Ikarus electric “rocket” – Thrust-vectored flying ducted fan [video]
youtube.com
youtube.com
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!
I could be wrong. I am not an aerospace engineer
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.
This sort of inverted pendulum type system would typically require at least 1/s^2 control. It also has the additional complexity of gyroscopic torques, center of thrust not through center of gravity and servo control lag.
This is similar to controlling a rocket, something the Germans took a long time to perfect with the WW2 V2 missile.
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.
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.
(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).
Is it because a single rotor is much harder?
Helicopter blades pull the vehicle up from the top, rocket thrust pushes the vehicle up from the bottom.
http://www.curtisyoungblood.com/legacy-product-support-curti...
I used to fly r/c helicopters before drones became popular. The pitch mechanism was routinely a source of problems for me. It’s pretty amazing to watch it work though.
(A high control frequency makes all the difference here for quadcopters. Compare a toy and a hobby quadcopter, it's easy to spot the difference.)
Also, lift generated due to the top and bottom of airfoils can be quite different.
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
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.
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.
https://aviation.stackexchange.com/questions/35764/are-helic...
Of course, you’re also right that the aircraft can decelerate faster, since each rotor can thrust in either direction (the same effect that allows for flying upside down and accelerating toward the ground faster than 1g).
Lastly, I assume that variable pitch quadcopters are able to autorotate in the event of a motor failure (not that that’s super important for relatively inexpensive unmanned aircraft).
Maybe the reason it hasn't been done much before is because one doesn't have to actually go and build this to know that it will be extremely inefficient and painful to fly...
Here you have a single rotor, and just try to imagine what happens when you vary its speed. It might bob around, fly up and then crash into something, but you won't be able to point it anywhere. Imagine trying to fly a ceiling fan.
This guy uses something called "thrust vectoring", i.e. "pointing the thrust of the single rotor in some specific direction" to steer it around, but for that you need something to redirect the flow of air, which he designed and custom 3D printed.
Which is pretty damn cool.
The duct itself offers some advantage but it's used here to vector thrust for control rather than just go up and down.
Battery power is quite constraining already for aircraft, ducted fan offers some benefit. The US military use a petrol powered ducted fan drone operationally, though i believe that's dual rotor, this is single rotor that offsets counter rotation with vectoring.
What would happen if rotors were added, ala Kamov helicopters.
On a multirotor, there are obviously 4/6/8 motor/rotor sets, typically positioned far from the mass centroid, so control is effected by 1) varying the thrust from each rotor (primarily pitch & roll), and 2) varying the speed of each rotor for inertial effects (primarily yaw). This uses a single rotor and thrust vectoring fins to influence the direction and reaction to the thrust.
I'm more interested in how the efficiency numbers work out.
Typically, a larger rotor produces more thrust per unit of energy. However, a ducted fan is also typically significantly less efficient than an un-enclosed rotor. Since I don't have numbers, my question is which effect dominates -- is it overall more or less thrust efficient than a multirotor?
Either way, it is a very cool design & build -- nice work Ikarus!
I’m surprised someone hasn’t hooked up a remote control interface to an existing car.
This kind of stuff was done in the Daemon/Freedom sci-fi books, which are entertaining and becoming concerningly less fiction with every passing year.
That’s not to say it won’t happen (Uber) but it shouldn’t.
They were extremely effective in combat, and called the "poor man's cruise missile" by analysts. Here's a video of a strike; note that they were often used in as the opening salvo of combined arms attacks. https://www.youtube.com/watch?v=AZBAU_TTZ-4
Of course there’s an aspect of their ideals that glorifies suicide so maybe they’ve already thought of this but just prefer to keep the suicide route.
Self driving cars already have everything required to control the car built in. They just need to hijack the existing controls and hook it up to a RC system (or just tell it to drive to location using internal controls).
I think the answer to defending against offensive UAVs is defensive UAVs. Just today a story[1] appeared about a USAF Reaper shoot down of another UAV. Supposedly a first.
[1] https://www.popularmechanics.com/military/aviation/a23320374...
Edit to add: of course, it’s a never ending cycle of attack vector vs countermeasures I guess.
I’m not really sure how we counter this type of threat.
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.
Then EM pulse weapons, lasers etc.
That's addressed in the film.
> EM pulse weapons
That's not actually a thing.
> lasers
Aside from being impractical, this is bringing a knife to a carpet bombing. The video is about the potential of autonomous drones being used against civilian targets. Unless you put all civilians in bunkers guarded with lazors, they are irrelevant (plus of course you still have created a nightmare scenario where humans need to live in bunkers to avoid random electronic micro-terrorists).
I believe this is also the biggest intent of Black Mirror (where I believe the video is from).
For example Facebook and Google have so much data about you that a drone can track you down by using this data. Geo data, face data, habits, family and friends, you name it.
Let's hope the video will never happen.
Black Mirror does have a very similar episode though: Hated in the Nation (S03E06).
Artillery travels faster than the speed of sound, you hear the impacts before you hear the guns firing.
Similar sort of story with fighter jets. The loud end is behind the jet, you just hear a faint whining as it comes towards you, and an almighty woosh as it flies overhead.
In both those cases, if you can hear the source of death, it means you've escaped it, at least momentarily.
It uses a lot of fuel, you can't maneuver easily, and you fly over your target too fast.
I'd imagine that takes a bit of time to hit the ground, unless it's rocket propelled. So you will probably hear the jet just as it's about to detonate, no?
Would that not be sufficient? Sorry if it's covered in the video I've only seen the beginning so far.
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.
Disclaimer: I believe building good wings is not a trivial task; even compared to this awesome rocket.