Thanks for letting me know about this amazing achievement.
So would this mean that we could fly a pair of kites, playing the role of a large rotor, and without the need for a kite lifter or active control?
It would be interesting to have more details, if possible from the author.
Great to see a new multi kite rotor configuration being tested.
I hope you get some good backing for your experimentation Jean-SĆ©bastien.
Rotor expansion is something Iāve been keen to see tested.
The expectation I have being that expansion enables, easier deployment handling, with a dense deployment form, which then leads to large rotors in operation, with minimal mass, and max speed. Thatās got the potential for a big step up in efficiency.
A hell of a lot to prove but - Nice start
Very impressed that there is no lifter.
As an aside - Iām still considering using a static lifter as the initiator for chained dynamic lifters.
Can we presume this test was being flown from a mast just off to camera top left where the tethers are all headed.
I canāt quite suss out what mechanism actuates the extra line length for expansionā¦
Would love to know more too
I presume the intent is to move toward yo-yo / phased tugging
Thanks @rschmehl for the share
They will probably need a lifter kite for lunch and land. In yo-yo mode, during wind gusts, sudden retraction of the lifter kite might prevent the system from falling to the ground.
Hi Rod:
No visible lifter.
So what are those suspension support lines going up to, a structure?
From what other source have we become accustomed to seeing 2-second āblink-and-you-missed-itā videos?
That might be a good goal for AWE: a system where you could go have lunch, then come back, and it is still flying! 
As stated in the video, there is āNo roll controlā because of āFixed bridlesā. But there is pitch control. Indeed this device works like a rotor and is a rotor. And a rotor (for helicopter for example) is controlled by the pitch (including collective pitch) of the aligned blades, and not by the roll. So there is an active control.
Like any controlled rotor, lift is ensured by pitch control. So there is no need for a lifter kite. And takeoff could be achieved and easier when the two blades are close each other.
It is an extendable rotor. There are two rigid blades which have a low aspect ratio, and whose shape is very simple.
It could be used in yo-yo mode, but also as torque transfer device in a simplified version of the The Pyramid, perhaps as flygen device with secondary rotors settled in the respective external wing chords.
It looks like a brilliant idea and a preliminary achievement. We wait for the sequel, or we make it happen.
About āPassive Cyclic Control Device for Helicoptersā:
Sounds great Pierre, as our imaginations fill in all we donāt see, but what are those upper suspension lines suspended from, in this 2-second video with its limited view?
A comment from the author:
āThanks for sharing! There is a lifter off the picture. The idea is to take off as a spinning drone in the future but we are not there yet.ā
@tallakt , @Windy_Skies , @Rodread and the complete team of the forum,
Jean-SĆ©bastion Brouillon indicates in one of his comments on Linkedin that he would like to be able to answer.
It would be desirable if you could indicate him the procedure to follow to open an account and be able to post, not only for this topic, but for all the topics on this forum. For now other topics may already be quite close, such as for example The Pyramid or Centrifugally Stiffened Rotor (CSR) as a model for an AWES? or A self-erecting passive Daisy (or other rotary). Thanks.
He did not receive the confirmation email.
How can he solve this problem?
I donāt get emails from this forum either.
I do still see new sign ups in the last couple of days, but none that were activated in the last two months, which probably means that they also didnāt get the activation email. Does anyone else still get emails from the forum? @Lukas or @tallakt could look into this.
Iāve activated his account now.
Note that until this is fixed you wonāt be able to change your password either.
So this is an interesting question as no roll control vs roll control is tricky to analyze.
I think [2] is quite clear that if the force is only aligned along the axis of rotation, the TRPT rig would never elevate from zero degrees, even if the lift force of the kite was varied over the full cycle. In short, force balance dictates that the kites would fall to the ground. One can use moment calculation and assume the whole soft structure is stiff due to tension, but that will not be a good assumption, because there is no force to keep the bridle between the kites taught.
So we would be discussing here some version of [2]. I would agree that this is possible. But, it would be a system with a lot less design freedom compared to a similar system where both roll and pitch [lift force and drag] were controllable. I would argue that a system like this [2] can only be proven to work in a very narrow window of operation, but for practical use, we would need both roll and pitch control. Whether or not we also would need yaw control is harder to know, I expect also being able to control yaw would make some things easier.
I do think for this particular problem, you need to tackle the full problem head on, or else it will be quite disappointing in terms of performance results. I am not trying to suggest that Mr Brouillonās rig is not an impressive accomplishment, just saying I think its just a small step on a ladder.
@someAWE_cb tries to do something similar. He instead uses a rigid rotor where he does cyclic pitch variation. I donāt think that and this will work without a built in roll angle to allow the pitch variation to result in force variation perpendicular to the axis of rotation.
Your video is difficult to analyze. Is it sped up, and how are you doing the pitch variation? Now it seems to do one rotation in a fraction of a second. One wonders if the kite will be able to change its pitch fast enough, and about the slow down of the kite at the top of the loop from the extra drag resulting from the higher angle of attack, and its weight. Tallak for that reason uses 3 kites that he connects together in his Pyramid concept.
And how are you doing launch and landing?
