2 posts were merged into an existing topic: Slow Chat
@floba Thanks for sharing.
Not really sure if I saw some propellers on the top of the two sticks to control pitch doing hover.
Congrats and making what looks like a working ground station 
Also the transition into crosswind isnât the most graceful I have a seen.
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Oh wow
Those dudes blow my mind.
The complexity of control they achieve with little resource is astonishing.
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If this is a prop/generator blade combined design, it would be interesting to hear what performance expectations Kitekraft had with this device
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During this flight we tested various controller settings. Blog post with more information coming soon to https://www.kitekraft.de/blog
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Thanks Kitekraft for sharing!
It seems they are flying stably.
The video shows a little bit how hard this is. Because once you have stable flight, the next generation of problems show up.
I see a wobble in flight that is probably detrimental to performance.
Also the angle tether vs main wing is so large in the turns that you canât expect it to be possible to fly smaller patterns. This is not a problem per se, just seeing that a design freedom is at itâs limits. And with larger scale and square-cube mass scaling, the pattern would be relatively bigger, increasing cosine losses.
Still, a good achievement from Kitekraft. This is a long flight, more than one hour and with takeoff and landing. Bravo!
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Looks like it was able to handle a wind shift backing from (Guessing) North to West
What surprises me is the relative large size of the gen/prop blades vs wing area
Well done KiteKraft
Another recent video:
Uncut Flight of Kitekraft Demonstrator - Tail Cam
Kite size: 2.4m wingspan (1:4 scale).
Location: Oberbiberg near Munich, Germany
Date & time: 24 July 2024, around 4 pm.
Wind speed: 1âŠ4m/s from west. (This is below the cut-in wind speed and thus too little for net-positive power generation. A product-version kite would remain on ground and wait for stronger wind.)
Name of kite: SN9 âEserâ
Itâs a great job, thank you @floba for sharing these last videos on Youtube.
I would also like to hear the sound (when stronger winds occur during tests) which is a simple way to communicate approximately the evolution of the power during the flight within this large (compared to the wing size) figure-eight path.
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Wow, ask and ye shall receive - Thanks Pierre.
Now Iâm not sure why they are calling this video âTail Camâ when it was a downwind view from proximate the base station, versus the previous video having featured a âTail Camâ.
And the date given: Date & time: 24 July 2024, around 4 pm - is 11 days in the future even from today - huh? Possibly confusion generated by the European way of writing dates?
It does seem like my suspicion of no power actually being generated might have been true for the previous video, since that is what they say about this video - winds too light for power production.
So this is a 1/4 scale model? Do they have the larger, full-size version yet, or is that just on paper?
I would note that I couldnât help mentally positioning a standard wind turbine into the same open field, imagining how much power it could be making, assuming there was any wind worth chasing after, at the timeâŠ
OhhhhKay
Which planet?
Pretty sure even American date naming convention and order has this as acceptably recorded in the past
They stated they would need to scale up to produce power at AWEC
Sorry I seem to always get July and August confused for some reason - you know, those boring, hot, late summer months. Thanks for catching that. I knew something was amiss!
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Yeah, no wonder it flew so well, maybe a ground-powered flight (?)
I guess I missed that statement, wherever it appeared.
Wind turbines are capable of producing power in a wide range of sizes, as we all know.
It kind of makes me wonder, was this scale model even capable of generating power?
Or was it just a first step toward a kite with extruded aluminum wings, using off-the-shelf normal propeller blades and electric motors?
My guess is the latter. There is probably some custom design, but not enough to get to the power generating stage. Totally uninformed guess though
My guess is just based on the amount of work and cash required to produce said blades and generators, and the amount of activity I am impressing happening at Kitepower
Some information:
About rotors:
Kitekraft system proves full control authority during hover in high winds.
