Messages in AirborneWindEnergy group.                           AWES9639to9689 Page 90 of 440.
Group: AirborneWindEnergy Message: 9639 From: Joe Faust Date: 7/17/2013
Subject: Re: NASA Technology Transfer Opportunity:

Group: AirborneWindEnergy Message: 9640 From: Joe Faust Date: 7/18/2013
Subject: HPK

Group: AirborneWindEnergy Message: 9641 From: Bob Stuart Date: 7/18/2013
Subject: Re: HPK

Group: AirborneWindEnergy Message: 9642 From: Joe Faust Date: 7/18/2013
Subject: Re: HPK

Group: AirborneWindEnergy Message: 9643 From: Joe Faust Date: 7/18/2013
Subject: Re: HPK

Group: AirborneWindEnergy Message: 9644 From: Bob Stuart Date: 7/18/2013
Subject: Re: HPK

Group: AirborneWindEnergy Message: 9645 From: Joe Faust Date: 7/18/2013
Subject: Design of a small-scale prototype for research in airborne wind ener

Group: AirborneWindEnergy Message: 9646 From: Joe Faust Date: 7/18/2013
Subject: Re: Design of a small-scale prototype for research in airborne wind

Group: AirborneWindEnergy Message: 9647 From: seanccostello Date: 7/19/2013
Subject: Re: Betz for Kites: Power Generation Using Tethered Wings

Group: AirborneWindEnergy Message: 9648 From: roderickjosephread Date: 7/19/2013
Subject: Re: Betz for Kites: Power Generation Using Tethered Wings

Group: AirborneWindEnergy Message: 9649 From: Joe Faust Date: 7/19/2013
Subject: Re: HPK

Group: AirborneWindEnergy Message: 9650 From: Doug Date: 7/19/2013
Subject: Re: Betz for Kites: Power Generation Using Tethered Wings

Group: AirborneWindEnergy Message: 9651 From: Joe Faust Date: 7/19/2013
Subject: Re: HPK || SEHPK

Group: AirborneWindEnergy Message: 9653 From: dave santos Date: 7/19/2013
Subject: Re: Betz for Kites: Power Generation Using Tethered Wings

Group: AirborneWindEnergy Message: 9654 From: dave santos Date: 7/19/2013
Subject: Re: NASA Technology Transfer Opportunity:

Group: AirborneWindEnergy Message: 9655 From: dave santos Date: 7/19/2013
Subject: Re: HPK

Group: AirborneWindEnergy Message: 9656 From: dave santos Date: 7/19/2013
Subject: Quasi Single-Skin LEI (Airrush 18m2)

Group: AirborneWindEnergy Message: 9657 From: dave santos Date: 7/19/2013
Subject: Doug on "the future of offshore wind energy"

Group: AirborneWindEnergy Message: 9658 From: Joe Faust Date: 7/20/2013
Subject: Re: Sikorsky Prize Won

Group: AirborneWindEnergy Message: 9659 From: roderickjosephread Date: 7/20/2013
Subject: Eaves-dropping with arch kites

Group: AirborneWindEnergy Message: 9660 From: Joe Faust Date: 7/20/2013
Subject: And the 600th goes to Rod Read !

Group: AirborneWindEnergy Message: 9661 From: Joe Faust Date: 7/20/2013
Subject: Peter S. Lee for US 8188613

Group: AirborneWindEnergy Message: 9662 From: Joe Faust Date: 7/20/2013
Subject: Solo traction AWES establishing a record

Group: AirborneWindEnergy Message: 9663 From: Joe Faust Date: 7/20/2013
Subject: Kite Patch for AWES field operators? Mosquitoes?

Group: AirborneWindEnergy Message: 9664 From: Joe Faust Date: 7/20/2013
Subject: Jan Hystad on Wind Power Plant

Group: AirborneWindEnergy Message: 9665 From: Joe Faust Date: 7/20/2013
Subject: Re: Jan Hystad on Wind Power Plant

Group: AirborneWindEnergy Message: 9666 From: Joe Faust Date: 7/20/2013
Subject: Luigi Adriano Giacalone

Group: AirborneWindEnergy Message: 9667 From: Joe Faust Date: 7/21/2013
Subject: Leonid Goldstein, AWE, non-AWE, and software development

Group: AirborneWindEnergy Message: 9668 From: Joe Faust Date: 7/21/2013
Subject: Re: Leonid Goldstein, AWE, non-AWE, and software development

Group: AirborneWindEnergy Message: 9669 From: Joe Faust Date: 7/21/2013
Subject: Re: HPK || Twp-pulley format

Group: AirborneWindEnergy Message: 9670 From: seanccostello Date: 7/22/2013
Subject: Re: Betz for Kites: Power Generation Using Tethered Wings

Group: AirborneWindEnergy Message: 9671 From: Doug Date: 7/22/2013
Subject: Re: Doug on "the future of offshore wind energy"

Group: AirborneWindEnergy Message: 9672 From: Doug Date: 7/22/2013
Subject: Re: NASA Technology Transfer Opportunity:

Group: AirborneWindEnergy Message: 9673 From: seanccostello Date: 7/22/2013
Subject: Re: Betz for Kites: Power Generation Using Tethered Wings

Group: AirborneWindEnergy Message: 9674 From: dave santos Date: 7/22/2013
Subject: KiteSat: "hello world"

Group: AirborneWindEnergy Message: 9675 From: Joe Faust Date: 7/22/2013
Subject: Re: WPI gets grant for undersea 'kite' project

Group: AirborneWindEnergy Message: 9676 From: Joe Faust Date: 7/22/2013
Subject: Re: HPK || Phased tugging maintains wing in flight

Group: AirborneWindEnergy Message: 9677 From: Joe Faust Date: 7/22/2013
Subject: Re: HPK || Phased tugging maintains wing in flight

Group: AirborneWindEnergy Message: 9678 From: edoishi Date: 7/22/2013
Subject: Re: KiteSat: "hello world"

Group: AirborneWindEnergy Message: 9679 From: Gabor Dobos Date: 7/23/2013
Subject: Re: Branches of FFAWE: some are kite systems; some are not kite syst

Group: AirborneWindEnergy Message: 9680 From: seanccostello Date: 7/23/2013
Subject: Re: Betz for Kites: Power Generation Using Tethered Wings

Group: AirborneWindEnergy Message: 9681 From: hardensoftintl Date: 7/23/2013
Subject: Rigid vs Soft Wings???

Group: AirborneWindEnergy Message: 9682 From: Gabor Dobos Date: 7/23/2013
Subject: Re: Betz for Kites: Power Generation Using Tethered Wings

Group: AirborneWindEnergy Message: 9683 From: Joe Faust Date: 7/23/2013
Subject: Re: Branches of FFAWE: some are kite systems; some are not kite syst

Group: AirborneWindEnergy Message: 9684 From: Joe Faust Date: 7/23/2013
Subject: Re: Branches of FFAWE: some are kite systems; some are not kite syst

Group: AirborneWindEnergy Message: 9685 From: Joe Faust Date: 7/23/2013
Subject: Re: Branches of FFAWE: some are kite systems; some are not kite syst

Group: AirborneWindEnergy Message: 9686 From: Rod Read Date: 7/24/2013
Subject: Re: KiteSat: "hello world"

Group: AirborneWindEnergy Message: 9687 From: Rod Read Date: 7/24/2013
Subject: Re: Betz for Kites: Power Generation Using Tethered Wings

Group: AirborneWindEnergy Message: 9688 From: Joe Faust Date: 7/24/2013
Subject: Theories of John Dabiri receive an opinion

Group: AirborneWindEnergy Message: 9689 From: Joe Faust Date: 7/24/2013
Subject: Siemens



Group: AirborneWindEnergy Message: 9639 From: Joe Faust Date: 7/17/2013
Subject: Re: NASA Technology Transfer Opportunity:
Some text clips:

NASA Langley's
Control and Tracking for Tethered Airborne Wind Energy (AWE) Vehicles
Vision-based system controls a flexible kite in a crosswind trajectory using only ground-based sensors

NASA Langley Research Center has developed hardware and software to track the flight of tethered vehicles, including kitelike, airborne wind energy (AWE) generation systems. The control system consists of a pan-tilt platform and a visible-spectrum digital camera, combined with tracking control software running 
on a standard PC. The system controls the flight of the vehicle to keep its position on a power-producing trajectory, maximizing velocity (but within limits). This trajectory produces tension, which turns the ground-based generator, producing the energy. The NASA system enables effective operation of groundgen or flygen types of AWE systems. NASA has a working prototype and prebeta software and is seeking development partners to make it more robust and user-friendly by testing in real-world systems.

Benefits
• Reliably tracks and controls a flexible kite 
• Uses low-cost components
• Uses a low-complexity approach that lowers total system mass by locating the mass of the system on the ground
• Optimizes power generation by keeping the kite in a position to capture crosswinds
• Potentially scales to enable groups of hundreds of kites to fly in flock formation for scalable power

The Technology
The technology of the system controls and tracks the flight of tethered vehicles, including 
kite-like AWE generation systems. Comprised of a camera, load cells, encoders, an 
anemometer, and software, the tracking system is based on digital photo analysis. The 
system tracks where the kite is 30 times every second. The controller makes an adjustment 
to the tether winch to keep the kite in the controlled trajectory to maximize power at high 
velocities without exceeding the limits of the hardware. Langley has built and generated 
power with a 2-kW demonstrator with two tethers (each with its own servo motor) and a 
pan-tilt unit to extend the field of view of the camera. NASA has flown the system many 
times and has collected an abundance of flight data. A video of the demo is available on 
the website http://www.youtube.com/watch?v=DCfw1B2XGQc     The system software is 
considered to be at the pre-beta stage. 

Applications
The technology has several applications in the AWE market. Specifically, it can provide tracking and control 
• For both groundgen and flygen systems (allowing the designer to move the control system from the kite-end to the ground)
• As either a primary or back-up system
• In both land-based and off-shore applications.

For More Information
If your company is interested in licensing or joint development opportunities associated with this technology, or if you would like additional information on partnering with NASA, please contact: 
The Technology Gateway
National Aeronautics and Space Administration
Langley Research Center
Mail Stop 218
Hampton, VA 23681
757.864.1178
LARC-DL-technologygateway@mail.nasa.gov
technologygateway.nasa.gov 
www.nasa.gov
Group: AirborneWindEnergy Message: 9640 From: Joe Faust Date: 7/18/2013
Subject: HPK
HPK  (human-powred kiting) already occurs in several formats. But other formats are yet to be operational. Today, a very common HPK is occurring in indoor kiting with the human staying on the ground.  The ancient "running" to get a wing kited is the most common; but again, the pilot is on the ground.   Look to "pilot-in-wing" or "pilot-in-tether" forms of HPK  to occur one day.   Here is some stepping in the direction of pilot-in-wing-set HPK: 

CC 3.0 license: 
Have ground or water vehicle as towing agent powered only by endless loop driven by human who is situated in the kite-system wing set; he or she causes the loop to move the grounded or watered vehicle to travel to tow the air-wing set.   No wind; only apparent wind from the towing.   This is a form of human powered kiting with the human power obtains from the flying human.   Please post a note about any trials of this method:
http://energykitesystems.net/HumanPoweredKiting/imagesHPK/HPK18July2013.jpg    The efforts in HPK will tend to lend some art to AWES matters. 

Ideas are certainly invited. 
Reports on builds and trials are welcome. 
Group: AirborneWindEnergy Message: 9641 From: Bob Stuart Date: 7/18/2013
Subject: Re: HPK
Most of the unsuccessful Human Powered Aircraft used powered wheels for take-off assistance.  I think it would be hard for this rig to beat the efficiency of an air propeller overall in still air, but it would do much better upwind.  Unfortunately, pure human-power aircraft are very slow and vulnerable to breaking by very low winds.  

Bob Stuart

On 18-Jul-13, at 10:26 AM, Joe Faust wrote:
Group: AirborneWindEnergy Message: 9642 From: Joe Faust Date: 7/18/2013
Subject: Re: HPK
Thanks, Bob. 
      The "bite" of the ground-hugging wheels and the dedicated sans-propeller wing in no-wind conditions is the the game.   Or the "bite" of a driven water-wheel for a watered situation is the water game.   I have not done the maths to compare the "bite" of an air propeller against the "bite" of ground wheels for propulsion; the slips in either situation will have their say. A streamlined ground vehicle with good "bite" to the ground (perhaps cableway with surround bite)?  Gearing for getting speed of the ground vehicle?    The matter of comparing with other means  forms chapters of interest.   Yet the game in itself may have merits.  
Group: AirborneWindEnergy Message: 9643 From: Joe Faust Date: 7/18/2013
Subject: Re: HPK
A distinct method is a near cousin to the first method: 

Self-tow without loop; just set out a long line connected to a fixed ground anchor; connect the kite-system wing  As pilot, be in the wing. Reel in the long line to launch inhabited wing into kited flight; then perhaps release line for a glide. This method might use a fixed anchor.  No-wind game.   If a headwind, then a different game ensues.  In either game, the apparent wind for flight of the kited inhabited wing occurs. This method collects line or lets the line drop down eventually to be fully released; or have a remote control to release the line at the fixed-anchor point when powering stops.   Lock-out dangers will need to be addressed. Stalls near the ground are to be avoided.  Either glide to a landing or catch a thermal and be off soaring.   
    Upon landing out someplace, hook into a fixed anchor again and have the remote-release-of-lower-end-of-line device.   Be win wing again; work hard again to gather the long line to effect kited launch; release lower end of line and collect line for use in another cycle of launching later.   Self-tow launch time and time again. Soar around the world.    On water, have a triggerable-depower water drogue for the anchor; work to kite launch by again gathering long line set out; remote control depower the water drogue and lift the material drogue to wing as one soars off to other realms.  Effect the launch in calm by pilot power or face headwind for the kited launch. 
Group: AirborneWindEnergy Message: 9644 From: Bob Stuart Date: 7/18/2013
Subject: Re: HPK
The "bite" on Daedalus was so good they put the air speed sensor behind the prop hub for convenience.  The Froude numbers are so high that even with other losses, overall drive efficiency was approaching 90%, AFAIR.  The ground cart would need weight for traction, and would need to follow hard, mostly level surfaces.  Even the wheel on the ground is not 100% efficient; adding traction causes squirm in the tread area.    The belt drive would have several complicating factors, at least as severe as a propeller drive, as well as the exposed tether.  Steering the cart gives the pilot another chore, with his feet already occupied.
In pedaling boats, I discovered that there was a good correlation between torque and RPM, so gearing changes were only wanted for unusual jobs that no aircraft could handle.  Acceleration to HPA speeds is very brief, and everything is optimized for cruise speed.

If we get back to regular kiting, using the wind power and a stationary tether, a pilot with a pedal powered reel would be able to save the day on some situations when a lull causes a stall, but an airframe suitable for even light crosswind work will sometimes need more power than anyone can produce even in a sprint.  I'd be inclined to store energy in a spring or lighter equivalent, so I could always supply enough power, even if the wind suddenly reversed.  That would make a safe manlifting kite with interesting performance.  HPA are flown in ground effect for safety as well as lift, being rated for maybe 1.1 g maneuvers and a VNE a half knot over cruise.  The energy storage device could also be on the ground, under radio control.  It might provide a launch, and then be replenished before the kite used much of the available tether length.  From altitude, the pilot could alternate between gliding and kiting in aerobatics.  Purists could crank up for the first launch by muscle power.

Bob Stuart

On 18-Jul-13, at 11:16 AM, Joe Faust wrote:
Group: AirborneWindEnergy Message: 9645 From: Joe Faust Date: 7/18/2013
Subject: Design of a small-scale prototype for research in airborne wind ener
Design of a small-scale prototype for research in
airborne wind energy 
 
Lorenzo Fagiano
and Trevor Marks

(or arXiv:1307.4215v1 [cs.SY] for this version)
Group: AirborneWindEnergy Message: 9646 From: Joe Faust Date: 7/18/2013
Subject: Re: Design of a small-scale prototype for research in airborne wind
References
[1] Makani Power Inc., http://www.makanipower.com
[2] SkySails GmbH & Co., 2010, http://www.skysails.info
[3] Ampyx power website, http://www.ampyxpower.com/.
[4] Windlift website, http://www.windlift.com/.
[5] Kitenergy website, http://www.kitenergy.net/.
[6] M. Canale, L. Fagiano, and M. Milanese, "Power kites for wind energy generation," IEEE Control Systems Magazine, vol. 27, no. 6, pp. 25–38, December 2007.
[7] A. Ilzhöfer, B. Houska, and M. Diehl, "Nonlinear MPC of kites under varying wind conditions for a new class of
large-scale wind power generators," International Journal of Robust and Nonlinear Control, vol. 17, pp. 1590–1599,
2007.
[8] M. Canale, L. Fagiano, and M. Milanese, "High altitude wind energy generation using controlled power kites," IEEE
Transactions on Control Systems Technology, vol. 18, no. 2, pp. 279 –293, mar. 2010.
[9] E. Terink, J. Breukels, R. Schmehl, and W. Ockels, "Flight dynamics and stability of a tethered inflatable kiteplane,"
AIAA Journal of Aircraft, vol. 48, no. 2, pp. 503–513, 2011.
[10] J. H. Baayen and W. J. Ockels, "Tracking control with adaption of kites," IET Control Theory and Applications,
vol. 6, no. 2, pp. 182–191, 2012.
[11] L. Fagiano and M. Milanese, "Airborne wind energy: an overview," in American Control Conference 2012, Montreal,
Canada, 2012, pp. 3132–3143.
[12] M. S. Manalis, "Airborne windmills and communication aerostats," Journal of Aircraft, vol. 13, no. 7, pp. 543–544,
1976.
[13] C. A. J. Fletcher and B. W. Roberts, "Electricity generation from jet-streams winds," Journal of Energy, vol. 3, pp.
241–249, 1979.
[14] M. L. Loyd, "Crosswind kite power," Journal of Energy, vol. 4, no. 3, pp. 106–111, 1980.
[15] L. Fagiano, M. Milanese, and D. Piga, "High-altitude wind power generation," IEEE Transactions on Energy Conversion, vol. 25, no. 1, pp. 168 –180, mar. 2010.
[16] ——, "Optimization of airborne wind energy generators," International Journal of Robust and Nonlinear Controll,
vol. 22, no. 18, pp. 2055–2083, 2011.
[17] Enerkite Gmbh website, http://www.enerkite.com/.
[18] L. Fagiano, K. Huynh, B. Bamieh, and M. Khammash, "On sensor fusion for airborne wind energy systems," IEEE
Transactions on Control Systems Technology, 2012, in press, doi:10.1109/TCST.2013.2269865, Pre-print available
on arXiv: 1211.5060.
[19] L. Fagiano, A. Zgraggen, M. Morari, and M. Khammash, "Automatic crosswind flight of tethered wings for airborne
wind energy: modeling, control design and experimental results," arXiv, vol. 1301.1064, 2013, submitted to IEEE
Trans. on Control Syst. Technology.
[20] EISG project "Autonomous flexible wings for high-altitude wind energy generation", experimental test movie,
September 2012. Available on–line: http://lorenzofagiano.altervista.org/movies/EISG_UCSB_auto_wing.mp4.
[21] R. Juvinall and K. Marshek, Machine Component Design, 5th Edition. Wiley, 2011.
[22] R. Craighton, "Wind energy industry: Go fly a kite." IEEE Spectrum (INT), vol. 49, no. 12, p. 40, 2012.
Group: AirborneWindEnergy Message: 9647 From: seanccostello Date: 7/19/2013
Subject: Re: Betz for Kites: Power Generation Using Tethered Wings
Hi,
I'm the first author of that paper. Any feedback/discussion is very welcome. Could you be more specific?
Sean
sean.costello@epfl.ch
Group: AirborneWindEnergy Message: 9648 From: roderickjosephread Date: 7/19/2013
Subject: Re: Betz for Kites: Power Generation Using Tethered Wings
Hi Sean,
Thanks for being welcoming of critique.
I hope I'm competent enough to reply.
And please accept my sincerest thanks for producing what is an excellent work.

My specific issue was the statement
"This paper describes how to evaluate the maximal power generating potential of any kite-power system"
Whereas in the paper itself , it is stated that...

The generic high-altitude system we will consider....

So the kite has to be a singular unit, & do all the lifting and work all by itself ? why?

I'm miffed that you didn't show how your method demonstrates power available in a transverse driven endless band

or from a ganged curtain of tacking jib like sails (I had a wayfarer dingy planning just on a jib yesterday, massively windy day out)

at heights of 10 km it is a significant burden which the wings must sustain; this means a large
portion of the system’s power producing potential is used to negate gravity, rather than to generate power.
That's not dissimilar to ground based turbine mass distribution ... but they're still worthwhile products.


Kites are wings (just like the blades of a turbine, the wings of an

airplane or the sails of a yacht) which are connected to the ground using a system of cables.

really different to most turbine blade profiles, but ok

 

Wings are generally designed to operate most efficiently (achieve the

greatest lift to drag ratio) for zero sideslip, i.e.β= 0.

What if the kites are designed to rotate? Surely we can consider that.

Do they absolutely have to always work in their optimal condition only?

I’d be surprised if 1 ever has except ~nearly a standard turbine.

 

If we could design a configuration such that this force is aligned with the wind

it would be easy to operate the wing optimally at all times. The only way to

exert a force in line with the wind would be if the wing was flying just

above the ground.

In one line dragging groundgen configuration. Why not design the force takeoff to come from the direction the kite is going instead?


But the whole point of kite power is to harness winds at

altitudes of at least several hundred meters.

Not when they’re made for generation it’s not. The whole point is cheaper generation. Yes efficiency drives everything but ROI advantage is ROI advantage.

 

Is that max power zone diagram starting to resemble a spinning cone? Yes.

 

This is because in general the direction of the restraining forces (transmitted using tethers)

 Does it always have to be...? NO


The results also highlight the importance of operating the wings and tether at full load.

Loads of well filled sails, networked to be controllable will do me just fine thanks.

 
Being such an open source fan boy, my other issue was that;

A confidential document put it’s assumptions at the end.

Let’s be up front with our weaknesses instead and build on the meagre scrapings of emerging potential instead.

