
Ikarus electric “rocket” – Thrust-vectored flying ducted fan [video] - inetsee
https://www.youtube.com/watch?v=RMeEh5OUaDs
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cyberferret
Great project. Though as a former pilot, I was wincing at all the foreign
object ingestion happening in the opening sequence! :)

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Serow225
Yeah it could have used a FOD trigger warning ;)

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leafario2
FOD: Fear of Destruction?

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Serow225
[https://en.wikipedia.org/wiki/Foreign_object_damage](https://en.wikipedia.org/wiki/Foreign_object_damage)
:)

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dimitriarendt
I had a similar project on Kickstarter.
[https://youtu.be/xRviasOMCvk](https://youtu.be/xRviasOMCvk)

We made 300k$ but then dropped the project and gave money back to backers.
Basically beyond the "damn cool" effect there is no edge over quadcopter. It
is less efficient. You gain something by the duct effect but the duct is
heavy. It is very noisy. More sensitive to wind, especially when you try to
reduce weight to make something affordable to build and sell. The only benefit
was safety due to ducted fan but the point vanishes against mini drone the
size of your hand like latest dji.

But for sure it s dann cool and fun tech to master. Kudos!

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madeuptempacct
This is really cool. I find it very strange that it's less efficient though.

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georgeecollins
I believe it is because propellers get lift from air pressure, which is more
efficient than just pushing air for thrust. If you are sucking air through an
engine you don't get that bernoulli effect.

I could be wrong. I am not an aerospace engineer

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dimitriarendt
The efficiency of a propeller depends on the ratio thrust/area, the smaller
this ratio the higher the efficiency. (See 11.7.3 at
[https://web.mit.edu/16.unified/www/FALL/thermodynamics/notes...](https://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node86.html))
The issue with the ducted fan is that the propeller size is constrained and
the weight is higher due to the mechanical structure. A small quadcopter has
twice or more propeller area for a portion of the weight.

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georgeecollins
Thanks! I learned something from this.

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jmpeax
Cool, add a camera and some AI and you've got an autonomous leaf blower.

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lostlogin
Oh wow. Making those way more annoying previously seemed impossible.

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chillingeffect
Wow, it seemed straight forward for the first 10 minutes or so, when he
introduced the biggest challenge: gyroscopic motion due to the high speed
rotation. this is a gripping video.

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stickfigure
I was expecting some sort of dynamic feedback system based on a gyro sensor,
but apparently the compensation is just hard-coded? I'm amazed that can work.

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Animats
Ducted-fan VTOL aircraft are surprisingly stable. Here's the Hiller Flying
Platform of the 1950s.[1] It's very stable, even though top-heavy. It's mostly
steered by leaning, but there are thrust-vectoring vanes to control yaw.

Many variations on this theme were tried in the 1950s, and many of them flew.
But it never caught on. There's been recent interest in larger ducted fan
drones. This apparently scales better than quadrotors. But nobody seems to
really need large ducted fan drones.

If you like early small VTOL craft, many of them ended up in the Hiller
Aviation Museum in San Carlos, CA.

[1]
[https://www.youtube.com/watch?v=W3FS3D1rCos](https://www.youtube.com/watch?v=W3FS3D1rCos)

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msadowski
I'm glad I'm not the only one that found this project fascinating (see my
[http://weeklyrobotics.com/weekly-
robotics-4](http://weeklyrobotics.com/weekly-robotics-4)).

If you are interested in drones/robotics then it's very well worth it to watch
this video. You can learn a lot from the author.

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sonaltr
I wonder how much more power you can provide it to lift a human for a say half
an hour.

I've always wanted to build a jetpack like that from xDubai [0]. This is
definitely easier to build for an amateur compared to the one professionally
built in the video.

[0] -
[https://www.youtube.com/watch?v=_VPvKl6ezyc](https://www.youtube.com/watch?v=_VPvKl6ezyc)

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aidenn0
It would probably look something like this:

[https://www.youtube.com/watch?v=rD8vcTCWpmo](https://www.youtube.com/watch?v=rD8vcTCWpmo)

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sonaltr
I saw that and while that is super cool - (it's being sold for ~$100K btw),
that's not what I was looking for. (think more human plane / human with wings
rather than an human + machine if that makes sense)

(more horizontal than vertical if you will - I'm getting my solo skydive
certification soon and my plan is to move on to wing gliding - which I want to
follow up with something similar to xDubai's suit).

