Toward the worst AWES

With about 20 m two lines, there was no take-off or/and the flight was about 1 second.
When I held it with about 2 m two lines, it went from one side to the other very quickly, being uncontrollable.
If the two rigid wings were connected it would be different.

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Way back when…
This video shows a disgustingly cheap & haphazard implementation of what can otherwise be a good design

This was one of the scariest AWES tests I’ve flown.
This calamity was a good early indicator that multiline and network formations have advantages when shit goes wrong. Bizarrely it keeps working and holds together.
A bit like me really…
I’m still completely skint but I make much better kites now.
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We attempted to mix rigid and soft and experienced what we affectionately refer to as “the angry chicken”. What a mess it was! Similar design to what Pierr eB has pictured above.


So let us produce a collaboratively chicken-farm!

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I measured the TSR of the two rotors on the picture below. Both are made with Naca12 blades.

The big (two blades 1 m/0.16 m, complete diameter 2.2 m, 0.7 kg) and old rotor was laminated with epoxy. Its TSR was only about 1, with 3 m/s wind speed.

The small rotor (two blades 0.5 m/0.08 m, complete diameter 1 m, 0.05 kg) was not laminated. Both blades were glued against each other with an offset of a few centimeters. The TSR was about 3-5, so much more. I don’t still know why there is such a difference.

I don’t think both could provide lift like an autogyro rotor as on the picture below, where the used rotor comes from a gyrokite.

With 6-8 m/s wind speed I tested the small parafoil lifter kite (0.2 m²) alone, elevation angle of 45°, then with the 55 cm diameter rotor rotating at full speed around the tether via a tubular axis, and after launching by hand: elevation angle of 35° until the rotor (as for the complete gyrokite whose the fuselage adds very little drag compared to the rotor). I have no video because I have only two hands.

I think there is a possibiity to stack rotors around ropes and produce a lot lift with numerous rigid (more lifetime) small elements. But I don’t know if this is really manageable. Particularly autogyro rotors should be launched to start-up in each cycle for reel-out phase. Even with 8 m/s wind speed the autogyro rotor did not start alone, while the two rotors above started alone with 2-3 m/s wind speed.


More info to help you answer that question could come from answering questions like this:

Did you balance the larger (and smaller) blades and are they in line with each other and have the same blade pitch? And what is the blade pitch of the small and large blades?

There are several points. My blades are old and my first intent was to build rotors in Darrieus type.
Then I tried to make two-bladed rotors, without aiming a careful building, using my profiles and some non-adapted material I had, without precise purpose.

So for the two rotors I quickly realized, the profile is Naca 12, which a symmetrical profile that is not really suitable for an autogyro rotor.

The pitch of the small blades (1 m diameter rotor) is about 0°, but a blade is some millimeters higher than the other and with an offset of few centimeters.
For the big rotor (diameter 2.2 m) the support is not precise enough, and the pitch can be different after years.

The pitch of blades for model autogyro can be negative: -1° or -2°.
The pitch of the blades of the black rotor I bought with the complete gyrokite is 0°, the blades having non symmetrical profiles.

Now I would want light rotors producing lift (as for autogyro rotors) while they start-up easily (unlike autogyro rotors). A 1-2 m diameter would allow a better and lighter realization as the rotor would not be full (as for a 8.4 m diameter autogyro rotor). Negative pitch (-1° or -2°) is used to facilitate start-up for some small models, but I think it is not enough for the use I intend, in reeling mode.
Multi-rotor reeling

The video below provides some explains for starting autogyro rotors:

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Multiple rotor reeling. Here’s something I came up with now after looking at that drawing. It’s a premature idea.

I haven’t read the reason for putting the rotors in a grid like that, so put all the rotors on a single line, some rotating clockwise, some counterclockwise. To try to eliminate, or reduce the need for, the lifter kite, let’s try to have the upper rotors point more upwards. How about trying to get a more pronounced curve in the line section that has the rotors by connecting the top and bottom of that line section with a shorter rope?

To get the rotors to stop and start… Maybe decrease the length of that extra shorter length line further so that maybe more/most rotors stall? Or mechanically lock the rotors together or to an extra element so that they work against each other?