 

I'm maybe not smart enough to get your approach yet ...
But it just seems to be missing a dimension

 
Group: AirborneWindEnergy Message: 9649 From: Joe Faust Date: 7/19/2013
Subject: Re: HPK
Some progress on the second method mentioned, i.e., the method with a single line to a fixed anchor. This second method crawls and collects line from a line that has been set out over land or water; the line could even surround the earth or some circle on the earth's surface or other planet or even a line set in space aiming to kite in the photonic streams.
http://energykitesystems.net/HumanPoweredKiting/imagesHPK/HPK18July2013LineCrawl.jpg  image is shown below, but might be too wide to show in group; click through text link if image does not show full for you. 
Group: AirborneWindEnergy Message: 9650 From: Doug Date: 7/19/2013
Subject: Re: Betz for Kites: Power Generation Using Tethered Wings
Hi Sean:
Good to always remember Betz when discussing wind energy system design. Without reading your paper specifically, I would point out that Betz always seems to apply in any wind energy situation. Saying one can overcome Betz, beat Betz, etc. has always turned out to be not true. The air molecules must be left with enough kinetic energy to leave the area, so you can process more molecules, to extract more energy.

In the case of airborne wind energy, nothing changes. Betz is still officiating, still in charge.

I liken a turbine to a movie theater turnstyle: You can only charge a certain portion of a person's income or they will be broke and unable to afford the ticket to push thru the turnstyle. If you try to extract ALL of a person's income for a movie, you will have an audience of zero. There's a balance that the movie theaters have found: they can extract 59% of a person's income to have them sit in a dark room, doing nothing, looking at an empty mirage that is nothingness, for 2 hours. "If you give us 59% of your income we will give you absolutely nothing but a few strategically-placed photons in return! - sound good?" (for most people that sounds like a good deal - another topic) Then, like the air molecules wonder where all their kinetic energy went, the movie patron wonders what has gone wrong with their life. Where did all their money go? Why are they treading water? Why does their actual life have no drama so they have to pay for artificial drama? Because they were at the movies!
To explain Betz you have to put it in language people can understand.
:O..............
Group: AirborneWindEnergy Message: 9651 From: Joe Faust Date: 7/19/2013
Subject: Re: HPK || SEHPK
A third form of HPK is herein noted, but this one is different from the two methods presented; this one stores energy whereas the other two methods did not store energy.  The following method has very many possible embodiments. We are not limited to the few immediately mentioned scenarios.  In group we have already reviewed different uses of dropping masses from above (hundreds or more practical uses for dropping masses from heights).   The mass is lofted by various means; then the mass is let down at controlled speeds or let down in free-fall. During the let-down, one may be interested in various ways of using up the potential energy of the lofted mass.The potential energy could be used directly or converted to a host of other forms: heat, light, noise, kinetic energy of another mass, etc. Tasks may be performed by use of the lofted-mass' potential energy. 
       I focus on a couple of embodiments in the following sketch:      Pilot stores his or her muscle-based energy by pulling a mass up to altitude; then the pilot hooks into his or her hang glider that is connected to the lofted mass through a lofted pulley. Trigger the mass to begin a fall while running into the wind with the wing. As the mass continues dropping and propelling the kited hang glider with pilot at the controls, the hang glider may climb to increasing altitudes; one does not want to stall the hang glider during the tow. At some point in the kiting, the hang glider may release for free-flight; a glide or soaring flight may be the full story. 
      In the hang glider scenario, after a first launch and glide, the pilot on the ground might use the wing to help pull the mass back up to altitude in getting ready for launching again in similar towing fashion. 
     The lifted mass could be just about anything: bag of water, bag of soil, junk car to be dropped, log, set of persons, bag of rocks, bag of sand, bags of 
SEHPK
Group: AirborneWindEnergy Message: 9653 From: dave santos Date: 7/19/2013
Subject: Re: Betz for Kites: Power Generation Using Tethered Wings

Hi Sean,

Your draft paper is very promising. There is not much to improve on, but a few small points.

A seeming gap in the concept-space you present is that open-source AWE has lately found strategies to improve AWES "Betz" streamtube efficiency over the classic Loyd single-kite paradigm. This work is well documented by Joe Faust and on the AWES Forum, in many posts. Rod Read has many variants modeled in 3D. Even given modest kite L/D ratios, the Betz efficiency of these new airborne architectures is roughly predictable to approach 20%, far more than the sparse models. 

We identify the relevant stream-tube as the rectangle defined by regulatory ceilings (like the provisional FAA 2000" ceiling) and the kite-cell land-footprint diameter. The wind-gradient with altitude is an important added dimension. The resulting rectangle is topologically equivalent to the Betz disc-assumption.

We developed high-density kite array concepts and methods that maximally fill this frontal airspace. A kite arch that spams the entire space and supports dense WECS arrays is typical of proposed solutions. Houska's multi-kite summed-power theorem points toward this, but Rod and others want more emphasis of this solution path.

Your identification Power-to-Mass as a a critical metric is quite correct. A note to older readers that this corresponds to legacy "power-to-weight" aeronautical usage and associated heuristics.

A burning open question in relating power-to-mass to the extreme cases of single-skin soft-wings like the NASA Power Wing v. a rigid composite like Ampyx. Soft-wings may sweep slowly, but are so large, by equivalent mass, in our most probable wind-velocity. Here is where a clear conclusion statement based on your data is hoped for.

Thank You for a very fine effort in understanding kite energy.

dave santos

PS Please disregard the comment by a willful non-reader who missed that you correctly find that ordinary kite models have a Betz efficiency so low its almost meaningless :)
Group: AirborneWindEnergy Message: 9654 From: dave santos Date: 7/19/2013
Subject: Re: NASA Technology Transfer Opportunity:
This is definitely a nice invitation to participate in developing flight-certified ground-based kite-farm machine vision.

Several of our better-known venture players will likely respond. On-board sensor dependence is being sorely challenged.

Small developers could form a class, like via the Kite Power Cooperative, for shared first-class NASA liaison for this beta-phase. 
 
Group: AirborneWindEnergy Message: 9655 From: dave santos Date: 7/19/2013
Subject: Re: HPK

 
There are specific cases where this strange HPK idea is favored. An HP aircraft that needs to go upwind can in fact do better by winching in kite-mode to windward, rather than be blown downwind, propeller and all. Similarly, if more cargo than an HP aircraft can lift must be transported, a tow-cart is a true, if freaky, solution. 

The mix of HP and WP is awkward, since wind is so much more abundant (if available :)  ). Most sailing does not bother with rowing as an equal motive force.
Group: AirborneWindEnergy Message: 9656 From: dave santos Date: 7/19/2013
Subject: Quasi Single-Skin LEI (Airrush 18m2)

 New LEI State-of-the-Art consistent with single-skin advances in other kite specialtes-


http://www.airush.com/2013/kites/lithium-zero/
Group: AirborneWindEnergy Message: 9657 From: dave santos Date: 7/19/2013
Subject: Doug on "the future of offshore wind energy"

Doug,

You are just one small logical step from discovering why kite-sailing is such a major branch of AWE, and yes, indeed, offshore towed turbines or haul-lines may someday aggregate vast kite power, just as your recently speculated.  Note that a KiteShip or SkySails systems net several hundred times the power of USWindLabs HAWTs, albeit to displace high-sulfur bunker diesel.

