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Topic for open discussion:
   Form Finding for AWE
What forms or topologies will GW AWES take?
-- topology optimization  :: TO 
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?next?
Nov. 21, 2020, post by Dave Santos
Dynamical Topological Surgery of Engineered Systems (AWES Form-finding)

Dear Stathis and Sofia,

Thank you for your fine paper on the extension of Topological Surgery to Dynamical Systems, which is not just essential for mathematically formalizing Natural Systems, but also many Engineered Systems.

Airborne Wind Energy Systems (AWES) is an fast-emerging energy-engineering field. Static Topology has become essential to formally classify a zoo of contending concepts. AWES further classify according to those architectures that employ Topological Surgery and those that do not. Your identification of diverse Natural Systems as Topological Surgery cases helps validate the idea that many Engineered Systems also vitally depend on Topological Surgery. Aviation in general is a broad Topological Surgery class, where aircraft moving from place to place constantly dynamically reconfigure Homeomorphic Space. As we do form-finding of complex dynamical AWES Rigging Networks, we employ Braid and Knot Theory State Transitions of many kinds, much as classic sailing ships radically reconfigured rigging and sail topology dynamically.

Tassos Kanellos, also an Athens-based researcher (copied above), is one of the key people thinking about AWES along these lines, in the context of computational Multi-Physics Multi-Solvers. A Topological State-Machine would be an ideal framework for dynamical AWES multi-physics. Hoping you and Tassos get acquainted to help Greece play a strong role in AWES engineering-science. Many AWE researchers will enjoy going over your paper carefully for the insights in our engineering problems. Dynamical Topological Surgery is a wonderful engineering-science subject to further develop. Please feel free to ask any questions and request more background information.

Με τις καλύτερες ευχές

Dave Santos
kPower
Austin, Texas
===============================================
Dynamical Systems and Topological Surgery     
S. Antoniou, S. Lambropoulou

Extending topological surgery to natural processes and dynamical systems     
Stathis Antoniou, Sofia Lambropoulou
October 30, 2020, post by Dave Santos

Dutch-Roll with Dynamic-Stall and Vortex-Lift components are proposed identified as ideal megascale kite flight modes for AWE.

A few "kite notes" that apply as well to aircraft, insect, and bird flight-

"Push-Turn"- very effective low-actuation-force turning by releasing tension on an inside wing (or wing tip), rather than pulling more tension on an outside wing (or tip).

"Pop"- pulling (or pushing) a sudden AoA increase for Dynamic Stall, ie. for kitesurfing jumping. The most energetic aerodynamic mode.

"Dance"- spontaneous Free-Energy oscillating motions of a kite (Dutch Roll), increasing in amplitude as wind velocity does. This motion can tapped as a damping factor.

These are substantially scale-invariant effects given constant "most probable wind velocity". They will manifest with simple km-scale AWE sail-wings.

More than mathematical-physics benchtop curiosities, these aerodynamic principles could power the world.
Welcome to Mega-scale Vortex-Lift in Airborne Wind Energy (Multi-r Form-Finding Group)

Dear Friends, especially Jun, Leif, and Jane,

Its very exciting to once again be in touch with Zun Zhang and Leif Ristroph, of NYU Courant Institute (where DaveS first met them), and to bring Jane Wang, of Cornell Physics Dept. (prev. also of NYU CI), into the Airborne Wind Energy (AWE) Multi-r conversation. Their unsurpassed expertise in biologically-inspired unsteady aerodynamics is urgently needed in the multi-disciplinary study of potential GW-scale AWES (AWE systems) being researched by TUKaiserslautern, kPower, and other fine players. 

Upper Wind is the global game-changing clean-energy resource. AWE is the technological quest. Recently, TUDelft and UC3M observed an anomalous Lift-Mode in a Delta Kite experiment, rediscovering (Delta) Vortex-Lift first discovered in kites, and early fighter-jet R&D. This Lift-Mode is now best understood by Insect Flight mathematical-physics experts, who study the wonderfully evolved complexities.

A key insight in AWE is that as a kite-wing scales, most-probable wind-velocity does not. Thus a larger wing in most-probable wind does not experience Re increase with higher minimum velocity like conventional aircraft. While larger rigid-wing mass becomes too much to sustain flight in common wind, under Galilean Square-Cube Scaling, a soft kite wing is able able to scale to 1000m2 and beyond, as repeatedly proven. Indeed, such giant kites are the largest wings ever. Kites typically fly semi-stalled at high AoA, and are also well known for their spontaneous harmonic oscillations ("dancing"), often exploited as "kinematic art", or damped-out by design.

