So the rigid ST driveshaft makes it not an AWES?
The fabric used for these kites is called «Chikara Ripstop Nylon».
My experience tells me that any fabric kite, after some use in the wind, will turn soft and less «crispy». When this happens water will soak into the fabric rather than bead.
Im sure there are better fabrics out there, and perhaps also some useful treatments, but I would challenge any nylon cloth for this issue after year after year of wear (month after month / week after week?)
Meanwhile, an airplane looks much the same after years of use. No stretch, no moist takeup, same wing profile and shape. Bird sh#% may be a real issue for which there already exists real solutions, with a cost in maintenance time, cost and environmental impactâŠ
The secret is to take good care of a quiver of kites, and pick the right kite for conditions. This afternoon I yet again flew my first modern power kite, from 2007, a second hand Peter Lynn beta-test prototype. Its still in good condition after having been flown more than any other kite I have, around a thousand hours. Its required one tiny stitch repair from a factory error, and is on its second set of lines.
There are UV-sealant treatments that renew kite fabric. Osborneâs kites from the 80âs, treated, still fly at festivals looking pretty good. New treatments donât crack and let UV reach the fibers. There is wild variance in how kite fabrics age, the best seem almost not to age even with hard use. When kites do go soft, they still fly, its often just something to ignore, like the loss of quality of an old car that still works. Save old kites for special risk or easy conditions, to leave your best kites in their bags.
The hard-wing laminar-flow bird shit issue is like the noise issue and a dozen other hard-wing deal-killers, if not as bad as crash total loss. A rigid kite resonates like a guitar, not just VTOL noise, but even line strum and aeroelastic noise, at high-speeds, seemingly minor noise can drive local residents mad in time. Soft kite noise is a faint whisper by comparison. The highest risk of killing birds is by a fast hard kite.
Safety is the number one issue in aviation, and AWE will be no different. Soft kites can be dangerous, but rigid kites are easily menacing. The highest risk of killing birds is by a fast hard kite.
The rag kite is easily scorned for shabbiness, but has many less failure modes and defects. I like both kinds of kite; truck and race car, if you can learn to bear the metaphor. Large unit-scale soft kites are the serious big AWES game, and the rest are toys.
Relevant remark. So I will correct âIf the tether is rigid, this is not an AWESâ in âIf the tether is rigid, this is presumed to not be an AWES, although it could partially be if some significant lift is produced, for example by using kites or/and tilted bladesâ.
Note: In structural engineering, ârigidityâ also applies to tensioned cables, a property measured by resistance to deflection. Similarly, a parafoil develops rigidity by ram-air pressure in proportion to velocity.
And yet you are always arguing for network kites.
Surely you see the advantages of high number deployment of overall net form rigid wings in AWES.
Soft kites also have dangers ⊠especially if they scale by unit ⊠who would be mad enough to do that?
vlieger neergestort in de supermarkt
No, I see no advantage to rigid spars for industrial-scale kite networks. Yes, soft kites can be dangerous, but adding rigid mass does not promise to make them safer. At best, if >1000m2 soft wings are to big, then fall back to smaller units, which will surely be safer than comparable-power rigid units.
I only argue for networks so insistently because of the relative R&D neglect. Of course single kites are great, and stick kites too. Did you see all those traditional Asian kites I was raving about? I âam always arguingâ for âtest-everythingâ, to show folks what does not work, to eventually end the arguing.
Hi i am new here and find AWES fascinating. And this thread interested me. Why are people here so interested in the scalability and crash safety of rigid wings when the big practical hurdle seems to be kite lifetime? A rigid wing on a airplane in commercial use is used many hours every day for decades before material fatigue etc. is starting to become a worry. While if we take a sailing boats sail as a standard for the soft kites it will last like 6 months in constant use before it needs to be replaced. And if we take current kitesurfing kites fabrics it will only be a matter of a few weeks in constant use before the kite needs to be replaced.
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I believe both alternatives may be worthwhile in an economical sense. And both strategies can only improve in time. Myself I just like to keep any option open, and then choose whatever suits me better in the end.
Btw: welcome to the forum!
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Welcome @Storm_Eagle,
The question is still not settled. A crosswind AWES is also a 1 km long tether moving fast and covering a large zone.
At current MTBF statistics (crashing in a few hours or days), rigid wings will need a few more decades to reach survival to capital payback, which Makani estimated to be about five years for its architecture, at AWEC2011.
High mass, high velocity, safety certification, low-TRL, insurability, etc., are all critical factors.
But what are we going to do with all of the fabric kites that is going to be discarded every few weeks?
I guess we can no easily recycle the nylon fabric because it will be coated to resist water and UV rays right?
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All begs the questionâŠ
Which wings are the best for recycling?
EPP & EPS foam, can be recycled but they take a lot of volume making it hard to handle.
HDPE (OMG dyneema) should the complete system be able to be bundled into the same shredder?
Might also make it easier to squirt a kite network out of a collection of nozzles and molds if we did thisâŠ
Pure fabric wings (without active digital-electrical systems) are currently better by sustainable lifecycle impact, as long as the rigid wings are crashing so quickly, as toxic impact-sites (including digital-electrical systems).
This may change, as rigid wings finally become statistically reliable, but meanwhile, fabric recycling tech will continue to advance as well, with AWES developers favored who solve the soft power-kite recyclability requirement.
I think we should differentiate between the different types of AWE systems. Clearly SS is favored for Lifter Kites since they have the highest lift/weight ratio, lowest cost and highest safety rating. I would expect that the same applies to Yo-Yo Groundgen. Flygen systems, because of their increased weight would require rigid elements.
Xf-film is 100% recyclable and I tested his duration during 3 years outdoors before deterioration. Perhaps it would be suitable for low-technology (without crosswind flight) yoyo rigs such as Guangdong High-Altitude Wind Power Technologyâs parachutes but in a simplier version.
Please can you provide some data supporting your statement? This does not seem to match your previous statements against rigid wings such like
Pierre, âScaling and robustnessâ of wings are qualitatively different social/engineering/economic parameters than recyclability and toxicity. Find âdata supportingâ in any English language dictionary.
As for existing crash data, we have an M600 crash in Norway and clues to an earlier (Wing3?) crash. If you have seen a composite UAV crash, it can be pretty messy and toxic. Thatâs not very good statistics for just a few hundred hours of testing.
Rigid wings are hoped to someday not be prone to crash, even while we also should be concerned that fabric wings might be badly designed and operationally abused, and release toxic particulate pollution.
There is no final data on how the engineering uncertainty will resolve. The future may belong to IFO rigid wings of about 3-10m2, a reasonable unit-scale, in vast numbers, or maybe Fusion Power will make AWE a niche tech.
So apparently you cannot support your statement that I quote again:
But perhaps you could indicate where âany English language dictionaryâ could provide âdata supportingâ that ârigid wings finally become statistically reliableâ.
Yes, I can find a dictionary for lexical data to distinguish ârecyclingâ, âpollutionâ, âscalingâ, and ârobustnessâ.
Limited AWES crash data can be found here and there on this forum. We must speculate that the rigid wing AWES developers do not have more than a few hundred hours of logged flight, since they do not provide public logs.
100khr MTBMF is a traditional UAV statistical horizon that AWE has not yet reached, if the lack of supporting data is any indication.