NASA has unveiled concepts of future, eco-friendly aircraft.

The stunningly innovative designs, which NASA calls greener flying machines for the year 2025, are being developed by three firms under contract to the NASA Aeronautics Research Mission Directorate's Environmentally Responsible Aviation (ERA) Project.

The target is to create designs that consume 50 percent less fuel than aircraft unveiled in 1998, with 50 percent less harmful emissions, and to shrink the size of geographic areas hit by high levels of airport noise by 83 percent, a NASA statement said.

The real challenge is we want to accomplish all these things simultaneously. It's never been done before. We looked at some very difficult metrics and tried to push all those metrics down at the same time, said Fay Collier, ERA project manager.

The Boeing Company in Huntington Beach, California, Lockheed Martin in Palmdale, California, and Northrop Grumman in El Segundo, California, have been engaged in the research and development of the new designs. The expert teams spent the whole of 2011 devising ways to develop the supermodels that meet all the desired goals.

We'll be digesting the three studies and we'll be looking into what to do next, Collier added.

Going by initial indications, the preliminary designs all met the pollution goal of reducing landing and takeoff emissions of nitrogen oxides by a half over engines that are currently in use. But meeting the two other goals can be really challenging.

All of the teams have done really great work during this conceptual design study. Their results make me excited about how interesting and different the airplanes on the airport ramp could look in 20 years. Another great result of the study is that they have really helped us focus where to invest our research dollars over the next few years, Mark Mangelsdorf, ERA Project chief engineer, said.

Have a look at the stunning aircraft models here: