Daisy progress with rigid blades


Daisy progress: 1.4 kW with three 20 cm chord blades.

See the discussion on

https://twitter.com/rodread/status/1073196048028459009,

https://twitter.com/rodread/status/1073293485132967937,

https://twitter.com/rodread/status/1073506511203250176.

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Hi @Rodread . Let me add some comments that might or might not be helpful, from my point if view.

First I think you should invest in a motor/generator with a VFD. This will give you a good power and speed reading, and give both accelleration and breaking torque, all in one package. Add some logging using eg. modbus serial adapter, and you’ll get more precise logs. These components need not be very expensive, eg look at the Vacon product range.

Im not sure if you have some kind of emergency stop on the wings themselves, to make sure you dont get into warp speed and then over-torque. A simple system consisting of a servo, airbrake and a battery on each wing would allow you to slow down the wing speed by reducing the efficiency of your wings controlled by a rc radio (eg the taranis at hobbyking is good and cheap). This will save you work, as I imagine building this is time and expense consuming. And still you dont need to go all in and create a conputer system to control the wing and communicate with the ground (that you perhaps dont ever want to have?)

Last, I see a low og warping on the largest diameter ring. This seems to me a recipe for disaster and putting a lot of load on the ring. Perhaps more supporting tethers towards the ground?

On the same subject, a triangular bridle connectibg all three wings would let the large circle stay circular even at high rotational speeds. Perhaps this will solve the warping issue as well.

Sorry for acting as mr knowitall, I dont know this rig nearly as well as you do, just perhaps this input may be of some help.

Also, what you are doing seems quite dangerous. Please be careful. If not for your own health, then just for not postponing your work (and thus perhaps postponing saving the world from global warming) for years while you are staying at the hospital. :wink:

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Thanks @PierreB and @tallakt

Yes I am hoping to avoid a hospital visit. I’d be in real trouble. My wife is on call too often to risk me seeing her at work. She’ll not be impressed when I leave the kids in charge of the kite turbine again. :crazy_face:

As for “I should invest…” Don’t whatever you do risk saying that in front of my wife.
Everyone who knows me, knows I am a freeloader, who ought to get a job.
There is no pay in what I do.

I set my VESC6.0 controller to use Field Oriented Control (basically VFD)
The VESC allows me to monitor speed, current and other parameters.
I use an arduino to communicate with and control the VESC.
Code and some project overview and 3d stuff is here https://github.com/rodread/DaisyKiteTurbineControl

This kite was a big bag o shite ok
Sooooo far from optimal and not good

The rigid wings were pure simple foam and rod… tied and locked in place, set into a rigid 3d printed cuff on a Dacron sleeved carbon ring tube. NO CONTROL. There were 6 lines to the centre axis line from the ring and 3 kite lines from down to the next ring. 1000s of improvements can be made

Yes lines between the kites (inside the ring arcs) would make the ring form more rigid. This is a good way to move the whole rotary rigging away from having a central lifitng line (such a shame lifting line clashes as a term with Prandtl)
Generally, Tensile innards holding a tensile cuff with a compressed rigid part inside it, is a very good naturally stiff form

The problem was the overtwist caught on a join in the lift line (why was that there doh) … You see it in the vid.

I was too lazy to reinstate a previous push button for manual overdrive to take twists out… doh
I also ought to go back to having a manual current control for careful slowing down…

Thanks for the hints and tips! Always good to have another perspective.
Hints and tips for how to have this as a sensible job are very welcome.
So much redesign to do after the lessons from that test.

Having this as a source of income is hard, life as an entrpeneur is hard in general. You need to find someone who would be willing to pay you for developing these ideas. I think the stuff you are working on is very interesting and has uniqueness to it. If you find someone who would fund you for the good cause that would be the best, but such funds often must come from someone who expects some return on the investement. In that case, to develop this into a business, I think most people believe a team is necessary to get enough traction. I havent got a clue how you would find such investors, I could only wish you the best of luck.

If you are paying this out of your own pockets, I’m sure you are alteady spending more than you are comfortable with.

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No, I’m quite happy for now. I don’t spend a lot on this. There is research funding. Just not for my time.
Which pisses me off… That’s the bit I’m not comfortable with…
I agree many more people need to be involved in this. I’d love that. There’s enough cheap work been openly published for household or even community level projects to be independently explored.It would be harder to stop progress on Daisy kites now than to continue.
If the employment of a group of people was the deal… I’d work for free for the largest hydrocarbon energy polluting conglomerate monster in the world if they fund it. There are businesses and governments willing to do this. They just don’t realise it.

A web of concentric bands of such tensile and compressed parts can be used as a unit “plate” or “frame” for a torque transmission network, where each web node links to the subsequent nodes. Using more than 1 ring diameter throughout the stack provides frameworks for structural rigidity in flown and transmitted energy components.
The geometry and spacing of individual or concentric bands and webs should vary along the stack with regard to stack energy requirements. Double and triple walling of torque transfer lines is considered in the OM kite types.