You are also quite prescient in suggesting the US Navy as a wind tech innovator. In fact, one of SkySail's first ocean-crossing missions was to deliver a US Navy contract payload, as a "cutting-edge" AWE demonstration. While we should not mindlessly endorse militarization of AWE, we can marvel at how you do not need to closely follow AWE developments to keep up :)

daveS



Doug wrote- 

"Clearly", kite-flying forms the largest base of past experience in tethered aviation, which is the closest thing to airborne wind energy we know of... right? And of course sailboat technology forms the multi-thousand-year base of experience for nautical utilization of wind energy. Therefore, "clearly" the future of offshore wind energy will utilize sailboat technology, just as AWE will be based on kites. right??? Kitelab? KiteEnergy? KiteSystems? Kite-this and Kite-that? Like sailboat-power. Like the U.S. Navy uses old sailing ship technology to develop cutting-edge offshore wind energy systems, right? OK."
Group: AirborneWindEnergy Message: 9658 From: Joe Faust Date: 7/20/2013
Subject: Re: Sikorsky Prize Won
http://blogs.thescore.com/fanatico/2013/07/18/a-human-powered-flight/

Snowbird and then Atlas ... 
saga of challenge
Group: AirborneWindEnergy Message: 9659 From: roderickjosephread Date: 7/20/2013
Subject: Eaves-dropping with arch kites
Not a power mode as such, more a reassignment of arch kites.
Or a conjecture on the collection of audible AWE.

A stretched cone with loads of sensors. That's an ear.
A large one with filtering has increased dynamic range & auditory
fidelity capabilities.

What could you do with such a structure?

Listen for speeding cars, weather approaching, flocks & shoals moving,
Google execs party chats, earthquake survivor location, communication
into off limit countries ..?
Use it as a speaker at an AWE rocks concert to give something back.

OK it's a bit Dr. Seuss , sounds do attenuate through propagation.

How big would the sensor field have to be to achieve each goal above?

ok, back to work
Group: AirborneWindEnergy Message: 9660 From: Joe Faust Date: 7/20/2013
Subject: And the 600th goes to Rod Read !
  1. flip jibs under mothra by Rod Read on July 20, 2013        2:47             
  2. v
  3. v
  4. v
Group: AirborneWindEnergy Message: 9661 From: Joe Faust Date: 7/20/2013
Subject: Peter S. Lee for US 8188613
We mentioned him in forum, but we did not give direct reference.  
Here is some work by Peter S. Lee: 
Publication numberUS8188613 B2
Publication typeGrant
Application numberUS 12/460,211
Publication dateMay 29, 2012
Filing dateJul 16, 2009
Priority dateJul 16, 2009
Also published asUS20110012361
InventorsS. Peter Lee
Original AssigneeLee S Peter
Patent Citations (16), Referenced by (2), Classifications (28)

External Links: USPTO, USPTO Assignment, Espacenet
Patent Drawing  Patent Drawing
More images than here presented may be seen larger at HERE  https://www.google.com/patents/US8188613
Group: AirborneWindEnergy Message: 9662 From: Joe Faust Date: 7/20/2013
Subject: Solo traction AWES establishing a record
Group: AirborneWindEnergy Message: 9663 From: Joe Faust Date: 7/20/2013
Subject: Kite Patch for AWES field operators? Mosquitoes?
Will it work? Will it be available?
This is not a repair-sail item, but a means to keep the females from biting so much!
Group: AirborneWindEnergy Message: 9664 From: Joe Faust Date: 7/20/2013
Subject: Jan Hystad on Wind Power Plant
Jan HYSTAD of Norway

WIND POWER PLANT  



Page bookmarkWO2013005182  (A2)  -  WIND POWER PLANT
Inventor(s):HYSTAD JAN [NO] +
Applicant(s):HYSTAD JAN [NO] +
Classification:
- international:
- cooperative:F03D5/00; F03D5/04; F05B2240/9151; F05B2240/917; 
F05B2240/921; F05B2260/30; F05B2260/75
Application number:WO2012IB53445 20120705 
Priority number(s):NO20110000991 20110707
First page clipping of WO2013005182 (A2)
Group: AirborneWindEnergy Message: 9665 From: Joe Faust Date: 7/20/2013
Subject: Re: Jan Hystad on Wind Power Plant
Group: AirborneWindEnergy Message: 9666 From: Joe Faust Date: 7/20/2013
Subject: Luigi Adriano Giacalone
http://patentscope.wipo.int/search/en/WO2011061774
WO2011061774 
Luigi Adriano Giacalone

Method summary: flygen with electrical conduction in cables from lofted generation. 
Shy of "kite"   they go with "self-supported" by interaction with the wind and the restraint of the tethers. 

Publication numberWO2011061774 A1
Publication typeApplication
Application numberPCT/IT2010/000422
Publication dateMay 26, 2011
Filing dateOct 20, 2010
Priority dateNov 20, 2009
Group: AirborneWindEnergy Message: 9667 From: Joe Faust Date: 7/21/2013
Subject: Leonid Goldstein, AWE, non-AWE, and software development
Leo has been busy!   See extended disclosures: 

Adds: 
Group: AirborneWindEnergy Message: 9668 From: Joe Faust Date: 7/21/2013
Subject: Re: Leonid Goldstein, AWE, non-AWE, and software development
And more!

Yes, it is Leo.    Priority date:  Dec. 28, 2011.    Patent application:

 "WIND ENERGY CONVERSION SYSTEM OVER WATER." 

http://www.wipo.int/patentscope/search/en/detail.jsf?docId=WO2013101791

HEREexplore
Group: AirborneWindEnergy Message: 9669 From: Joe Faust Date: 7/21/2013
Subject: Re: HPK || Twp-pulley format
Group: AirborneWindEnergy Message: 9670 From: seanccostello Date: 7/22/2013
Subject: Re: Betz for Kites: Power Generation Using Tethered Wings
That's a good analogy allright. Actually the point I'm making in the paper is that Betz efficiency is rather meaningless for many of the kite-power systems currently being investigated. Kites can extract wind from such a large area, that they will likely never approach Betz's 59%.
Sean
Group: AirborneWindEnergy Message: 9671 From: Doug Date: 7/22/2013
Subject: Re: Doug on "the future of offshore wind energy"
Sure thing Dave S.
What's the topic today? Anything BUT AWE?
Maybe we should change the name of this group to the "anything but AWE" group...
:)
Group: AirborneWindEnergy Message: 9672 From: Doug Date: 7/22/2013
Subject: Re: NASA Technology Transfer Opportunity:
It looks like a technology trap for the star-struck to me.
Few fields are able to waste as much money and show as few results yet remain optimistic as wind energy. Why? Air is invisible.
:)
Group: AirborneWindEnergy Message: 9673 From: seanccostello Date: 7/22/2013
Subject: Re: Betz for Kites: Power Generation Using Tethered Wings
Hi Rod,
Thanks for such detailed feedback! This kind of feedback is really very precious.
So I'll try to answer those points one-by-one:

QUESTION 1:
ANSWER 1:
True, my claim is that this paper "describes how to evaluate the maximal power of any kite-power system" is perhaps too strong. The claim I would stand behind is that the theoretical part of the paper (section 4) gives one the mathematical TOOLS to analyse the maximal power of any kite-power system.
Section 5 applies this result to particular cases to get more tangible numbers. These cases are not all encompassing as there are so many diverse ideas out there. I defined the 'generic' kite system such that "the `kite system', may be any combination of wings, attachments, weights or balloons". So this part of the analysis does not hold for wings with turbines on them for example. However, it is easy to apply the theoretical result from section 4 to wings with turbines on them. I've done it myself, I just didn't include it in the paper.

COMMENT 2:
ANSWER 2:
I will certainly try to, if you give me a precise definition of your system. Do you mean like a Ladermill?

COMMENT 3:
ANSWER 3:
I disagree, the wind generally does not exert any upwards force on a wind turbine. A kite must always derive an upwards force from the wind simply to maintain its altitude = deflect wind downwards = put energy into accelerating the air downwards = loss of overall power producing capability.

