Kirigami-inspired parachute deploying to slow down the delivery of a water bottle from a drone. Credit: Frédérick Gosselin
Parachutes work by increasing the surface area of whatever they’re attached to – from people to supplies or aid – increasing air resistance and slowing down its descent.
Some are rectangular and can be steered like the wings of an aeroplane, others are round and simple but can carry heavy payloads.
You wouldn’t want to put lots of little cuts in them, right?
Engineers designed a new kind of parachute that takes inspiration from the Japanese art of kirigami, in which paper is cut in complex patterns to produce 3-dimensional designs, which they suggest would be especially useful for humanitarian aid delivery.
The kirigami-inspired parachutes are made by laser-cutting patterns into flexible plastic discs. The slits open as the disc falls through the air, and it reconfigures into a 3-dimensional, vase-like network of interconnected beams.
This generates drag while preventing tumbling, resulting in a slow, controlled and stable descent.
“Apart from being easy to fabricate, our parachute reduces lateral displacement during descent, unlike conventional designs that often drift randomly and far from an intended target,” the researchers, from Canada’s Polytechnique Montreal and France’s Institut Polytechnique de Paris, write in a Nature study presenting their findings.
Kirigami-inspired parachute attached to a drone before launch. Credit: Frédérick Gosselin
Experiments revealed the kirigami discs successfully reconfigured in different environments, from the laboratory to a wind tunnel and in realistic outdoor conditions.
“We fabricated a large-scale kirigami parachute that successfully delivered a water bottle from a drone flying at an altitude of 60m,” they write.
“We show that at low load-to-area ratios, kirigami-inspired parachutes exhibit a comparable terminal velocity to conventional ones.
“However, unlike conventional parachutes that require a gliding angle for vertical stability and fall at random far from a target, our kirigami-inspired parachutes always fall near the target, regardless of their initial release angle.”
The researchers suggest that the terminal velocity of the parachute could be reduced even further by covering the cuts with a soft and stretchable membrane.
They say that manufacturing could be scaled up with the use of industrial-sized laser cutters and cutting dies and would not require manual assembly.
A water bottle can be delivered from a drone by simply mounting it in the center of a thin sheet cut with a kirigami pattern which will act as a stable, ballistic parachute. Credit: David Melancon
“Sceptics might wonder how a parachute riddled with holes can function, but this is far from a new trend,” writes Pierre-Thomas Brun from Belgium’s KU Leuven in a related News & Views article.
“Most modern parachutes that are designed to slow down fast objects, including the parachute used by NASA to deliver the Perseverance Mars rover to the ground, feature stabilising holes.
“Remarkably, once deployed, these kirigami-inspired parachutes, or ‘kiri-chutes’, resemble the feathery bristles of dandelions and other wind-dispersed seeds, echoing solutions that nature developed long ago.
“Kiri-chutes excel at small, precise and low-cost delivery. Thanks to their holes and shape, they minimise lateral drift, so can land reliably on a targeted area. Furthermore, because they are so simple to make, they could be produced cheaply in large numbers.
“Imagine fleets of kiri-chutes carrying essential supplies into disaster-stricken or remote regions – places where minimising costs is key, and where landing might be a challenge, even for a drone.
“What began as a series of simple cuts on a flat sheet could become a practical technology with real-life impact.”