Messages in AirborneWindEnergy group.  #167 to 218
Page 4 of 552.

Group: AirborneWindEnergy Message: 167 From: dave santos Date: 6/28/2009
Subject: Flying Generator

Group: AirborneWindEnergy Message: 168 From: Lou Groner Date: 7/4/2009
Subject: Re: Tripod Tether COTS AWE Demo

Group: AirborneWindEnergy Message: 169 From: dave santos Date: 7/5/2009
Subject: Re: Tripod Tether COTS AWE Demo

Group: AirborneWindEnergy Message: 170 From: christopher carlin Date: 7/5/2009
Subject: Re: Tripod Tether COTS AWE Demo

Group: AirborneWindEnergy Message: 171 From: harry valentine Date: 7/5/2009
Subject: Re: Tripod Tether COTS AWE Demo

Group: AirborneWindEnergy Message: 172 From: santos137@yahoo.com Date: 7/6/2009
Subject: Re: Tripod Tether COTS AWE Demo

Group: AirborneWindEnergy Message: 173 From: Joe Faust Date: 7/6/2009
Subject: Message posting and edit limits in the Yahoo program.

Group: AirborneWindEnergy Message: 174 From: christopher carlin Date: 7/6/2009
Subject: Re: Tripod Tether COTS AWE Demo

Group: AirborneWindEnergy Message: 175 From: dave santos Date: 7/7/2009
Subject: Re: Tripod Tether COTS AWE Demo

Group: AirborneWindEnergy Message: 176 From: harry valentine Date: 7/7/2009
Subject: Boone Pickens Wing Power Project

Group: AirborneWindEnergy Message: 177 From: Joe Faust Date: 7/8/2009
Subject: Welcome Prof. Ugo Bardi

Group: AirborneWindEnergy Message: 178 From: Joe Faust Date: 7/15/2009
Subject: A setting for group program function has been installaed.

Group: AirborneWindEnergy Message: 180 From: davemart2009 Date: 7/16/2009
Subject: SkySails in relation to generating electricity

Group: AirborneWindEnergy Message: 181 From: davemart2009 Date: 7/16/2009
Subject: Re: SkySails in relation to generating electricity

Group: AirborneWindEnergy Message: 182 From: Joe Faust Date: 7/16/2009
Subject: Re: SkySails in relation to generating electricity

Group: AirborneWindEnergy Message: 183 From: Joe Faust Date: 7/18/2009
Subject: Secondary uses of EKS lifter kytoon skyhooks

Group: AirborneWindEnergy Message: 184 From: davemart2009 Date: 7/18/2009
Subject: Massimo Ippolito's figures on efficiencies.

Group: AirborneWindEnergy Message: 185 From: dave santos Date: 7/22/2009
Subject: Liftopia- 1896

Group: AirborneWindEnergy Message: 186 From: Carlo Perassi Date: 7/26/2009
Subject: Self introduction (KiteGen/WOW)

Group: AirborneWindEnergy Message: 187 From: Joe Faust Date: 7/30/2009
Subject: Progress on materials

Group: AirborneWindEnergy Message: 189 From: roundtheglobe Date: 7/31/2009
Subject: Re: Tripod Tether COTS AWE Demo

Group: AirborneWindEnergy Message: 190 From: dave santos Date: 7/31/2009
Subject: Re: Tripod Tether COTS AWE Demo

Group: AirborneWindEnergy Message: 191 From: Darin Selby Date: 7/31/2009
Subject: Re: Tripod Tether COTS AWE Demo

Group: AirborneWindEnergy Message: 192 From: Gabriele Date: 8/1/2009
Subject: Re: Tripod Tether COTS AWE Demo

Group: AirborneWindEnergy Message: 193 From: dave santos Date: 8/1/2009
Subject: Re: Tripod Tether COTS AWE Demo

Group: AirborneWindEnergy Message: 194 From: Joe Faust Date: 8/1/2009
Subject: Re: Tripod Tether COTS AWE Demo

Group: AirborneWindEnergy Message: 195 From: Gabriele Date: 8/2/2009
Subject: Re: Tripod Tether COTS AWE Demo

Group: AirborneWindEnergy Message: 196 From: dave santos Date: 8/2/2009
Subject: Re: Tripod Tether COTS AWE Demo

Group: AirborneWindEnergy Message: 197 From: Gabriele Date: 8/3/2009
Subject: Re: Tripod Tether COTS AWE Demo

Group: AirborneWindEnergy Message: 198 From: harry valentine Date: 8/3/2009
Subject: Re: Tripod Tether COTS AWE Demo

Group: AirborneWindEnergy Message: 199 From: spacecannon@san.rr.com Date: 8/3/2009
Subject: Re: Tripod Tether COTS AWE Demo

Group: AirborneWindEnergy Message: 200 From: Dave Lang Date: 8/3/2009
Subject: Re: Tripod Tether COTS AWE Demo

Group: AirborneWindEnergy Message: 201 From: harry valentine Date: 8/3/2009
Subject: Re: Tripod Tether COTS AWE Demo

Group: AirborneWindEnergy Message: 202 From: dave santos Date: 8/3/2009
Subject: Re: Tripod Tether COTS AWE Demo

Group: AirborneWindEnergy Message: 203 From: harry valentine Date: 8/4/2009
Subject: Re: Tripod Tether COTS AWE Demo [3 Attachments]

Group: AirborneWindEnergy Message: 204 From: davemart2009 Date: 8/4/2009
Subject: Re: Tripod Tether COTS AWE Demo [3 Attachments]

Group: AirborneWindEnergy Message: 205 From: Dave Lang Date: 8/4/2009
Subject: Re: Tripod Tether COTS AWE Demo [3 Attachments]

Group: AirborneWindEnergy Message: 206 From: Dave Culp Date: 8/4/2009
Subject: Re: Tripod Tether COTS AWE Demo

Group: AirborneWindEnergy Message: 207 From: brooksdesign Date: 8/4/2009
Subject: Re: Tripod Tether COTS AWE Demo

Group: AirborneWindEnergy Message: 208 From: Dave Lang Date: 8/4/2009
Subject: Re: Tripod Tether COTS AWE Demo

Group: AirborneWindEnergy Message: 209 From: Gabriele Date: 8/4/2009
Subject: Re: Tripod Tether COTS AWE Demo

Group: AirborneWindEnergy Message: 210 From: dave santos Date: 8/10/2009
Subject: Kite Anchor Geology, Soil Kites, Design Issues

Group: AirborneWindEnergy Message: 211 From: dave santos Date: 8/10/2009
Subject: Cooperative AWE Business Model

Group: AirborneWindEnergy Message: 212 From: dave santos Date: 8/16/2009
Subject: Kite Vibes- AWE Flight Dynamics

Group: AirborneWindEnergy Message: 213 From: christopher carlin Date: 8/19/2009
Subject: Re: Kite Vibes- AWE Flight Dynamics

Group: AirborneWindEnergy Message: 214 From: Darin Selby Date: 8/20/2009
Subject: Re: Kite Vibes- AWE Flight Dynamics

Group: AirborneWindEnergy Message: 215 From: dave santos Date: 8/20/2009
Subject: Re: Tripod Tether COTS AWE Demo

Group: AirborneWindEnergy Message: 216 From: allisterfurey Date: 8/20/2009
Subject: Nature AWE article

Group: AirborneWindEnergy Message: 217 From: Darin Selby Date: 8/20/2009
Subject: Re: Nature AWE article

Group: AirborneWindEnergy Message: 218 From: spacecannon@san.rr.com Date: 8/20/2009
Subject: Re: Nature AWE article




Group: AirborneWindEnergy Message: 167 From: dave santos Date: 6/28/2009
Subject: Flying Generator
Attachments :
Flying a generator is a popular AWE idea. Magenn, Sky Windpower, & Makani are major advocates. Brooks will remember small tethered generator-turbines i made & flew in the late eighties at Silicon Barrio & Robot Group school outreach events in Austin. The simple kite-based generator system presented here is a descendant of those devices swung from a bamboo pole over school children.
 
Attached images show a 6 watt 6 volt bike generator that flew today under a 15 sq ft parafoil lifter capable of lifting a couple of hundred feet of conductor wires. The tiny image is a frame grab from video not provided as the slow frame rate caused the irksome illusion that the high-speed whirring turbine jumps, freezes, & even reverses. The larger image shows the components in detail. That black bulky object is the battery pack.
 
The turbine blade is about 50 x 5 x 1 cm of helical-pitch carved blue EPS with mylar tape reinforcement on the windward side. It turns fast enough to drive the bike generator at its rated voltage. Hanging the turbine under a stable lifter avoids active controls.
 
KiteLab's Finding- Small generators flown low or as auxiliary power aloft work ok, but larger generators with long heavy conductors create severe safety & operational limitations related to high mass aloft.

  @@attachment@@
Group: AirborneWindEnergy Message: 168 From: Lou Groner Date: 7/4/2009
Subject: Re: Tripod Tether COTS AWE Demo
What is the point of the lifter kite? Can the looping kite not also provide lift?

Group: AirborneWindEnergy Message: 169 From: dave santos Date: 7/5/2009
Subject: Re: Tripod Tether COTS AWE Demo
Hi Lou,
 
The Lifter Kite provides "passive control", the autonomous flight function, without avionics. Without the lifter the unstable sport kite would quickly crash. That's why these demos are so easy & cheap compared to "active control" (or helium aerostat) based AWE. You'll find a lot of related discussion in earlier posts & linked off JoeF's site.
 
