More laddermill / spidermill ideas

Beginning with this comment, further down this topic, I begin to explore how one might build a simple crosswind spidermill / laddermill today, where optionally the kites spin around the tether going up, and not going down, as a thought exercise:

Similar topic, but here the whole laddermill rotates around its longitudinal axis:

A lot of people’s reaction to scaling TRPT is
Don’t send the torque along the axis.

Why don’t you try putting a band over the shaft and taking power from more directly underneath the rotor.
Stick a chain (curtain bead line) over the rotor and tethers then use it to drive a parallel pulley on the ground.
(kinda where my backline goes when I use one)

Well that idea may have some new support from a very unlikely backwards operation case…
Instead of driving a rope around and sending power down… These folks drive a rope up


Im waiting for the handheld TRPT shaft

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Looks like a laddermill.

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Perhaps this could become a Laddermill by using a ribbon a little like the Skybow kite, but not a rotating ribbon with Magnus effect, rather an aerodynamic ribbon whose shape remains to be found, maybe a sort of profiled ribbon including a rope for the trailing edge.

Maybe we should have a separate thread for the most ridiculous AWES you can contrive based on using a rope loop shooter…

Freeflying dynamic soaring AWES gather charge in super capacitors, at the lowest bounds of their course they discharge to the rope loop (run at same speed and direction, or a speed to add kinetic boost to the AWES)
The rope loop shooting is maintained by these charges and the (obviously enormous) surplus feeds humanity…

OR - the most cool scaled down AWE toy. Maybe to the scale of a phone charger or even less (~10 W)

This is basically a rope drive that works even when there is no tension between the pulleys. In hindsight you could have predicted the bunching up, and he solved that nicely.

This, or a different place where you clamp two rollers together, permanently or not, seems like a good way to handle the rope slipping on the pulleys when your tension is too low. It is also how you feed fabric through a machine.

This might be one component of an automated, two stage, laddermill. You put a minimum of two pulleys some distance from each other on the ground, to which you can clamp a roller so that the rope doesn’t slip when you try to brake it or slow it down.

The first stage is launching the individual kites and unwinding their tether, the second stage is attaching the kite tethers to the loop. You can attach and remove the kite tethers to and from the loop between the two pulleys, while letting it out / reeling it in. You would need to brake the loop for those operations, letting out / taking in the loop at the same time as you are adding / removing the tethers. You would also need to stop or slow the loop when the loop tension gets too low.

One argument against laddermills I’ve seen is that only half the kites are producing power at any one time. Maybe it’s worse than that as a good portion of those half will be at lower elevations with worse wind.

Well so many said it was a great idea when first popularized, then if it is not a good idea, what does that say about their general clarity of thinking? A million flies? Kite-reeling itself suffers from a similar drawback, that the same single kite that pulls up then must be retracted, using power while making no power. As a kid, after flying kites for years wishing I had an automatic winder, and realizing such a winder could generate power when letting line out, it seemed like the next step would be to have the kites traveling in a loop to multiply the power and make it continuous. Really, how many wind energy schemes require shutdown and reversal every few minutes? I mean, seriously. Come on. Give me a break. Anyway, all I was saying about the string loop is it works and is similar to laddermill, indicating that, at minimum, a system with a loop of tether going through a single base station can operate successfully. All the other details of your extrapolation, to the extent I can understand them, may work or not, but I’m not necessarily saying a laddermill should operate exactly like that string-flinger, just that topologically and functionally, there are similarities, and the string-flinger does actually work, so it may point in a direction of possible functionality for a laddrmill too. :slight_smile:

Who are they and where are they saying it is not a good idea? Are both theys the same theys?

It is a difficult idea, for now, as the flight control is difficult, for now. It also basically requires rigid planes I think because you want to be able to control the kite, generate more lift, and reduce the drag of the kite going down.

It is a multi kite system with quickly moving, high drag, kite tethers branching from a slow moving, low drag, loop, that is a plus. It pairs multiple kites to a single ground station, that is a plus. IIRC Tallak had the idea somewhere of decoupling the kite from the loop when it is going down, that would be a plus too, and does actually seem achievable. Time will tell if the positives outweigh the negatives.

