A bit of background to this WindLift news: I was perhaps the first figure directly invited by the US Army to participate in their AWE R&D, but turned them down based on the conviction that kite energy should not be militarized (AWE Military Moratorium). Rob, who I was already in contact back then, founded WindLift and took the Army work, based on his family tradition of military service. We learn in this new source that WindLift military funding has now reached 2.3M USD. Providentially, from my point of view, Windlift has not succeeded in creating a viable military asset, since Rob's background in molecular biology was not ideal to lead in an innovative aviation technology.

The WindLift Item-

https://www.wraltechwire.com/2018/11/21/morrisvilles-windlift-closes-on-125000-debt-raise/

Endnote- The US Army's Futures Command, a new "brain center" of innovative warfare tech, has located in Austin, so stay tuned for further information on a dialogue between our pacifist local culture and the Army's leading tech thinkers. I will soon be advocating to them the strategic reformulation of world militarism, away from mass lethality, toward mass humanitarian response to global natural disasters, by means of kites, while resolutely opposing the adaptation of kites to modern war. AWE should be to comfort victims, not create them.

Doug's Sky Serpent clearly had a groundgen at its base. I did not see it connected to any load, but that's ok; it could have been anytime when I was not inspecting it. Where is the exact misrepresentation Doug claims? The main critique of the ST AWES architecture has nothing to do with its connection history, but to the poor scaling potential of a driveshaft to upper wind, by low power-to-mass and angular-velocity. Typically, Doug stated he was leaving the Forum, but remains engaged, promoting empty argument. Perhaps the best effect of this dynamic is that less-diligent observers of AWE are driven away, while the most-diligent hang in there.

Good Luck to Doug succeeding in AWE on merits claimed.

Pierre, I am happy with any kind of AWES prototype, no more a new flapping version than Makani's M600. They are all needed under the "test-everything" ethos.

Baptiste, This is a welcome new link in the class of flapping wings (wingmills). Thanks to JoeF's special insight, have come to define any wing in action as embodying the the universally applicable kite principle represented in its abstract force diagram (thus a glider carries its own "anchor" in its CG), and we further see any wing in water as a water-kite (paravane or hydrofoil), with common fluid-dynamics.

The Eel Team is clearly onto a fertile design space (physics that birds and fish share), but are experimenting too elaborately to test endless variations at highest pace. Their wings should eventually tend to resemble higher AR precedents in our circles, dating back over a decade, also tested underwater. "FlipWings" are claimed to have the highest power-to-weight potential of any WECS known.

daveS

Thanks again, Baptiste.

Circumnavigating the globe by kite and solar panel is the sort of tangible AWE progress on the timeframe the best analysts have expected. SkySails continues to lead by example, and Dave Culp (KiteShip) continues to be validated as the modern father of ongoing ship-kite progress. This is only the most evident progress- several added players continue their own ship-kite development.

There's also airseas, an airbus spinoff since september. https://www.airseas.com/
(I know you were talking about tangible progess, but I just wanted to put it out there as it's new and probably some people haven't heard of it yet.

Tallak, 

I am definitively signed in. Iam just unable to write anything sometimes. Happens on my phone and laptop..

1.  Direct email: 

1. Consider using direct email to the group: 

Woops I meant Oroville in 2009, not 2008. If I am going to insist on factual statements, I'd better be sure my own facts are right.  :)  Anyway, this is an example of how easy it is to keep your credibility intact: if you realize you said something wrong, just admit it and move on.

Power Kites continue to develop at a tremendous rate, which is fast basic AWE progress as well. Note that our "SS" (single-skin) nomenclature may be supplanted by "monoskin" usage.

From the website-

"The SHAMAN is built with the best innovative construction from the latest paragliding technology. It’s a mono-skin construction mixed with a precise balance of cells: it’s the first ever mixed construction for a snowkite! We have collaborated with the Swiss designer Olivier Nef, one of the most influencial designers in the paragliding scene. The results are exceptional with a super versatile, safe and performing kite."

https://www.ginkites.com/product/shaman-snowkite-freeride/

Thank You, JohnO, for the sympathetic note.

For those unaware of the history of military technology, there have been many specific technical moratoriums on moral grounds since ancient times down to our day, so we continue optimistically in that spirit to propose a more humane future, including our efforts in AWE.

Our friends at Zhang Lab, and other key researchers, have greatly advanced flapping science in the last twenty years. We now look at a flapping flag with far more insight. This latest news, a France-based hydro-flapping case (the Eel), extends flapping science toward engineering R&D, and suggests extending our past discussion. We now better see a distinction between high and low AR (aspect ratio) flapping dynamics and associated design factors.

