From Wayne:

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

Whelp yeah that is why I was gonna suggest that a simple crankshaft may be the way to translate your reciprocating motion to rotary motion. I mean a crankshaft is kind of the basic way to accomplish that.
However there are distinct reasons why wind turbine design traditionally does not benefit from upwind/downwind oscillating action.
It is because if your kite is traveling downwind at half the wind speed, your force is reduced to 1/4 and so is your power.
And no power is being made on the upwind stroke but it is instead being used, so now you are mathematically already at max 1/8th the power of blades traveling across the wind, best-case scenario, and that is being optimistic. This is the most basic aspect of wind energy.
But it requires many of times the same area per unit blade area. All-in-all the total mathematical derivation comes out that you use about 500 times the material for the same power if you insist on a drag-based upwind/downwind design. No exaggeration. 500 times. Imagine driving by a windfarm. You see a giant wall hundreds of feet high, reciprocating upwind and downwind. Imagine when you are told that this weighs a hundred times a regular wind turbine, and makes 1/16th the power for the same area.
Myboombox

Volcano ash collection.

Power generating from lofted HAWT.

Use power from the AWECS onboard ship.

Komai Arata

 

"if you insist on a drag-based upwind/downwind design",but it is very different with a lift-based design.
A reciprocating crosswind scheme (and other pathes) contains a partially upwind part and a partially downwind part,that with progressive intermediate positions.
Is it possible to know the specific power of a kite when the path is (for a used flight window of wind = 90° ,and an average angle of flight = 45° for example) 1) eight path,2) loop path,3) reciprocating or alternating straight crosswind path?

PierreB 

The myth that downflow power never pays is basic & apparently requires repetitive answering.   Many existence proofs prove drag devices can pay-

I don't entirely disagree with your thesis, Dave, but the logic behind the evidence you offer below is flawed.

Regarding spinnakers; first, a racing spi typically increases the effective sail area of a racing yacht to appx 250% of its normal, working sail area. Much less than "500x" but much more than "moderately."

Second, only hulls which are speed-constrained, such as fully displacement-borne hulls, ever sail directly downwind anymore. Any multihull, any planing hull and most ballasted hulls as well, *always* tack downwind in order to increase apparent wind, net power and ultimately, velocity made good, dead downwind--and their sails are cut more and more like Genoas and other upwind sails because of it--and of course because the apparent wind comes forward. Even when "making good" a net course dead downwind, most modern sail yachts have their apparent wind forward of dead abeam. Hot multihulls (cf recent America's Cup challengers) are almost always "hard on the wind," regardless of true course. Ditto for land yachts and iceboats. Velocity changes, angle of apparent wind does not (within relatively small tolerances).

Third, just to nail down the above; most racing classes have no limit on sail area when sailing off-wind (and many have no limits on any course--if you'll carry the requisite ballast or beam, you can put anything you like on them). Today's practical limits are control and cost, not rules.

Regarding an autogyro versus "drag bucket;" be it drogue or sea-anchor. The autogyro has a much higher capacity for generating thrust than any pure drag device--even if comparing total area to swept area. If comparing total area versus blade area, one quickly approches Doug's "500X" number.  500X may be hyperbole, but it's better than an order of magnitude accuracy, i.e., the number is very likely larger than 50; less than 5000. The fact that no-one has built an extremely high-lift autogyro to use in place of parachutes and drogues speaks to specific applications (like, folding it up into a small package which is self-deploying in your rocket), not aerodynamic capability.

The jellyfish analogy is cool, but I think you'd need to compare the jelly's locomotion with, say, the albacore tuna's, to make a valid comparison. The jelly subsists; at extremely low reynolds numbers, very low energy sources and minuscule muscle mass; the tuna is a lightning bolt by comparison. The difference in energy imparted to the sea, per sq unit of propulsive surface, is far higher than Doug's 500X

You rightly maintain the only potentially valid point, IMO--that the bigger (MUCH bigger) drag bucket may be cheaper to build, deploy, maintain and recycle (cradle-to-cradle ROI) than the higher-tech autogyro, but you offer no useful evidence to back your position in this post.  20+ year lives for fiberglass turbine blades is pretty tough to go up against. Mind you, neither does Doug offer compelling evidence disproving your thesis; we are back again to playing simple "my dick is bigger than yours" games.

There is a field for testing such assertions; it's called mathematics. Perhaps you guys have heard of it? Make some assumptions--drive a stake into the sand--and see where the numbers lead you. The sooner "researchers" in the field stop mistaking each other for rank fools, the sooner real advances *might* be made.

