[HN Gopher] DaVinci-style drone with 600-year-old screw rotor de...
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DaVinci-style drone with 600-year-old screw rotor design
Author : clouddrover
Score : 95 points
Date : 2022-02-03 01:57 UTC (1 days ago)
(HTM) web link (www.thedrive.com)
(TXT) w3m dump (www.thedrive.com)
| masswerk wrote:
| Fun fact: Historically, these air screws came from China and were
| sold as child toys on markets in Venice as early as in the 1200s.
| (This is probably also, where DaVinci picked up the idea.)
| BrS96bVxXBLzf5B wrote:
| The embedded fun fact here is that by the 13th century China
| was already exporting small goods like children's toys to
| Europe! til my knowledge of trade doesn't go any deeper or
| further back than "Marco Polo traded some things some time
| ago".
| dekhn wrote:
| See also https://en.wikipedia.org/wiki/Ming_treasure_voyages
| pasabagi wrote:
| They had deep enough trade links that some refugee sassanid
| princes ended up being absorbed into the chinese nobility
| after the muslim consquest of persia.
| agumonkey wrote:
| who else played with maple seed leafs~ as helicopters ?
|
| https://duckduckgo.com/?t=ffab&q=maple+seed+helicopter&iax=i...
| jacquesm wrote:
| Just to add: this is not a joke, though it could easily be seen
| as one.
| sounds wrote:
| Here's a direct link to the video:
|
| https://vimeo.com/672877397
|
| (The article is completely choked with overlapping autoplaying
| video ads.)
| hollander wrote:
| This looks more like a proper airship, like the ones from fifties
| and sixties scifi books.
| Hokusai wrote:
| That is just a Archimedes' screw. Well known way before DaVinci.
|
| It's cool that DaVinci got to the conclusion that if moves water
| it can move air, thou.
|
| There original design used materials from the time, but with an
| enough powerful engine you can probably make it fly.
| andrewla wrote:
| I don't think this is true. Archimedes screw is a similarly
| shaped helix but contained or partially contained in a tube so
| that it can move substances by rotary action.
|
| Using a helix as a simple machine is an old concept and
| probably predates writing; that's about as much of a common
| ancestor as they share.
| dtgriscom wrote:
| Agreed. Archimedes' screw depends on gravity pulling the
| water to one side of the mechanism; it can't work vertically.
| jjeaff wrote:
| Archimedes screw, that's just a wedge invented by cavemen.
|
| Archimedes just had the idea to wrap it around a post.
| annoyingnoob wrote:
| One has to wonder if DaVinci had his own model.
|
| https://instructional-resources.physics.uiowa.edu/demos/10c1...
| adolph wrote:
| From presentation at 9th Annual Electric VTOL Symposium [0]:
| Revolutionary Flight Vehicle Based on Leonardo da Vinci Aerial
| Screw: A Paradigm Shift in VTOL Technology Austin Prete,
| Vengalattore Nagaraj, Inderjit Chopra, Univ. of Maryland
|
| The team is from Alfred Gessow Rotorcraft Center Department of
| Aerospace Engineering University of Maryland. The PDF below [1]
| is very detailed and comes from a design competition there [2].
|
| 0. https://vtol.org/events/2022-transformative-vertical-flight
|
| 1. http://vfs.umd.edu/assets/downloads/2020_elico.pdf
|
| 2. http://vfs.umd.edu/designGrad.html
| JamesUtah07 wrote:
| That is so wild
| rasz wrote:
| Anything can fly if you slap modern 7K RPM BLDC hobby motors on
| it.
|
| FliteTest does this regularly, here flying an Ikea chair
| https://www.youtube.com/watch?v=QlKC5qUS80o or Santa's Sleigh a
| month ago https://www.youtube.com/watch?v=n9IlkYnx-34
| jacquesm wrote:
| Except that this is absolutely nothing like that.
| wolpoli wrote:
| And this is a video of Flitetest flying a circle plane. I doubt
| it's very efficient but it still flies with the help of their
| powerful motors.
|
| https://www.youtube.com/watch?v=YP9PizYicxY
| 0xbadcafebee wrote:
| I never thought the day would come that I would type the words
| "I am very excited by that Ikea chair"
| zydex wrote:
| But they're using traditional blades so obviously it can lift
| anything. Isn't the whole point of the original article that
| the motors work with DaVinci's screw rotor design, generating
| lift?