QUESTION 4:
ANWER 4:
No, they don't, but you should use the kite's maximum L/D in this analysis as it only gives you an UPPER bound. If they spend time operating at lower L/Ds you will generate less power than the upper bound. I know, an upper bound is relatively meaningless if you're nowhere near it. It doesn't tell you what you WILL produce, but at least you know where the ceiling is in terms of power generation..

QUESTION 5:
ANSWER 5:
sorry, don't follow you there.

COMMENT 6 + ANSWER 6:
Certainly, the restraining force on the kite need not always be from tethers. Again, I only assume this in the 'application' section 5.

Like I said, if you have a particular architecture, give me a detailed spec of it and I will try to apply my theory to it and give you a maximum power generating capacity.
Sean
Group: AirborneWindEnergy Message: 9674 From: dave santos Date: 7/22/2013
Subject: KiteSat: "hello world"
hello world.. 
Group: AirborneWindEnergy Message: 9675 From: Joe Faust Date: 7/22/2013
Subject: Re: WPI gets grant for undersea 'kite' project
Same topic, but with some new details and a new acronym: 

Energy harvesting from tethered undersea kites 

TUSK ::
Tethered undersea kite
Group: AirborneWindEnergy Message: 9676 From: Joe Faust Date: 7/22/2013
Subject: Re: HPK || Phased tugging maintains wing in flight
Phased tugging installs kinetic and potential energy into wing in calm: 
Group: AirborneWindEnergy Message: 9677 From: Joe Faust Date: 7/22/2013
Subject: Re: HPK || Phased tugging maintains wing in flight
Another good example of HPK with phased tugging ...
seed of some future AWES flight maintenance: 
Group: AirborneWindEnergy Message: 9678 From: edoishi Date: 7/22/2013
Subject: Re: KiteSat: "hello world"
please check out this brief video from the TX AWE Encampment:


 
with these elements:
Ninja Star Turbine and Lifter Kite  by New Tech Kites
Red Cross Hand Crank Radio with USB output (Fly Gen)
Cell Phone WiFi Hotspot
notebook computer

More media to follow shortly...



--- In AirborneWindEnergy@yahoogroups.com, dave santos wrote:
Group: AirborneWindEnergy Message: 9679 From: Gabor Dobos Date: 7/23/2013
Subject: Re: Branches of FFAWE: some are kite systems; some are not kite syst

JoeF,

  Thank you for listing and short explanation of several types of  FFAWES. ( I would much appreciate receiving the link of the most relevant paper of each device) I have embedded your list into a "family tree". It is free for extension in order to have an up-to-date full list.




Some comments:

On the one hand: classification is free. Everybody can choose arbitrary aspect on which to classify. One could do it. Someone else can do something else. And everybody is right, based on his own point of view.

On the other hand, everybody has the right to define and to name the product based on his own idea. It is something like the right of the discoverer to give name to the island or the planet that he discovered. But independently of this unwritten law, the first sentence is also valid.

Regarding tethering:

"To be or not to be ... (tethered) --- that is the question" :)

I think the question is about the way of exerting the counter force against the wind that ensures energy harvesting.

NOT using tethering ensures that there is in this case no other means or way of exerting the counter force against the wind but flight technique (e.g. Dynamic Soaring). Therefore, this is a totally free flight, since we do not use anything else against the wind than the wind itself and the device. It is a clear situation.

Another extreme is a device tethered to the ground. This device is totally NOT free.

Between these extremes any other possible scenario may be positioned. I have added two of them to the extremes as follows:

1.) Tethered to the ground ---------------- Not free--
2.) Tethered to a ship or boat ------------ Slightly free? Or not?
3.) Tethered to a flying device --------- postulated to be free - German and co.
4.) Untethered ------------------------------- Free flight

I have several questions, and only a modest number of answers. E.g. the difference between versions 1 and 2 is that the tether in case 1 is fixed to one point on the ground, that is, the degree of freedom of fixing is 0, while in case 2 the degree of freedom is 2. Since you have not listed case 2 as "FFAWES", it is probably classified as a not free-flying device.

You postulated case 3 to be free flight. What is the difference between case 2 and 3? I think the obvious difference is in the motion perpendicular to the water level. Namely, in case 2, this motion is hampered, while in case 3 it is not. In a horizontal plane the equations of motion (two degree of freedom) are probably analogous. The difference is the larger drag of water than that of air. If so, is case 2 a two-dimension German's device, being the ship the second "wing"?

I think we need a definition of what we mean under "Free flight" to make further statements. Do you have any? A possible definition that covers our previous phrasing concerning the system is: free flight is what isn't disturbed by "outer " forces, other than wind and gravitation.

Though "free motion" belongs to the terminology of classical mechanics or rather dynamics (e.g.: free falling motion, etc.) that is a special case. One has to decide what are the unnecessary aspects of this situation. I suppose you have made these decisions as well as computer-simulations. May I have some info about them, and the physical model you have applied? (Especially regarding tethering.)

Thanks,       Gabor
Group: AirborneWindEnergy Message: 9680 From: seanccostello Date: 7/23/2013
Subject: Re: Betz for Kites: Power Generation Using Tethered Wings
Hi Dave,
Thanks for taking the time to go through the draft paper. As I said to Rod, critical feedback from people who read the paper is very much appreciated.

It's true that the concept-space will need an update for the final version of the paper (the current version is a draft, written one year ago).
I looked for Joe Faust's posts on Betz efficiencies for, I searched the for the keyword Betz on the forum, but only found one topic. Perhaps you could point me towards some relevant keywords.

I am certainly not suggesting in this paper that kite's have low Betz efficiencies, and are therefore 'worse' than wind turbines. Rather, for the solutions I currently see under development by startups, Betz efficiencies are pretty meaningless. That is why we tried to develop an alternative efficiency metric in this paper.

You would like a clear-cut conclusion as to whether rigid wings (heavy, high L/D) are better than soft wings (light, low L/D). I can only answer part of that question, because the answer also depends on economic factors I know little about.

In method we outline for analyzing a (certain class of) kite system's maximum power producing factor is the following:
1. Determine the kite's P_max (this is proportional to the kite's area, its max L/D squared and the windspeed cubed)
2. Determine 3 reduction factors:
a) Due to the kite's strength/weight ratio (i.e. max aerodynamic force the kite can
withstand/weight)
b) Due to the tether sag (depends on the kite's operating height and the tether material
properties)
c) Due to the ground tether angle

Now let's assume that for the same cost you can build a very big flexible kite, and a small rigid kite, such that they both have the same P_max. You are flying both wings using tethers made with the same material, at the same height. Both kites are trimmed to operate at their maximum L/D, and the wind is such that the maximum wing loading is achieved.

Now let's look at the reduction factors for each wing:
b) and c) will be the same for both wings.
In general a) will be worse for the rigid wing, because as L/D increases, maximum wing loading/wing weight tends to decrease. (about 50 for a surf kite, 16 for the Ampyx rigid wing).

So all other factors being equal (launching difficulties, cost of manufacture, etc..), the wing's strength/weight ratio is key. And if you have to keep your kite in the air in sub-optimal winds (i.e. where the wing is not operating at full loading), then the reduction factor a) is likely to completely kill your power generating capacity if you are using a rigid wing, whereas the lighter flexible wing will be much less affected.

