The most basic airborne wind energy system

A kite

@Kitewinder It was a Roy Mueller skybow arch… A rotary arch ribbon kite. http://rexresearch.com/skybow/mueller.htm
Here’s another test I did where we flew the skybow in mid air between 2 x lifter kite lines


How many more skybows could you stick on a pair of lift kite lines?
Can you modularly add lifters and skybow arches at the same time to a 2 side line curtain of wind energy capture?
the lifters would pull out sideways and up to assist the skybow doing it’s thing

Another test video

Guangdong High-Altitude Wind Power Technology tested a low technology wing as a parachute, using yoyo method, that makes sense in my opinion. The ground installations seem yet complex. Some photos on:
https://www.google.com/search?safe=off&rlz=1C1CHNV_enUS423US423&tbm=isch&sa=1&q=site:.gdgkfn.com&oq=site:.gdgkfn.com&gs_l=img.12...7533.11299.0.14758.6.6.0.0.0.0.122.499.4j2.6.0...0.0.0..1c.1.17.img.CtFeEKukQ0w&bav=on.2,or.r_cp.r_qf.&biw=1454&bih=713&imgdii=_&cad=h#imgrc=gjhW-5PlgAzGKM:&spf=1548944167901.

Some details are on the attachment below.
chinese umbrella description.pdf (1.3 MB)

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Basically what I want to do with lifters with pitch control instead of parachutes.
Their description and the groundstation design is overly complicated. Seems like they like to display things as complicated, can’t think of any other reason why they would include a drawing of planetary gears.

The parachute can be simple. But the groundstation is overly complicated as you mention.

Basically a playsail is a rectangle connected by a tether in each corner. So it can be a current tarp with eyelets.
In the the first video the two lower corners are close, perhaps in order to improve some aerodynamic features and the elevation angle. Yoyo method can be used.

It is difficult to make a less expensive and complex airborne wind energy system. Can be it efficient and safe enough?



I have some ideas to improve the performance of the umbrella kite energy device. With this system the umbrellas are subject to cosine cubed losses. These losses are always more than the gain in performance due to higher winds at altitude. The best performance will be obtained at minimum tether angle. Instead of using a lifter kite or helium balloon to support the train of parachutes, we should use a lightweight structure which is supported by guide wires. The load on this tower is minimal since most of the force is the pulling of the parachutes on the unwind reel.
For example, if the unwind reel is located 4 meters above the ground and the top of the tower is 30 meters high, then most of the area below the system can be used for farming or recreation.
The natural sag of the tether might be advantageous because downwind parachutes will be less affected by the wake of those upstream. We may be able to space the parachutes closer together.
A big advantage of this system is that problems of launch and land will be eliminated because the parachutes can be retracted and stored on the tether. For low wind conditions the parachutes can stay in place draped over the tether.
For changes in wind direction, rather than relocating the tower, the winder station can be moved in a circle around the tower.
Which produces more power, parachutes or autorotating turbines sweeping the same area? Which is heavier? Q

The simplest airborne wind energy system is one you never build, and just talk about on the internet. They are problem-free, maintenance-free, and always perform exactly the way the promoters wish.

Doug,
I would appreciate your opinion of using a tower to support parachutes, autorotating turbines or your Skyserpent. Their efficiency is best when the tether angle is low. In the case of the Skyserpent, you can tolerate heavier torque tubes between turbines.

Rod,
Why can’t you use the tower to support your Daisy system? Continuous tension in the tether will ensure that the system will not hockle when the wind dies. Perhaps you can redesign the tensegrity system based on this fact. Having a constant tether angle simplifies the power takeoff.

I’m planning to have another mast mount test within the next couple of weeks.
This is purely for research purposes and mast mounting is definitely not my long term intention.
Sure, great for a clean wind day. Great for holding a low elevation angle in low wind. (hockling shouldn’t be a problem any more with good ring and spacing geometry ratios)
In this case it is going to be good, purely for the sake of clean rotor performance data collection.

Hi Gordon: What I’ve observed is the process of inventing in wind energy usually turns out to be the inventor slowly figuring out why all useful wind turbines look similar, and that the only “improvement” their invention needs is to get rid of every feature that defines it, until they arrive back at the standard design from their roundabout path to get to what is already known, like Dorothy from the Wizard of Oz realizing “there’s no place like home”. Like “The only thing wrong with my airborne system is the “airborne” part.” Or “The only thing wrong with the parachute idea is the parachutes”. This is why I encourage kite-reelers to examine how their system would look as a ground-based or tower-supported system, such as a towered wind turbine on wheels, running unloaded, pulling cables downwind along the ground, then being reeled back upwind again - whacky. It’s like with so many ideas people run by me, “the only thing wrong with your invention is its main features, otherwise it looks great!” Yes I think towers and landforms are both great ways to elevate any wind energy system. Of course most wind energy inventors never get to any truly workable or useful system at all. One factor that I realized long ago is the lack of even a decent product, until you get up to commercial-scale machines. The odds of having a good experience with even the “best” small wind systems is very low. They cost many times what they are worth in output. They break down a lot and have a lot of problems. Most do not deliver the expected power. Improving wind energy is not the easy “slam-dunk” many outsiders and neophytes assume.

