[HN Gopher] Researchers build a solar-powered hovering drone tha...
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       Researchers build a solar-powered hovering drone that weighs only 9
       mg
        
       Author : thunderbong
       Score  : 49 points
       Date   : 2024-07-17 18:52 UTC (4 hours ago)
        
 (HTM) web link (arstechnica.com)
 (TXT) w3m dump (arstechnica.com)
        
       | bunabhucan wrote:
       | Paper link, includes videos of the prototypes:
       | 
       | https://www.nature.com/articles/s41586-024-07609-4
        
         | UncleOxidant wrote:
         | https://archive.is/Yi8Fn
         | 
         | ...but that's still paywalled.
        
           | popcalc wrote:
           | Still paywalled.
           | 
           | Here's the unlisted demo video:
           | https://www.youtube.com/watch?v=LBoee1l4OXo
        
       | abeppu wrote:
       | I'm aware of several past solar-powered airplanes. Is this the
       | first solar powered rotary-wing aircraft? (Looking for 'solar
       | drone' mostly turns up drones used to clean solar panels)
        
         | m-watson wrote:
         | I would guess the key here is the "researchers reported that
         | they had developed a drone they're calling the CoulombFly,
         | which is capable of self-powered hovering for as long as the
         | Sun is shining."
         | 
         | It only seems to operate off the solar power, no additional
         | power. So the light keeps shining, the drone keeps flying.
        
           | abeppu wrote:
           | Right, I'm can see that. I'm asking, is this the _first_
           | example in the solar rotary-wing (miniature) aircraft
           | category, or are there any other prior examples?
        
             | nathancahill wrote:
             | Also.. ground effect?
        
         | f154hfds wrote:
         | For those curious about solar powered fixed wing airplanes:
         | 
         | https://en.wikipedia.org/wiki/Airbus_Zephyr
         | 
         | > One Zephyr can replace 250 cell phone towers. It can be used
         | to perform intelligence, surveillance and reconnaissance (ISR)
         | with a wide visual payload coverage of 20x30 km (12.4x18.6 mi)
         | and can be equipped with radar, LIDAR and infrared
         | technologies.
        
       | tomasf wrote:
       | Video: https://www.youtube.com/watch?v=LBoee1l4OXo
        
       | GenerocUsername wrote:
       | Article says 4g title says 9mg
        
         | Jtsummers wrote:
         | > However, the design can be miniaturized, and the researchers
         | built a version that weighs only 9 milligrams.
         | 
         | Ars A/B tests their titles so I don't know if the submitter
         | editorialized or if they saw a different title than the rest of
         | us, but the text of the article does include building a 9 mg
         | version.
        
           | GenerocUsername wrote:
           | Interesting. Thanks for clarification
        
         | commodoreboxer wrote:
         | The second and penultimate paragraphs both explain that.
        
       | ugh123 wrote:
       | Only? Can it carry any extra onboard chips and sensors?
        
       | throwup238 wrote:
       | Every time I see one of these drone tech demonstrations, I can't
       | help but wonder how they will be adapted for warfare.
       | 
       | This one... I'm seeing flying solar powered landmines (skymines?)
       | that can flutter around an active combat zone aimlessly for hours
       | until it detects a personnel target and bops them near the temple
       | with a small round. I wonder if there are any actual benefits
       | over just putting a solar panel on a regular quadcopter and
       | having them charge a battery, maybe staying stationary in field
       | or ditch near the road, relocating once in a while and waiting
       | for a target.
       | 
       | Slaughterbots, assemble!
       | https://www.youtube.com/watch?v=9CO6M2HsoIA
        
         | 7734128 wrote:
         | https://en.m.wikipedia.org/wiki/Loitering_munition
        
         | jessriedel wrote:
         | > and bops them near the temple with a small round.
         | 
         | The smallest commercially available centerfire cartridge was
         | the 2.7mm Kolibri round, which was too underpowered to inflict
         | significant damage to a person other than maybe if you hit them
         | right in the eyeball. That round weighed 5.3 grams while the OP
         | article talks about a drone weighing 9 _milli_ grams.
         | 
         | https://en.wikipedia.org/wiki/2mm_Kolibri
         | 
         | This drone just doesn't have enough payload for
         | explosives/bullets to be useful against a person. More
         | plausible is some sort of biological attack, like a nerve gas,
         | although you'd be pushing the limits even there. The LD50 for
         | sarin gas is 1 milligram, and you would need a delivery
         | mechanism.
        
           | jxcole wrote:
           | If you look carefully you see that they actually started with
           | a much bigger drone and then shrunk it down. The minimum is 9
           | mg (that they could build) but it sounds like the design can
           | be expanded to almost any size. A more obvious question would
           | be is there any functional difference between this and a
           | balloon.
        
           | gertlex wrote:
           | Thanks for the insights on that half of the hypothetical! 9mg
           | is indeed wild, and made me go check the article... The
           | article is a bit confusing, or I'm missing some nuances. It
           | seems to talk about 2-3 drones, I think, mentioning weights
           | of: 9 mg, 1.13 g, and 4 g. I think the one in the video is
           | not the 9 mg version.
        
           | throwup238 wrote:
           | From TFA:
           | 
           |  _> The total system required just over half a watt of power
           | to stay aloft. Given a total mass of 4 grams, that works out
           | to a lift-to-power efficiency of 7.6 grams per watt. But a
           | lot of that power is lost during the voltage conversion. If
           | you focus on the motor alone, it only requires 0.14 watts,
           | giving it a lift-to-power efficiency of over 30 grams per
           | watt...._
           | 
           |  _> But one thing they don 't have to optimize is the
           | vehicle's size since they already built a miniaturized
           | version that's only 8 millimeters high and weighs just 9
           | milligrams but is able to generate a milliwatt of power that
           | turns its propeller at over 15,000 rpm._
           | 
           | 9mg is just the smallest version they managed to make. Based
           | on the size of the solar panel in the video, there's plenty
           | of room to scale to tens of grams per drone. And this is a
           | laboratory proof of concept, not a well funded weapons
           | prototype.
        
       | RIMR wrote:
       | >9mg
       | 
       | Yeah, just make stuff up...
        
       | lawlessone wrote:
       | Not remotely controlled or autonomous. It's cool but it isn't a
       | drone.
        
       | bitwize wrote:
       | Localizers (from A Deepness in the Sky)!
        
       | jafarlihi wrote:
       | Ever heard of wind?
        
       | squarefoot wrote:
       | I wonder how feasible would be adding an actuator that slightly
       | tilts the propeller axis, driven according to the direction from
       | which the drone is receiving sunlight, so that the drone would
       | turn always to the sun, remaining airborne as long as it can
       | follow its light.
        
         | denotational wrote:
         | I think you might be describing a (photosynthetic) moth!
        
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       (page generated 2024-07-17 23:06 UTC)