I hope that answers your question. Bear in mind that this paper is only part (but an important part I think) of a jigsaw puzzle that an entrepreneur would need to assemble if he really wanted to compare different kite power concepts from an economic point of view.
Best Regards,
Sean Costello
sean.costello@epfl.ch
Group: AirborneWindEnergy Message: 9681 From: hardensoftintl Date: 7/23/2013
Subject: Rigid vs Soft Wings???
"So all other factors being equal (launching difficulties, cost of manufacture, etc..), the wing's strength/weight ratio is key. And if you have to keep your kite in the air in sub-optimal winds (i.e. where the wing is not operating at full loading), then the reduction factor a) is likely to completely kill your power generating capacity if you are using a rigid wing, whereas the lighter flexible wing will be much less affected....
I hope that answers your question. Bear in mind that this paper is only part (but an important part I think) of a jigsaw puzzle that an entrepreneur would need to assemble if he really wanted to compare different kite power concepts from an economic point of view "
- Sean Costello
Thanks, Sean.
John Oyebanji
Hardensoft International Ltd
Nigeria
Sent from my BlackBerry wireless device from MTN
From: "seanccostello" <seanccostello@yahoo.com
Sender: AirborneWindEnergy@yahoogroups.com
Date: Tue, 23 Jul 2013 10:49:17 -0000
To: <AirborneWindEnergy@yahoogroups.com
Subject: [AWES] Re: Betz for Kites: Power Generation Using Tethered Wings

 

Hi Dave,
Thanks for taking the time to go through the draft paper. As I said to Rod, critical feedback from people who read the paper is very much appreciated.

It's true that the concept-space will need an update for the final version of the paper (the current version is a draft, written one year ago).
I looked for Joe Faust's posts on Betz efficiencies for, I searched the for the keyword Betz on the forum, but only found one topic. Perhaps you could point me towards some relevant keywords.

I am certainly not suggesting in this paper that kite's have low Betz efficiencies, and are therefore 'worse' than wind turbines. Rather, for the solutions I currently see under development by startups, Betz efficiencies are pretty meaningless. That is why we tried to develop an alternative efficiency metric in this paper.

You would like a clear-cut conclusion as to whether rigid wings (heavy, high L/D) are better than soft wings (light, low L/D). I can only answer part of that question, because the answer also depends on economic factors I know little about.

In method we outline for analyzing a (certain class of) kite system's maximum power producing factor is the following:
1. Determine the kite's P_max (this is proportional to the kite's area, its max L/D squared and the windspeed cubed)
2. Determine 3 reduction factors:
a) Due to the kite's strength/weight ratio (i.e. max aerodynamic force the kite can
withstand/weight)
b) Due to the tether sag (depends on the kite's operating height and the tether material
properties)
c) Due to the ground tether angle

Now let's assume that for the same cost you can build a very big flexible kite, and a small rigid kite, such that they both have the same P_max. You are flying both wings using tethers made with the same material, at the same height. Both kites are trimmed to operate at their maximum L/D, and the wind is such that the maximum wing loading is achieved.

Now let's look at the reduction factors for each wing:
b) and c) will be the same for both wings.
In general a) will be worse for the rigid wing, because as L/D increases, maximum wing loading/wing weight tends to decrease. (about 50 for a surf kite, 16 for the Ampyx rigid wing).

So all other factors being equal (launching difficulties, cost of manufacture, etc..), the wing's strength/weight ratio is key. And if you have to keep your kite in the air in sub-optimal winds (i.e. where the wing is not operating at full loading), then the reduction factor a) is likely to completely kill your power generating capacity if you are using a rigid wing, whereas the lighter flexible wing will be much less affected.

I hope that answers your question. Bear in mind that this paper is only part (but an important part I think) of a jigsaw puzzle that an entrepreneur would need to assemble if he really wanted to compare different kite power concepts from an economic point of view.
Best Regards,
Sean Costello
sean.costello@epfl.ch
Group: AirborneWindEnergy Message: 9682 From: Gabor Dobos Date: 7/23/2013
Subject: Re: Betz for Kites: Power Generation Using Tethered Wings
On 2013-07-23 12:49, seanccostello wrote:
Hi Sean,
please, type in your browser "Betz limit"
You will receive about 20 000 hits

The following link contains a very nice flesh-simulation, a lot of links
and a clear explanation.

http://www.flapturbine.com/betz_limit.html

By the way, it schould be called as "Lanchester-Zhukowsky-Betz limit",
since these three researcher discovered this law, independently.

See: http://en.wikipedia.org/wiki/Betz_limit

Regards,

Gabor
Group: AirborneWindEnergy Message: 9683 From: Joe Faust Date: 7/23/2013
Subject: Re: Branches of FFAWE: some are kite systems; some are not kite syst
Thanks, Gabor, for your furthering work over FFAWES and the wrestling with classifications and categories. As you seem to point ... as Dave Santos has repeated, there is ever a wide flexibility in forming classifications and categories; Santos reminded us that any classification scheme is apt to miss matters that may be important in some other perspective.   During the efforts one may expect to find insights that help another exploration.    
     I will aim to address the points you just mentioned.  However, the work will be over several posts, not just this one.  Piecemeal for some while ... before another go at synthesis.       

This post will take only a tiny corner of the adventure in a rough manner.  The corner might at first seem strange, but Nature is a leader in the following: 

Tether as aircraft and as FFAWES    (just tether and nothing else)  This is a kite system. 
Have one type of  FFAWES be just tether.  
One embodiment to illustrate:  Take a 30 m strand of  1 mm thick by 2 mm wide Mylar film. Let us for just this note abbrevite the example as MFT.   Set MFT on the ground of earth. Wait for a gust to lift and carry MFT into the skies; then the device is an aircraft.   While MFT is in the atmosphere, notice that segments of MFT are tethering adjacent segments of MFT.   One end of the 30 m, say the 1 m segment at one end is "tethering" the 1 m segment of MFT that is situated at the opposite end of the aircraft.  During the flight of the tether-as-aircraft  one may examine the interactions occurring with the winds, gusts, helicities, and gravity.  There will be segmental accelerations along MFT; a segment will be for some while wafted one way and then be wafted another way; the mass of segments in motion will have airspeed and motion direction and these quantities will be changing during the flight of the whole device. The winds will be affected by the device, and the device will be affected by the winds; all the while gravity will be doing her part.     Our example MFT will soar until she makes her way back to the ground to be snagged by trees and things; her flight may be short or very long in duration.
 
      While soaring, MFT parts will be bending this way and that way; in the bending there will be work being done at the cost of slowing the wind or its gusts; that is, harvesting of energy will be occurring while the tether-aircraft is in flight.   The wind's energy will be harvested and converted to mechanical energy and then to heat, sound, light. Gradually some of the work done will fatigue parts of MFT and she will eventually fall apart into disconnected segments forming multiple shorter MFTs.   MFT, once flying, is in one media, but parts of MFT will be experiencing varied immediate local winds of that one media. A global resultant flight path will occur. 
      
    Consider making MFT more complex. Perhaps have in MFT some sensors and smarts and perhaps some muscles. Maybe some piezoelectric sensors and GPS guidance. And perhaps a transmitter.  Perhaps have the surfaces be PV collectors also.  Aim to have some of the harvested energy of MFT's flight be for controls and some for transmitting some energy out to some exterior object situated on earth's surface or in the air or in space.  But still keep the 30 m by 1 mm by 2 mm dimensions for the gross tether body.   Even without active controls or the complexity, MFT would be a FFAWES doing its soaring thing.   But with the complexity there may come some active controls to enhance the soaring and harvesting and placement of mined energies.   Yet the device is seemingly globally configured to be just a "tether."        Parts of MFT are rising and falling at times; at other moments parts are moving in 3D space and changing the motion and direction with time. The parts are gliding; the parts are often "kiting" other others as the tug-of-war unfolds. Shapes, twists, folds, unfolding. stretches ...ever changing unless a "wad" results and L/D of the global MFT declines to that of a wad or ball ... more likely to cause an end to the flight.   But if the more complex MFT muscles parts just right, then flight might continue for a longer time; parts might muscle to gust soar; parts might be smartly constrained so a net kiting occurs here and there to face the gusts and helicities ... microsoaring parts.    