Large-scale soft-kite aerodynamics in real wind (with turbulence) more closely resemble insect flight than conventional aircraft flight. Most kites develop vortex lift, and power-kites exploit dynamic-stall, when a kite-surfer pops up in a jump. These special aerodynamic modes are far more powerful by Cl/Cd than high L/D wings by Mass (and Area, transiently). These vortex-lift modes can be tapped for AWE by km-scale soft-kite formations at GW-rated-power. Furthermore, embodied bio-cybernetics are a wonderful guide to passive-dynamic flight control design (of flight "gait" modes).

Multii-r AWES research is now a few years old. In principle, a megascale iso-radial tensile network of unit-kites can accept wind from any direction and even launch and maintain flight in calm by sequential pumping. Unit-cell proof-of-concept is already multiply validated. Multi-kite formations are also standard in classic kites. No other concept in AWE promises to scale so effectively as Multi-r, with greatest safety, at lowest cost. Passive-dynamic unsteady-aerodynamics is a key engineering requirement. Will share prior work en-masse with Jane, Jun, and Leif, in a separate post.

Best to all,

Dave Santos
Joe Faust
kPower
etc.
Misc. Vortex-Lift AWE Notes-

--------- Message this week to Upper Windpower Forum ----------

Starting Context- novel but marginal unsteady-aerodynamics wind energy by Saphonian (bluff-disc) and Razor (bluff-tube)

Secret Life of Kites and Bumblebees:

Saphonian and Razor WECS are limited by rigid mass. Razor is further limited by quasi 1D narrowness.

The golden solution is highly-stalled high-AoA high-area SS unit-kite in unsteady aerodynamic oscillation.

In HG analogy, high L/D best-glide is not the most energetic mode, the strong Cl/Cd flair-for-landing is.

Its possible to find cyclic dynamic-stability modes of tethered wings that use brief vortex-lift stalled-states.

This sort of powerful pumping mode is famously the "Bumblebee" flight principle, misunderstood at first.


------------- Good Reference -------------

Unsteady forces on an accelerating plate and application to hovering insect flight 

D. I. Pullin1 and Z. Jane Wang2  2004        [(Received 7 August 2003 and in revised form 10 November 2003)]

1. Graduate Aeronautical Laboratories, 105-50, California Institute of Technology, Pasadena, CA. 
2. Theoretical and Applied Mechanics, Cornell University, Ithaca, NY


Dynamic Stall

" ...it is well known that most hovering insects employ angles of attack much higher than the stalled angle of an airfoil. Typical values during the translational phase are about 300 − 500 (Ellington 1984). Dragonflies and butterflies employ even higher angles of attack. At these ‘stalled’ angles, the wing can generate higher transient lift coefficients compared to the steady state value, a phenomenon called dynamic stall. Recent discussions have mainly focused on the role of dynamic stall on lift enhancement (Dickinson & GĻotz 1993; Ellington et al. 1996; Wang 2000b). A side effect of dynamic stall is the increase of drag. In fact at such high angle of attack, it is no longer most convenient to separate lift and drag in the traditional sense, which was appropriate for an unstalled airfoil. Wang recently argued that insects might use both lift and drag to maneuver in air (Wang 2003). In particular, a wing executing idealized kinematics similar to those used by dragonflies uses mostly pressure drag to generate the vertical force to hover (Wang 2003). Classical steady and unsteady airfoil theories, however, were designed to treat the regime of small angle of attack where the flow is attached at the leading edge; they do not predict pressure drag. To extend these theories to a full range of angle of attack, it is necessary to include both the leading and trailing edge vortex. The theory presented here is a second-order unsteady theory for a stalled airfoil. In §5.1 it was shown that the combination of vortex- and attached-flow added mass forces produces a maximum lift coefficient at an angle between 45o and 52.2o, in fair agreement with observation."

---------------------------
Jane Wang | Department of Physics Cornell Arts & Sciences 

"Research

"I am fascinated by the physics of living organisms, with a focus on understanding insect flight. How does an insect fly, why does it fly so well, and how can we infer its ‘thoughts’ from its flight dynamics? The movement of an insect is not only dictated by the laws of physics, but also by its response to the external world.

We have been seeking mechanistic explanations of the complex movement of insect flight. Starting from the Navier-Stokes equations governing the unsteady aerodynamics of flapping flight, we worked to build a theoretical framework for interpreting and predicting the functions of an insect’s internal machinery for flight. In this approach, the physics of flight informs us about the internal computing scheme for a specific behavior. 

Our most recent work makes new connections to neural science. We build physical models for quantitative analyses of flight reflexes, and relate our findings to the underlying neural feedback circuitries for flight."

v==================
TUK's Landmark 3r Paper (Multi-r Unit-Cell)-    

Context- 3r already would involve Vortex-Lift/Dynamic-Stall Modes, as standard power kites do.

