They are the sort of striking images that wouldn't look out of place in a scene from a sci-fi movie.
However, one of these could soon be the face of modern aviation with the unveiling of a new generation of passenger aircraft.
NASA has revealed three concept designs for quiet, energy efficient aircraft that potentially could be ready for flight as soon as 2025.
Future flight? Boeing unveils its innovative design for a faster, bigger and cleaner aircraft
Three companies - Lockheed Martin, Northrop Grumman and The Boeing Company - came up with the designs and, at the end of last year, all three won a contract from NASA to research, develop and test their concepts in 2011, meaning these futuristic ideas could have the potential to take flight.
The designs came about after NASA revealed it was aiming to develop a line of 'super planes' that are faster, larger, quieter - and burn fuel more efficiently and cleanly than their present counterparts.
Cutting edge: The Northrop Grumman concept is twice as nice as current aircraft
Criteria set by NASA meant that each design had to fly up to 85 per cent of the speed of sound, cover a range of about 7,000 miles and carry between 50,000 and 100,000 of payload; either cargo or passengers.
Now, each of the three companies will spend the rest of this year exploring, testing and simulating their designs in the hope that NASA will choose it for development.
Cleaner: All three designs - including this one from Lockheed Martin - were required to have green credentials
How likely it is for these designs to get off the ground is under debate. A spokesman from technology and innovation website Fast Company told the Huffington Post: 'Given how long it usually takes to craft an aircraft from scratch, and bearing in mind how many technical hitches the revolutionary Boeing 787 Dreamliner has suffered, these are the sorts of aircraft that these three firms are probably beginning to design for real right about now.'
Scroll down for other weird and wonderful designs of aircraft for the future...
NASA's Solar Flapper is an unconventional concept for a plane that would use solar power and flapping of the aircraft's 'wings' to propel itself up and forward
Industrial designer Luigi Colani came up with this concept for Japan Airlines
To infinity and beyond: The 'Puffin' Personal Aircraft concept by NASA bears more than a passing resemblance to Toy Story's Buzz Lightyear. It is targeted to reach speeds of more than 150mph with a range of about 50 miles
This futuristic 'flying saucer' design is not only space-age but eco-friendly too, designed by the CleanEra project, led by Etnel Straatsma of Delft University of Technology in The Netherlands
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