| [deleted]
| suifbwish wrote:
| I don't understand why so many people find it difficult to
| imagine ancient people understanding something as finite as
| aerodynamic mathematics. Their understanding of all other
| maths was phenomenal. Newton didn't invent Newtonian physics
| and he probably wasn't even as savvy as some of the ancients
| were. There is far too much inductive reasoning in history
| and historically science.
| ajuc wrote:
| > I don't understand why so many people find it difficult
| to imagine ancient people understanding something as finite
| as aerodynamic mathematics
|
| Because they had no calculus.
| iamjackg wrote:
| From the way you worded this, I was expecting them to use the
| chair and sleigh as propellers. What's special about OP is that
| the propeller design is unusual, proving that Leonardo wasn't
| that far off when he came up with the idea.
| matheusmoreira wrote:
| I thought the exact same thing. Clicked the link fully
| expecting to see chairs spinning at 7000 rpm. Was actually
| wondering if these objects could handle the forces involved
| without disintegrating.
| tshaddox wrote:
| Yeah, those YouTube videos really just demonstrate
| that...airplanes can carry things.
| cobookman wrote:
| The report also shows it to have superior thrust to a
| traditional rotor for the same RPM.
|
| https://www.thedrive.com/content-b/message-
| editor%2F16436679...
| dr_orpheus wrote:
| Although a better metric might be to look at the thrust to
| motor power and get an idea of its efficiency relative to
| traditional rotors. I can put larger blades on the motor
| and will get more thrust at the same RPM but the motors
| will have to work harder to push those blades.
| dTal wrote:
| Indeed, the screw shape is essentially a large number of
| rotor blades, welded leading edge to trailing edge.
| Undoubtedly it produces more thrust for a given RPM, and
| undoubtedly the efficiency is horrifically bad.
| adolph wrote:
| Is the efficiency the number of amps required to
| gain/maintain a particular rotational speed? So given
| rotational speed 4k conventional is 50g thrust and
| DaVinci 75ish g, if conventional costs 10amp then DaVinci
| would be less efficient if it uses more than 15 amps?
| dTal wrote:
| >Is the efficiency the number of amps required to
| gain/maintain a particular rotational speed?
|
| Thrust, not RPM. Efficiency for any actuator is defined
| by (work done)/(power in). You could replace the
| Archimedes screw with a simple axle, and it would be much
| easier to maintain RPM - however it would move no air no
| matter how much power you dumped into it, and so would
| have 0% efficiency.
|
| > So given rotational speed 4k conventional is 50g thrust
| and DaVinci 75ish g, if conventional costs 10amp then
| DaVinci would be less efficient if it uses more than 15
| amps?
|
| Not quite. Thrust / power for disk-shaped actuators is
| not a constant ratio, but a curve - an x^(3/2) power law,
| to be exact. You need exponentially more power to
| maintain a linear increase in thrust. So while it's
| correct that thrust/amps[note] describes the efficiency,
| it's not fair to compare conventional at 50g and DaVinci
| at 75g.
|
| However I guarantee you if you put the same power into
| this rotor, you'll get less thrust than if you put it
| into a regular prop.
|
| [note] Watts, really, but same thing if voltage is held
| constant
| zackbloom wrote:
| > would move no air no matter how much power you dumped
| into it
|
| Fun pedantic correction, it would move air via the Magnus
| effect [1], but of course it would be orthogonal to the
| direction you want it to be moved!
|
| See the Turbosail [2] for a fun application of that
| effect.
|
| [1] - https://en.wikipedia.org/wiki/Magnus_effect
|
| [2] - https://en.wikipedia.org/wiki/Turbosail
| Panzer04 wrote:
| Yep. Traditionally, drones use 2-3 bladed props, each
| additional prop blade increases thrust per rpm, but
| increases load by significantly more, hurting actual
| thrust per watt.
|
| I'd expect a screw to be the degenerate case and probably
| worse than a conventional many-bladed prop.
| adolph wrote:
| It would be interesting to understand why load increases
| more quickly than thrust for increasing blade counts.
|
| Do ducted fans have similar changes in load-to-thrust
| ratio given an increase in blade count?
| zelphirkalt wrote:
| In my imagination: Don't rotor blades also profit from
| air getting "in between" them, so that they have
| something to push against and thus push upwards? The
| screw relies on air getting in from the sides, while that
| air is being pushes outwards by the rotating screw.
|
| Am I totally off here?