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walrus01
earlier: [https://en.wikipedia.org/wiki/Honeywell_RQ-16_T-
Hawk](https://en.wikipedia.org/wiki/Honeywell_RQ-16_T-Hawk)

[https://en.wikipedia.org/wiki/Hiller_VZ-1_Pawnee](https://en.wikipedia.org/wiki/Hiller_VZ-1_Pawnee)

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consp
Not quite, as they use contra rotating fans to counter the gyroscopic forces
the creator had to tackle. The RS-16 might have a single but can't find any
info on it.

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kaffeemitsahne
Somewhere in the youtube comments it says it uses fans below the propeller to
counteract the torque.

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est
Total noob here, what's the difference between wrapping a quadcopter with a
duct and this?

Is it because a single rotor is much harder?

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hoorayimhelping
I believe a quadcopter has variable-pitch wings that spin to create lift. This
is a fan that pushes a column of air down to create thrust.

Helicopter blades pull the vehicle up from the top, rocket thrust pushes the
vehicle up from the bottom.

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Ao7bei3s
No, not at all.

The technical difference is how the overall thrust is steered:

* Quadcopter: the speed of four (fixed pitch[1]) propellers is managed independently. Spinning a single propeller a bit more tilts the copter away from that propeller[2]. This is very unstable, so speed needs to be adjusted at kHz rates[3][4].

* "Electric rocket": the thrust of the single propeller is steered using the control surfaces at the bottom to deflect the thrust. This is called thrust vectoring. Since the propeller is not directly used to steer, the speed doesn't have to be adjusted that often. However, the position of the control surfaces does.

* Helicopter: tilts the rotor plane[5] to tilt the aircraft, and inclines the individual rotors to change the magnitude of thrust. The rotor speed typically remains constant.[6] Helicopters are aerodynamically stable and don't require an automatic control loop [edit: no, see follow-up post!].

In theory the "electric rocket design" with a single propeller might allow
higher efficiency: larger propellers are generally more efficient (thrust per
watt). (However, the model in the video won't be very efficient, the props are
quite small. And there'll be other tradeoffs too.)

Also, this is a refreshing take on RC aircraft that hasn't been done as much
before.

Lift is generated on both sides of the propellers in both cases.[7]

Optional reading:

[1] Generally - variable pitch quadcopters exist. However that gives up the
mechanical simplicity that's one of the main advantages of quadcopters over
helicopters. Their advantage is that they can actively decelerate a lot more
efficiently and also fly upside down easily.

[2] And turns the copter (yaw). Quadcopters use two pairs of counter-rotating
propellers to be able to cancel the yaw.

[3] Quadcopters are unstable and need to measure linear and angular
acceleration and correct the propeller speeds very quickly. Control frequency
of 100Hz flies, 1kHz is somewhat standard, 32kHz is state of the art. (Note:
Propellers have significant inertia. To give an idea, reversing prop turn
direction in-flight takes ~1sec (and requires special symmetric props if it's
supposed to work efficiently).

[4] This is feasible since the propeller is smaller (less mass, less inertia)
than for helicopters.

[5] Due to gyroscopic effect, the tilt of the aircraft is 90 degrees out of
phase.

[6] Assuming the typical variable-pitch helicopter. There are other options
both for real life helis as well as for models (fixed pitch, coaxial, ...) but
they're rare (or very cheap toys).

[7] Side remark: lift is generated due to flow turning, not due to different
pressure differences caused by different airspeeds over top/bottom of wings as
is taught in school. Search for "NASA incorrect lift theory" to learn more.
[https://www.grc.nasa.gov/www/k-12/airplane/wrong1.html](https://www.grc.nasa.gov/www/k-12/airplane/wrong1.html)

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bboreham
> Helicopters are aerodynamically stable

That’s not my experience as a helicopter pilot.

I believe the textbooks say they are “statically stable and dynamically
unstable”, but the bottom line is you surely do need a control loop.

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Ao7bei3s
Thanks for correcting that part then.

I've never even been in a real helicopter unfortunately. I really wish I could
touch the stick of one once to see how it compares to models in terms of
touchiness... it's (un)fortunate that there's probably no realistic way to try
that.