The largest kite in history, the biggest wing ever, was Osborne's parafoil "lifter" flown near Ilwaco here (Long Beach, Washington), just over 17,000 sq. ft., so the scaling potential of this approach is vast. (Such a lifter could easily loft a hot 5000 sq. ft. looping parafoil as its multi-megawatt power element.)
 
Sadly, Osborne's Monster killed Edeiken on its maiden flight, but many lessons were learned. The fact that a community college sewing teacher could create such a wing is significant. Osborne also set the "official" kite endurance record (180 hours) on this same beach. Stormy Weathers topped 12,000 ft. altitude here with his sparred sled, a lifter (lifting line). Many of KiteLab's AWE experiments take place on this hallowed spot. The World Kite Museum is also located here. The winds are great year around.
 
Kite show lifters carry large exotic "line laundry" aloft & lifting AWE elements is a natural application. The greatest professional practitioners of giant show lifters are Peter Lynn & David Gomberg, with much online info available. KiteShip's (Culp & Jordan) huge OL traction kites can be stabilized as super lifters (KiteLab has stabilized an OL). Jordan's large parafoil lifters are some of the best ever.
 
Its been an honor to meet & learn from these pioneers, who have considerably advanced & perfected the art of giant kites. Its funny how certain "kite gods" forget the festival ancestors & fall for UAV aerospace to develop AWE.
 
daveS
 
 



Group: AirborneWindEnergy Message: 170 From: christopher carlin Date: 7/5/2009
Subject: Re: Tripod Tether COTS AWE Demo
Dear Dave,

I find the numbers that get bandied about here very interesting and may be about to draw an incorrect analogy but a big full rigged ship has about 50,000 sq meters of sail which at about 25 knots of breeze must put out on the order of 4000 horsepower. To hold that thrust must require a 2 or 3 inch diameter cable. Now if the wind goes to 40 knots the load will be up by a factor of 4 I believe. While the weight to be supported won't change. I think what I'm getting at is the lifter kite will need active control of some sort to keep the cable size reasonable. I'm not suggesting that it can't be done just that it will be required. I do think managing these large spreads of "canvas" will be a challenge to put it mildly.

By the way who was Edeiken and what is the accident story. I collect engineering accident stories. They are very useful in doing safety analysis.

Regards,

Chris
On Jul 5, 2009, at 9:00 AM, dave santos wrote:


Group: AirborneWindEnergy Message: 171 From: harry valentine Date: 7/5/2009
Subject: Re: Tripod Tether COTS AWE Demo
Hi Dave & Chris,
 
 
Your discussion provides insight into the wisdom behind the LadderMill . . . how to support the weight of large (and heavy) cables needed to access the powerful winds at higher elevations. At lower elevations, the LadderMill leading airfoils merely support the weight of the cable below them while the airfoils at higher altitudes generate the power.
 
 
Harry
 

To: AirborneWindEnergy@yahoogroups.com
From: christopher.m.carlin@btinternet.com
Date: Sun, 5 Jul 2009 18:47:09 +0100
Subject: Re: [AirborneWindEnergy] Re: Tripod Tether COTS AWE Demo



Dear Dave,

I find the numbers that get bandied about here very interesting and may be about to draw an incorrect analogy but a big full rigged ship has about 50,000 sq meters of sail which at about 25 knots of breeze must put out on the order of 4000 horsepower. To hold that thrust must require a 2 or 3 inch diameter cable. Now if the wind goes to 40 knots the load will be up by a factor of 4 I believe. While the weight to be supported won't change. I think what I'm getting at is the lifter kite will need active control of some sort to keep the cable size reasonable. I'm not suggesting that it can't be done just that it will be required. I do think managing these large spreads of "canvas" will be a challenge to put it mildly.

By the way who was Edeiken and what is the accident story. I collect engineering accident stories. They are very useful in doing safety analysis.

Regards,

Chris
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    Group: AirborneWindEnergy Message: 172 From: santos137@yahoo.com Date: 7/6/2009
    Subject: Re: Tripod Tether COTS AWE Demo
    Hi Chris (& Harry),
     
    Excuse the long post, but the issues are fascinating & complex.
     
    (You must mean 5000 sq meters or 50,000 sq ft, not 50,000 sq meters, for a large tall ship sail area. JoeF might edit the typo out of the list archive)
     
    A key point is that a displacement vessel is hull-speed limited & not able to accelerate like a kite & sweep a vast area in apparent wind many times true wind. So your correct estimate of about 5 megawatts for the ship is much less than the potential of a kite of similar area. The 5000 sq ft sweeping wing under a 17,000 sq ft lifter mentioned could in principle be sweeping a quarter mile loop at around 300 kts & roughly match or exceed the power of the tall ship's greater sail area in the same true wind. Existing parafoils like the 80's Flexifoil can do 100+ kts.
     
    Yes, actuation force required to stabilize a kite increases with wind speed/load. The simplest way to input this force is to pull strings from the ground, not fly servos. A beauty of passive-control is that it is self-powered. In rising wind the kite gets increased actuation force for key stability mechanisms. Holland identified "snowplow stability" where a side gust kicks a leading edge back & the kite yaws (kiter's "roll") to meet the new wind direction. Weathercocking assisted by a tail does the same correction but with useful dampening & added drag. These mechanisms scale reasonably. 
     
    Unfortunately the pendulum stability of a CG aft of the bridle-point/tether-axis does not increase in higher winds & the kite becomes more prone to flat spin (kiter's "roll" or "loop"). Adding tail adds aft mass & water ballast might be taken on, but only to  the point the added mass becomes a greater liability. Active onboard actuation does not scale well, weight penalizing the kite critically in normal wind, but a "quiver" of actuation packages to match conditions might serve.
     
    You are so right that flying clouds of "sail" in the sky will be a challenge, but what a glorious job it will be, a New Golden Age. The problem will be broken down into managable pieces (~100 sq m units?), just as a tall ship rig is a thicket of stability & control features allowing the "ants" to cope. A useful analogy is how crystaline solar cells cannot be made large & must be ganged. Another is to remember how discrete transistors gave way to integrated circuits. Kite elements can be interlinked in arrays for enhanced stability & even achieve general synchrony, effects already seen in festival kite trains & arches.
     
    Harry, you make a good point about kite trains & how multiple elements can support each other. This will make a good topic to discuss further.
     
     
    NOTES-  1) A kite with sufficient ground clearance can loop periodically without anything bad happening. There is a small loss of altitude to make up, which a lifter module handles well for a looper module. 2) A deeply keeled kite can lock into a dive by random initial conditions. 3) Weak active actuation can interfere with the harmonic process of repeated undesirable looping (chaotic control). Similarly, a small trim input can poise a lifter kite against the handedness of prevailing wind helicity. 4) Wind chaos near a kite's limits creates momentary crisises to deal with. "Punch turning", as used by stunt fliers, is the sudden release of "stored" tension on one side of the kite (punching motion) to shift CP. This does not require high real-time force, but the tension has to be replenished, perhaps by the same tiny servo-winch that provides trim input. 
     
     
    Re: Edeiken Tragedy
     
    Your interest in failure cases is ultimately very valuable. In computer science such analysis is processed as case-based reasoning (CBR) as inspired by best legal & medical practice. It is a worthy compliment to Alister's connectionist genetic algorithm (GA) approach to solve poorly defined problems. but is opaque compared to CBR's transparency. CBR over GA would be so cool.
     
    Poor Edeiken was swept up by the bridle lines as The Monster launched unexpectedly with what was described as the "roar of a 747". Several lines had parted due to poor attachment & one of these coiled like a snake around an ankle. When it released him he was about 100 feet high. Kay Buesing, director of the World Kite Museum witnessed the fatality & described it to me just last week. 
     
     
    The 25th anniversary of the tragedy just passed & the AKA magazine devoted a section to it which i clipped. Its yours for you file when we next meet.
     
    The PTSD continues to traumatize fun kiting & the AKA's highest prize is the Edeiken Award. Peter Lynn describes being tripped by sweeping lines on launch in his excellent big=kite safety piece on Gomberg's site. Another common big kite accident is like ballooning where tag line handlers don't let go & are lofted.
     
    The Monster only came down when it parted its 3 inch Kevlar cable. Aft bridles should be elastic & passively dump excess tether force by reducing AoA, allowing lighter lines. Traditional kiting changes tethers with wind changes. at the drop of a hat I was astounded watching Jim Patton promptly reverse the completed hour-long launch process of his 1000 ft classic train simply to substitute lighter line in anticipation of changed conditions. As with sailing one must fly the hell out kites to  fully maximize performance.
     
    Some Lessons- 1) Stay out of the lateral scope of the launch/flight & never stand or walk inside the bridle/control lines of a big kite, 2) Kite Killers required for high consequence operation, 3) No loose lines or seams allowed, 4) Controlled launch mechanism required. 5) Hook knife required for all handlers & maybe a clip on carabiner/body tether if one is somehow dragged aloft.
     
    The Controlled Launch requirement can be met by various means. A kite can be stoppered like a spinnaker or packed like a parachute, lofted, & popped at altitude. Towing or winching a kite aloft is a powerful technique. Stands with releases might be practical, etc.. Foxholes &/or trenches may be useful on mega-kite field. Large kite handling robots might be a solution.
     