   Such an MFT is a seed  conceptual for morphs that might seem more familiar.  Gather the material to a tighter format and have a sailplane for dynamic soaring (Osoba, Kiceniuk, Dobos, etc.). Or gather materials of the MFT to one end to form a more familiar wing while doing the same at the other end to get a Kramer soaring machine ( as Miller, Wayne German, Santos, Woglom, etc. as found on the FFAWE club page) where the ends tether each other.     Such morphs of MFT have degrees of "tethering" of parts to parts in their integrities.    All are AWES in one media; all have the "tether" aspect, although when squished to a rigid integrity into the sailplane, one may have a challenge to "see" the tethering that is occurring between the parts of the sailplane during flight; tension plays her part even in the sailplane integrity. 

     When perchance or control the MFT has an end dragging in water or in soil while the other parts are soaring in the air, then two quite distinct media are being "flown" ... one: air, the other: water or soil.  Water and soil also have more than surface; they have depth also; and time and motion from one spot to another may occur; sometimes the motion is zero or is a fixed situation (fix an end of MFT to the base of a tree or to an anchored water hull).  When the two media situation occurs for MFT, analysis of forces stay in the same Nature where physics applies.   How much one respects the differences of water from air as opposed to air moving this way and the different air moving a different way, is a matter of category, case, classification.   In all the systems the same global physics will apply. But to capture studies and niche applications, we set up categories of terms in order to apply ourselves to specific instance to get practical tasks done.  Air-only MFT, water-only MFT, split media MFT, oscillating-media MFT, etc.   Ultimately there is a grand spectrum with fuzzy lines of demarcation.   Yet, tension and tethering  get involved with accelerations that may be used to format energies for tasking.      The variants are free to fly in air or water or soil while obeying the laws of Nature; all have the same freedoms, but some of the directions are constrained passively or actively relative to some frame of reference.    

For some Nature:  kiting spiders (erroneously classed as ballooning spiders) put out a MFT-like set of silks that dynamically soar; the spider uses some of the harvested energy to transport her mass from one place to another; her kinetic and potential energy is altered by the AWES as she enters FFAWES mode; she uses gained potential energy to set her mass to ground or tree or ?  at some other point in time.   
Tag: spider silk industrial engineering

Have purpose. Design to fulfill purpose. Check out one's ROI. How dominant will "tethering" be in one's energy-harvesting aviation system?  Even "un-tethered" systems involve some tethering, although such tethering might be artificially defined out of analysis for some practical purpose or for some classification scheme, say for the dynamically soaring sailplane energy-harvesting schemes.  

When the amount of freedom of a degree of freedom goes to zero, then such degree is said to be absent. However, in real systems "zero" is rarely, if ever, actually absolutely achieved; but for practical purposes near-zero oscillations in a degree of freedom are taken out of calculations.  We form artificial definitions in our attempt to efficiently handle complex matters; we neglect many parameters in order to capture practically some system.   E.g., we might assume the railroad track does not change shape when a rail car rolls over a spot on the rail; but some other study might not make that assumption and find the rail being indented as the rail car rolls over a spot. 
                                                         

Group: AirborneWindEnergy Message: 9684 From: Joe Faust Date: 7/23/2013
Subject: Re: Branches of FFAWE: some are kite systems; some are not kite syst

Group: AirborneWindEnergy Message: 9685 From: Joe Faust Date: 7/23/2013
Subject: Re: Branches of FFAWE: some are kite systems; some are not kite syst
She, in the art video, illustrates several kite systems including the soil kite, the breakaway Malay with connection to tether as wing in free-flight, and the tether-only kite-system: 

Group: AirborneWindEnergy Message: 9686 From: Rod Read Date: 7/24/2013
Subject: Re: KiteSat: "hello world"
Oddly,
I tried a similar test yesterday, whilst camping with my boys in Uig, Isle of Lewis.
Unfortunately too far from 3 network 3G signal even at 60m above the hills.

Mercifully normal comms resumed today

Rod Read

Windswept and Interesting Limited
15a Aiginis
Isle of Lewis
HS2 0PB

07899057227
01851 870878
Group: AirborneWindEnergy Message: 9687 From: Rod Read Date: 7/24/2013
Subject: Re: Betz for Kites: Power Generation Using Tethered Wings
Sean,
What can I say but,  thank you so much for your well considered answers.
This kind of discussion is vital for overall progress.

If I may continue / elaborate...
My Q1, Comment 3, Q4 and Q5 are all trying to get at the same things.

Asymmetric kites can be conjoined to induce group spinning around a distance from an axis...

Large arch kites and webs of kites can be set to collectively give an overall drive vector.

My point on q3 was the large part of the mass of a standard turbine used to "lift" the turbine is still essential to their useful operation. We can consider many kiteforms other than just arches and webs capable of the same lift only function.

Check out some of my youtube stuff for a glance of where I'm trying to go with this...
Assuming I get enough childcare organised I can post a new design concept on Mothra arch kite configuration by tomorrow.

Thanks again Sean



QUESTION 1:
ANSWER 1:
True, my claim is that this paper "describes how to evaluate the maximal power of any kite-power system" is perhaps too strong. The claim I would stand behind is that the theoretical part of the paper (section 4) gives one the mathematical TOOLS to analyse the maximal power of any kite-power system.
Section 5 applies this result to particular cases to get more tangible numbers. These cases are not all encompassing as there are so many diverse ideas out there. I defined the 'generic' kite system such that "the `kite system', may be any combination of wings, attachments, weights or balloons". So this part of the analysis does not hold for wings with turbines on them for example. However, it is easy to apply the theoretical result from section 4 to wings with turbines on them. I've done it myself, I just didn't include it in the paper.

COMMENT 2:

ANSWER 2:
I will certainly try to, if you give me a precise definition of your system. Do you mean like a Ladermill?

COMMENT 3:

ANSWER 3:
I disagree, the wind generally does not exert any upwards force on a wind turbine. A kite must always derive an upwards force from the wind simply to maintain its altitude = deflect wind downwards = put energy into accelerating the air downwards = loss of overall power producing capability.

QUESTION 4:

ANWER 4:
No, they don't, but you should use the kite's maximum L/D in this analysis as it only gives you an UPPER bound. If they spend time operating at lower L/Ds you will generate less power than the upper bound. I know, an upper bound is relatively meaningless if you're nowhere near it. It doesn't tell you what you WILL produce, but at least you know where the ceiling is in terms of power generation..

QUESTION 5:

ANSWER 5:
sorry, don't follow you there.

COMMENT 6 + ANSWER 6:
Certainly, the restraining force on the kite need not always be from tethers. Again, I only assume this in the 'application' section 5.

Like I said, if you have a particular architecture, give me a detailed spec of it and I will try to apply my theory to it and give you a maximum power generating capacity.
Sean


Rod Read

Windswept and Interesting Limited
15a Aiginis
Isle of Lewis
HS2 0PB

07899057227
01851 870878
Group: AirborneWindEnergy Message: 9688 From: Joe Faust Date: 7/24/2013
Subject: Theories of John Dabiri receive an opinion
Group: AirborneWindEnergy Message: 9689 From: Joe Faust Date: 7/24/2013
Subject: Siemens
Topic thread to follow Siemens
as anyone wishes. 

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