Aeronautical engineers working with both NASA and DARPA (Defense Advanced Research Projects Agency) are putting their ideas for faster flight to actual use.

After having done all they can with computer models for the past years, they are now taking what they have learned and are actually building experimental aircraft to test the new technology, which is set to revolutionize plane travel for both commercial and military use.

One such line of aircraft that are getting ready to be worked on is aptly called the X-plane with a number of different versions.

NASA's plan regarding the X-plane is extremely ambitious, setting out to develop a whole series of new X-planes over the next 10 years. One of the planes will be roughly the size of a business jet that burns low-carbon bio-fuels and generates such quiet sonic booms that people on the ground will barely hear them

Meanwhile, DARPA is working on a design of their own for an X-plane with a stacked wing frame that has a series of rotors mounted in between. The rear-mounted wing would create a vertical thrust for takeoff and landing, then rotate to provide horizontal thrust for cruise and second, smaller wing near the nose of the plane would work the same way. DARPA says its X-plane would fly as fast as 460 mph and could be in the air by as early as 2018.

Other planes that are now in development include the four-seat Tecnam twin replacing the wing and engines with a series of electric-powered propellers which aims to produce an emissions-free flight.

Another hybrid design that looks like a flying fish could be the airliner of the future, with turbofan engines in the back shielded by two vertical tails to protect people on the ground from engine noise.

The agency hopes to develop efficient, energy-saving technologies that can be adopted by commercial and military aircraft manufacturers. NASA said if funding comes through, the new planes could grace the skies as early as 2020.