    Current giant kites are still belly launched & tend to flip over as one side gets more lift, a severe scaling limitation restricting handler ants to the current 10,000 sq ft.  A giant parafoil or sled might best be launched flaked & laid on its side so it can be constrained from the key nose point with launch crew ideally always outside the scope. Such a prepared kite inflates progressively by unfanfolding, stands up, & lift off; a pretty sight. This is how sleds self relaunch after landing on a side. This launch method avoids launching directly into the power zone. Note also that an overly short-lined kite tends to oscillate violently as the line's natural frequency matches/couples with the kite's natural frequency, a hazard of short-line launch.
     
     
    ds
     




    Group: AirborneWindEnergy Message: 173 From: Joe Faust Date: 7/6/2009
    Subject: Message posting and edit limits in the Yahoo program.
    "might edit the typo out of the list archive"

    Posted messages cannot be edited. A workaround when wanted: An author may delete their own post and posted an edited version again on a thread. Or the author may ask me to delete a post entirely with or without a new edited version.

    Moderator
    JoeF

    PS: Differently, any page in http://EnergyKiteSystems.net may be edited; please send corrections, additions, deletion reequests to me for that space. Thanks.
    Group: AirborneWindEnergy Message: 174 From: christopher carlin Date: 7/6/2009
    Subject: Re: Tripod Tether COTS AWE Demo
    Dear Dave,

    Your absolutely right the number is 50,000 sq.ft. sorry about that. I had two thoughts really one is simply the loads involved, the other I was thinking of it as a lifter rather than the power kite.  

    Regards,

    Chris 
    On Jul 6, 2009, at 7:17 PM, santos137@yahoo.com wrote:


    Group: AirborneWindEnergy Message: 175 From: dave santos Date: 7/7/2009
    Subject: Re: Tripod Tether COTS AWE Demo
    Chris,
     
    The loads are fantastic but manageable, as they are purely tensile. Currently Spectra is the preferred load path fiber across ripstop polyester or nonprepreg carbon ribbon sandwiched in a polyester membrane is also good. Graphene (bucky tubes) is in the pipeline & will give another order of magnitude to play with.
     
    Wingloading by unit area remains constant across scale, so the same fabric is used in mega kites as small ones, but a progressive loadpath network must gather the mega stress to the bridle/flight lines. 50,000 sq ft flies on paper, but looks like an operational "kitemare"
     
    Reinforced loadpaths can run fully within the single skin of KiteShip's OL to its minimalist 3 line bridle. It has been scaled to 5000 sq ft.. To scale up giant parafoils proliferate bridle lines as needed all along the span. "Sticky" kite designs are limited to about 100ft dimensions using airbeams. Carbon or bamboo spars only work to 30 ft or so before becoming too weak or heavy. Giant kites must be soft.
     
    Spectra & Kevlar mooring & towing lines exist for shipping at least 8 in across & have been hyped as able to carry the power of a nuke plant, but by my calcs only if moving at high speed. One could spin/weave these together into ever greater diameters.
     
    A key insight is that the ground itself is "free" kite structure to spread out & hold kites in shape or place ("staking out"). Since it doesn't fly it adds no weight aloft. Lift & drag provide spreading function in the remaining dimensions.
     
    For a Lifter/Looper combo each kite lives in its own load & performance regime. A 5000 sq ft hot parafoil for the looping element seems to limit the whole system at present. The Membrane Wing Mill with airbeam battens might expand this scale constraint by perhaps 2X.
     
    ds
     



    Group: AirborneWindEnergy Message: 176 From: harry valentine Date: 7/7/2009
    Subject: Boone Pickens Wing Power Project
    I just received a news item that T. Boone Pickens is scaling back his (tower-based) wind power venture in Texas. Instead of a mega-wind farm, he's opting for several smaller wind farms. Perhaps one of the airborne wind power proponents could let Mr Pickens know of the advantages of airborne wind power and towerless wind power.
     
     
    Harry 


    Internet Explorer 8 makes surfing easier. Get it now!
    Group: AirborneWindEnergy Message: 177 From: Joe Faust Date: 7/8/2009
    Subject: Welcome Prof. Ugo Bardi
    Welcome Ugo Bardi.
    http://www.energykitesystems.net/KITESA/FAQelectric/researchers.html#UgoBardi

    http://tinyurl.com/UgoBardi

    The favorable response of his July 6, 2009, post
    along with the responses' content's points for discussing
    are energizing AWE. Ugo, welcome. And thanks for your
    works and investing.

    High altitude wind power: an era of abundance?
    Posted by Ugo Bardi on July 6, 2009 - 7:06am in The Oil Drum: Europe
    Topic: Alternative energy.
    See:
    http://europe.theoildrum.com/node/5538

    http://www.energykitesystems.net/notices/membersent.html
    Several members introduced Ugo Bardi to me. Thanks to DaveS and Wolf.

    Ugo Bardi is founder and president of Association for the Study of Peak Oil (ASPO Italia)
    http://www.aspoitalia.it/

    Benvenuto,

    JoeF
    Group: AirborneWindEnergy Message: 178 From: Joe Faust Date: 7/15/2009
    Subject: A setting for group program function has been installaed.
    Up to today, a member could not hide their e-mail address.

    A change has been made.
    Now a member may configure his or her membership to hide or not his or her e-mail address. Choose for yourself. However, please note that a consequence of hiding one's e-mail address is that suring such configuration one may post message to the group only at the web view of the group; that is, for members hiding their e-mail address may not post message via e-mail. Just go to the gorup online and use the posting tools there.

    A secondary consequence is that our group may not use the Yahoo Polls funciton. If polling is needed, we can have a workaround.

    Some new members have requested the ability to hide their e-mail address. If such is wanted, go to online view of the group. Log on. Then edit your membership.

    Lift to all,
    JoeF
    Group: AirborneWindEnergy Message: 180 From: davemart2009 Date: 7/16/2009
    Subject: SkySails in relation to generating electricity
    Hi, I am a new member and am trying to get my head around some of the figures
    implicit in high or medium altitude wind

    Instead of the Kitegen set-up, I looked at the SkySail, which is, if not fully
    operational, at least well into prototype sea trials.
    Of course the technologies are not identical, as it is being used by them to
    drag a ship along, but it is certainly analogous.
    They provide fair documentation of what they are up to, but being no engineer
    the exact calculations are beyond me.
    Perhaps someone would be interested in taking a look and coming up with some
    figures?
    We are told here that it takes around 500square metres of kite to generate 5MW:
    http://www.livescience.com/environment/ ... s-big.html

    On the SkySails site they prefer to talk in terms of effective load, and say
    that their base system, of 160square metres, generates an effective load of 8
    tonnes, which they say equates to around 600-1000kw of main engine force
    depending on tractive conditions and resistance.
    http://www.skysails.info/fileadmin/user ... profit.pdf
    The largest they are current in the process of building is 600 sq metres.

    They aim, we are told, in the present series of product development to go up to
    130 tons of effective tractive load.

    Am I right in figuring that this might be a kite of around 15MW power?
    And as a pure guess, would the area of the kite be around 2500 square metres?

    I don't really see why the swept area would be much larger than the smaller
    system, but perhaps the whole relationship in what they are doing with swept
    area and the physical area of the kite is very different to this naive
    extrapolation.

    In any case, I am pretty confident that SkySails are well aware of the strengths
    of the materials they are using, although of course the costs may escalate more
    than they hope.
    Presumably using such a system for energy generation rather than traction could
    also alter the rate at which the line needed to spool, so the materials
    constraints might be rather different.

    I would be grateful if anyone could shed any light on this whole system.

    I found it argues here that parasitic loss would be very important indeed,
    greatly reducing available power:
    http://windlift.wordpress.com/2007/06/2 ... er-output/
    So apparently for towing you have no parasitic phase.
    He reckons you get around 1/5th the energy that you would for towing.
    That means that to get a 3MW power kite you need to go to the same level as you
    would get at the end of the Skysail development program, and on those figures
    and assumptions you end up the same as an offshore wind turbine.
    Capacity factors would still be higher though, and you could possibly avoid the
    heavy infrastructure and stick to a buoy.


    http://www.livescience.com/environment/ ... s-big.html
    '"One of the major problems for offshore wind parks today is the needed time of
    excellent weather to install the units," Hoffschmidt said. Kites, on the other
    hand, could be installed on anchored buoys, "which can easily be installed and
    de-installed with a lower environment impact."


    Since I am based in the UK I am particularly interested in systems which could
    be moored on buoys, as this would be a lot cheaper than building conventional
    wind turbines off-shore, and would take advantage of the high winds available at
    around 300 metres at sea, comparable I understand to around 800 metres for most
    areas on land.
    This would overcome the severe space constraints in England and allow siting
    much nearer to where it is needed.

    My interest in the SkySails project in relation to wind is that many of the
    control systems must be analogous, and they have done sea-trials for some time
    with fairly large kites.
    Of course generating power and providing traction are two very different things.
    Group: AirborneWindEnergy Message: 181 From: davemart2009 Date: 7/16/2009
    Subject: Re: SkySails in relation to generating electricity

    Group: AirborneWindEnergy Message: 182 From: Joe Faust Date: 7/16/2009
    Subject: Re: SkySails in relation to generating electricity
    Welcome David.

    I am still studying your welcomed post. Others will probably chime in on the calculations.

    A first reply concerns your final sentence:

    Such teases out one of my niche favorites:
    Let traction work hydro turbines (for oceans, lakes, ponds, seas, bays) (or soil-friction wheel-driven turbines on land) Let huge kites tow a hydro-turbined-saturated barge; use the ambient solar and the hydro-turbined generated electricity to convert ambient water to obtain and compress hydrogen for delivery to need points. The barge could path freely or on constrained crosswind cable for constrained space use. The barge of turbines might be an at-sea vacation ship that just enjoys being out at sea.
    Group: AirborneWindEnergy Message: 183 From: Joe Faust Date: 7/18/2009
    Subject: Secondary uses of EKS lifter kytoon skyhooks

    Consider various secondary uses of skyhook lifter kytoons

     besides a main use of giving a tensional tower in the sky for holding AWE systems. 