Dave

DaveC,   Thanks for the 250% number, which clearly shows how moderate a spinnaker's use of area (not counting lower apparent wind alowing lighter cloth) is to succeed as a sail, less than 1/4 an order of magnitude more than your reaching sail, compared to Doug's 2 1/2 orders of magnitude (500 to 1) estimate to compete. Its not the logic that was flawed but my mathematical sense v. yours of what is "moderate".   Racing yachts do win directly downwind at hull speed & also planing as "rig speed limited" in big wind. Pioneering AWE seems to favor "old fashioned" sailing styles before advancing. Of course we have no "class rule" on AWE area & the sky is big.   Note there is no historic data for fiberglass turbines like you mention winning as AWE, they are simply too heavy to be safe or fly well. Kite-like parachute-like structures do have a far more suitable history to project as workable AWE.   Our latest understanding of applied drag or drogue is to see it as partially self-cancelling lift. So a parachute's margin is a radial-lift ring-wing & its center zone a sort of high AoA tail acting like wing flaps. There is no non'linear break between high to low L/D AWE applications. A drag-bucket at low Re wins as surely as a hot wing does at high Re & both regimes are useful. The numbers do in fact support such assertions. But its hard for some folks to give up the old language of lift & drag.   Folks also forget to sum overall L/D of an AWE system. Lift hides in the pilot-lifter holding up a varidrogue loop. Light weight designs reduce lift requirement, which need only be enough to hold a drag system aloft.   KiteLab has tested a very broad L/D range of AWE devices & the major finding is they all work well when tuned to their Re regime. A lifter can hold up a hot wing or drogue, each with its own Re, & get similar net power out by similar capital-cost. The magic is working the cheapest raw material as hard as practical.

No it is not hype.
The derivation goes something like this:
Assume a reciprocating drag-based wind energy machine, whose working member (kite, sail, blade) is PUSHED downwind at 1/2 the windspeed.
1/2 the windspeed means 1/4 the force pushing downwind, translating to 1/4 the power of the same area covered by blade(s)traveling across the wind. Now let's be honest and realize that half of the blades are traveling upwind at any given moment.
So now you are down to 1/8th the power, for the same blade (sail, kite) area deployed. Half of the blades are not making power, all the time.
Then add in the undeniable fact that the returning upwind blades MUST use SOME power (traveling upwind at 1.5 times the windspeed)- now you are down to say 1/10th the power for the same intercepted area.

Note: the upwind blades encounter wind 3 times as fast as the "power-producing" downwind-traveling blades, so you have to do a LOT of sheielding or something or else your upwind blades on their return path will be producing 9 times the power of the downwind blades.

Now here comes the good part:
Rotor Solidity:
A rotor featuring lift-based blades that travel ACROSS the wind, at a high speed relative to the wind itself (perhaps 8 times the windspeed)
has a LOW SOLIDITY, meaning that these fast blades capture wind from a far larger area than any blade itself can cover standing still.
A modern rotor may feature say 3% solidity, meaning the circle has all available energy extracted by blades that cover only 3% of the area of the circle they sweep.
So multiply 1/10th by 1/33 and you are down to 1/330th of the power per unit blade area from a drag-based machine.

I tried to look up the original derivation (could not find it immediately) and I think it may have been from Dan Bartmann / Dan Fink of otherpower.com in the "facts for beginners who know nothing" section of one of their books.

I don't remember the exact derivation but change the solidity to 2%, which is still reasonable, and you are at 500-X. No lie, no exaggeration, no hype, just simple math. 500-X - it may describe how inefficient a machine is or it may describe how ignorant a nascent newbie wind energy designer is. (We all started that way.)

How can this be?
2 miracles:
1) The mircale of lift-base operation that nets many times the force of mere downwind thrust per unit area;
2) Crosswind operation at a high tip speed ratio that covers a large area using a small amount of blade.

I didn't invent any of this and I didn't derive the original numbers. I simply pass this known-in-the-art, established knowledge along: some basic facts of wind energy, learned over 3000 years, since someone said they wanted to have an adult discussion of wind energy.

Please, stop with the "Doug says" stuff. All I'm telling you is what anyone can look up in the beginning chapter of any number of books on wind energy. It is not me, it is reality. I am just relaying the well-established information. :)
Thank you.
Doug Selsam
http://www.USWINDLABS.com

The point about ground-based electrical generation equipment is well taken. On a related note, the CEO of NYPA (New York Power Authority) issued a directive on Dec 2/09 to increase wind power generation in the Empire State. There may be potential oportunity to install TEWP in some of the valleys in the Catskill Mountains and in the Adriondack Mountains.
 