Hi Doug, it is well seen! But this could also apply to SuperTurbine ™ :wink:.

Yeah Pierre, how do you think I know all this? I’ve taken my turbine designs full-circle, going through several multirotor designs, all the way back around to the standard side-furling concept with a gravity-tail, to many single-rotor versions, seeing how they make power and most importantly, survive high winds. We have a large collection of burned-out stators, for example. It took several years, and much trial-and-error, to get even just one model fine-tuned to survive storms without burning out. It’s all about limiting output. I’ve found many valid niches and configurations within this spectrum. One, as I have mentioned, has been running for something like 9 years now, with one blade replacement a few years ago, with no generator burnouts and no bearing failures. The reason ST designs have success and promise is they do not try to reinvent everything, and do not throw away 2000 years+ of knowledge, but rather use the knowledge to get to some next-step workable configurations. My designs go mostly forwards, not backwards. However, there are factors lately I’ve been realizing point toward some of my earlier concepts having more potential survivability than the ones that veer back more toward the standard design. You don’t really know what you’re dealing with until you’ve had a given model running long enough to experience all sorts of conditions, especially strong winds, gusty winds, turbulence, and sustained high winds which can go on for hour after hour, slowly cooking your windings. You can’t know if a given model is good until you’ve had many operating, for years, in many locations. This is why people testing a model designed from their desk, in a wind tunnel for a few minutes, are usually delusional. Making good power is not that hard, it’s controlling it that is difficult. Imagine your assignment is to develop a better formula-1 race car to compete with the top designs in the world: As I’ve pointed out, most people show up with a wheelbarrow. Assuming you even know how to make a machine with good suspension, steering, power, etc. you have to make sure you will not be the next Dale Earnhardt and hit the wall at high speed. You need failure avoidance. Your race car needs good handling, suspension, steering, and good brakes to match the power of its engine. All that is probably more important that how much power it makes. I think of wind energy systems as sophisticated, automated aircraft. Every engine has a throttle for instance, because if it is powerful, you need a way to control that immense power. You can’t just say “It’s always floored!” You will crash. You will “hit the wall”. My repeated quote: "Overspeed protection: It’s not the main thing, it’s the ONLY thing.

Sure, but generally AWE prototypes are tested during only some hours, so overspeed protection cannot be examined.

Beside this the Serpentine could be a suitable AWE option if the shaft was a tether. But for what I saw the transfer with the tether is not good. The rotors turn but transmit little torque with a tether. But perhaps my tether was not suitable.

Doug do you remember how much power did you obtain with your Serpentine with a tether as shaft on the video below?

Yeah after a billion dollars spent, and thousands of people having group photos taken, there’s still not one AWE machine running on a daily basis yet. How is this possible? Mass delusion?

Never measured. I was mostly just goofing around, with that machine, and in that video.

Managed to run a mast mount 6 blade ring rotor test today.
Ran well for just over 10 mins before I was careless with braking and crushed the shaft.
Kinda lucky I did, there was a powercut here just after and data which was saved just in time would otherwise have been lost.

The data will be run through thoroughly by @Ollie before publishing.
Control algorithm ramped up the current really well. Chuffed with that…
Just wish I’d used it better for slowing the rotor down…doh.

The ring took a crash spectacularly well (all blades and fuselages fine after ground strike at ~85+rpm) as I had left the fuselages loos-ish on the ring.

Highlights of the data were… Peak power 624W at peak rpm 146 @~7.5m/s 8m/s
Looks like it had 100kg line pull …although the mechanism that sensor is on …don’t trust it… bodgy.

The really exciting thing today was the use of GOLD Duck Tape
Aye Aye POSH
And if you see the video…yes I should have had a helmet. A mini mohawk hairdo, although it looks hardy, isn’t going to be enough in a worst case.

Fun day out (in lockdown on the croft)

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Networked Arch kites are very simple kite forms, they can generate huge lift forces, but are hard to rotate, elevate and keep tuned in a turbulent wind. They can fair gallop too.
I made this one from old windsurfer sails today for some lockdown entertainment…


I used a forward guide line instead of having pure leading edge span load tension to help hold the form… I probably needed a bit more tension on the undersides to hold it without the forward (upwind) tether.

How do you erect the system with the mast? Do you lift the mast with the Daisy attached, or lift with a pulley?
What is the tether angle with the mast?
If the wind dies and starts up again, will the system automatically restart?

Hi Gordon, The rotor was hoisted from a pulley tied up to the mast head.
The hoisting line was attached to a 12kg Bucket … The bucket was occasionally lifted as things changed. The hoist to the mast had the shaft up to about 24 degrees elevation from the ground.
With 6 blades at 4 deg to the rotor plane the system does not need spun up to start.
The controller reacts to change torque load as conditions require.