     Tensional towers will be a disruptive technology for renewable sustainable energy production; having secondary and tertiary uses of the skyhook ...the ever-up platform... will enhance the scene.   Watch out,  Sir Hard-Towered-Turbine Industry, for there is a new player in town: tensional towers for AWE ...with secondary uses.

    1.   Communications antenna.  Relay station.   $$$  Part of a constellation ...ringing earth.

    2.   Observation deck. Have admission $  involved.

    3.   Entertainment platform. Parties. Weddings.  Fee-based. $$

    4.   Rangers' perma-home.     Even have an indoor swimming pool. Capture atmospheric water.

    5.   Home sweet home for some people.

    6.   Launch pad for hang gliders of the framed sort and the unframed limp sort (paragliders).   $$$

    7.   Telescope station.  Photography.   Fee-based. $$

    8.   Manufacturing environment where the given cold, solar radiation,  clean air, and atmospheric pressure form a just-right situation.   Drop-fly-glide the products to destination points in rural or urban areas.

    9.   Recreational ride. Ride up the Laddermill and fly down or ride the Laddermill down.

    10.  Super bungee launch pad.   $$$      

    11.  Above-cloud PV station for energy making also besides the main AWE situation.

    12.  Vacation-days destination.   $$

    13.   Solar-powered aircraft landing strip. Fly from one AWE lifter kytoon to the next AWE lifter kytoon.

    14.   Super big swing adventure ride.   $$

    14. . ..............................................[  All members are invited to this thread for posting  more secondary and tertiary uses ...  .   ]

     

     

    Group: AirborneWindEnergy Message: 184 From: davemart2009 Date: 7/18/2009
    Subject: Massimo Ippolito's figures on efficiencies.
    There was a very valuable post over on the Oil drum by Massimo Ippolito of Kitegen on the projected efficiencies of the kite plus cable in his system.
    I trust he will not object to my pasting it here:
    'The data are you looking for, can be summarized in the aerodynamic efficency of the arieal part of the kiteGen, wing+cables.
    Up to now we operated with 8-12 efficent systems and our foreseeable target is about 28.

    This value mainly affect the minimun wind speed requirement needed to produce the full (130% of nominal) power of the KiteGen Stem.

    based to the current design, an efficency of:
    8 require a wind of 23,8m/s to reach the machine full power
    here follow the list:

    efficency / min wind speed m/s
    8 / 23,8
    12 / 13,3
    16 / 9,7
    20 / 8,0
    24 / 7,1
    28 / 6,5
    32 / 6,2

    with an efficency over 24 the KiteGen Stem supply about 8760 MWh/MW
    Group: AirborneWindEnergy Message: 185 From: dave santos Date: 7/22/2009
    Subject: Liftopia- 1896
    Attachments :
      Attached Image:
       
      Chicago Times Herald, 16 August 1896.
       

        @@attachment@@
      Group: AirborneWindEnergy Message: 186 From: Carlo Perassi Date: 7/26/2009
      Subject: Self introduction (KiteGen/WOW)
      Greetings to the subscribers of the AWE mailing list.

      Joe Faust wrote to me with kind words, accepting my request to be
      added to this mailing list: he also suggested to introduce myself.
      I think I won't write so much because I'm here to read and learn.
      I'm one of the founders of WOW
      http://www.windoperationsworldwide.eu/en/who-we-are/

      I added a link to AWE on our website and let me link here a page
      http://www.windoperationsworldwide.eu/en/faq/
      which contains long technical papers on KiteGen that are not so easy
      to find on the net, perhaps (I mean the works of Fagiano and Maneia).

      Thank you and have a nice day.

      --
      Carlo Perassi - http://perassi.org/
      Group: AirborneWindEnergy Message: 187 From: Joe Faust Date: 7/30/2009
      Subject: Progress on materials
      Dream of AWE systems' applications of what looks like will fly out of flying carpets and nanokites:
       
       
      and collection of general news notes:
       
      Post the AWE dream as you might.   I am excited with the progress being made. And it is neat that the coming products have a root in "nanokites."
       
      Group: AirborneWindEnergy Message: 189 From: roundtheglobe Date: 7/31/2009
      Subject: Re: Tripod Tether COTS AWE Demo
      Hi Dave,
      I was just wondering if you could illustrate the working principle behind the TTCA (Tripod Tether COTS AWE) further so to replicate the experiment at home.
      ..It looks like lines are hoocked somewhere on the ground in a circle pattern around the generator ..
      Hope you are not on vacation yet (so selfish).

      Gabe


      Group: AirborneWindEnergy Message: 190 From: dave santos Date: 7/31/2009
      Subject: Re: Tripod Tether COTS AWE Demo
      Hi Gabe,
       
      The legs of the string tripod in the video run to an equilateral (~30ft/9m) triangle of three sand anchors with a "corner block" pulley each. The strings run from there to a center crank & drive it by a three phase sequence of tension-slack with no "dead zone".
       
      The tripod is much more robust to line maladjustment than i first thought, requiring only crude slacking of a "sheet" line from pulley to a windward anchor to tilt the tripod downwind as the wind rounds. Simple variations are under study to automate this adjustment for true "fly & forget" & you may hit on a good solution.
       
      One minor problem with the looping kite scheme is that the swivels may need a tiny line spreader to operate freely (see JoeF's AWE DIY page coming soon). Sand is a problem for me & i am currently using a  fisherman's six step swivel for the least resistance. Oiling & over-specifying fishing swivels is smart as they overheat in air.
       
      An improvement may be to have three sheets, from the crank workcell to the anchors, which can place the mobile workcell wherever best adjusts the tripod tilt. Also consider merely turning a bike on its side & driving a pedal, as a drive train. A generator can be driven off the rear wheel at high speed.
       
      Please get back to JoeF or the list with your progress.
       
      dave
       
      PS stay tuned for an even simpler "passive eights" COTS demo
       



      Group: AirborneWindEnergy Message: 191 From: Darin Selby Date: 7/31/2009
      Subject: Re: Tripod Tether COTS AWE Demo
      Please resend the attachment video link.  Thanks

      To: AirborneWindEnergy@yahoogroups.com
      From: gb2910@gmail.com
      Date: Fri, 31 Jul 2009 09:32:10 +0000
      Subject: [AirborneWindEnergy] Re: Tripod Tether COTS AWE Demo

       

      Hi Dave,
      I was just wondering if you could illustrate the working principle behind the TTCA (Tripod Tether COTS AWE) further so to replicate the experiment at home.
      ..It looks like lines are hoocked somewhere on the ground in a circle pattern around the generator ..
      Hope you are not on vacation yet (so selfish).

      Gabe



      Bing™ brings you maps, menus, and reviews organized in one place. Try it now.
      Group: AirborneWindEnergy Message: 192 From: Gabriele Date: 8/1/2009
      Subject: Re: Tripod Tether COTS AWE Demo
      Hi Dave,
      thank you very much for being so exhaustive and patient with this 'wind power guide for dummies' thing  :)
      I sketched up a kite(s) / generator set as I evinced from video and description you provided :

      http://sites.google.com/site/closedsteam/Home/TTCA.jpg


      Can you spot any anomaly ?

      Questions:
      1. How many lines do control the kite (3)?
      2. How do you prevent kite lines from getting tangled while kite keeps rotating around Z axis ?
      3. (Deriving from my kite dynamics ignorance) Is the 'cheap X-kite sport-kite' allways facing the right direction  without external intervention ,not being influenced by wind changes ?

      I keep my ears open for:
      •  'even simpler "passive eights" COTS demo'
      •  JoeF's AWE DIY page coming soon..

      and I surely will keep you updated with eventual progresses .

      x Darin You can check the video here:

      video:
      http://d.yimg.com/kq/groups/24857016/1398141728/name/tripodtether.mpg

      message:
      http://tech.groups.yahoo.com/group/AirborneWindEnergy/message/166








      Group: AirborneWindEnergy Message: 193 From: dave santos Date: 8/1/2009
      Subject: Re: Tripod Tether COTS AWE Demo
      Gabriele,
       
      The drawing is close, but there are key details to refine-
       

      Group: AirborneWindEnergy Message: 194 From: Joe Faust Date: 8/1/2009
      Subject: Re: Tripod Tether COTS AWE Demo
      --- In AirborneWindEnergy@yahoogroups.com, Gabriele <gb2910@... Gabriele and All:
      The folder and offerings for the new DIY AWE are modest yet.
      All are invited to generate notes, images, and detail plans
      for AWE experiments that have some successes involved.

      http://www.EnergyKiteSystems.net/DIY/\

      Lift,
      JoeF
      Group: AirborneWindEnergy Message: 195 From: Gabriele Date: 8/2/2009
      Subject: Re: Tripod Tether COTS AWE Demo
      Hi Dave,
      I re-uploaded an updated version of the sketch :
      http://sites.google.com/site/closedsteam/Home/TTCA.jpg
      ..did I get it right this time ?

      (If positive should the sketch image be posted to JoeF's AWE DIY page ?)




      Group: AirborneWindEnergy Message: 196 From: dave santos Date: 8/2/2009
      Subject: Re: Tripod Tether COTS AWE Demo
      Hi Gabriele,
       
      Wow, your sketch is very beautiful & clear. JoeF will surely feature the illustration & any others you do. Maybe KiteLab can help you somehow, like a small stipend. Your drafts are, of course, already online in this message thread. A comparative set of concept sketches would be, well, AWEsome.
       