Line vortexes develop in a flapping flag's billows, starting near the flag pole, and grow in size and power until they shed at the TE (trailing-edge). The Eel program seeks to tap the vortical energy at TE. Most other flapping PTO (power take-off) schemes tap the LE (leading-edge), which is not as direct, and has a slower load-motion. KiteLab/kPower has usually tapped the whole flapping surface (flipwings), with considerable power evident.

Any matter vortex is, in quasiparticle language, a phononic roton (rotary phonon). Consider line vortexes in flag billows as flywheel storage devices that are created and charged as they drag along the fabric downwind. A vortex's flywheel basis uses low pressure at its center and high pressure at its margin as its flywheel structure. Wind flow around the flag spins up these vortexes, much like cross-axis Savonius or Flettner Rotors, but with the astounding capability to grow (charge). Entrainment is the term for the coupling of a vortex to structure in flow.

The trick is to tap the flywheel energy in these vortexes at maximum development, neither damping the flag too much nor letting too much vortical energy pass into the wake. This is generally practical by tapping the pressure differential between the flag surfaces, as Eel's design does; more like a piston than a rotary PTO. This is a novel area of study well worth developing for further lessons. Its an open question how far the unique principles may apply in future AWE.

For ten years, I believe to have consistently only stated that the Sky Serpent's generator had no load connected at HAWPcon09, when I inspected it. Let Doug or anyone provide a referenced quote of any actual mistaken statement, for proper correction. Yes, Doug is back on the Forum with his obsessive complaints, but where is his positive contribution to AWE knowledge? Losing Olivier over the still unresolved Netiquette gap between us; what a poor trade.

Let Doug fairly live up to his own old AWE claims (eg. that he could solve AWE if he chose), and form helpful Forum topics on creative merits, rather than be the most unhappy in posting.

Interesting how you love to denigrate "Doug" at every opportunity.  Doug who?  Now you're trying to weasel your way out of what you said before.  Not interested in playing your game.  Olivier stayed in touch with me.  It never seems to occur to you or Joe that you might be the problem.  It would be refreshing if people could express an opinion on here without having to run the gauntlet of you trying to tear them down by "correcting" whatever it is they said. 

Using force sensors on the tether must surely be prior art? The tether force measurement is an important, easily aquired data point. If this is not possible due to patent infringement, succeeding in AWE will become that much more difficult.

The record stands, that Doug is unable to substantiate any mistaken claim of "no generator", much less explain why such mistake even matters. Any mistake fairly and properly cited will be corrected.

The search results cited owed more to Google's shortcomings than actual AWE domain knowledge. The AWES Forum has been the top source of serious AWE news for the last decade. Meanwhile, Google was convicted of mass cooking of search results in the EU. We even documented a Makani "news" bias in Google results, in past years. Poor Google AWE search results are old news here.

We can classify the general direction of these Russian AWE patents as speculative schemes that do not depend on kites as they generally exist (classic kites, power kites, etc.). We are seeing Russia's patent system mirror the dynamic of other countries, where small inventors hope for a commercial monopoly very unlikely to materialize. At best, languishing AWE patents will be pooled in future R&D rounds, with no new patents predicted to create decisive value, since AWE's few core patents are now public domain.

No Google/Makani/Joby patent that we have reviewed has ever contained a considerable inventive leap; all have been tame steps to build an IP portfolio in "venture checkbox" fashion. Its great news for the world; that Google failed to sew up a monopoly in AWE IP, as originally feared.

Another new tethered aviation patent building on ideas long known. Pete Lynn (Jr) in particular sparked modern discussion of this old aviation concept space, but the core concept dates back centuries (flying schemes like tethering to a flock of eagles, now drones). There is a big future to this concept space, nevertheless, and this patent may well contribute useful details. Lets hope for successful prototype cases.

We also credit the Roeseler family, Corwin Hardham, and others, who first pioneered kite boarding on the Lower Columbia River a decade earlier, plus many other kite surfing antecedents. Kite sailing may even have figured in the ancient Polynesian colonization of Hawaii, and its rather likely they also both surfed and kited on occasion-

https://www.surfertoday.com/kiteboarding/14739-kitesurfing-pioneers-release-must-listen-audiobook

No, the Sky Serpent was not the only demo at HAWPcon09; KiteLab also flew several AWES-related devices, as witnesses can confirm. None of the demos apparently powered anything. Let time tell which concepts demoed at early conferences were the most promising in principle.

