NASA's released images of three commercial aircraft designs that it says could be appearing in the skies by 2025.
Late last year, NASA awarded contracts to three teams — Lockheed Martin, Northrop Grumman and Boeing — to develop advanced designs for the year 2025.
While all final designs have to meet rigid criteria for noise, exhaust and fuel consumption, the three concepts look very different.
The Boeing design looks like a cartoon version of a Stealth Bomber, with a hybrid winged/lifting body design. It can handle a truly enormous payload and has its engines mounted on top to reduce ground noise.
Northrop Grumman's design has a double fuselage, like a pair of aeronatical conjoined twins. It looks strikingly like Virgin's White Knight space launch vehicle.
Lookheed Martin's is the most conventional of the three, looking pretty much like a standard airliner, but has its engine at the rear - only one engine, meaning it will have to be pretty reliable.
The proposed aircraft will all have to work safely with modern air traffic management systems. Other criteria include the ability to fly at up to 85 percent of the speed of sound; cover a range of approximately 7,000 miles; and carry between 50,000 and 100,000 pounds of payload, either as passengers or cargo.
The three designs will now be developed further. Each team will spend the rest of this year exploring, testing and simulating refinements to their designs.