If you are using lines or motors to control the pitch, you could also use the same to control the roll angle? Would it be easier and quicker to control pitch angle or roll angle, and which would result in more control authority?
@tallakt I canāt follow your numbering, or maybe you made a mistake somewhere? Iād do something like [1] no fixed roll angle, [2] some fixed roll angle, [a] zero elevation angleā¦ [ā¦] percentage of stall speedā¦ [ā¦] centrifugal forceā¦
Welcome to the forum @JS_Brouillon.
Congratulations for both your test and device, which seems to give rise to a first in-flight view of such a device.
If you have the opportunity to provide additional information, please do not hesitate.
In the meantime here is a device (from Bladetips Energy ) that might perhaps have some similarities (in addition to other mentioned devices), but only a rendering is shown in the video reproduced below (see from 0:43, where I started this video):
Bladetips Energy technology and vision
They are rotating the whole AWE axis of rotation I think, to generate lift force.
I edited my numbering scheme somewhat to make it more readable. there is just option 1 and 2, i guess tilting the axis of rotation would have been [3]ā¦
Hi everyone, thank you for all the positive and constructive criticism! Sorry that I could not answer earlier. I did not expect to get that much attention, the video was mostly meant to explain my peers in the control community how I intended to control that seemingly complex system.
Thank you all for sharing the similar past inventions. Although I was familiar with some of them the breadth of knowledge is very helpful. I think what really sets this system apart and why I am pursuing it is the possibility of using bridles without reels to actuate them all. Similar to bridges, where past a certain length the road must be supported by cables or regular pillars, when I crunched the numbers, I found that supporting the wingās structure is the only thing that makes economical sense at scale. Iām sure you know that there are some very nasty square-cube laws.
I would also like to answer the more negative points to avoid any misunderstandings.
Although we started simulations and calculations about a year ago, our earliest prototype dates back only 2 months. There is a long road ahead and hopefully we can show improving results. Iāll try to stay active on social media if you are interested.
Is it not the same for the Two kites orbiting each other do not need roll control?
@JS_Brouillon , I think a complete plan of the device in flight would be welcome, including the lifter kite even if it is temporary, including also the ground station.
@PierreB I have most of the theoretical details written down in the provisional patent application I submitted in November. You can find it here: Scalable and controllable airborne wind energy systems. Note that most of the contents are background and not new. This is a provisional application so I included everything I could. It will be rewritten this year. The lifter drone (itās a drone at the moment not a kite) and base station are not included but there are some pictures on my linkedin profile. The ābase stationā is a simple bearing with two anchors for the tethers, not generating energy yet.
We also have a very extensive simulation framework with dynamics identified from a model plane and tether drag calculations. The renders are still a bit difficult to interpret so I am not sharing them yet.
@JS_Brouillon , thank you for this document.
Remarks on formal details concerning the numbering: from 500 in figure 5, from 600 in figure 6 (which is normal) but respectively from 900 and 1000 in the description on pages 14 and 15 for the same figures 5 and 6, so that for example the element 901 described on page 14 for figure 5 is assigned to another element and another figure (figure 9).
Please what is the meaning of the term āelevonsā on page 17? Ailerons? Elevators?
Basically, although they are described, it is difficult to identify the essential elements which define the new solution in relation to the state of the art in spite of the quoted prior art. However the new solution appears very well on the video (fixed bridle and the means for a rotation in extension).
For example the āfairingsā are not specific to the invention even it uses them. Perhaps a first draft of the claims would make it possible to better highlight what is new.
The title itself āScalable and controllable airborne wind energy systemsā does not allow to direct towards the main specificity. Perhaps something like āScalable rotating airborne wind energy systems with simplified controlā, then quickly in the description disclosing the means (fixed bridle, increase of the swept area by using the extension of the lateral tether using centrifugal force).
You have to wait for Figure 6 to see the new elements as they appear in the video. Figures 1, 2 and 3 and corresponding texts describe elements which appear to be part of the state of the art, except for elements justified by equations, but which would then find a better place in the dependent claims (other than the first claim).
Apart from that, as a curiosity, we can see something apparently similar, but only in appearance. We do find the extendable side tether, but in this case it is used for power take-off (PTO).
Stretch kites,
Thank you very much for your feedback! Indeed this is a provisional application to obtain a priority date and be able to share the details with you and others. It does not meet the clarity standards of the EPO yet, but I will ask an experienced lawyer to take care of that. I am working on a more ādigestableā document but these things take time to write. Elevons are both elevators and ailerons, i.e., an elevator with independent movement on each side. Having the ability to slightly shift the tension from one side of the wing to the other may still be useful, even if the roll angle stays constant. But I agree this is not necessarily needed so you can just think of them as elevators.
Iāve seen the stretch kites invention before, It is very different because the tether connecting the two kites moves during the generating phase. Our tether is orthogonal to the movement. I am not sure if anyone tested stretch kites in practice since the invention to see if one can gain efficiency using such a pull. At medium to large scale, I canāt imagine the pulleys have a D/d ratio large enough not to destroy the tether after a few days of operation, otherwise the drag would eat all the efficiency away. That is the main concern we try to avoid with fixed bridles. Even Dyneema rope fatigues extremely quickly, but if the reel is on the ground it can be bigger.