Sorry if Doug feels so unfairly treated. He did get good coverage by SF press.

A power kite student begins by exploring the "kite window", the flying zone of a kite in relation to its anchor and wind. The window is laterally, but not vertically, symmetric. Toward its center is the "power zone". At top is "zenith", and the "edge" zones lie to the sides. The "surface" scope has its own set of special kite-handling properties. The kite window is complex because its contains many non-linear surprises. Wind veering is the veering of the entire kite window, a major source of uncertainty and compounded computation.

No AWE R&D team has yet fully automated kite window operations, focusing first on simple pattern-flying. Kite pro flying shows just how far AWES automation lags. Pros fly wildly diverse patterns to match load demand to whatever the wind does, just don't ask them to explain exactly how they do it. They fly solutions that are the despair of a conventional avionics programmer. Flight automation will advance, but rather slower than most folks imagine.

A next step in single-kite automation is to formalize the kite window state machine. Learning algorithms may soon partly replicate a kite pro's performance, but the clean-room ideal of certified avionic software will favor a transparent validated kite window state machine. Desired flight performance is not just what a kitegod might do, but also to output semantic kite state in real time, to ease troubleshooting and upgrading. Kite window states are key semantic states.

Most AWE developers have presumed single-kite control, as their first-order control assumption, where their kitefarms are to consist of multiple kite control threads maintaining bottom-up order between themselves. In contrast, KiteLab has long presented the unit-kitefarm as the key AWES control abstraction, an approach known as Process Control. In this view, the simplified kitefarm state machine is the load demand, the weather, and the gross state of the AWES, without complex calculations of trajectory. Passive dynamic stabilities are the preferred unit-kite control solution in the AWES Process Control paradigm.

In our time, process control has flourished, from power plants to chemical plants. Such plants tend to contain many control processes, but the overall process is seen as one simplified control thread. Wikipedia's Process Control article nicely surveys modern practice as it has emerged from ancient roots. Perfected AWE at the largest scale will be a process control regime-

https://en.wikipedia.org/wiki/Process_control

Formal exploration of a long-discussed VTOL launch assist assumption, a welcome reference model in the broader AWES launching design study. Not discussed are severe scaling limits, or closely related alternatives.* This paper poses a mild challenge to rigid kiteplane/multicopter thinking-

Vertical Takeoff and Landing of Flexible Wing Kite Power Systems
Journal of Guidance, Control, and Dynamics · July 2018 DOI: 10.2514/1.G003535}
Sebastian Rapp & Roland Schmehl
Delft University of Technology

https://www.researchgate.net/publication/326587380_Vertical_Takeoff_and_Landing_of_Flexible_Wing_Kite_Power_Systems

===========
* like balloon and ballistic launch methods, and launch assist from pilot kites winch-towed up into working wind, many as demoed by KiteLab Ilwaco 2007-9

Some of the paper's references might be reached by paths than than indicated:

References
[1] Fagiano, L., and Schnez, S., “On the Take-off of Airborne Wind
Energy Systems Based on Rigid Wings,” Renewable Energy,
Vol. 107, 2017, pp. 473–488. doi:10.1016/j.renene.2017.02.023.

[2] Haug, S., “Design of a Kite Launch and Retrieval System For a
Pumping High Altitude Wind Power Generator,” Master’s
thesis, University of Stuttgart, 2012. doi:10.18419/opus-3936.

[3] Ahrens, U., Diehl, M., and Schmehl, R. (eds.), Airborne Wind
Energy, Green Energy and Technology, Springer, Berlin
Heidelberg, 2013. doi:10.1007/978-3-642-39965-7.

[4] Cherubini, A., Papini, A., Vertechy, R., and Fontana, M.,
“Airborne Wind Energy Systems: A review of the technologies,”
Renewable and Sustainable Energy Reviews, Vol. 51, 2015, pp.
1461–1476. doi:10.1016/j.rser.2015.07.053.

[5] Bauer, F., Hackl, C. M., Smedley, K., and Kennel, R., “On
Multicopter-Based Launch and Retrieval Concepts for Lift Mode
Operated Power Generating Kites,” Book of Abstracts of the
International Airborne Wind Energy Conference 2015, edited by
R. Schmehl, Delft University of Technology, Delft, The Netherlands,
2015, pp. 92–93. doi:10.4233/uuid:7df59b79-2c6b-4e30-
bd58-8454f493bb09.

