Ar-Rehman

Kirigami-inspired parachute design achieves near-perfect, straight descents every time

Engineers from Polytechnique Montréal have unveiled a new parachute concept based on kirigami, the Japanese art of folding and cutting. The design is simple, robust and low-cost, with potential to transform humanitarian aid deliveries and even space exploration. Professors David Mélançon and Frédérick Gosselin from Polytechnique’s Department of Mechanical Engineering in Canada led the project. Tests show it stabilizes instantly, lands on target and could be scaled up for humanitarian aid or space exploration. It's a simple plastic disc, cut with a looping pattern, can do something parachutes rarely manage: fall almost perfectly straight. In repeated tests, the thin Mylar disc steadied itself in mid air and hit within about three feet of its target from 54 feet up, even in gusty indoor and outdoor conditions.

Professors David Mélançon and his team, working with engineers at École Polytechnique in France, turned a flat sheet into a stable, inverted-bell parachute which drops straight rather than wandering sideways in crosswinds. Their team cut a plastic sheet with a “closed-loop” kirigami pattern, giving it new mechanical properties. In free fall, the sheet deforms into an upside-down bell when a weight is attached at its centre. “One advantage of this parachute is that it quickly stabilizes and doesn’t pitch, regardless of the release angle,” Mélançon said. “And unlike conventional parachutes, it follows a strict ballistic descent trajectory.” The parachute relies on a single suspension line rather than many cords, which reduces tangling and speeds up deployment. “We made these parachutes by laser cutting, but a simple die-cutting press would also do the trick,” Mélançon said. “What’s more, the parachute is seamless and is attached to the payload by a single suspension line, making it easy to use and to deploy.” Engineers borrowed kirigami, a Japanese paper cutting art, a method of slicing a sheet to control how it bends and stretches. Instead of sewing fabric and lines, they laser-cut a closed loop pattern into a Mylar disc and hung a small weight from its centre. The disc was made from Mylar, a tough polyester plastic film used in kites and balloons. It keeps its shape well under load and tolerates clean laser cuts without fraying or loose fibres. The pattern forces the disc to puff into an upside-down bell as air flows by. The shape is stiff in the right direction and flexible where it needs to be, which keeps the descent straight. The researchers tested prototypes in simulations, wind tunnels, laboratory trials and outdoor drone drops. They observed that the descent path remained straight and predictable.

In the lab, the researchers compared three Mylar discs, one uncut, one with many concentric slits and one with the simple closed-loop pattern. Only the third design stabilized instantly and landed within roughly three feet of the target in repeated drops. They then ran wind tunnel trials and outdoor drops with a drone carrying a water bottle from about 200 feet. The parachute again settled into a steady fall with little sideways drift and no pitching, even when launched off-level. “It will always realign and then fall straight down,” said Mélançon. That steady, straight path is what gives the design its accuracy. In a 54-foot indoor test, the team also tried release angles of 0 degrees, 45 degrees and 90 degrees. The landing spread stayed small, which makes aiming simpler for drops in tight spaces. The team sees multiple uses for the parachute. Deliveries of food, water and medicine to remote regions stand out as the most immediate application. The low production cost makes large-scale deployment feasible. “The kirigami-patterned parachute could prove to be the best solution for this type of use,” Mélançon said. The slits add porosity. They also add flexibility, so different parts of the disc reorient until the forces balance, calming jitter as the fall begins. The result is flow-induced reconfiguration, a shape change driven by moving air, which trims drag growth as speed rises. The disc aligns with the air and stops tumbling, so the payload does not swing wildly or shed parts. Once the motion settles, the system reaches terminal velocity, the steady fall speed when drag equals weight. This trades a little speed for a lot of control, a swap which improves accuracy when wind and release angle vary. The same behaviour showed up from palm-sized samples to half-meter builds. Changes in size did not undo the self centring effect or the clean, vertical path in indoor and outdoor trials.

The researchers also pointed to potential roles in parcel delivery and planetary exploration. Unlike conventional parachutes, which often drift, the kirigami design lands close to the target. Gosselin explained that the parachute’s unique inverted bell shape is crucial to its performance. The kirigami cuts stretch open during free fall, creating many small slits which allow air to pass through in an orderly way. This prevents the formation of large turbulent swirls which can destabilize a conventional canopy. The result is a smooth airflow which keeps the parachute steady and its descent highly predictable, even under varying conditions. He also pointed out that the design scales without losing its properties. Tests showed that the parachute behaves consistently whether it is small or significantly larger, making it a flexible option for many uses. Most parachutes need sewn fabric, cords and careful packing. This one is a single thin sheet, cut by laser or a die press, then clipped to a single line, a manufacturing path which lowers costs and makes scaling easier in standard workshops.

Lower drift means fewer lost packages when wind shifts hit mid-drop. For aid groups, this can translate to more food, water or medicine arriving where people require, rather than scattered across a field or a riverbank, and fewer risky retrievals. Because the method is pattern based, production can adapt to different weights without redesigning a whole canopy. It also avoids knots, seams and tangles that ruin many small drops in rough conditions by adjusting ring spacing or slit count. The cuts can be stamped by the thousand on rolls of plastic using common tooling. This opens a route to disposable or recyclable parachutes for emergency logistics where recovery is unlikely and to classroom kits which teach physics safely. According to Gosselin, this opens the door to developing larger-scale models suitable for heavier payloads or broader applications. The project began when Gosselin attended a US conference where a researcher showed how kirigami patterns alter plastic sheets. He later discussed the idea with French collaborator Sophie Ramananarivo. When Mélançon, a specialist in foldable structures, joined Polytechnique, the two developed the idea into a full project. The team sees a path to slower descents by covering the slits with a soft, stretchy film. This could raise drag without losing the self-aligning behaviour, extending use to fragile payloads and sensor packages, including medical swabs.

They also point to ballistic-trajectory, a nearly straight path set by gravity and the initial release, as a feature engineers can tune. With asymmetric cuts, a drop might spiral gently or glide a short distance before settling on the target, which allows steering without motors. There is room for precision delivery across Earth and beyond. Tests in thin air, like high mountains and Mars analogue sites, will demand rugged, simple gear that tolerates cold, dust and thin air, which is where a cut sheet has an edge. The current parachutes are meant for small loads and short drops, not people or high-altitude entries. Yet for drones, sensors and aid packets, the mix of simplicity and accuracy is hard to ignore for missions. Several students, including master’s candidate Danick Lamoureux, contributed by adjusting patterns and running trials. Their work showed how the design could maintain stability and land with precision. Now the Montréal team wants to go further. They plan to experiment with new cut patterns to alter descent styles. “We want to change the patterns in order to go even further: the parachutes could descend in a spiral, for example, or glide before dropping,” Mélançon said. He added that trajectories could be customized depending on payloads, even allowing mid air sorting of cargo. With its combination of simplicity, stability and cost-efficiency, the kirigami parachute may soon find its place in both relief missions and advanced aerospace tests around the world.