Ananova:

A future aircraft may be able to change its shape during flight - just like a bird.

The plane's wings and jets would alter shape in response to the flow of air in the same way an eagle flexes as it comes in to land.

Nasa says the aircraft will be one of its most important research projects over the next 20 years.

It would use smart materials which could improve fuel consumption and safety.

Dan Goldin, Nasa administrator, said: "The seemingly effortless flight of birds provides the inspiration for new aircraft utilising wings that reconfigure in flight.

"The vehicle changes, or morphs, from a low-speed configuration to one more suited for high speed."

Its wings would sweep back while engine inlets and nozzles would also change shape.

Small jets of air and feather-like control surfaces would allow the machine to make high speed manoeuvres.