[6] Fechner, U., van der Vlugt, R., Schreuder, E., and Schmehl, R.,
“Dynamic Model of a Pumping Kite Power System,” Renewable
Energy, Vol. 83, 2015, pp. 705–716. doi:10.1016/j.renene.2015.04.028.

[7] Jehle, C., and Schmehl, R., “Applied Tracking Control for Kite
Power Systems,” AIAA Journal of Guidance, Control, and
Dynamics, Vol. 37, No. 4, 2014, pp. 1211–1222. doi:10.2514/1.62380.

[8] Valavanis, K. P., and Vachtsevanos, G. J. (eds.), Handbook of
Unmanned Aerial Vehicles, Springer, Dordrecht, 2014.
doi:10.1007/978-90-481-9707-1.

[9] Stevens, B. L., Lewis, F. L., and Johnson, E. N., Aircraft control
and simulation, Wiley, Hoboken, New Jersey, 2016.
doi:10.1002/9781119174882.
36

[10] Bosch, A., Schmehl, R., Tiso, P., and Rixen, D., “Dynamic
nonlinear aeroelastic model of a kite for power generation,” AIAA
Journal of Guidance, Control and Dynamics, Vol. 37, No. 5, 2014, pp.
1426–1436. doi:10.2514/1.G000545.

[11] Falconi, G. P., Heise, C. D., and Holzapfel, F., “Fault-tolerant
position tracking of a hexacopter using an Extended State
Observer,” 6th International Conference on Automation, Robotics and
Applications, ICARA 2015, Queenstown, New Zealand,
February 17-19, 2015, IEEE, New York, NY, 2015, pp. 550–556.
doi:10.1109/ICARA.2015.7081207.

[12] Lavretsky, E., and Wise, K. A., Robust and adaptive control,
Springer-Verlag London, 2013. doi:10.1007/978-1-4471-4396-3.

Another fine link from Surfer Today, the story of how the Lagainoux brothers started, including a clear reference to Dave Culp's kite sailing as an inspiration. The French story compliments the kite sport pioneer narratives of the Lower Columbia River and Hawaii. Who better to recognize revolutionary kite design progress today than the likes of BrunoL? The article shares rare vintage photos and history-

https://www.surfertoday.com/kiteboarding/13556-bruno-legaignoux-inventor-of-kitesurfing-kites-are-a-fantastic-vehicle

In conventional wind tech, utility-scale HAWTs are designed to last for 20 years or more; but in the history of wind tech, and in forward looking AWE theory, no single number applies. For example, traditional Dutch windmills are effectively immortal, lasting centuries if properly maintained. Cheap power kites might only last a few months in heavy service, yet reach economic payback in a few weeks, far faster and potentially more profitable than any HAWT. The kitefarms AWES will operate from, and much of the surface hardware, could last centuries.

Its misleading to apply conventional HAWT lifespan thinking to AWE. For a small AWES, lifespan may hardly matter at all in actual practice. A single expedition or disaster response can be an acceptable AWES lifespan. HAWT design comparisons are more about profound difference than shared reality. AWES don't even seek the same wind, but a far higher stronger resource.

Aerospace systems on the whole last from single use to indefinitely long lifespans. A 747 airframe may be rated at so many pressure cycles, but even this does not settle absolute lifespan if, for example, conservative operations limit pressure cycle extremes. The expected AWES design lifespan paradox is that a shorter lifespan build is so superior by power-to-mass and capacity-factor, that only such a design can win economically.

AWES lifecycles will depend as vitally on maintenance as build, as is the case in aviation. Expect continued confusion over design lifespan in AWE when simplistic comparisons to conventional wind lifecycles are made. A bird is not built to last like a brick house, and the brick house is not built to fly.

JoeF first noted the BrunoL page a few days ago, part of a treasury of linked Surfer Today content filling dramatic gaps in kitesurfing history. Don Monague's page is a launching point for specific AWE discussion, even invoking Wubbo. Surfers naturally feel kite energy deeply. Follow the links to content about other pioneers, and even a Peter Lynn big kite page. Members of the early AWES Forum can recall huge additional pieces of this history from the preceding lineage of Culp, Lynn, Roeseler, etc.. Many of us in technical kites long know each other personally, and the story only continues to develop. In truth, anyone reading this as its posted is inside the ongoing early revolution, nowhere near its ultimate climax.

https://www.surfertoday.com/kiteboarding/13987-kitesurfing-pioneers-the-story-of-don-montague

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