[HN Gopher] Kirigami-inspired parachute falls on target
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       Kirigami-inspired parachute falls on target
        
       Author : sohkamyung
       Score  : 83 points
       Date   : 2025-10-02 12:54 UTC (4 days ago)
        
 (HTM) web link (physicsworld.com)
 (TXT) w3m dump (physicsworld.com)
        
       | ugh123 wrote:
       | Linked paper:
       | https://www.nature.com/articles/s41586-025-09515-9.epdf
        
       | twp wrote:
       | This is really cool and innovative thinking, but anything
       | aerodynamic does not scale linearly. It's really easy to make
       | something light fall slowly. Baby spiders use "ballooning" -- a
       | single thread -- to fall so slowly that they can travel far in
       | thermal updrafts.
       | 
       | What's missing here is any evidence that the same cool parachutes
       | will work on anything of significant mass, e.g. a parcel weighing
       | 2kg or an average human weighing 80kg.
        
         | SiempreViernes wrote:
         | The tested it with a standard size waterbottle, so you know it
         | works fine for 0.8 kg paloads.
        
         | observationist wrote:
         | Depending on the use case, a hot-air balloon sized parachute to
         | safely drop a person might be perfectly acceptable.
         | 
         | It looks like adding flexible ailerons or whatever they'd be
         | called could give a big advantage in precision landing, with
         | slower forward/sideways speeds but much better control.
         | 
         | Making it modular, with interlocking but separate parts, might
         | make great sense for repairability and safety for skydiving?
         | From the little I know of the sport, things tend to fail
         | catastrophically, going from perfect condition to total
         | disaster without a whole lot of graduated steps in between. I
         | also wonder if there's some utility in paramotoring - multiple
         | kirigami stabilizers, maybe, with a central parafoil, or one
         | big kirigami rig with the fan blowing straight up its skirt?
         | 
         | This is awesome research. Paper drone-delivery parachutes are
         | definitely a use case, but maybe some of the more dangerous
         | flying sports could be made much safer, as well.
         | 
         | edit: Apparently no, 100 meter radius kirigami chute would be
         | needed for a single person parachute, not exactly practical.
         | Apparently it's just really, really good at ensuring things
         | drop straight down with a lot of drag.
        
         | hermitcrab wrote:
         | Spider ballooning is an interesting phenomena. I also assumed
         | that the spider is just falling a bit slower than the air is
         | rising, due to convection. However some people think there is
         | also a strong electrostatic component to spider ballooning. I'm
         | not sure how that works once the spider is well clear of the
         | ground though.
        
         | drpixie wrote:
         | >> does not scale linearly
         | 
         | It looks like it depends on the stiffness of the material
         | (paper), so scaling it up to human (or bigger) sized will come
         | with "interesting" challenges :(
        
       | aaroninsf wrote:
       | Related work that his lab was doing when I got to take a seminar
       | with him at IU:
       | https://gwern.net/doc/design/typography/1993-mcgraw.pdf
       | 
       | Gary was one of the TAs in the class. The non-reducibility of
       | letterforms has remained a fascination--I always did like the
       | (computational) linguistics corner of cognitive science!
        
         | Jtsummers wrote:
         | https://news.ycombinator.com/item?id=45495711 - I think you
         | meant to comment on this one.
        
       | baxtr wrote:
       | The journal Nature (where the original article was published) has
       | a video about that parachute:
       | 
       | https://www.youtube.com/watch?v=6rrDW6YIbXI
        
         | CGMthrowaway wrote:
         | I had to wonder if Nature (the Mother, not the journal) had
         | first created anything similar, because she always does.
         | 
         | One answer is a dandelion seed. Not exactly the same, but a
         | dandelion seed is about 85%+ "porous" - the pores here being
         | the space between the spindles, not actual holes per se. And it
         | turns out that high porosity is critical to stabilizing the
         | wake turbulence not unlike what is described in the Nature
         | video. https://sites.nd.edu/biomechanics-in-the-
         | wild/2021/06/01/inn...
         | 
         | A learning that kirigami parachute researches might apply: The
         | dandelion pappus is less porous near the center and becomes
         | more porous toward the outer edge. A lower porosity near the
         | central hub can increase shear flow, helping to detach and
         | strengthen the vortex
         | 
         | Furthermore, spiders which have been known to "balloon" on the
         | wind even across entire oceans use multiple strands of silk
         | which are negatively charged to repel each other, thus forming
         | some of the same gaps that are seen in a dandelion pappus, with
         | similar aerodynamic benefits.
         | https://journals.aps.org/pre/abstract/10.1103/PhysRevE.105.0...
        
         | stronglikedan wrote:
         | Is that really Nature's channel? It sucks that I have to ask,
         | but I just ran across that video (and channel) on the weekend.
         | I have a new policy where I don't trust videos to not be AI
         | slop when they don't have a real, on screen presenter. This one
         | didn't, but it also didn't really feel like AI slop, but it
         | could have been stolen content since that is very common
         | nowadays because it goes unpunished.
        
       | ashton314 wrote:
       | Regretting my choice to do a PhD in CS instead of whatever this
       | cool thing is...
        
         | golem14 wrote:
         | your PhD probably gives you the wherewithal to do the cool
         | things now or after a few years of work ...
        
           | ashton314 wrote:
           | [delayed]
        
       | fallingmeat wrote:
       | now swoop it!
        
       | hermitcrab wrote:
       | Modern parachutes can be packed relatively small and open quite
       | quickly. Not sure how you would pack one of these parachutes,
       | especially if they are made from a relatively stiff plastic.
        
         | tempestn wrote:
         | It comes as a flat disc. For some applications that might be
         | more convenient packaging than traditional parachutes.
        
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