      There are key small details you may want to add-
       

      Group: AirborneWindEnergy Message: 197 From: Gabriele Date: 8/3/2009
      Subject: Re: Tripod Tether COTS AWE Demo
      Hi Dave,
      as we manage updating the sketch of your kite power-set I would like to thank you for your appreciation.
      I won't ask any money for having fun :)
      I would be more than happy to illustrate other stuff if needed , just ask.

      updated illustration:
      http://sites.google.com/site/closedsteam/Home/TTCA.jpg




      Group: AirborneWindEnergy Message: 198 From: harry valentine Date: 8/3/2009
      Subject: Re: Tripod Tether COTS AWE Demo
      Gabriele and Dave,
       
       
      I commend you both on your innovative thinking in regard to the single-kite and tripod system to drive a crankshaft. While there is merit to using sprags (one-way clutches), the crank system will ultimately involve less complication and require less maintenance over the long-term.
       
       
      The tripod and crank system will have application on a larger scale in many parts of th world. Gabriele's illustration shows a desert setting . . . and there is wind galore over many of the deserts (and offshore islands) around the world. Lets hope that this idea gets developed on a larger scale.
       
       
      Quite often its not the massive amounts of money given to the politically-favored that produces worthwhile results. There are many examples of some one's hobby that was undertaken on a shoe-string budget that ultimately evolved into somethng that served the needs of a large population.
       
       
      Regards,
       
      Harry 
       

       

      To: AirborneWindEnergy@yahoogroups.com
      From: gb2910@gmail.com
      Date: Mon, 3 Aug 2009 12:16:53 +0200
      Subject: Re: [AirborneWindEnergy] Re: Tripod Tether COTS AWE Demo

       
      Hi Dave,
      as we manage updating the sketch of your kite power-set I would like to thank you for your appreciation.
      I won't ask any money for having fun :)
      I would be more than happy to illustrate other stuff if needed , just ask.

      updated illustration:
      http://sites. google.com/ site/closedsteam /Home/TTCA. jpg







      Attention all humans. We are your photos. Free us.
      Group: AirborneWindEnergy Message: 199 From: spacecannon@san.rr.com Date: 8/3/2009
      Subject: Re: Tripod Tether COTS AWE Demo
      Hi Gabriele, do you do illustrations, for hire and if so how much and do you have a resume. I have some designs that need touching up. spacecannon
      ---- Gabriele <gb2910@gmail.com
      Group: AirborneWindEnergy Message: 200 From: Dave Lang Date: 8/3/2009
      Subject: Re: Tripod Tether COTS AWE Demo

      BTW in examining this scheme (for some given ground tripod scale length), it appears that at some altitude, the required "geometrical underpinnings" may "wash out", ie.  as the lines get longer, differential tensions tend to disappear (for a given oscillation amplitude), and the loaded generator crank may stall as it resists rotation. This is of course because the effective "end-to-end line stiffness" goes down with length, and the subtended oscillation angles (viewed from the ground) of the oscillating kite becomes smaller which washes out geometrically induced strain differential  (assuming that the kite's oscillation amplitude is not increased with altitude).

      1. Has anyone looked at this potential effect in terms of practical power generation?  2. What is the relationship between oscillation amplitude and altitude (ie. effect of ground constraint on the oscillation)?

      The reason I bring this up, as it seems to me that for AWE to successfully take on the conventional turbine industry, AWE power schemes will have operate at least out of the boundary layer in which the turbines live....I would thing 500 feet  and above

      BTW it seems like a natural for the upper support kite to simply be a balloon....voila, the no-wind situation is solved :-)!

      DaveL

      Gabriele, Thanks for the nice illustration.


      At 12:16 PM +0200 8/3/09, Gabriele wrote:
      Group: AirborneWindEnergy Message: 201 From: harry valentine Date: 8/3/2009
      Subject: Re: Tripod Tether COTS AWE Demo
      The crank may drive through a planetary gearbox to increase rotational speed on a flywheel that would maintain momentum. Another method is to actually build a small scale model of the tripod and develop ways to keep the crank continually rotating using cyclic-tension inputs only. In actually practice a compound winch mechanism would translate large movements of the kite into the required stroke of the crankshaft.
       
       
      Harry
       

      To: AirborneWindEnergy@yahoogroups.com
      CC: gb2910@gmail.com
      From: SeattleDL@comcast.net
      Date: Mon, 3 Aug 2009 10:35:25 -0700
      Subject: Re: [AirborneWindEnergy] Re: Tripod Tether COTS AWE Demo

       

      BTW in examining this scheme (for some given ground tripod scale length), it appears that at some altitude, the required "geometrical underpinnings" may "wash out", ie.  as the lines get longer, differential tensions tend to disappear (for a given oscillation amplitude), and the loaded generator crank may stall as it resists rotation. This is of course because the effective "end-to-end line stiffness" goes down with length, and the subtended oscillation angles (viewed from the ground) of the oscillating kite becomes smaller which washes out geometrically induced strain differential  (assuming that the kite's oscillation amplitude is not increased with altitude).

      1. Has anyone looked at this potential effect in terms of practical power generation?  2. What is the relationship between oscillation amplitude and altitude (ie. effect of ground constraint on the oscillation) ?

      The reason I bring this up, as it seems to me that for AWE to successfully take on the conventional turbine industry, AWE power schemes will have operate at least out of the boundary layer in which the turbines live....I would thing 500 feet  and above

      BTW it seems like a natural for the upper support kite to simply be a balloon....voila, the no-wind situation is solved :-)!

      DaveL

      Gabriele, Thanks for the nice illustration.


      At 12:16 PM +0200 8/3/09, Gabriele wrote:


      More storage. Better anti-spam and antivirus protection. Hotmail makes it simple.
      Group: AirborneWindEnergy Message: 202 From: dave santos Date: 8/3/2009
      Subject: Re: Tripod Tether COTS AWE Demo
      The single center generator scales poorly, but the tri-tether itself scales well. To scale into upper winds a tri-tether merely needs more distance between legs. The triangle base can be quite small the lower stretch the tethers are, the thinner (less wind catenary), the lighter (less grav catenary), & the better tuned the tri-tether. To get to the stratosphere an anchor triangle of six miles to a side, with a reel-generator at each anchor, will not suffer too much "wash-out". Other measures will work too, a net geometry can be suspended aloft by various means for as tensioners, spreaders, or a "leg up" for tri-tethers.
       
      Yes, helium can serve the pilot lifter function nicely, but at a considerable cost. I've done small helium UAVs since the eighties, & find Helium problematic. A compromise is to use a tiny helium pilot to launch a lifter that then launches the looper. In 2007 i used single party balloons with a "skyhook" kite wing & soft delta to initiate staged relaunches with fine results. [see attached jpgs]
       
      If we are talking grid scale AWE at truly high altitudes, the best solution for calm may be to tow the kites in a circle by the tri-tether, perhaps at a lower altitude. As for competing with conventional wind turbines at low altitude, its plausible that low capital cost AWE can dominate where financing is scarce & labor is cheap, or "instant" or mobile wind energy is desired.
       
       


        @@attachment@@
      Group: AirborneWindEnergy Message: 203 From: harry valentine Date: 8/4/2009
      Subject: Re: Tripod Tether COTS AWE Demo [3 Attachments]
      An anchor triangle of 6-miles per side is possible on some offshore islands and in remote windswept regions. There are some 1600 offshore islands on the eastern side of Hudson Bay and James Bay, just to the west of Quebec . . . and within range of the James Bay hydroelectric installations (transmission lines along Quebec's west coast along Hudson Bay and James Bay). There are powerful winter winds that blow over the eastern side of both bays.
       
      Perhaps we have a suitable North America geographic location for a large-scale tri-tether power kite wind conversion technology. Power Authority of New York has initiated discussions with Canadian authorities on increasing pumped hydraulic capacity that will involve a new international hydroelectric installation . . . which would certainly be compatible with high-altitude wind power.
       
       
      Harry
       

      To: AirborneWindEnergy@yahoogroups.com
      From: santos137@yahoo.com
      Date: Mon, 3 Aug 2009 22:37:43 -0700
      Subject: RE: [AirborneWindEnergy] Re: Tripod Tether COTS AWE Demo [3 Attachments]

       
      [Attachment(s) from dave santos included below]

      The single center generator scales poorly, but the tri-tether itself scales well. To scale into upper winds a tri-tether merely needs more distance between legs. The triangle base can be quite small the lower stretch the tethers are, the thinner (less wind catenary), the lighter (less grav catenary), & the better tuned the tri-tether. To get to the stratosphere an anchor triangle of six miles to a side, with a reel-generator at each anchor, will not suffer too much "wash-out". Other measures will work too, a net geometry can be suspended aloft by various means for as tensioners, spreaders, or a "leg up" for tri-tethers.
       
      Yes, helium can serve the pilot lifter function nicely, but at a considerable cost. I've done small helium UAVs since the eighties, & find Helium problematic. A compromise is to use a tiny helium pilot to launch a lifter that then launches the looper. In 2007 i used single party balloons with a "skyhook" kite wing & soft delta to initiate staged relaunches with fine results. [see attached jpgs]
       
      If we are talking grid scale AWE at truly high altitudes, the best solution for calm may be to tow the kites in a circle by the tri-tether, perhaps at a lower altitude. As for competing with conventional wind turbines at low altitude, its plausible that low capital cost AWE can dominate where financing is scarce & labor is cheap, or "instant" or mobile wind energy is desired.
       