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nradov
If you can afford $150 some helicopter flight schools offer prospective
students a brief introductory lesson where you can touch the stick.

[https://www.specializedheli.com/helicopter-
training/](https://www.specializedheli.com/helicopter-training/)

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dbatten
The YouTube codec did some wild stuff with that slow-mo flying mulch at the
beginning... any video experts around that can explain?

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vizzier
Tom Scott did a video on this very subject with a decent amount of depth:
[https://www.youtube.com/watch?v=r6Rp-
uo6HmI](https://www.youtube.com/watch?v=r6Rp-uo6HmI)

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dmix
In the future I have a feeling that's the sound you hear before death is
approaching in a battlefield. Much the same way as the sound of jets overhead
or the squeal of dive bombers in WW2 or the whistling of artillery in WW1.

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rblatz
This is our future
[https://youtu.be/TlO2gcs1YvM](https://youtu.be/TlO2gcs1YvM)

I’m not really sure how we counter this type of threat.

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krob
Wow, mind blown, your video link scares the shit out of me.

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atrilumen
Yeah, wow; it's just an application of existing tech. very scary.

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rtkwe
There's a couple sizable leaps in there in particular the combination of size,
payload, and autonomy for the main mini murder drones. Particularly
quads/drones of that small size just don't have the payload/flight time
combination to really do that, they're extremely sensitive to weight and have
really short flight times that are hard to extend because more weight requires
more power in kind of a mini version of the rocket equation.

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pluma
Well, if you deploy them close to the targets, they don't need much flight
time to deliver the charges.

The idea is that instead of packing a truck with explosives (which create a
large but very localised detonation) you just deploy a swarm of these and let
them take out whatever group of people you want to target.

Unlike in Black Mirror's _Metalhead_ this isn't a scenario that requires long-
lived machines. You just need them to be readily available at scale and to use
facial recognition (or whatever -- the US already targets drone strikes based
on cell phone signals I hear) to determine their targets.

Or hey, imagine a white supremacist group (not like the US has any of those)
using them to just kill people of color. Terrorism doesn't need anything
approximating a 100% success rate to achieve its goal.

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nodesocket
Amazingly cool. If he can find some lighter batteries with the same output it
would make a huge improvement in stability I am assuming.

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patpatpat
If it's heavier it's actually more stable because it's harder to move a
heavier object. But maybe you mean that a heavier craft is slower to
stabilise?

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52-6F-62
I think it's because the batteries are teetering above the centre of gravity?

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rasz
you want center of gravity above the propeller, its the classic balancing a
broom on the tip of your fingertip trick

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atrilumen
So glad birds don't make that kinda noise.

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sonium
As I understand, much of the difficulty controlling this comes from the
gyroscopic effect. So wouldn't it be feasable to add a gearbox and a secondary
rotary mass to cancel out the angular momentum? If you spin the secondary mass
fast enough it also wouldn't add that much weight.

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k__
Adding weight to solve this problem doesn't sound like a good idea to me.

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p1mrx
This almost looks like the original App Engine logo.

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kjeetgill
Pardon my ignorance. Is this that different from a helicopter besides having
walls? Does this mechanism serve a different purpose?

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danboarder
A helicopter uses a rear rotor to counteract the main rotor rotation. Here he
is using thrust vectoring to perform that task.

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kjeetgill
Ah, thanks! Some helecoptors also just use a second main rotor spinning in the
opposite direction instead right?

Would that not be sufficient? Sorry if it's covered in the video I've only
seen the beginning so far.

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Moru
Yes but he only had one fan. Just a rotating ring mounted somewhere would help
too. But not as much fun I guess :-)

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archi42
Nice! I wonder if it would be possible to add wings and build a VTOL plane
with thrust-vectoring?

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cybrjoe
Fixed wing and let the thrust-vectoring pitch it over for forward-flight.
Pitch up for SpaceX style landing.

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ansible
It's been done with two electric motors. This is the E-flite X-VERT:

[https://www.horizonhobby.com/efl1800](https://www.horizonhobby.com/efl1800)

You can fly it like a regular plane, or hover like a quad. It doesn't do that
well hovering in wind though.

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archi42
But no trust vectoring :( still looks neat.

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jazzyjackson
the future is loud

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newnewpdro
Very cool, some nice hands-on engineering going on here.