Because I am inable to post anything in Yahoo groups, id like to comment «dougselsam»’s comment on rotary daisy rigs:

«Stealing a saying from pro football (“Winning is not the main thing, it’s the only thing.”), I’ve warned all the newbies here: "Overspeed protection is not the main thing, it’s the only thing»

Breaking is a non issue with long tethers. just reduce the Cl of the wing (anyway you like). The drag of the tether will make your effective L/D ratio so low that depower is very

This is a double edged sword. A reduction in Cl or glide ratio will have a more than linear detrimental effect on produced power. But low power is a lesser problem, solved by optimization if the underlying physics make sense.

(Let me add that dougselsams serpent rig is not tethered in the sense of this ang eg. Kitemills single wing yoyo rig. His view on breaking may be skewed by the fact that his rig does not have this breaking effect built in. Let me also add that tether drag is more a negative effect than positive, but for most AWE, it is unavoidable)


Parachute launcher. I thought these were much more common. For model airplane recovery and in model rocketry. Or mabye I just didn’t have the right search terms. Anyway- maybe this is an option.

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There is some discussion on survival winds for daisy rotor. I am not sure what you have planned. To slow down you need to change AoA relative to the tether. If your wings look like a plane with tail, they might find the correct AoA by themselves without further control. (This is after you find a means to slow down, either by adding drag or reducing lift). This holds for all kites…

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Less stupid, but still stupid:
Drone drop system
I really thought there would be more plug and play devices in this area.
But I guess they’re not really neccessary since anyone in the space can make a release mechanism with a servo themselves.

Not easy to implement a relase to change aoa since aoa is fixed in the current daisy kite design.
Fire a model rocket engine retrograde? Would definitely up the coolness factor, simpler than a braking surface and no chute tangling.

Suggestion: using one rotor, double the number of rigid 1 m x 0.2 m blades (6 instead of 3), double the diameter, then measure. But please don’t make it if it is too dangerous.

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@Ollie keeps on telling me to make a ring with more blades (higher solidity)
I really have to shorten the cuffs on the main ring compression was one conclusion from today’s testing.
Oh and Mr Gates your Excel program is a bag o Sh!^£ as a robust DAQ (PLX DAQ from arduino)

More blades, more money, more torque, less speed…
To me it seems increasing blades number will not help daisy

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Well a completely new control architecture seems to have definitely helped today.
Most significant seems to have been the TTR (Tension Torque Ratio) and TSR live analysis and setpoints. Low wind performance seems to have gone way up. and a lot smoother. Will confirm after a lengthy delve into the data… I did manage to save a heap despite loosing loads of controller running stats arrrgggghhhh swears swears … and relax… was a good test

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So if I never get any recognition, accolade or further successes…
At least I can say I was out-standing in my field today.

Actually you can see a kink in the main ring here. One of the tubes has popped out of the next tube cuff. The ring sleeve needs to be tightened to ensure better compression of the tubes… doh

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Indeed doubling the diameter will allow increasing the swept area as the blades become further away from the centre and travel more space, that by keeping their initial length. Increasing their number is a cheaper mean to fill the higher swept area since there are already 3 blades, perhaps more. Thus the linear (but not angular) speed could be kept in a similar way as that of current wind turbines as they grow, leading (for current wind turbines) to a gearbox with more gearing as the angular speed decreases, or (for Daisy) to a sort of rim transmission.

By contrast increasing the chord or the length requires new and more expensive blades, and with respectively a lesser aspect ratio or a lesser relative efficiency (the root being far slower than the tip in comparison with initial blades).

Doubling the diameter is only a possibility for Daisy to scale up, knowing that high altitude winds are several hundreds meters above the ground. Daisy or other torque transfer systems like SuperTurbine ™ reach 10 or 20 m altitude. Going far higher without increasing the diameter looks to be a not trivial task. But is it really possible?

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It is possible, just not very economic. Wubbo taught we can choose the AWES we prefer. I would like to see at least one high-altitude torque AWES. Yes it would take the greatest kite pros to make it work, if someone is willing to pay them (take over AWEu).

Just add enough pilot lift and guy lines, operate from bunkers, to make anything fly. Big Daisies and STs are worth testing, if not as cheap and handy as rope driven TRL9 COTS power kites.

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All going well, I will test with another rotor on top today.

Have you considered testing a triangle structure as top ring? I know you’ve tested a triangle torsion transfer tube. No need to replace the tube, but just the ring with the propellers. Needs new 3D printed parts though. (Can do quickly in Fusion 360, if Rhino is making trouble) Bridle the triangle corners to three or so that when in operation all tethers are under tension. Not equal tension though due to trigonometry, except if you make a load distribution system.