Yep, and when the tension comes back on the winch which was looser in retraction…
As @Windy_Skies was looking at yesterday … that’s gonna pinch, wriggle, twist, mangle, bite, snarl and generally go bye bye
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Hi Doug, I have just seen a comment from Massimo. The beginning of this comment:
My experience is the opposite, KiteGen fully designed and industrialized both the ground machines and the wings. No more research or experimental activity is required. The energy conversion is hundred times cheaper than a wind turbine.
With such ideas you cannot fail…to fail. That said, KiteGen has the merit of seeking to exploit as wide a frontal sweep area as possible of the powerful high altitude winds. This is where KiteGen stands out. A small prototype could be made.
About KiteGen:
I like those guys from Italy - they’ve even stopped by here for a visit, and we all had fun.
But statements like “a hundred times cheaper than a wind turbine” point toward a departure from reality.
If they have something to run, run it! 
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Do you think anyone is going to want to build a carousel 1 km or more in diameter?
I made one 1 m in diameter, driven by a tilted rotor, and called a rotating reel. It doesn’t spin well. Things are far better when the carousel and the rotor are parallel (examples Daisy or The Pyramid).
http://www.kitegen.com/pdf/IEEECSM200712.pdf
An extract page 2:
The KiteGen project has designed and simulated a small-scale prototype (see Figure 2). The two kite lines are rolled around two drums and linked to two electric drives, which are fixed to the ground. The flight of the kite is controlled by regulating the pulling force on each line. Energy is collected when the wind force on the kite unrolls the lines, and the electric drives act as generators due to the rotation of the drums. When the maximal line length of about 300 m is reached, the drives act as motors to recover the kite, spending a small percentage (about 12%, see the “Simulation Results” section for details) of the previously generated energy [4]. This yo-yo configuration is under the control of the kite steering unit (KSU, see Figure 3), which includes the electric drives (for a total power of 40 kW), the drums, and all of the hardware needed to control a single kite. The aims of the prototype are to demonstrate the ability to control the flight of a single kite, to produce a significant amount of energy, and to verify the energy production levels predicted in simulation studies.
A video of KiteGen Kite Steering Unit (KSU):
Hello @ChristianH , do you think if we can transform the KiteGen Kite Steering Unit (KSU) into a OKE Precision Winch "Reel and Rotate" Technology?
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This two line system has tremendous control, you can see the power in the system by the responsiveness of the kite. The OKE actually does not possess a right line control winch in the nacelle, The purpose of the OKE is primarily to facilitate the rotation of the left line (orbital line) around the tether line (right line). A secondary feature is that it has independent reeling and depower functions.
To answer your question Pierre, an OKE would control the left and depower lines in the KiteGen system shown above, The right line would pass through the center of the OKE and connect KiteGen’s winch to the kite.
The addition of an OKE would allow the KiteGen system to perform any maneuver a two line kite can produce without twisting the line. Control engineers would really enjoy plotting efficient flight paths irrespective of line twisting.
Is it not rather “around the tether line ([right or fixed] line)”?
Does this also cause the orbital line winch to rotate around the fixed line winch?
apologies, it’s late here, I’ve edited it
“The purpose of the OKE is primarily to facilitate the rotation of the left line (orbital line) around the tether line (right line).”
The Tether line or left line passes through the center axis of the OKE. And the Orbital line is free to rotate parallel to that axis. Both lines emitting from the front face of the OKE are parallel
As the KiteGen KSU comprises two winches, doesn’t this make it necessary to also rotate the winch corresponding to the orbital line?
A swivel is placed between the tether and the kite to resolve this issue.
What makes the OKE unique is that it is a reeling and rotating winch, The only lines that need to actively rotate are the Orbital and Depower lines. Since the Right line is conveniently in the center of this axis, it does not need rotational provisions besides the addition of a swivel.
Yes, but how is it possible with the orbital line and the corresponding winch? A sketch would help to understand.
In this video you see a an orbital line (going through a pulley) this is associated with the OKE winch, and a tether line (runs through the center face of the OKE) This can be the KiteGen’s winch in this example.
You can see in this arrangment how it can rotate without twisting, (or under active control it could rotate along with the axis of the kite, always keeping lines straight). But the Winch can be configured to also Reel both lines (as shown below).
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How does the kite rotate while reel-out (unwinding) phase is ensured?
On the video it looks like the mechanism anti-tangling rotates, or reel-out/in is ensured, but not both?
When the clutch mechanism is engaged, the anti-tangling device rotates, but reel-out/in (unwinding, winding) looks to not be ensured, and when the clutch mechanism is disengaged, the anti-tangling device does not rotate, while reel-out/in looks to be ensured?
