Flygen systems are generally seen as a main AWE possibility. On Rope-drive transmission discussion a potential advantage is the motionless rope in y or rotating configurations, avoiding a too fast wear that occurs when the rope transmits mechanical power.

Some interesting possibilities are on See page 9, the Centrifugally Stiffened Rotor-wing (CSR), and also Roeseler’s prior art mentioned on

@someAWE_cb’ and @Rodread’ rotors can have propellers in their tips of blades.

Flygen systems are torque or stationary systems (IMHO) with 16/27 potential Betz limit, continuous power, and only one flight mode.

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See also Dave Santos’ topic “The Secret Life of High Voltage Tether Insulation” on : “There are severe limits to how high voltage insulation will tolerate AWES winching cycles when integrated into a primary tension rope (like the M600). Strenuous wear and single-point damage will cause insulation air gaps with moisture intrusion, promoting destructive arcing and steam, and maybe total platform loss…”.

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Not sure about the “only one flight mode” @PierreB
in the case of the rotor of a tilted hollow axis network kite (Such as Rotating Reel, Daisy, OTS…) They can be driven to rotate with mechanical torsion supplied from the ground end of the shaft… I’ve tried it… it’s fun… Would love to know if it could be used for transport too.


“only one flight mode” in regard to the two flight modes for yoyo systems.


My original SuperTurbine patent had claims directed towards vehicle propulsion.


There is no limit to how many decades people can go on “analyzing” the millions of potential details, in lieu of ever building and running machines that work. Like the proverbial “blind men describing the elephant” - except there is no elephant. In AWE, the “elephant” is hypothetical - in the future. I would suggest that many here are overly-influenced by people who purport to be leading researchers, while never showing meaningful results (power generation). This type of self-described “expert” claims, on the one hand, to be leading the field in AWE research, talking alternately about generating GigaWatts then TeraWatts, while simultaneously claiming that generating any electricity at all, even 100 Watts to power a standard light bulb is not something they are even interested in pursuing. Depends on whether they are bragging or making excuses. I would recommend forget the endless on-paper or on-screen analysis and gets something running. Then you’ll find you didn;t really even know what you were talking about (Oh gosh, why is it doing this???) or what the main factors were, until you built and ran something and hopefully generated some electricity.

#7 is an interesting message from Dave Santos about “tethered flygen or groundgen control-pod” potentially available on and also on .

FlygenKite could be controled with RC, then fully:

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Yoyo and flexible kite, flygen and rigid wing?

And of course Makani.


Some components as motors, RC and wings on


Looks like they’re still playing the “shell-game” of shifting “future activity” locations. “Where is the bean” at any given (future) moment? Under which shell? (Please excuse the pun.) Alameda? Hawaii? Norway? Hurray hurray, step right up and take your best guess!


A problem I see is the tip speed of the secondary turbines, leading to noise and perhaps a lower lifetime. There are also efficiency losses but they look to be not too significant (5-10%) as there is not a second Betz limit.


Betz is the wrong (2D) model for turbine-on-a-wing (3D) and other specific turbines. Power-to-weight is the best First-Order Factor to reveal FlyGen inferiority. There is no competitive kite sport where a flygen powering a traction-motor drive can rival the direct traction of a simple power kite, of equivalent mass.


"7.1. Effect of flying mass
In all AWESs, increasing the flying mass decreases the tension of the cables. Since Ground-Gen systems rely on cables tension to generate electricity, a higher mass of the aircraft and/or cables decreases the energy production [107] and should not be neglected when modelling [109]. On the contrary, increasing the flying mass in Fly-Gen systems does not affect the energy production even though it still reduces the tension of the cable. Indeed, as a first approximation, the basic equations of Fly-Gen power production do not change if the aircraft/cable mass is included and this is also supported by experimental data[108]. "


Dave, it is difficult to argue with such an irrelevant comment. Betz limit and power-to-weight ratio are two different things. Please read the quote about the “Effect of flying mass” I introduced. Arguing power-to-weight vs efficiency in regard to Betz limit doesn’t allow a clearer debate.

Concerning Betz limit it applies for all wind systems, possibly as a first approximation. When a 3D space system is analysed, like an AWES, Betz limit applies to the front airspace which is swept.

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Pierre, The question is which factor is more important, not how wildly different they are as First Order AWES choices. Betz is a very poor flight analytic compared to power-to-mass.

Given excess mass is known toxic to kite performance, what to make of claims that increasing flygen mass does not “affect the energy production”. Increased mass should increase production, not leave it the same.


Dave, the power-to-mass ratio per wing area is not the same as the power-to-mass ratio per swept area.
And the power-to-mass ratio can be measured with all components, or only with the components aloft.

The Betz limit is a mean to appreciate the power-to-mass ratio per swept area.


There is no flight-mass term in Betz. Swept area by itself does not predict highest power-to-mass. A more efficient AWES can beat a poorer AWES with a higher swept area. Highest power-to-mass best predicts lowest LCOE, in kPower’s standard aeronautical-engineering view, definitely not based on Betz or sweep (TSR) numbers.


Kite-reeling AWES can reach high altitude but have severe efficiency limits of which a discontinuous power with two phases.
Some torque systems are efficient but cannot reach high altitude.
Flygens can reach both high altitude and efficiency.


That’s such a cool page thanks @PierreB
Do you have a list of components that you used on flygenkite?
I’d really love to see what experiments have been done using remote control paramotors rigged as kites with turbine blades instead of prop for onboard power.
Anyone tried it yet?


Several propellers of which Master Airscrew 9x4, Graupner or Mabuchi DC motors used as generators, Ozone 1 m² or 1.5m² two lines kite, molded support in two parts (see on video below) containing the generator, adhesive led tape.

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