Scientists plot new flying machines based on dandelion seeds

But scientists have discovered the flying ability of the humble dandelion seed is only possible thanks to a form of flight that has not been seen before in nature.

This new “sustainable technology”, they say, could be used in future engineering projects. These include the design of stealth drones advocated by defence companies such as BAE Systems and Lockheed Martin.

The discovery, which confirms the common plant among the natural world’s best fliers, shows movement of air around and within its “parachute-shaped” bundle of bristles often enables seeds to travel half a mile or more, kept afloat entirely by windpower.

Gardeners generally dislike dandelions as they are viewed as weeds which have huge taproots that break easily when being removed.
It can also regenerate from the tiniest piece to four times the size of what gardeners were trying to remove in the first place. 

The featherweight seeds carry on the lightest breeze and lodge themselves into every crack in the ground and every millimetre of bare soil. 

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Dandelion pollen is not particularly nutritious, compared with that of clover and vetches, but it is available when little else is about.

From March to November it offers a reliable source of food for all species of bees, beetles, butterflies and hoverflies.

Now researchers from Edinburgh University have carried out experiments to understand why dandelion seeds fly so well, despite their parachute structure being largely made up of empty space.

The findings show the seeds could be used in helping design under-the-radar technology such as drones for spy missions by the security services.

The study revealed that a ring-shaped air bubble forms as air moves through the bristles. 

This enhances the drag that slows each seed’s descent to the ground. 
The newly found form of air bubble, which scientists have named the separated vortex ring,  is physically detached from the bristles and stabilised by air flowing through it.

Researchers found that the amount of air is critical for keeping the bubble stable and directly above the seed in flight, and is precisely controlled by the spacing of the bristles. 

The flight mechanism of the bristly parachute underpins the seeds’ steady flight and is four times more efficient than a conventional parachute.

Scientists say the dandelion’s porous parachute may inspire the development of small-scale drones that require little or no power.
Such drones could also be useful for remote sensing or air pollution monitoring.

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They hope their findings can be used to help engineering and sustainable technology fields.

Dr Cathal Cummins, of the university’s Schools of Biological Sciences and Engineering, who led the study, said: “Taking a closer look at the ingenious structures in nature, like the dandelion’s parachute, can reveal novel insights. 

“We found a natural solution for flight that minimises the material and energy costs, which can be applied to engineering of sustainable technology.”

BAE Systems recently unveiled an aircraft design that is viewed as a major advance in stealth technology.

The Magma drone does away with aircraft control surfaces, which has resulted in an aircraft whose shape remains constant throughout its flight. 

The small demonstration aircraft, which has completed a successful first flight, uses blown air to change direction instead of complex mechanical controls.

Most aeroplanes look unmoving in flight, like a wing hanging off a giant tube flying through the sky. 

But conventional aircraft use a system of elevators, rudders and ailerons to control their direction in the pitch and roll directions. 

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These mechanical devices are usually in the shape of control surfaces attached to the rear of the wing, horizontal and vertical stabilisers and are controlled by the pilot – or sometimes an onboard flight computer.
Control surfaces have been an instrumental part of aircraft since the early 20th century. These mechanisms can and do fail, limiting an aeroplane’s manoeuvrability.

But among a new generation of stealth warplanes, control surfaces can also affect an airplane’s carefully shaped stealth profile, as the fin-like device moves upward or downward, momentarily making the aircraft slightly more visible to radar.

Now the Edinburgh University researchers are hopeful that the dandelion seeds can help advance the technology further. 

The study, published in science journal Nature, was funded by the Leverhulme Trust and the Royal Society.