Please use this thread to keep track of airborne wind articles, podcasts, media blogs, etc.

To get this thread started, here is some recent airborne wind coverage by editors covering National Instruments. Our goal is to encourage broad support for airborne wind within the engineering community.

ScienceNews Network Radio - The Promise of Tomorrow
http://www.promiseoftomorrow.biz/bizradio/022811/022811.htm

WindSystems Magazine - The Advent of Airborne Wind
http://windsystemsmag.com/media/pdfs/Articles/2011_January/0111_NI.pdf

Automation World - Going for the Wind Above the Turbines
http://www.automationworld.com/feature-8388

Design News - Portable, Airborne Wind Energy System
http://www.designnews.com/blog/Automation_and_Control/40532-Portable_Airborne_Wind_Energy_System.php

Megalink Eco - Airborne Wind (Swiss magazine, German language)
http://issuu.com/megalink/docs/ml_10-eco

Case Study - Powering Remote Villages with Revolutionary Airborne Wind Technology Using NI CompactRIO
http://sine.ni.com/cs/app/doc/p/id/cs-13295

Hi Dave S. and thanks for defining the appropriate scales for onboard generators versus ground-based. Many were wondering about that question.
Now that you have your product, I guess it IS time to hire a "Manager in Partnership for AWECS". A great example of a new emerging clean energy technology creating green jobs! Recession over!
Doug S.
PS what about a higher-level manager to manage the manager?

Theo wrote:"I would guess that the main difficulty is the terrific
tension required to support the line and the enormous safety problem
should the line come down."


What are solutions?Nanotube-tethered AWE like Mark Moore suggests?

PierreB

Some notes on this thread:

1. Scouts in 1980 Japan Kite Festival apparently had flying fence  or very wide playsail in a non-rotating fly.     See some diagrams.

2. http://www.kiteplans.org/planos/eddybuek/eddybuef.html  has three photos.

3.  http://tuulelohed.com/index.php?option=com_content&view=article&id=38    has two pages on topic of Arch Ribbon ...

4. Consider playsail wide. Consider drying clothes and blankets on a long clotheslines.

5. Consider super-wide parafoil with two anchors, left and right.

  at KitePlans 

7. Consider high and wide and down-wind-thick sky matrices of working elements ... that have control smarts involved.  Bring on SuperTurbine(R) on steroids.    Gather the energy with working parts.  ...

George Peters  advanced the non-rotating WindBow or wing arch or wide-wing arch. Notice his detailing.

http://www.kiteplans.org/planos/windbow/windbow.html 

Maybe Sellers will come out of the past to do multi-plane arch bow. Then go deep beginning with Montgomery tandem set; go further to very deep downwind on a Sellers SDO.  Some images. 

Just came across this web page about wind forecasting.

http://www2.ucar.edu/news/484/ncar-forecasts-will-help-xcel-energy-harness-wind

It is a relevant issue by itself, but what I found most interesting was
their diagram showing their modelling of the wind over hills. If a
turbine installer wanted to get its turbines into the strongest wind it
would have to build extra tall towers in the valleys. On the other hand,
if an AWE installer wanted to do the same it could build its generators
on the top of the hills. Yet another advantage for AWE.

Robert.

Very-wide  single-surface sail received an unintended launch:

http://www.youtube.com/watch?v=AxRT60-kw78&tracker=False

Super Wall    
SDO type.   Latticework kite system. Exampled by art
by Davr Santos extrapolating extant walls:
 

[[Turbine on each tail?  Maybe have high dancing-wiggling with piezoelectric materials?  What else?  This is just a beginning ... ]]

Like this?
http://www.youtube.com/watch?v=7iHZKMDvdNI

http://www.youtube.com/watch?v=_iq1d3wBHfE

Yes.  Thanks. 

DFA   Distributed Flight Array         http://www.idsc.ethz.ch/Research_DAndrea/DFA

• Dynamic Assembly of Large-Scale Airborne Structure & NextGen SDO
• http://www.youtube.com/watch?v=hZWUq_HgSVM The Big Kite
• http://www.youtube.com/watch?v=pvCIeWlJdms Giant Chinese Dragon Kite

Consider 100 side-by-side long giant Chinese Dragon kites forming dense wall.  Instead of just 100 m from mooring to top-wing, consider 1000 m with wing-step separations set for efficiency.

Just to note in this thread:

Flying generators need not assume electrically-conductive tether for AWECS. 