| adolph wrote:
| The authors did test having a "lip" around the edge of
| the screw:
|
| _It was hypothesized that a down facing lip would
| prevent air from escaping radially outward from the
| rotor, but this was proven incorrect. All rotors tested
| (3,4 and 5 in Figure 2.2) have 1 turn, a pitch of 100 mm
| (3.94 in), a radius of 76 mm (3 in), and a 1:1 taper
| ratio._
|
| _A downward facing lip showed reduced thrust and an
| upward facing lip showed negligible impact on thrust in
| Figure 2.7._
|
| _Flow visualization conducted during this trial revealed
| that air was being ingested radially inward during
| operation of the no lip and up facing lip aerial screws,
| and that this flow was disrupted by the down facing lip.
| These results support the findings of the CFD studies
| detailed in Chapter 3._
|
| _Figure 2.8 indicates that the presence of a lip in
| either direction increased the power requirement of the
| rotor. Figure 2.9 shows that the presence of a lip in
| either direction also reduced the FM of the aerial screw.
| Therefore, a lip is not a useful design feature at all,
| and was discarded._
|
| http://vfs.umd.edu/assets/downloads/2020_elico.pdf
| whiddershins wrote:
| There might be times where longer blades would be less
| desirable though, could this have some niche use?
|
| Also seems like the screw shape could be less prone to
| breakage.
| dr_orpheus wrote:
| True, they mention in the article some possible
| advantages of reduced noise and downwash.
| [deleted]
| walrus01 wrote:
| on a quadcopter or similar the useful metric is grams of
| thrust as measured instantaneously on a thrust stand vs
| watts consumed by the motor.
|
| see users guide here for details.
|
| https://www.tytorobotics.com/products/thrust-stand-
| series-15...
|
| it's basically a load cell and an inline DC ammeter with
| some logging software.
|
| usually denoted as g/w or kg/w on big things.
| roughly wrote:
| > Anything can fly if you slap modern 7K RPM BLDC hobby motors
| on it.
|
| "With sufficient thrust, pigs fly just fine."
|
| (https://datatracker.ietf.org/doc/html/rfc1925)
| pengaru wrote:
| > Anything can fly if you slap modern 7K RPM BLDC hobby motors
| on it.
|
| Is 7K RPM supposed to be an impressively high number?
| dekhn wrote:
| No, but the real point is that the power to weight ratios of
| hobby BLDCs have absolutely gone crazy over the past 2
| decades. Lots of work put into their power efficiency to
| maximize flight time on batteries.
| xwdv wrote:
| What is the maximum possible RPM of something if it could
| spin at the speed of light? Shockingly low.
| mlac wrote:
| It's ~10,052,473 times faster than the earth spins, so it's
| got that going for it.
| pengaru wrote:
| And it's the same speed the iron 4-cyl ICE in my shitbox
| redlines...
|
| 7K strikes me as an exceptionally slow hobbyist scale
| electric motor, not the kind of thing I'd point out as
| capable of making _anything_ fly.
| 0xbadcafebee wrote:
| Just because a motor can sit on your desk and turn at 7k
| rpm doesn't mean it can pull a flying chair off the
| ground
| mihaic wrote:
| Does anyone know how old the toys that launched a propeller from
| a stick-spiral are? I used to play around with these as a kid,
| and was fascinated how low tech they could be and still fly.
| adolph wrote:
| _This helicopter-like top originated in Jin dynasty China
| around 320 AD_
|
| https://en.wikipedia.org/wiki/Bamboo-copter
|
| Edit: _This Chinese helicopter toy was introduced into Europe
| and "made its earliest appearances in Renaissance European
| paintings and in the drawings of Leonardo da Vinci."_
| Wingman4l7 wrote:
| Pretty old -- the Wrights played with something similar as
| children: https://www.wyso.org/news/2017-12-25/the-toys-of-
| orville-wri...
| novosel wrote:
| Wright brothers were also quoted saying that they can make
| this table fly (the table where the interview was taking
| place at) if they could have a powerful enough motor at hand.
| This was, of course, after the first man flight was achieved.
| hnbad wrote:
| Can I just point out how jarring it is to read "pretty old"
| followed by a mention of the Wright brothers, the last of
| whom died in 1948.
| function_seven wrote:
| Not the thing you're talking about, but I remember having a lot
| of fun with these:
|
| https://instructional-resources.physics.uiowa.edu/demos/10c1...
|
| Just a stick with a 2-blade prop on the end. You spin the stick
| between your hands and see how high it'll go. But that got
| boring real quick! The real fun was trying to shred your
| friends' faces with it at 10 paces away.
| carabiner wrote:
| I'm actual size!
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