       





      Attention all humans. We are your photos. Free us.
      Group: AirborneWindEnergy Message: 204 From: davemart2009 Date: 8/4/2009
      Subject: Re: Tripod Tether COTS AWE Demo [3 Attachments]
      Sounds a bit greedy to me!
      On-shore you get very decent winds at around 800 metres, offshore at
      around 300 metres.
      For the UK, a few moored buoys should provide a base for the tripod, and
      get a fair amount of wind without pushing the technology.
      Helium is a very scarce resource, which escapes the atmosphere and
      leaves the earth forever.
      It is useful or essential for a lot of uses such as in medicine and much
      sophisticated equipment.
      It would seem foolish to me to use it to float balloons.
      Hydrogen would do fine - it's explosivity is much exaggerated.

      --- In AirborneWindEnergy@yahoogroups.com, harry valentine <harrycv@... wrote:
      islands and in remote windswept regions. There are some 1600 offshore
      islands on the eastern side of Hudson Bay and James Bay, just to the
      west of Quebec . . . and within range of the James Bay hydroelectric
      installations (transmission lines along Quebec's west coast along Hudson
      Bay and James Bay). There are powerful winter winds that blow over the
      eastern side of both bays.
      large-scale tri-tether power kite wind conversion technology. Power
      Authority of New York has initiated discussions with Canadian
      authorities on increasing pumped hydraulic capacity that will involve a
      new international hydroelectric installation . . . which would certainly
      be compatible with high-altitude wind power.
      Attachments]
      scales well. To scale into upper winds a tri-tether merely needs more
      distance between legs. The triangle base can be quite small the lower
      stretch the tethers are, the thinner (less wind catenary), the lighter
      (less grav catenary), & the better tuned the tri-tether. To get to the
      stratosphere an anchor triangle of six miles to a side, with a
      reel-generator at each anchor, will not suffer too much "wash-out".
      Other measures will work too, a net geometry can be suspended aloft by
      various means for as tensioners, spreaders, or a "leg up" for
      tri-tethers.
      considerable cost. I've done small helium UAVs since the eighties, &
      find Helium problematic. A compromise is to use a tiny helium pilot to
      launch a lifter that then launches the looper. In 2007 i used single
      party balloons with a "skyhook" kite wing & soft delta to initiate
      staged relaunches with fine results. [see attached jpgs]
      solution for calm may be to tow the kites in a circle by the tri-tether,
      perhaps at a lower altitude. As for competing with conventional wind
      turbines at low altitude, its plausible that low capital cost AWE can
      dominate where financing is scarce & labor is cheap, or "instant" or
      mobile wind energy is desired.
      speed on a flywheel that would maintain momentum. Another method is to
      actually build a small scale model of the tripod and develop ways to
      keep the crank continually rotating using cyclic-tension inputs only. In
      actually practice a compound winch mechanism would translate large
      movements of the kite into the required stroke of the crankshaft.
      length), it appears that at some altitude, the required "geometrical
      underpinnings" may "wash out", ie. as the lines get longer,
      differential tensions tend to disappear (for a given oscillation
      amplitude), and the loaded generator crank may stall as it resists
      rotation. This is of course because the effective "end-to-end line
      stiffness" goes down with length, and the subtended oscillation angles
      (viewed from the ground) of the oscillating kite becomes smaller which
      washes out geometrically induced strain differential (assuming that the
      kite's oscillation amplitude is not increased with altitude).
      power generation? 2. What is the relationship between oscillation
      amplitude and altitude (ie. effect of ground constraint on the
      oscillation) ?
      successfully take on the conventional turbine industry, AWE power
      schemes will have operate at least out of the boundary layer in which
      the turbines live....I would thing 500 feet and above
      balloon....voila, the no-wind situation is solved :-)!
      to thank you for your appreciation.
      ask.
      it simple.
      Group: AirborneWindEnergy Message: 205 From: Dave Lang Date: 8/4/2009
      Subject: Re: Tripod Tether COTS AWE Demo [3 Attachments]
      DaveS

      If the aero derivatives for the looper-kite were known, I could simulate this whole Tripod Tether COTS AWE with my GTOSS software. Of course it would not be a trivial job (and I am busy trying to make an actual living, so could not drop everything to do it). Be that as it may, such a simulation would expose any weaknesses such as "wash-out", wind/gravity line deflections, wind/gust behavior, natural (and possibly unwanted) systemic oscillations occurring between the components and the lines, etc, etc. When such designs are scaled up in size, all sorts of un-expected issues can emerge that are not necessarily exposed by small-scale prototyping (unless said prototypes are designed with specific intent to "dynamically model" the full size scheme).

      DaveL





      At 10:37 PM -0700 8/3/09, dave santos wrote:
      Group: AirborneWindEnergy Message: 206 From: Dave Culp Date: 8/4/2009
      Subject: Re: Tripod Tether COTS AWE Demo
      It is not necessary to go directly from a 5 watt system to gigawatt
      system. It should be a simple matter to build a 100-1000 watt
      (continuous, average power output) test model, and determine many of
      these answers. A cooperative effort (Dave S. does the hands-on work;
      from materials and cash raised/donated by the group; technology
      belongs to all, for instance) might be indicated.

      Dave

      Group: AirborneWindEnergy Message: 207 From: brooksdesign Date: 8/4/2009
      Subject: Re: Tripod Tether COTS AWE Demo

         I too have a biz to run and have been too busy to be involved lately but what DaveL brings up is a very important issue. One thing that would really help the research here is a good set of data acquisition tools. Accelerometers and load cells and wind speed sensors with data logger mounted on kites
      and several locations on the lines so all of these forces may recorded in synch. Wireless com to a ground based controller could provide enough data to use those forces to our advantage.

         If the funding were to become available I may be able to convince my  brother to take a look at the technology. His company Signalysis does vibration monitoring and both destructive and non-destructive  QC testing and one of their software products is called ResTrak. ResTrak looks for resonant frequencies in objects as they are being vibrated and adjusts the shaker frequencies to force a fatigue failure. If we were to develop a good system of kite and line testing procedures I think we could come up with a way to use all of those drawbacks of long lines as an advantage. A feedback control system that tunes the kite's motion to the resonant frequency of the lines in real time could actually enhance the desired forces. 

        I know this would be an expensive and time consuming project to undertake (I still have yet to find the time to build out my universal energy harvester I started last year) but it would go a long way in helping sell the idea to the rest of the engineering community. My limited experience with designing test fixture for the company tells me the cost of such a data acquisition system would run about $30,000 to $50,000 to have them do it. In the past I have suggested that they look into it but their main customers(GM) kept them really busy. As we all know GM subcontractors have a lot of free time on their hands these days and since Signalysis's latest jobs have been validating wind turbine blades they may be more likely to take a look at the project, (although the tower/turbine people my want to squash any competing tech) .

         Anyway, at some point there will need to be some really good detailed testing to make this tech competitive and we need to figure that into any future funding request.

      Just  a thought.....

      -brooks




      Group: AirborneWindEnergy Message: 208 From: Dave Lang Date: 8/4/2009
      Subject: Re: Tripod Tether COTS AWE Demo
      DaveC,

      I agree much can be learned from proto-typing and gradually scaling-up in that fashion. However, at some point, the cost of proto-typing (both h/w expense and test operations) starts to become too great to "shoot from the hip", at that point, some analysis and simulation can become cost effective allows much to be learned about what really "makes a design tick". Not sure where that point is in this particular AWE design, and, of course if you can't generate a few kw reliably and cheaply (which should be well within cut-n-shoot experimentation), then scaling up any further become a moot point as there will be no lure for funding to move it all ahead anyway.

      DaveL



      At 10:22 AM -0700 8/4/09, Dave Culp wrote:
      Group: AirborneWindEnergy Message: 209 From: Gabriele Date: 8/4/2009
      Subject: Re: Tripod Tether COTS AWE Demo
      So kind of you,I am not taking credit for Dave's creation though ..
      I think it is a very functional set that could evolve to a practical
      application, exspecially in less developed countries.

      My pleasure ..

      I am not into illustrations (average programmer resume) ..
      'I have some designs that need touching up' -- You can maybe avoid human intervention by using:
      - a cheap pc and
      - a simple neural net based computer vision system
      - that learns from humans
      - how to perform kite flight maintenance.

      Gabe
      Group: AirborneWindEnergy Message: 210 From: dave santos Date: 8/10/2009
      Subject: Kite Anchor Geology, Soil Kites, Design Issues
      Anchoring is a major AWE requirement. This post describes how powerful kites are securely moored for safety, reliability, & performance, at minimal cost.
       
      Fabric Sand Anchors hold tons of pull with ounces of material & can be scaled up. David Gomberg sells a low cost version. Peter Lynn is a proponent. One can improvise a sand anchor by knotting & tethering the corners of suitable canvas. Adding an apex retrieval line can be helpful.
       
      Soil Kites are close analogues to Sky Kites, despite soil's thousand-fold or greater density. The holding power of a tiny soil kite "flying upside down" deep in good soil is impressive. A soil kite may actually dive deeper with increased pull.  Boat anchors suited to soft bottoms, like the Danforth, are soil kites, but generally unsuited to land kites; Lynn points out that a dragging sand anchor is safer than a runaway "hook" when things go wild. The potential is real for super kites to pull down buildings & create mayhem plowing across highways.
       
