional civil aircraft, in which the engines are located in nacelles below the wing.
"This presents a different set of issues to the designer," he said.
Martin Brodie, a spokesman for the engine makers, Rolls-Royce, told Reuters that the project had the potential to shape future aircraft design.
"We have a very strong record of involvement in environmental programs anyway, so this is just a logical thing for us to get involved in," Mr Brodie said.
"This is really a clear blue sky thing for the moment and we'll have to wait to see what develops."
The plans for the plane were unveiled at the Royal Aeronautical Society in London. A video of what the plane would look like in flight is available here.