The second batch of test runs focused on mapping the performance of different rotor configurations, shown in the image below. On the left, one of the CFRP rotors is shown which were optimized in-house. These rotors consist of different symmetrical airfoil cross-section and were optimized for the motoric as well as the generative mode.
On the right, one of the currently used, off-the-shelf injection molded rotors with two blades is shown. This rotor was also tested in stacked configurations, using two or three of these two-bladed rotors at the same time, resulting in a four- and respectively six-bladed setup.
Left: CFRP rotor, designed with Kitekraftâs in-house optimization. Right: 2-bladed off-the-shelf rotor, which was also tested in stacked configurations.
All rotors were tested at speeds of up to 8000RPMs (tip Mach Number of around 0.54) and various airspeeds. The CFRP rotors and the six-bladed configuration of the injection-molded rotors already generated the same thrust at lower rotational speeds, which is beneficial for noise reduction. While Kitekraftâs systems will definitely be fitted with customized rotors in the near future, such a stacked configuration could be used as an economic shortcut for improving the performance and reducing the noise emissions of our current demonstrator immediately (see also: How to Develop Flying Wind Turbines Quickly and Cost-Efficiently?).
The efficiency of the in-house designed rotors is over 80% - a very good performance.
The efficiency of the CFRP rotors was measured with values of over 80%. This is a very good value and stands as proof to Kitekraftâs in-house optimization algorithms, which will be of great value for the design of future system sizes.
To sum up, the conducted tests and findings made mark a significant milestone in the path to a rugged flying wind energy system. Firstly, it was demonstrated that the kite can hover stably for launching and landing in high winds. Secondly, it was shown that Kitekraftâs newly optimized propellers performed efficiently.
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About this flying turbine:
Thanks Pierre. As usual, you seem able to dig up the facts.
Nice lecture on engineering from 2020 - they discovered extruded aluminum - amazing.
âHow to develop flying wind turbines quicklyâ - wait - quickly? Dateline 2020, still working on getting a scale model to generate any power whatsoever? Because they discovered extruded aluminum, one of the most common materials?.
A nerd-fest?
Looks like they are using off-the-shelf plastic large-scale model airplane propellers, like both Pierre and I did with our early experiments. Great for flying, not so great for producing power. Sure, developing generators and props takes a huge budget, unless you are a good fabricator and can do everything yourself⊠No âHuman Resources Departmentâ is required, if you can tie your own shoes.
A few years back, I could not believe my eyes when reading about some of these fledgling wannabe AWE companies spending millions on ârenting office spaceâ and hiring huge staffs, just to predictably accomplish next-to-nothing and eventually âjust give upâ. This is all about people stuck on their computers, with no natural ability to just build something.
Do you realize, as one of the few examples of success in wind energy, the worldâs leading small turbine manufacturer is just a small family operation with just a few employees? And with that, they produce turbines that actually work as advertised, last for 20 years or more, and can easily power your home.
To me, this next project looks like âmore of the sameâ - the âall-talk formatâ: helpless teams struggling to achieve anything even remotely approaching basic functionality, with, of course, all real accomplishments, even at such a basic level of just producing power, which was the main idea and only purpose, perpetually âin the futureâ. Itâs the smartphone generation, living in a fantasy world, disconnected from reality.
I obtained about 67% Betz limit by car with a tiny propeller that rotated by the trailing edge, in an unorthodox way (it turned slowly, generating low power, when it faced the wind). In fact this propeller was so tiny (23 cm diameter) that it was almost flat. So perhaps, in a multiple rotor system, it is a not too bad temporary solution for flygen AWES.
Now concerning Kitekraft, one thing bothers me. Below are quotes from the respective Youtube videos:
(power production mode; during this flight wind was too low to actually produce power)
The wind always seems to be too low. Is it so difficult to test with 5 or 6 m/s wind speed in order to know the real average net-positive power?
This reminds me a bit of the Makani technical videos. In one of them we can see that even with a wind speed of 10 m/s, the average power still seems negative:
