'Flying carpet': Princeton team's plastic sheet can hover above ground (w/ video)

Oct 01, 2011 by Nancy Owano weblog
'Flying carpet': Princeton team's plastic sheet can hover above ground (w/ video)

(PhysOrg.com) -- A thin sheet of plastic has been making headlines at Princeton as a magical flying carpet, after the publication of a paper describing experiments by the team with their prototype sheet of plastic that uses piezoelectric actuators and sensors to move. The sensors and conducting threads create "ripples" of air moving front to back of the sheet, and the sheet is propelled into the air.

The creator, graduate student Noah Jafferis, and team described their device and findings in , which published their article online earlier this month.

"We use integrated piezoelectric actuators and sensors to demonstrate the propulsive force produced by controllable transverse traveling in a thin plastic sheet suspended in air above a , thus confirming the physical basis for a 'flying' carpet near a horizontal surface," wrote the three authors, Noah Jafferis, Howard Stone, and James Sturm. “Experiments are conducted to determine the dependence of the force on the height above the ground and the amplitude of the traveling wave, which qualitatively confirm previous theoretical predictions.”

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The undulating allow the sheet to move at a speed of a centimeter per second, and Jafferis believes it should be possible to increase the speed to about a meter per second.

An earlier paper written by Harvard Professor Lakshminarayanan Mahadevan inspired Jafferis to look into his hovering plastic sheet project shortly after starting his doctoral studies. Jafferis at the time had been on another project, printing electronic circuits with nano-inks. Instead he turned to the plastic sheet project and spent two years working on and performance improvements.

A BBC interviewer was told by Sturm that it was not easy to control the sheet's behavior as it deformed at high frequencies.

Even though news reports are referring to the sheet as a flying carpet, weaknesses in propulsion and lift hardly make the device comparable to magic carpets. Jafferis is careful to point out that flying should be in quotes because the object does not fly, nor does it go fast. The sheet hovers above the ground as electric ripples flow, moving air along its underside.

Jafferis points out that the prototype’s tiny conducting threads anchor it to heavy batteries. On the development agenda is a solar-powered upgrade that could enable it to fly over large distances.

Applications for such a device, according to reports, might include a planet Mars rover. Prof Mahadevan looks forward to sophisticated improvements in the near future, suggesting the approach could progress to "mimicking the beautiful two-dimensional undulations of the skate or manta ray.”

Explore further: Researchers demonstrate ultra low-field nuclear magnetic resonance using Earth's magnetic field

More information: Traveling wave-induced aerodynamic propulsive forces using piezoelectrically deformed substrates, Appl. Phys. Lett. 99, 114102 (2011); doi:10.1063/1.3637635

Abstract
We use integrated piezoelectric actuators and sensors to demonstrate the propulsive force produced by controllable transverse traveling waves in a thin plastic sheet suspended in air above a flat surface, thus confirming the physical basis for a “flying” carpet near a horizontal surface. Experiments are conducted to determine the dependence of the force on the height above the ground and the amplitude of the traveling wave, which qualitatively confirm previous theoretical predictions.

via BBC

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User comments : 8

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Isaacsname
5 / 5 (4) Oct 01, 2011
" The sensors and conducting threads create "ripples" of air moving front to back of the sheet, and the sheet is propelled into the air. "

...it says it hangs on " conducting threads "...that's more like an epileptic on a swingset if it's flexing with actuators.

I wonder if they ever heard about David Swenson's electrostatic wall at the 3M plant o,O

...also....was that filmed with a potato ?
TehDog
not rated yet Oct 01, 2011

...it says it hangs on " conducting threads "...that's more like an epileptic on a swingset if it's flexing with actuators.

"Jafferis points out that the prototypes tiny conducting threads anchor it to heavy batteries."
I take that to mean the batteries are below, not above.
axemaster
not rated yet Oct 01, 2011
Hmmm... I and a friend of mine did something very similar last year, which also flew due to the waves "sucking" air underneath the plastic...

I kinda wish we had published it... we didn't think it was worth bothering with though, since the effect is so simple.
NTJ
5 / 5 (2) Oct 01, 2011
Just to clarify, the current work is about demonstrating a propulsive force
produced by traveling waves in a thin plastic sheet, not lift as of yet. To
achieve lift, the sheet has to be untethered to allow it reach faster speeds
(while still being only a few mm above the ground).
We performed such measurements in two setups - one with the sheet suspended
using an air table, and the other with the sheet hanging from elastic threads.
The propulsion only works when the sheet is suspended ~1-2mm above the ground, as expected from theory.

The BBC also did not include the description of the videos, that I had given them:

The first video is demonstrating the propulsion caused by the traveling wave.
The sheet is supported on a cushion of air from the air table, ~1mm above it,
and is connected to conductive threads to supply power. When the sheet is off,
its equilibrium position is near the center of the air
table, and it does not move significantly.
NTJ
5 / 5 (2) Oct 01, 2011
When the sheet is on, in this case
with a traveling wave propagating to the left, it is propelled in the opposite
direction (to the right in this case). The video shows the sheet turning on and
off in several cycles, and it thus moves back and forth. Because the frequency
of vibration is 100Hz, the actual wave shape can not be seen; rather the sheet
seems to "shimmer" when on.

In the second video, the vibration is only a few Hz, to allow viewing of the
actual traveling wave vibration. But frequencies this low are not sufficient to
propel the sheet. In addition, the sheet is suspended from elastic threads in
this case (~1cm above the ground, so no propulsion would be observed even at
higher frequencies). Also, the second video is not displaying properly here, presumably due to skipped frames, so it does not look like a traveling wave. The BBC version is better.

Several other errors in the bbc article:
NTJ
5 / 5 (2) Oct 01, 2011
It is not really like a hovercraft, which pushes air down to create lift - our device pushes air backwards to propel itself forward.

The sentences "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." were completely made up by the BBC.

The sheet would actually only need to be 50 feet on each side to carry the weight of a person, not 50 meter
kaasinees
1.7 / 5 (6) Oct 02, 2011
geeksaresexy.net/wp-content/uploads/2011/09/science-reporting.jpg

Pretty much sums it up.
Jeffhans1
not rated yet Oct 02, 2011
Has everyone else just ignored the implications using this to cool electronics? The air hugging the surface is the biggest insulating effect so by making that layer move you have a happy middle ground between passive and active cooling. Make a version of this work for water and you can decrease the time needed to boil water.