
Cleo Robotics Demonstrates Uniquely Clever Ducted Fan Drone - jonbaer
https://spectrum.ieee.org/automaton/robotics/drones/cleo-robotics-demonstrates-uniquely-clever-ducted-fan-drone
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mickronome
Unless the fit of the casing parts is atrocious, there appears to be a slit
right above the grey ring the camera is mounted in.

Due to the shape, and it's location it's quite possible that internal shutters
or ducts can be configured so as to allow partially disrupting the coanda
effect on either side by selectively allowing air to exit through the slit.
Possibly, but not necessarily ducted in from the fans high pressure zone.

This would likely cause a rather strong vectoring of the thrust as it would
also almost certainly lower the lift on the detached side due to interactions
with the fans.

If that isn't how its done, I'm quite positive it can be done in this way.
I'll be happy to be named inventor in any thusly aquired patent and collect a
very modest licensing fee, if only that would be how the world works...

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blamestross
My wild bet: The two rotors are not coaxial. It is a very narrow bicopter (if
the two rotors are not actually on the same axis and contrarotating then you
get 3 degrees of freedom)

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knob
Throwing my idea out there: What if the to propellers are synched. Depending
on desired direction, they are "un-synched" ever so slightly. This causes
additional thrust on one side of the "duct".

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bigiain
ATH Zurich have a single prop craft that uses just a single channel high speed
motor control to stabilise and steer it:
[https://www.youtube.com/watch?v=P3fM6VwXXFM](https://www.youtube.com/watch?v=P3fM6VwXXFM)

I wonder if this maybe has two contra rotating single blade props that they
can control quickly enough to be able to speed them up for half a revolution
to generate asymmetric thrust to provide pitch and roll?

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usrusr
Pictures show 2*3 blades (well, one three bladed and two blades of a similar
layout, with one obscured)

But it could still be based on the same idea: if the blades are not flexing in
the same way under acceleration, any asymmetry might do it, if it can be
properly controlled.

Which brings us to how I thought this thing does pitch/roll until I noticed
that I just got hung up on a difference between a prototype in the picture and
a later iteration in the video: contrarotating propellers will influence each
other when blades meet, creating nonuniform efficiency over the duration of a
rotation. Three peaks and three troughs, like the legs of miniscule of
pressure differential. I don't know where the peaks would be relative to the
meeting points, but given the general fickleness of aerodynamics thrust of
contrarotating propellers just can't be perfectly even all around the
rotation. But that's still three-symmetric. It could become a control option
when overlapped it with e.g. an n-symmetric grid where n is not a multiple of
three, even if not a good one (mixing it with yaw would be a wobbly mess). The
prototype picture shows five arms which is how I got the idea, but in the
video it seems to be six/three, so this candidate is out (unless the
specifically made a misleading dummy for the video, which I don't think, even
though the video is cut in a way that it might be).

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sterlind
Perhaps the attitude of each fan blade rotates independently. To angle the
drone, say, forwards, the fan blades might angle flat when they're at the
forward position, every cycle, and angle tilted at the backwards position?

Seems expensive and tricky though.

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hedgehog
"An Underactuated Propeller for Attitude Control in Micro Air Vehicles"

Paper is not free but video conveys the idea well:
[https://www.youtube.com/watch?v=KZe7l5_LfoA](https://www.youtube.com/watch?v=KZe7l5_LfoA)

Likely with clever two-material molding you could do away with the hinge and
it would look similar to the prototype shown in the article.

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mannykannot
That is very clever, but the article says that this drone "introduce[s]
control surfaces into the airstream to change the direction of the airflow and
create a thrust vectoring effect." My guess is tiny spoilers around the inside
of the duct to cause separation of the flow in one quadrant of the duct,
allowing the Coanda effect to draw the stream in the opposite direction.

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brandonjm
I don't know a lot enough about aerodynamics or airflow to be sure, but could
they be moving pieces of plastic on the inside of the donut to block some of
the airflow on one side to make it bank in that direction?

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BugsJustFindMe
> _Cleo, meanwhile, boasts a useful battery life in the 12-15 minute range_

For some definition of useful. Batteries really are the worst thing ever. We
got dense energy from oil so early, and then nada.

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thisacctforreal
If there is a charger at each desk only 5 minutes of battery is needed.

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Yaggo
> With fewer motors than conventional quadrotors, it promises to be more
> efficient as well [...]

I doubt that, because in "stacked propellers" configuration the second
propeller gets very turbulent air, causing extra noise and vibration, i.e.
loss of efficiency.

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foota
Could you flex the shape of the inner donut somehow to change the vortex?

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akhilcacharya
+1. This is what I was thinking but I'm not a a MechE. Would it work?

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foota
I'm not a mechanical engineer either :p

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api_or_ipa
Very interesting. I wondered when someone would try to mesh coaxial rotors [0]
with quadcopter use cases.

To make a real co-axial vehicle, you'll need to handle changes in the 3
translational axes (forward/backward, strafe left/right and up/down) as well
as the rotational axes. Despite being a complicated movement, it's pretty well
understood and Kamov has been making coaxial helicopters for many years.

My best guess based on the video is that there are two contra-rotating fixed
pitch props in the middle. This gives you up/down and by varying the speed of
the props gives you yaw right/left. A couple of clever ducts forward, aft,
left and right on the duct give you stability forward/backwards and
left/right.

I look forward to actually learning how they did it. It certainly looks cool.

0
[https://en.wikipedia.org/wiki/Coaxial_rotors](https://en.wikipedia.org/wiki/Coaxial_rotors)

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taneq
You only need four degrees of freedom to control an air vehicle in gravity
(upward thrust and roll/pitch/yaw). You could still use internal ducting (as
you suggest) to do that, but it'd probably be easier and more effective to
have little flaps that deploy into the airstream under the rotors to divert
the airflow.

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phinnaeus
Would it be practical to use a gyroscope to control one axis of rotation in a
"drone" like this?

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ziqiaojin
That is a cool idea, if you can get really light and efficient mechanical
gyro.

A boring solution will be fins operated by micro servo/

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salty_biscuits
Coanda effect? Some little jets somewhere to entrain the flow?

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sebastos
Yep, perhaps just coanda effect with control surfaces on the bottom. Sort of
like what the AESIR guys did:

[https://www.youtube.com/watch?v=KXVtUCABiv8](https://www.youtube.com/watch?v=KXVtUCABiv8)

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tudorw
Anyone seen any tip driven motors in drones ? I found one test but not much
detail,
[http://ieeexplore.ieee.org/abstract/document/8101907/](http://ieeexplore.ieee.org/abstract/document/8101907/)

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tritium
Did anybody else notice that this is a flying saucer?

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andygates
With a little control autonomy, it's the throwable flying map-ball bots from
Prometheus.

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linguistbreaker
they could just deform the shape of parts of the duct, altering lift generated
on one side or the other.