Thats a great question, Pierre.
When the baler (or rotor) is stationary, the reel operates as expected. But when the baler rotates at the same RPM as the reel, the line doesn’t move - relativistically speaking, they’re both in sync and free to rotate. (What is shown is a 2014 model of the winch, the 2023 model has independent control of the baler.)
Now imagine a scenario between the two above examples:
- If the baler rotates faster than the reel, the reel releases line.
- If the baler rotates slower than the reel, the reel pulls in line.
With a little algebra, this allows for rotation while reeling line
Thank you for the explain Christian.
During reel-in recovery phase, there is no need for rotation since the kite is depowered. So the described system looks perfect.
During reel-out power phase, perhaps it depends to the scale of the rotating kite. The larger the kite is, the slower anti-tangling rotor (baler) tangential speed is. There is no requirement of a large rotor (baler) because only pull force is transmitted. The tangential speed of the anti-tangling rotor (baler) would be far lower than the reel-out speed which is 1/3 wind speed. So the system would likely work well. Is it correct?
Exactly correct. Currently, the bailer is limited to about 50RPM. An interesting point I think you’d appreciate is how the kite rotates around the line with the most tension. In our system, that line flows through the center of mass, with the orbital line rotating around this axis. When the tether line is pulled (or the orbital line is let out), the tension mounts on the tether line. As the kite rotates and the system compensates, the geometry of our arrangement minimizes unwanted vibration. It’s akin to shaft alignment in marine engine repair. If we don’t maintain a balanced geometry in the winch, we encounter a similar problem to misaligned shafts in engines. This misalignment leads to increased wear and an unpleasant experience,
This is a likely procedure
- Line Deployment:
- The system can reel out the lines without the need for the baler, ensuring a smooth and controlled deployment.
- Steering and Depower:
- The independent reels allow for both steering and depower adjustments as necessary, providing precise control over the kite’s orientation and power generation.
- Propulsion/Motor Mode:
- In this mode, the baler is locked to the Orbital reel using a clutch, while the depower and tether (steering) remain free.
- This configuration allows for modulation of the kite loop’s radius and control over tension, making it ideal for boat propulsion or pulling loads (Mobile).
- Generator Mode:
- Here, the lines reel out while maintaining relative line length, enabling the kite to ascend in a controlled spiral (or programed flight path).
- This ensures consistent control during ascent as all lines extend at a similar rate during maneuvers, optimizing power generation.
- Retrieval:
- The system uniquely combines two motor systems, resulting in an exceptionally fast reel-in capability.
- To initiate retrieval, the system goes into full depower. It then releases the Orbital line just enough so that the kite aligns parallel to the Tether line.
- The system then rapidly pulls in all the lines as the kite side slips. Once the kite reaches a lower altitude, the system returns to its standard tether lengths and resumes normal flight.
- Such a retrieval mechanism ensures minimal power consumption during the retrieval cycles, making it energy-efficient.
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I think this describes the generator mode during reel-out power phase.
I have a question: as the clutch mechanism is engaged, the baler rotates as expected, but now reel and rotor disk are synchronized. This means that a reel-out (unwinding) leads to the rotor disk rotation at the same RPM as the reel, so to the following:
If the clutch mechanism is engaged, the baler(rotor disk) and reel are synchronized.
Reel out is not possible when the clutch is engaged because relative rpm of the reel and baler will be the same. This mode only serves to rotate the load, not reel out.
Anytime the baler and orbital reel rotate at the same RPM the Orbital line will be “locked” however the whole assembly can rotate.
We can get the same effect if we control it digitally (via algebra program) or mechanically (via clutch)
If we want to reel out line and produce orbits that extend into the sky, we would not use the clutch. Instead we would use sensors and monitor the RPMs of the baler, orbital reel, tether reel, and depower reels.
Say the kite is rotating at 60 RPM, the bailer must rotate at 60RPM. To extend lines, the orbital reel, depower reel, and tether reels must exceed the RPM of the baler.
Yes, we want to reel out, since the initial question of this discussion was:
It is because KiteGen KSU also comprises two lines. But after the discussion it seems to turn that this can almost be the only common feature. Nevertheless, it might be worth going to the end of this discussion to see what a KiteGen KSU (which is a reeling = reel-in/out = pumping = yo-yo AWES) adapting the OKE system to make loops easier would look like, if it is achievable.
I wonder what mechanical way would be used in order to rotate the baler without clutch, since it is driven by the motor.
Without clutch: baler rotation looks to not be achievable, but tether reel-out is.
With clutch: baler rotation is achievable but not tether reel-out.
I am afraid that the use of sensors and RPM-check would not change anything until a mechanical way is found?