---------------

Conjecture: High speed aerobatic murmurations of starlings are collective synchronous dynamic-stall based.

---------------

Wake-cancelation by tandem-wings to prevent F1 tornados downwind of megascale metakites (?)

Deflected wake interaction of tandem flapping foils 
N. S. Lagopoulos (a1), G. D. Weymouth (a2) and B. Ganapathisubramani (a1)
(a1) Aerodynamics and Flight Mechanics Group, University of Southampton, Southampton, UK
(a2) Southampton Marine and Maritime Institute, University of Southampton and Alan Turing Institute, London, UK

http://www.energykitesystems.net/AirborneWindEnergy/kPower/strip-mine.jpg
http://www.energykitesystems.net/AirborneWindEnergy/kPower/tri-unit-cell.jpg
http://www.energykitesystems.net/AirborneWindEnergy/kPower/TUK-3r.jpg
http://www.energykitesystems.net/AirborneWindEnergy/kPower/TUK-GW-scale.jpg
===========================

[Reference Correction at bottom]

AWES Engineering Challenge is to network together all the validated engineering-science at large scale.

Medley of short kPower clips showing unsteady aerodynamics in passive autonomy.

========
Flapping Wing Flight Can Save Aerodynamic Power Compared to Steady Flight
Umberto Pesavento and Z. Jane Wang*
Department of Theoretical and Applied Mechanics, Cornell University, 2009

Another fine contribution! Recalling anomalous unsteady efficiency playing with paper and foam wings in the '80s (Robot Group). Efficient ornithopter and wingmill wings is a matter of patiently finding ideal spring-mass aero-elastic  tunings. Poor tuning is worthless.
==============
=============
On Friday, October 23, 2020, 01:09:49 PM CDT, dave santos <santos137@yahoo.com> wrote:


Dear Friends, especially Jun, Leif, and Jane,

Its very exciting to once again be in touch with Zun Zhang and Leif Ristroph, of NYU Courant Institute (where DaveS first met them), and to bring Jane Wang, of Cornell Physics Dept. (prev. also of NYU CI), into the Airborne Wind Energy (AWE) Multi-r conversation. Their unsurpassed expertise in biologically-inspired unsteady aerodynamics is urgently needed in the multi-disciplinary study of potential GW-scale AWES (AWE systems) being researched by TUKaiserslautern, kPower, and other fine players. 

Upper Wind is the global game-changing clean-energy resource. AWE is the technological quest. Recently, TUDelft and UC3M observed an anomalous Lift-Mode in a Delta Kite experiment, rediscovering (Delta) Vortex-Lift first discovered in kites, and early fighter-jet R&D. This Lift-Mode is now best understood by Insect Flight mathematical-physics experts, who study the wonderfully evolved complexities.

A key insight in AWE is that as a kite-wing scales, most-probable wind-velocity does not. Thus a larger wing in most-probable wind does not experience Re increase with higher minimum velocity like conventional aircraft. While larger rigid-wing mass becomes too much to sustain flight in common wind, under Galilean Square-Cube Scaling, a soft kite wing is able able to scale to 1000m2 and beyond, as repeatedly proven. Indeed, such giant kites are the largest wings ever. Kites typically fly semi-stalled at high AoA, and are also well known for their spontaneous harmonic oscillations ("dancing"), often exploited as "kinematic art", or damped-out by design.

Large-scale soft-kite aerodynamics in real wind (with turbulence) more closely resemble insect flight than conventional aircraft flight. Most kites develop vortex lift, and power-kites exploit dynamic-stall, when a kite-surfer pops up in a jump. These special aerodynamic modes are far more powerful by Cl/Cd than high L/D wings by Mass (and Area, transiently). These vortex-lift modes can be tapped for AWE by km-scale soft-kite formations at GW-rated-power. Furthermore, embodied bio-cybernetics are a wonderful guide to passive-dynamic flight control design (of flight "gait" modes).

Multii-r AWES research is now a few years old. In principle, a megascale iso-radial tensile network of unit-kites can accept wind from any direction and even launch and maintain flight in calm by sequential pumping. Unit-cell proof-of-concept is already multiply validated. Multi-kite formations are also standard in classic kites. No other concept in AWE promises to scale so effectively as Multi-r, with greatest safety, at lowest cost. Passive-dynamic unsteady-aerodynamics is a key engineering requirement. Will share prior work en-masse with Jane, Jun, and Leif, in a separate post.

Best to all,

Dave Santos
Joe Faust
kPower
etc.