Let us recall positively other flygen species:

• Electric generator aloft makes kitricity for use aloft. No need to send the kitricity to ground in this genre. Perhaps use the electricity aloft to charge a battery; then drop or glide or kite-lower-and-retrieve the charged battery.   Or use the stored energy aloft for special applicaitons (communications, music playing, advertising  lights, hazard lighting, powering controls, providing power for running machines aloft, drive microwave or laser beam maker for sending energy from aloft to other aircraft or ground stations,  etc....).
  +
• Sound generators aloft:  Have aloft a sound generator as opposed to an electric generator. Use the sounds for various purposes (perhaps bird scaring, entertainment of crowds, scientific experimentation over sound-agricultral concepts, environment enhancement, ...)
  +
• Heat generators aloft:  Have a heat-generator. Use the heat for various aloft causes (warm bath water in a kite-held recreation hut, etc. ???)
  +
• Air-pressure generators aloft (pump that air!): Send pressurized air down a hollow tether (sorry, this is a conductive tether, but it conducts a gas or chemical rather than electricity). Send pressurized air into inflatable wing parts.
  +
• Potential-energy generator aloft: Drive the system to lift mass from low to high. Use that lifted mass for various reasons (Drop mass to help crush rock; drop sky divers for recreation or other purpose; drop lifted hang gliders for recreation or other purpose; drop fire-fighting materials and liquids; drop food and medical supplies to needed receptors; move materials or people or animals from A to B; lift up seedlings and drop them for piercing planting;  etc. ....!!!
  
• Kinetic-energy generator aloft:  Give fun rides to people. Slosh and mix chemicals. Swing a demolition ball.  Etc. ??
  
• Tension generator:   Drive the tethered wings to provide tension in the tether. Use that tension to move ground items in very many productive ways for high-count causes.  Flying the wings in various ways may produce variable tension events that may be used in many ways.  
  +
• +??? ...all are welcome to highlight other generators aloft.  Wonderful opportunities!

JoeF

Consider having a non-conductive flight tether while having also a
drop-line that is electrically conductive. Notice that a vertically-set
drop line is shorter than the flight tether. In some niche situations,
this might be efficient.

And recall DaveS' fly-by charge releasing system where charge is
accumulater aloft and then the wing is driven near a ground conductor
and drags a short conductor wire for transferring the generated charge
to a collecting ultracapacitor. Then the wing keeps flying to generator
more charge to be release upon a repeated drag.

JoeF

Adding a couple of notes:  

Heat:  Heat LTA gases for  buoyancy

Aloft: compressor to reduce the volume of a buoyancy gas in a balancing strategy.

This keeps arriving in my notes about an aloft generator of special type:

Type: Shade generator

The flown system generates a blocking of sunlight.

Such blocking of sunlight might be used simply for generating shade for ground operations in special circumstances. Perhaps one wants shade for special agricultural reasons. Maybe for moviemaking reasons. Maybe for the comfort of spectators. Maybe for keeping animals comforted in specially hot days.

While the shade is being generator, pehaps the same surface could be converting the impinging sunlight to electricity and heat for aloft uses.  Flagging of the shading surfaces might involve piezoelectric elements, messaging, advertising, active video, etc.      Flown shade generators might save the lives of refugees.

Other uses of flown shade generators may be found.

JoeF

Hi,

Discussions such as these (about what to make tethers from) need hard
figures before accurate conclusions can be drawn.

The tether will experience numerous stress strain cycles in its life so
close attention must be paid to fatigue resistance. For some materials
there are published Wohler's curves (or S-N curves) to help decide how
thick to make the tether. These are plots of the stress that broke the
test specimen against the number of times the stress was applied. The
trouble is that measuring this data takes time on sophisticated test
apparatus so it is not as easy to find as tensile strength data which
requires a single pull.

I have prepared an Open Office spreadsheet to look at the tether
material issue (and others to come). This is just the beginning and some
of the data is just an estimate, but it is in the right ball-park and it
allows some early conclusions. I will make an Excel version later when
it is a bit more developed.
http://www.copcutt.me.uk/Kite_design.ods

High tensile steel (not stainless) is the clear winner partly because it
is readily available and far cheaper than the alternatives.

Using pure copper, that has been cold worked, as the only material in
the tether is a surprisingly viable option. Better alloys are of
interest for many applications so there has been a lot of work on
developing them. eg. Hitachi Cable report developing a strong fatigue
resistant copper alloy but I could not find the S-N curve so it is not
included on the spreadsheet.

If the tether resistance is too high it will be heated and this will
decrease its strength.

Although kevlar and dyneema are strong and light their resistance to
frictional wear is poor, and they are expensive.

All known insulating materials would not last long if used to encase
metal cables under high tension on a drum (reel or winch). That means
the kite needs to be tethered by 2 or 3 bare wires that are kept
separate to prevent short circuits.

Robert.

I'm surprised that aluminum, as the third-best conductor, is not being considered.  It can be "plated" onto 'glass fibers, and presumably others, which might improve fiber fatigue life, and it might even benefit from the hollow section of the conductor, as some bus bars do.  Does anyone know how the electrical resistance of the high-strength alloys compares to pure metal?

Adding anything to the metals that conduct well makes them more
resistive. This has been studied in detail and things like copper,
silver, gold, iron and aluminium all conduct best when very pure.

Pure aluminium is soft and would soon rub off if plated onto a stronger
material. I have discovered that copper alloys were extensively studied
to find the best materials to use in CERN. Hence the list of copper
alloys in my spreadsheet. I have not found such work for aluminium
alloys. Maybe aluminium tether materials will be developed in the
future, but for now steel wins by a large margin, particularly when you
consider cost.