The reason is allowing implementing more rotors without undergoing collisions with several independent units comprising a single line each. And if the rotors are on a single line, it will be too long. A single line would be a step. That said the complete scheme could be for later.

Now I am experimenting a single line with one then several rotors. Clockwise and counterclockwise rotors are already envisaged to prevent twisting of the line.

For some other points I will see later. There are options you describes, and perhaps other options. The current issue concerns the rotor. Now I can test with my three autogyro 0.55 m diameter rotors but it is limited.

It is very difficult or perhaps not possible to orient the rotors by themselves when they are not connected to a respective body as for autogyros. And without stable lifters the rotors tend to loss lift, as for Daisy without a kite lifter. That could be perhaps possible if the (small) bodies are integrated to the line to reorient the rotors in respect to the line.

And also to increase the elevation angle upper rotors should point relatively less upwards in respect to the line as the elevation angle of the line is already 35°, leading to an already very high angle of attack of 55° if the rotor is perpendicular to the line as it is naturally.

Yes. You’d have them rotate around a rod. You could change the center of gravity of the rod + (vane) + … + rotor to suit some need, or/and you could change the shape of the rod. You could vary the tension of the tether to make the whole thing more or less “rigid,” but I assume the point is to have a tether tension as high as is possible. Perhaps when that tension drops, due to a rope shortening somewhere for example, you could try to use that to stall the rotors.

It is not what I mean. A rotor could rotate around a rope if it has an even (but not too) short perpendicular tubular axis assuring its perpendicular position in regard to the rope thanks to its tension. However changing its orientation in regard to the rope is not easy if it is really possible. That requires a complete autogyro where the body is fixed to the line, and adds in weight and complexity. In some way the configuration is comparable to Daisy’s or SuperTurbine ™ version with rope as shaft: rotors + lifter (a kite or/and also a Sharp rotor which can be used also as separator). The difference is the use of pull instead of torque transfer.

That makes it easier I think. Not having to worry about how to transfer the rotation, you could just put a bend in the rod.

My idea above was to change the curvature of the tether as another way to deal with that problem. Another idea, you could put a loop of string between your hands and play with varying the distance between your hands, the relative lengths of the top and bottom parts of the loop, and where you could put rotors (weights) on that loop to get your rotors pushing in the direction you want. At the bottom of your loop you could vary the length of the bottom and top parts of the loop to make it behave differently. At the top of the loop you’d still need a tether pulling up I think.

If it needs saying, this is just brainstorming. I don’t particularly like my or your idea.

I mentioned the use of pull from a while.

There is only rotors with their respective hollow axes and the rope within, not rod.

I don’t see why we should change the curvature of the tether. Each rotor could have the same angle of attack (AoA). Dealing with different AoA is not needed in this configuration for what I think, even as it can be desirable in another context.

Brainstorming is better than nothing, especially since none of the AWES is close to succeeding on a significant scale. It is a mean to simplify the management, avoiding crosswind complications, and perhaps allowing a better maximization of the space as it scales by the number of small rotors. But some other problems can occur.

Concerning your idea, a detailed explain with a sketch could be useful.

To resume this is like the device below but by replacing a large rotor with numerous small rotors since a rope can be used. One could make the same by replacing rotors with numerous small kites but the implementation of rotors look to be easier as they are settled around the rope.

I waited a clear reply from @Ollie to my question about the ratio kite lifter area/rotor area, and he confirmed it on Daisy progress with rigid blades.
So that can be a brake for the system I just described. But I am not still sure of this as the torque is not used as such, only pull.

In my idea, there would be a bearing, perhaps a plain bearing, between the rod/tube + … + (vane) and the rotor.

I think the rod is mandatory. You could try it, what happens when you put a rotor on an inclined rope? I think it would just slide up and down the rope with no way to transfer the pull. You could put stoppers on the rope, but then you’ve already introduced the rod, really. The rotation would also wear down the rope and be a source of friction.

You’ve got the rope and the rotor, you could try this out now.

To make the top rotors pull more upwards.

