Flying carpets are real!

A miniature magic carpet made of plastic has taken flight in a laboratory at Princeton University.

The 10cm (4in) sheet of smart transparency is driven by "ripple power"; waves of electrical current driving thin pockets of air from front to rear underneath.

The prototype, described in Applied Physics Letters, moves at speeds of about a centimetre per second.

Improvements to the design could raise that to as much as a metre per second.

The device's creator, graduate student Noah Jafferis, says he was inspired by a mathematical paper he read shortly after starting his PhD studies at Princeton.

He abandoned what would have been a fashionable project printing electronic circuits with nano-inks for one that seemed to have more in common with 1001 Nights than 21st-Century engineering.

Prof James Sturm, who leads Mr Jafferis' research group, conceded that at times the project seemed foolhardy.

"What was difficult was controlling the precise behaviour of the sheet as it deformed at high frequencies," he told the BBC.

"Without the ability to predict the exact way it would flex, we couldn't feed in the right electrical currents to get the propulsion to work properly."

What followed was a two year digression attaching sensors to every part of the material so as to fine-tune its performance through a series of complex feedbacks.

But once that was mastered, the waveform of the undulating matched that prescribed by the theory, and the wafting motions gave life to the tiny carpet.

In the paper describing the design, Mr Jafferis and his co-authors are careful to keep the word "flying" in inverted commas, because the resulting machine has more in common with a hovercraft than an aeroplane.

"It has to keep close to the ground," Mr Jafferis explained to the BBC's Science in Action, "because the air is then trapped between the sheet and the ground. As the waves move along the sheet it basically pumps the air out the back." That is the source of the thrust.