It is too much for me to follow all the flawed thinking and account for every person and what they say in AWE. What I saw was a huge popularization of the laddermill concept. with lots of articles and renderings, then suddenly kite-reeling was being pursued while still using the name laddermill. At some point I’ve been told more than once, maybe on this forum, it had been “decided” that the laddermill concept space was not such a compelling idea after all. Seems like I just saw an old paper or something on this forum by Bas Lansdorp (if I am even close with that name - maybe Jap-somebody? Bosch? Really sorry but I don’t remember all the names.) about laddermill, but I do not even know what was meant by the term laddermill at that point. I think I glanced at it and it was about kite-reeling - I just can’t even remember. Really, to me, all the kite-reeling people and companies start to sound about the same, and I get them mixed up. I mean we have Kitepower, the kPower, kite-this, and kite-that - at some point who cares? It’s just the million flies again, trying to find the next turd to land on. Yes I mean the same people (“them”) got all excited about laddermill, then quickly abandoned it when they realized it would take the least bit of effort and creativity to build one. I mean, you can just buy a kite and it works, so that seems like an easier starting place, right? The whole subject gets a bit silly to even talk about. I think some version of laddermill could probably be built in a weekend, if anybody cared and had the least bit of real interest, and maybe some talent in fabrication. Well, OK maybe more than a weekend, but still… :slight_smile:

I don’t know if it was huge. For years the only thing I saw was Bryan Robert’s idea. Then there was Altearos and Magenn and so on. Compared to that the laddermill concept seems to hold much more promise, if the kites are actually moving crosswind. IIRC that wasn’t actually the case, so if I remember that right, it is good that that was abandoned. The text below does mention flight computers though.

Compared to a laddermill, kite-reeling seems better to many people, or at least simpler, for now, so the switch in focus to that. When something better comes along and seems to hold promise people will switch to that.

But that would be rubbish. It would need a lifter kite, it would use high drag soft kites, the kites would not be moving crosswind, barely making power, the generator would not be optimized, and so on. Why bother.

Wind-driven driving apparatus employing kites

US6072245.pdf (198.3 KB)

The creators of the name “Laddermill” went for the reeling yo-yo kite by keeping this name, while the inventor of the concept went for SuperTurbine ™. Both seem to work in their own way.

Windy Skies thank you for illustrating my point better than I could ever hope to.
“Currently, there are several master students, PhD students and PhD graduates working on the laddermill in the fields of ground station mechanics, lightweight structures and flight mechanics. It is our intention to have a working demonstrator 2008. The laddermill project is an extremely multi-disciplinary project and it will lead to a radical change in wind energy doctrine.”
OK so all that “talent” and they could never build the simplest model at any scale?
The whole thing is SILLY.
The people involved are SILLY.
The idea that all experimentation can be invalidated on paper without ever trying the simplest version of such a simple device is ridiculous.
The statements made are SILLY and utter bizzleshizzle.
It all amounts to just excuses.
And I do not agree that any of the supposed operational parameters you cite are necessarily required, and to me, the reasons given for not ever trying it are invalid.
Sorry but I’m still convinced that people have only tried a small fraction of a huge number of valid, simple AWE possibilities. The operative word here is “LAZY”.


They pivoted to something that they felt was better. And that patent doesn’t look like it would survive an encounter with current reality, which they perhaps also realized. It was a newish project that now received some attention from these students, graduates and researchers, it is to be expected that they would gain new insights and change course based on that.

Excuses take forms of words such as “pivoted”.
And whatever patent you are referring to need not define the exact form.
I just don’t understand why anyone would want to keep coming up with so many excuses.
Oh well, have a nice weekend! :slight_smile:

I think this is true to a large extent. I would not so much say lazy, though I think lazyness is a big factor. The even bigger factor though is being content to focus on a detail without considering the big picture. Academia lends to this as the goal is producing papers rather than a working and dare I say even profitable product.

I do think the work done in academia though provides a lot of value, and there is real talent there, providing useful stuff. I think it works better for an incremental improvement, eg wing sections for an existing HAWT, than for AWE where the field is wide open and the bigger picture matters more than minute details.

I do think this is observable in AWEC talks where eg optimization of a trajectory using advanced control theory for a concept so in its infancy that there is no chance the current description of it could work get oral presentations, while nitty gritty useful stuff like how to actually fly a rigid kite on a tether [my submission] is downselected to the poster section where the 1/3 poorest submissions end.

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You don’t even get to present? That’s absolutely ridiculous.


I know this has been broached on the forum before?
A continuous wind powered magnetic tape? Just depends on the coil arrangements?
It just a question of how you can get the wind to do this?

Would satisfy ground based awes?
Anyone know of a current system in operation?
Relevant patents? It does fit some freeflying requirements? Quick cheep and easy to build. With portability? Then you could have an variable swept area? @PierreB mentioned it a while back? I don’t know if anyone has made it to market? As everyone love the kiss Monica? How simple does it need to be?