… so above I’ve put a bend in the rod. You could also make that a hinge, which would give you some control in the direction the rotor would be pulling. You’d need that hinge to always be oriented correctly, otherwise you have a chance of the rotor pulling more or less left or right or down instead of more or less up. What should that hinge do and what are possible inputs to it? Other than actively controlling it from the ground [1], there’s perhaps relative wind speed, tether tension, tether angle, rotor pull, gravity. You could try to use some of those inputs to control the hinge. You’d want to control tether angle I think.

Or instead of or in addition to adding a hinge, you could make some bends in the rod that control in which direction the rotor is pulling based on how strong it is pulling, the rotor would be sliding up and down the bendy rod.

[1] If you’re going to be actively controlling it from the ground, you could make a program that keeps the (graph of the) tether curve within what you want. Every hinge could potentially receive different inputs.

I tried it and that works. I put small stops upstream and downstream of the hollow axis of the rotor. The rotor provides thrust in the direction of the rope as it is perpendicular to the rope. No need for long rods.

I did it (see above). If you want, stoppers, and also the hollow axis of the rotors between them, can be seen as rods, but their whole length is minimal compared to the rope length: 10 cm/1 m with stacked rotors at most, likely less.

Indeed, and the rotation twisted the rope, even with bearings. To avoid rope twist using paired rotors rotating in both directions. Wear and friction could perhaps be mitigated with bearings within the hollow axis. Or the rope should be changed: by using yo-yo mode the wear occurs quickly.

Please can you provide a sketch with the force vectors? I think it is not easy if it is even possible. If it is possible the force along the rope would be modified, so its curvature. For this I see only two ways: the lifter kite as it has a bridle with settings changing and stabilizing its AoA, or putting complete autogyros with their respective bodies (on the line) working as bridles.

I didn’t say anything explicit about their length. I think I’d express that as a fraction of the rotor diameter. I’d say that would probably be less than 1. That would vary with how much you want to offset the rotor angle with the tether angle (and the tether tension and …), more difference needs a longer rod I think.

Let’s also introduce rotor diameter over tether length, d/l, as a measure of the distance between rotors. You would vary that and try to find an optimum.

That would imply I know how it would work. I don’t. I’d sooner play around with a loop of string to see if I could understand how it could possibly work, if it could work. I like my bendy or pivoty rod idea better, right now.

Yes, my rod + (vane) + … + could be thought of as a simple autogyro.

The high and low parts of the rope can also be replaced with wire ropes in order to resist wear by respectively the rotation of the rotors and the winch during reeling phases.

In someway complete gyrokites could perhaps offer more possibilities but they would be difficult to implement on a line without tanglement risk, while rotors turning around a rope is a natural configuration, like the example below, but where the larger part of the pull seems to be generated by the relatively large lifter kite, the rotors providing torque (unlike the gyrotors I experiment for their pull):

That’s assuming you’d tie the gyrokite on a line branching away from the main line I think. That’s one way to do it. I don’t like that as then you’d need to make the gyrokite/rod more complex to make it fly stably. If you make the line go through the rod, the top and bottom of it are relatively fixed in place.

If you’ve got your gyrokite/rod, you’d just have a rod section above and below the hub of the rotor. You would tie your line to those. The only added entanglement risk then comes from the rotor no longer being perpendicular to the line, which you could ameliorate by making the rod sections longer.

Indeed that could work with a long enough rod/gyrokite. I will try to see some other pros and cons to both configurations.

As a rotor is naturally unstable, the gyrokite should be complete, comprising a stabilizer and a rudder, even allowing AoA change by moving the point of attachment of the rod/gyrokite as for a current gyrokite or other kites. Moreover for this configuration a lifter kite is not required.

For the configuration I describe and test, the stability of the rotors is assured by the tension of the line via their respective hollow axes, the rotors losing any freedom. But the lifter kite (or the Sharp rotor) should be large enough to ensure the inclination of the assembly even in turbulent wind conditions, probably according to a proportional ratio of lifter area / rotor area. Perhaps there is a possibility if the size of the lifter area is not too large compared to the size of the rotor area.

After the flight functionalities, the easiness of the management of the elements in operation can be examined, even considering that the chances of success are limited whatever the configuration.