      Soil viscosity ranges from slurry to broken rock. Under stress soil begins to act as a fluid, so anchors usually fail by leaking soil around edges as flow. Heavier drier more solid soils hold best. Engineering tables crudely predict the holding power of various soils but direct testing & adding a large safety factor is essential. Eight to one is is considered very safe in many structural contexts, but kite surge can be a very extreme peak compared to common dynamic applications.
       
      The life cycle of an anchor is a critical consideration. Hidden galvanic corrosion is a particular hazard to avoid by selecting galvanized & stainless components. Inspection & programmed replacement are long term necessities. Water saturated weakened soil should be presumed even in a dry place. Even earthquake liquefaction may be a design factor.
       
      Powerful soil kites can be made at modest cost with buried steel plates or concrete slabs bridled like kites & attached to the surface with galvanized or stainless wire rope. Delivering a folded or oblique anchor to depth, which then tips crosswise or expands, greatly reduces excavation requirement. "Mud-jacking", pumping concrete under high pressure, or expansion cement around a wire rope clamped or looped in a bore hole creates a "belled" footing & locks into hard soil.
       
      Drilled pins & hooks are suitable for rock anchors. Sea anchors are powerful solutions if downwind creep is acceptable. A "deadman" buried beam or log is soil-kite like & holds well. Stakes are not so good as kite anchors as the pull is generally upward. Spiral stakes like those used for dogs hold better. Kiters use impact wrenches to set large versions. Plants are sometimes used as living anchors. Hobby kiters even tie off on tufts of grass. Trees have an easily hurt living layer under the bark to protect by belting.
       
      A kite anchor has associated connector hardware such as an eye, ring, carabiner, or shackle. Often smaller fittings are ganged on a larger one. Rigging Plates have a set of holes to organize multiple fittings. Quick release hardware, Kite Killers, are a good precaution to douse a berserk kite.
       
      Anchoring situations demand flexibility. A complex anchor field in varied geology will need multiple solutions. Some anchors may be mere dead-weights & even be designed to drag in a peak event allowing other failsafe anchors act as kite killers. Small water or sandbags may even operate dynamically in "teabag" mode as downwind drogues.
       
      The world's top Kite Geologist, a pro soil kiter pro, BobL, is helping KiteLab determine best AWE practice. Ask KiteLab about your particular Kite Geology challenges ;^)
       
       
       
       
       
       
       
       

      Group: AirborneWindEnergy Message: 211 From: dave santos Date: 8/10/2009
      Subject: Cooperative AWE Business Model
      Its been uncertain how AWE will develop as a business. Monopolies based on secrecy & private intellectual property have notorious shortcomings. AWE has several well-funded initiatives employing patent trolling, insider connections, & stealth. These efforts take whatever they want from the public domain offering as little as possible in return. AWE could look a lot like Big Oil, the technology & resource owned by a dominant few. Transparency & open knowledge is philosophically desirable but individual creators despair of making even a modest living competing with "sharks".
       
      Fortunately friendly associations of small players banded together can succeed against powerful monopolistic forces. This is the Cooperative Model. A Cooperative License is proposed for AWE where knowledge is created & shared under a high profile "honor system".. Good behavior can be encouraged by praise, incentives, & so on. Abuse can be countered by bad repute, boycott, & other disincentives. 
       
      A small creator of useful AWE knowledge who shares it with the world might qualify for peer reviewed compensation. Such a program can begin as a statement of intent, a pledge, & materialize nicely as the AWE field blossoms. As a cooperative, members contribute according to the benefits of holding a cooperative license to key AWE knowledge. A big player's fair share is bigger on both ends.  A cooperative patent pool could protect & reward smallholders & bridge the biz model gap.
       
      There are natural partners for a cooperative AWE movement. Academic institutions top the list. Non-profits like the World Kite Museum & the Drachen Foundation are key open players. Xerces Blue is an Italian AWE non-profit that could step to the plate as a cooperative umbrella.. W.O.W./Kitegen is a cooperative oriented business. WindLift has a high public mission. These are natural allies.
       
      Good cooperatives are efficient & grow on meager capitalization. Successful cooperatives accumulate & leverage good will & resources & leverage to reach major goals. Joe Faust gets a trickle of ad revenue for his essential AWE website. SkyWindPower sells AWE T-shirts to raise funds. I've put 15 grand of my own cash into AWE research &, *sigh*, hope to get reimbursed if the ideas merit.
        
      The KiteLab "banner" is freely offered to localized cooperative AWE efforts. There are a handful of these locations already (like "KiteLab Austin"). But call your part of the cooperative anything you want. Cooperative corporations & individuals are all welcome. Share to fly.

      Group: AirborneWindEnergy Message: 212 From: dave santos Date: 8/16/2009
      Subject: Kite Vibes- AWE Flight Dynamics
      AWE physics is powered aviation "run backward" using well known aircraft flight dynamic modes to extract energy. Sweeping Figure-Eights is but vigorous Dutch Roll. Phugoid mode is the tug & furl pumping cycle idealized. Short Period Instability is the membrane wing-mill's bread & butter. Looping kites tap powerful Spiral/Spin Instabilities. These are minimal energy geometries, basic Lissajous patterns, the simplest harmonics of mixed pitch, roll, yaw, heave, surge, & sway. 
       
      Change one motion anywhere in the system & the effects propagate in odd ways to all the motions, exciting or dampening adjacent or remote oscillators. Kites are thus revealed as harmonic systems of linked cycles or oscillators dynamically similar to orbital-mechanics, electronics, & life science. Every part of a multi-body kite system is tunable, an essential exploration path.
       
      The aerospace aeroelasticity revolution is underway & might just as well be called the aeroinertial revolution, for it is the interaction of aerodynamic, elastic, & inertial forces that determine flight. Controlled Aerodynamic Instability has been identified by AWE watcher Cristiano Trein, et al [4], as a prime wind energy mechanism. For useful oscillations merely reverse Eddy's kite train formula of dancing diamond kites over stable Hargrave box kites.  Bondestam's passion for the dancing kite is paying off; the dance is self-organized control suitable for AWE [6].  
       
      Single-line kite dynamics long resisted adequate explication. Ito & Komura, after years of admirable focused study, admitted defeat [1]. After thirty years of trying Peter Lynn, the world's leading all-around kite designer, still struggles to wrap his mind around the subject. [2]. Van Veen hit on a fundamental insight, that kite flight is a quintessentially chaotic regime [3].  Windfields are chaotic, the kite itself is a fine source of chaos, & such combinations are called hyperchaos. Science maps deterministic structure in chaos. Gran-pa's Statistical Mechanics & Nonlinear Dynamics evolved into Dynamical Systems Theory illuminating  problems in many fields, including kite dynamics.  As formal numerical methods initially prove inadequate to predict exotic combinatoric dynamics, empirical & heuristic tinkering advances, as high art.
       
      Small perturbations couple or uncouple critical system oscillators in often unpredictable ways & the system crashes. On the other hand tiny well-timed & nicely calibrated tunings, "chaotic control", can greatly enhance AWE system stability.
       
      Close observation of kite dynamics reveals a banding effect or interference pattern in many tuned parameters. There are dimensions where you tune in stability, keep tuning & lose it, continue & find a new stability, & so on. A classic case is bridling up or down to improve stability in changing wind. Some kite fliers do one & some do the other as increasing wind detunes. Both succeed albeit at different elevation angles. A suggestion is to up-bridle a heavy kite & down-bridle a light one. As wind lightens a heavy kite will need downbridling. A wide unswept wing is particularly upsettable as large span sections experience sudden major flow separation.
       
      Secondary elements like kiteline & tail contribute their own complex motions. The effect of a dynamic tether acts like an added variable acceleration source. The sequential tensioning of  bridle & the roving CE/CP really makes things dynamic. Simple analysis is confounded. A thick kiteline or long tail usefully dampens higher frequency motion but a rare unlucky helical wind input can still drive the kite, dampeners & all, into a 1st mode spiral wave that hooks the kite into the ground. Events in transparent air are often mysterious & hard to troubleshoot.
       
      A kite's yaw frequency at a given windspeed is limited by its periphery mass & drag, as it flywheels against its pendulum stability. Keelless flat kites dampen yaw with long tails &/or a beard of fringe. Fighter kites use a rapid yaw rate to select a course & a tug on the line pulls a keel into shape & the kite tracks. Box kites & 3D kites generally have highly dampened yaw.
       
      In hand launching there is a moment when the short tether roughly matches yaw frequency, the two oscillators then interact as a double pendulum & chaotic gyrations ensue. Jerky motion spikes the line's frequency. Follow the kite fast & loose with your hand as you play more line out and the bad tuning suddenly goes away. This instability is commonly attributed to surface layer turbulence, but the kite is still in the surface layer, considered to extend to about 25m. The risk here is that a surface vortex will now couple with the line's (lowering) frequency & cause a first harmonic mode "death dive".
       
      Once clear of the surface a kite settles down into static or dynamic stability; either "pasted to the sky", or a happy dancing or waggling flight. A pasted kite is more prone to 1st mode harmonic coupling into a death hook. A dancing kite may loop intermittently, but generally dances out of a dive.
       
      Tails are a valuable tuning parameter. Despite the anti-tail prejudice common in "serious" kiting Marc Rickets developed a variable tail system & drogues are a major category of kite gear. A quiver of tails allows adaptation of a single kite to a wide wind range. Recent KiteLab experiments have shown the value of a bit of mass between tail & kite. As the kite leans this mass droops & curves the entire kite/tail combination into a prompt recovery. Another tail trick is to put an elastic section before the tail so that momentary slack never lets kite yaw get too far before correction.
        