Misc. Vortex-Lift AWE Notes-

--------- Message this week to Upper Windpower Forum ----------

Starting Context- novel but marginal unsteady-aerodynamics wind energy by Saphonian (bluff-disc) and Razor (bluff-tube)

Secret Life of Kites and Bumblebees:

Saphonian and Razor WECS are limited by rigid mass. Razor is further limited by quasi 1D narrowness.

The golden solution is highly-stalled high-AoA high-area SS unit-kite in unsteady aerodynamic oscillation.

In HG analogy, high L/D best-glide is not the most energetic mode, the strong Cl/Cd flair-for-landing is.

It is possible to find cyclic dynamic-stability modes of tethered wings that use brief vortex-lift stalled-states.

This sort of powerful pumping mode is famously the "Bumblebee" flight principle, misunderstood at first.
October 15, 2020, post by Dave Santos
Form-Finding Iso Unit-Kite

Happy Halloween ...               Click image for large size:
Oct. 30, 2020, post by Dave Santos

Dutch-Roll with Dynamic-Stall and Vortex-Lift components are proposed identified as ideal megascale kite flight modes for AWE.

A few "kite notes" than apply as well to aircraft, insect, and bird flight-

"Push-Turn"- very effective low-actuation-force turning by releasing tension on an inside wing (or wing tip), rather than pulling more tension on an outside wing (or tip).

"Pop"- pulling (or pushing) a sudden AoA increase for Dynamic Stall, ie. for kitesurfing jumping. The most energetic aerodynamic mode.

"Dance"- spontaneous Free-Energy oscillating motions of a kite (Dutch Roll), increasing in amplitude as wind velocity does. This motion can tapped as a damping factor.

These are substantially scale-invariant effects given constant "most probable wind velocity". They will manifest with simple km-scale AWE sail-wings.

More than mathematical-physics benchtop curiosities, these aerodynamic principles could power the world.
Oct. 31, 2020, post by Dave Santos

On the engineering side of mega-scale aerodynamics, these graphics bring together constraint-resolutions from many sources. 

Its all work-in-progress, lots more to resolve-
http://www.energykitesystems.net/AirborneWindEnergy/images/TriTetherTower001.jpg

http://www.energykitesystems.net/AirborneWindEnergy/images/PersistentFlightWithPlaySail001.png


http://www.energykitesystems.net/AirborneWindEnergy/kPower/kPowerGW3rSpidermillSketch2020October.jpg
Nov. 1, 2020, post by Dave Santos

A Dynamic-Stall AWES concept by Alex Muzichkov, in 2011, that combines ancient Dragon Kite (kite network) with clever phase-shift crankshaft control. WPI and others have applied dynamic stall cycles in prototypes.

The emergent follow-on flight dynamics paradigm is a mostly-passive Dutch Roll Cycle, with a blended sequence of flight modes that include Dynamic stall, Vortex-Lift, Side-Slip, and best L/D Glide; with Crosswind-Cableway PTO basis.


http://www.energykitesystems.net/AirborneWindEnergy/kPower/BasicDynamicStallCycle.png
I

Dutch Roll Dance:
Even an "ugly" (KiteShip OL) wing can do it-
http://www.energykitesystems.net/AirborneWindEnergy/mages/LeastMotionPrincipleInAWE001.jpg



From the US Patent that set Loyd to write- 
Crosswind Kite Power
Miles L. Loyd, 1980
Lawrence Livermore National Laboratory




Read the Classic Paper-
Crosswind Kite Power
Miles L. Loyd*
Lawrence Livermore National Laboratory, Livermore, Calif

=========================

Alex,

Hope you are well. Russia is needed in kite-energy research cooperation. Big things are happening.

Do you know Andrew? (Андрей Казанцев) If you declare a Russian Kite Tech Group, we can include them.

Your old model was an early example of "dynamic stall" principle, like in Insect Flight, Aviation (flare-landing), etc..

The principle is sound, but there are more energetic modes, with power extracted crosswind instead of upwind.

Its important to work with true Power Kites in good wind. Heavy kites in low wind have no extra power to share.

Kite surfers jump by dynamic stall in a more crosswind direction, with opposed fast load-motion. Its very powerful.

New progress to include some dynamic-stall in the power-kite figure eight pattern, mixed with other flight mode phases.

с дружественными приветствиями
======================================= 
Dear Colleagues                                Nov. 1, 2020

I did some experiments at that time trying to get energy from a stretched cable coming from the kite and creating longitudinal vibrations. Unfortunately, the high inertia of the cable (sag and pull) does not allow to get much energy.
This is clearly visible in the video with my experiment. I think that the variant with the Chinese kite may also fail, although I did not do such an experiment.Perhaps the close position of the first kite will eliminate this effect.