Robert.

Flying generator aloft: Not to forget Dave Santos' early mention of
bare wires in arch systems where shroud would not be needed, as the
left line and right line would be far separated.

Reasonably priced insulating materials of a realistic thickness are only
good for a few thousand volts. Air is not much worse (maybe 10 to 100
times, depending upon what you are comparing with). Again, some real
figures will help. The spark gap voltage for 2 needle points 0.85 cm
apart is 10 000 volts (10 kV). For 100 kV the gap is 15.5 cm.

Lightning is not going to care if your tether is a conductor or not or
whether it is insulated or not. The fact is kites needs to be out of the
sky when lightning is around - end of story. However, that in no way
limits AWE. The approach of lightning can be measured by monitoring
certain radio frequencies. Someone needs to investigate this in more
detail.

Robert.

Following  Robert Copcutt,

 lightning notes are invited in this thread and group folders.

  sparks with needle gaps

And files may also be placed in Files under  Lightning     (files section)

And links in the Links seciton for similar topic: Lightning     (links section) where already are a couple of links.

Some investigators of past and some still:  hoping to capture the energy in lightning; will very large ultracapacitors make a difference?

What hope could there be in staying flying during lightning storms, if any?

Blue-sky lightning? 

JoeF  

On Fri, 2011-03-18 at 11:16 -0700, Dave Lang wrote:

Firstly, all surfaces attract dirt and water. Although the bulk material
of the tether might have a higher resistance than air its surface would
inevitably be lower, even without rain.

Secondly, what makes lightning choose the path it does? Could tiny
eddies in the air caused by the tether create a favoured path? Probably.
I would not want to take the chance even if I had installed a fancy
tether cleaning device.

Lightning rarely lasts long and a special radio receiver could provide
automatic guidance about when to pull the kites down. In fact that is
probably something for the coolIP section. A device to work out the
chances of a lightning strike based on the strength of radio waves at
particular frequencies, or maybe based on the potential gradient in the
atmosphere. This device then sends a signal to tell the human or
computer that controls the kite what the strike likelihood is. Once
developed such a device need not be expensive and one would probably
suffice for a whole farm of AWEs.

Robert.

On Fri, 2011-03-18 at 18:06 +0000, Joe Faust wrote:
The problem is that lightning is so rare, and so powerful when it comes,
that the investment in capture devices cannot be justified.

Big turbines have steel towers and they run an aluminium lightning
conductor down their blades. There is a spark gap between the nacel and
the tower and these usually bear witness to past strikes. The whole
construction philosophy is about being tough enough to last through
storms with their high winds and lightning because there is no option of
pulling the thing down when conditions are bad. That is why they are so
expensive. The whole idea of AWE is that all the heavy-weight
construction at high altitude is eliminated. That means it has no chance
of surviving storms with their high winds and lightning. It is easy
enough to pull a kite down when conditions are wrong, so why not just do
it.

Another reason for retracting the kites is aircraft approaching too
close. AWEs above a certain altitude will probably need radar so they
can react before lost pilots get threatened by invisible tethers.

Robert.

We can pull down kites if an electrical storm is approaching, but what if it starts up right on our site?

On Fri, 2011-03-18 at 13:40 -0600, Bob Stuart wrote:
The techniques I mentioned work independently of the history of nearby
strikes. The potential in the clouds that causes lightning builds up
over time. If the potential gradient near the ground can be monitored it
will give warning of strikes. The radio frequency emissions also warn of
developing strikes. I am not talking about the wide spectrum
interference heard on ordinary a.m. radios from actual strikes.
Apparently there is a pre-strike signal.

Robert.

AWECS

Patent party is just getting started,

and you are invited!   Find a missing patent and post. Comment now or later or later again on a specific patent (or one of its claims). Patent applications are invited also. 

http://www.energykitesystems.net/KitePatents/index.html

A forum just for specific annotation and discussion for each specific patent is available: KitePatents. A link for that forum is on the above URL.      Let any disorder be a window of fuzzy creativity.

Wikipedia editors have deleted my Wikipedia list of patents; the page has been preserved and is linked also in the above URL.     

The collections are far from complete. When anyone finds a non-USA AWECS-related patent, then post it in KitePatents forum; before the post gets viewed, moderator will search the forum to see if the same patent already has a starting thread.

 There is much duplication in patents and even "novel" claims; finding such duplicaiton and discussing such almost always helps to uncover nuances that may have been missed; the party is one tool for advancing AWE tech at some scale in some niche applicaiton.

Lift,

JoeF

 

See Figs 65-73 of US 6616402

--- In AirborneWindEnergy@yahoogroups.com, "Doug" <doug@...

Excepted for schemes like KiteGen carousel,the power of kites is not
regular when the (more powerful) crosswind configuration is used.Schemes
like reel-out and flygen are concerned,reel-out yet more because of
reel-in phase.So without smoothing devices or management of unities in a
farm the quality of produced electricity could be low.

Have existant simulations taken into account the quality of produced
electricity?

PierreB