      Key long-period non-mechanical AWE cycles are easily overlooked in the building of a state-machine. One must consider life cycles & maintenance cycles: diurnal, work-shift, weather pattern (frontal, seasonal) cycles; & so on. It helps to imagine the kite in super fast motion.
       
      A powerful method of taming a wild kite is to increase its "capture factor", to constrain it with added lines that dampen or prevent unwanted oscillation & state changes. Despite the potential added lines as new failure points overall reliability is enhanced One can even drive a persistently positive Lyapunov Exponent (instability) negative (stability). Cross-linked kites cancel out noise, rogue waves, single failures, & can even move in phased synchrony by simple tunings. The most powerful stabilizer is the ground surface, "free structure" excellent for staking apart unruly kite elements.
       
      Kitelines are a study in themselves. As a line is stretched its internal "speed of sound" increases. Many neat effects are possible. A set of thin high tension lines in parallel with the thick primary load lines might enable real-time control input to far higher altitudes than otherwise. The aeolian music one hears in kite lines are a good source of state information.
       
      Natural windfields are weird & complex. Turbulence, the famous nightmare of classic physics, has at least grown familiar. Each kite/wind situation is an animated fingerprint of mass-energy in space-time. Kite & wind interfere harmonically in "hypercomplexity". There are few quality data sets of specific windfields, so make your own. There is hardly understanding of what to do with such data. For kites to become reliable the knowledge gap must end.
       
      AT least one aspect of Awe harmonics is simple; desired power out. Driving a generator is nicely done with a triple phased mechanical input, as Loyd proposed [5]. Just as with electrical supply. single. double, or higher polyphase inputs of tensile kite energy will find specific uses.
       
       
      Kite Dynamics Vocabulary
      A crude partial list, but the flavor is evident-
       
      Aeroelastic, Aeroinertial
      Stability, Instability, Astable, Polystable, Unstable, Unistable, Bistable
      Harmonics- 1st mode, etc.; Complex Harmonics
      Chaos- Attractor; Hyperchaos
      Lissajous Pattern
      Phugoid & Short Period Instability Dutch Roll/Lazy Eight
      Oscillator- Dampened, Excited, Driven, Critically Dampened
      Frequency, Amplitude,
      Cycle, Limit Cycle, Stable Cycle
      Q-Factor
      Phase, 3-Phase (linear to rotary without dead band)
      Multivibrator (dynamics borrowed from electronics)
      Stocks & Flows (dynamics borrowed from economics)
      Pitch, Roll, Yaw, Heave, Surge, Sway
      Aeroelasticity- Aerodynamic, Elastic, & Inertial interaction
      Synchrony
      Lyapunov Instability
      Kolmorgorov Spectrum
      Dynamic Systems Theory, Nonlinear Dynamics, Statistical Mechanics
       
       
       
      REFERENCES
       
      [1] Kites: The Science and the Wonder, Ito and Komura
       
      [2] peterlynnhimself.com/Why_Kites_Dont_Fly.php
       
      [3] The Tao of Kite-Flying, Harm van Veen,
       
      [4] cristianotrein.comli.com/
       
      [5] Loyd's AWE patent shows three-phase string power
       
      [6] Martin Bondestam, the great Finnish kite visionary

      Group: AirborneWindEnergy Message: 213 From: christopher carlin Date: 8/19/2009
      Subject: Re: Kite Vibes- AWE Flight Dynamics
      Dear Dave,

      Nice discussion. I would suggest the winner in the whole thing will be
      the one who takes a KISS approach.

      Regards,

      Chris
      Group: AirborneWindEnergy Message: 214 From: Darin Selby Date: 8/20/2009
      Subject: Re: Kite Vibes- AWE Flight Dynamics
      That will depend upon what the last "S" in KISS stands for.


      To: AirborneWindEnergy@yahoogroups.com
      From: christopher.m.carlin@btinternet.com
      Date: Wed, 19 Aug 2009 17:41:59 +0100
      Subject: Re: [AirborneWindEnergy] Kite Vibes- AWE Flight Dynamics

       
      Dear Dave,

      Nice discussion. I would suggest the winner in the whole thing will be
      the one who takes a KISS approach.

      Regards,

      Chris




      With Windows Live, you can organize, edit, and share your photos. Click here.
      Group: AirborneWindEnergy Message: 215 From: dave santos Date: 8/20/2009
      Subject: Re: Tripod Tether COTS AWE Demo
      What is needed is more comparative evaluation of the most promising AWE schemes rather than one-off studies. DaveC's suggestion of group sponsored validation of the looper under a lifter tugging on a tri-tether is welcome, but it would be even better to micro-fund all the talented experimenters on this list. Some independent study of the AWE options could begin this fall by University of Texas Aerospace students, on a shoestring budget, as suggested last winter.
       
      Empirical study is great at the human scale, but nothing scales better than good speculative calculation in advance of upsizing. DaveL is probably the worlds leading tether dynamicist. His tethered physics program would be a great foundation to build on. Brooks'  brother (& dad) would be excellent researchers of kite harmonic physics, they are a vibration science dynasty. The dad, who taught me a lot back-in-the-day, worked on Space Shuttle vibration modeling & the son founded a business doing such analysis. (Yo Brooks, if they can start to just look at the AWE problems now there seems to be opportunity for all who get prepared.) Jeroen Breukels with the Delft group is also a gifted numerical AWE dynamicist. What a team all four might make.
       
      Many helped get to the better understanding of the AWE problem. It was Dave Culp who told me about the the looping kite idea in '07, which seemingly originates with Payne & McCutchen in '76. Loyd's '78 filing does not add much new, yet he did see that a tri-tether  from a crankshaft aloft can drive a crankshaft below by three phase sequential tugging. His solution had several shortcomings in detail- complex triple-crank shaft, twisting/chafing issues, etc..These are solved in the latest tripod/swivel geometry.
       
      Looping tethered foils were reviewed in "03 by Pete Lynn, but but he was skeptical of power transfer by simple mechanical means to a ground generator. Payne & MacC's scheme of directly driving a crank by a single line suffered from the washout factor Dave Lang mentioned. P & C also considered a kite flying crosswind along a long pulley loop, which had little washout.
       
      Peter Lynn & David Gomberg in the 90s revived the Victorian pilot kite (pioneered by Eddy (Blue Hill), Baden-Powell, & Cody) for stabilizing modern giant inflated theme kites.
       
      The latest scheme combines the best of various approaches & adds a spread 2D (triangular) footprint to operate in any wind direction by minimal means. The advance is intuitive & qualitative & does not require very deep analysis to see the power of it.

      __________________________________________________
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      Group: AirborneWindEnergy Message: 216 From: allisterfurey Date: 8/20/2009
      Subject: Nature AWE article
      Hi all,
      it doesn't seem to have been mentioned here that I remember but 'Nature' had a 3 page report on high altitude wind energy a couple of weeks ago.

      For those who have a subscription the article is here:
      http://www.nature.com/news/2009/090729/full/460564a.html

      I don't really want to put the article online as I don't want to risk the University's subscription (it's unbelievably expensive). But I'll send the pdf to people who are interested, just email me.

      Actually, considering it is one of the two premier journals, there's nothing new or particularly insightful in there. Makani feature prominantly as expected (their 30m carbon fibre wing weighs a tonne!), as do skywindpower, also Joby Energy?
      There is the typical failure to differentiate between ground level generation of power and generating the power at high altitude and wiring it down- so no real critical analysis of different ways of making the technology work. Still, it's good to see it featured in such a high impact publication, even if the tone of the article is not exactly super enthusastic- it ends with the story of a prototype snapping in two in flight!.....

      Well, there's a 28mph cross-shore breeze on. Time for a break from C coding I think!
      Group: AirborneWindEnergy Message: 217 From: Darin Selby Date: 8/20/2009
      Subject: Re: Nature AWE article
      Yes, please send me the .pdf article to: darin_selby@hotmail.com  Thanks!  ~Darin
       

      To: AirborneWindEnergy@yahoogroups.com
      From: adjf20@sussex.ac.uk
      Date: Thu, 20 Aug 2009 16:01:51 +0000
      Subject: [AirborneWindEnergy] Nature AWE article

       
      Hi all,
      it doesn't seem to have been mentioned here that I remember but 'Nature' had a 3 page report on high altitude wind energy a couple of weeks ago.

      For those who have a subscription the article is here:
      http://www.nature. com/news/ 2009/090729/ full/460564a. html

      I don't really want to put the article online as I don't want to risk the University's subscription (it's unbelievably expensive). But I'll send the pdf to people who are interested, just email me.

      Actually, considering it is one of the two premier journals, there's nothing new or particularly insightful in there. Makani feature prominantly as expected (their 30m carbon fibre wing weighs a tonne!), as do skywindpower, also Joby Energy?
      There is the typical failure to differentiate between ground level generation of power and generating the power at high altitude and wiring it down- so no real critical analysis of different ways of making the technology work. Still, it's good to see it featured in such a high impact publication, even if the tone of the article is not exactly super enthusastic- it ends with the story of a prototype snapping in two in flight!.....

      Well, there's a 28mph cross-shore breeze on. Time for a break from C coding I think!




      Get back to school stuff for them and cashback for you. Try BingT now.
      Group: AirborneWindEnergy Message: 218 From: spacecannon@san.rr.com Date: 8/20/2009
      Subject: Re: Nature AWE article
      please send a copy to me also.
      ---- Darin Selby <darin_selby@hotmail.com