 
Harry
 

 

---

To: airbornewindenergy@yahoogroups.com
From: santos137@yahoo.com
Date: Sat, 2 Jan 2010 22:00:51 -0800
Subject: [AWECS] KiteNote: Airborne Wind Turbine Tri-tether to Groundgen Crankshaft

 

True, if a suitable foil can travel fast enough it can match or far exceed a 1/500 area ratio of a low-speed wing for the same work.   In real world AWE there are strict limits on what is workable. For example, Alister pointed out the calculations of line drag limit a parafoil or LEI wing to an L/D of little more than 10. A solid cantilevered high-speed wing is far heavier in construction & will have severe disc scale limitations & safety-critical issues. High speed turbine hubs & drive shafts are heavy too. Another turbine limitation we eventually face is mach limits.   A funny aside is that low speed wings of only moderately greater area & far lower weight fill in the power curve below what a "super turbine" can do. The world's ultimate backyard turbine may need wide membrane multiblades & do micropower in the poorest wind & quite resemble AWE able to "float" thru lulls.   It will be interesting to see what Doug eventually learns from the AWE experts. If power extraction by wing area were the key factor he might be in the lead in tapping upper winds. If maximum power extraction by minimal weight aloft is key then KiteLab seems to lead.

 

Douglas,
 
 
It would interested to see your technology installed on well-spaced towers in a valley where uni-directional winds blow. The entrances to most valleys usually imposes a boundary layer effect on winds, literally steering the wind into the valley where the channel effect acts to keep the valley wind essentially uni-directional.
 
There would be potential cost advantages to having more turbines being carried by fewer towers and driving into a single electrical generator. How does 15-turbines on a single  driveshaft being carried by 3-towers sound to you? 
 
 
The one drawback to small high-RPM turbines is the bird strike problem. The mega-blade turbines that rotate at 10-RPM are believed to be less harmfull to birds. How about several (8) big beasts on a single, massive and hollow driveshaft being carried by 3-towers in a valley. Such a beast may also be suspended by cables strung across suitable valleys where uni-directional winds blow.
 
 
 
Harry 
 

---

To: AirborneWindEnergy@yahoogroups.com
From: doug@selsam.com
Date: Sun, 3 Jan 2010 15:33:16 +0000
Subject: [AWECS] ~500 times the blade area for the same power

 

Sorry about those address attributions. Your faithful moderator is working on a lashup system after a crash.

Bob Stuart

Hi Joe:
Happy New Year to you too and great to hear from you!
This was me skiing yesterday:
http://www.youtube.com/watch?v=-ayyfLj-WKs

You illustrate why this topic is too complicated for mere soundbytes, slogans, or bumperstickers.
As you hint in pointing out the well-known fact (at least for those who pay attention) that power is proportional to windpeed cubed, not squared, the real case may be even worse than the kind treatment (500-X)I presented.
I was trying to quote what someone else worked out.
I think it's something to do with the drag-based blades just being pushed slowly by wind, and mostly not producing anywhere near the potential power, with most of the wind going around rather than thru the intercepted area (inefficient design), implying no cubic power factor is taken advantage of anyway - not sure, or I forgot the reason.

Regardless of the rationale, I was being kind, and the reality is probably even worse - this is just what is easy to show mathematically without having to add a few more proofs for the persistent reality-deniers in the crowd.
The actual push force is proportional to velocity of each wind particle squared, but as you point out, when we include the speed again as regards the volumetric flow rate of said particles, you get into a cubed situation.
More subtleties, but can the audience comprehend such fine subtleties when they are so far away from understanding even the rough ideas? Yes maybe it is 1000 times less power per unit blade area for drag-based designs, rather than the conservative 500 times less power I quoted.
Doug

---- Joe Faust <joefaust333@gmail.com

Hi Reinhart,
 
           Beautiful Project, Thanks for sharing with us all, welcome aboard!
 
                                                                                  Dan'l
 

---

To: AirborneWindEnergy@yahoogroups.com
From: rein-art@hotmail.com
Date: Sun, 3 Jan 2010 19:52:03 +0100
Subject: Re: [AWECS] ~500 times the blade area for the same power

 

Hi Dave S.
Well it appears that I cannot post any facts on this list without you arguing back something or other. I'm sorry to bring the dim reality of known facts from wind energy to cloud the fantasies of those who think kites pulling lines upwward is an easy answer.
I did see you speak at the conference where you waved the kite trailing from a stick back and forth thru the air. I have to admit, at that point, I felt as though I had walked into an insane asylum.
After listening to the unfocused stammering of some of the attendees in general, then seeing you waving that kite back and forth like you were making an impactful statement, I had a vision that I was in a nuthouse and you were one of the inmates waving a butterfly net back and forth, trying to make a point about something or other. Sorry, but I just had to share that brief feeling I had. That is the reality I felt as I sat, listening to the nonsense while I watched my prototype outside bobbing motionless in the rain, with no wind, waiting for the FAA at the airport directly next door to come and drag me away in chains for being over 50 feet in the air, since nobody had cleared having a demo up next to the airport. I DO wish I had had the chance to hear the talks by Skywindpower and McConney. I think both of those entities, or at least the concepts thay are chasing, may have a fighting chance.
Like I say, talk seems cheap (unless you consider the expense of wasting one's entire life on empty talk) but I am waiting to see a working model in daily use that makes any power whatsoever.
Come on guys, it can't be that hard!
OK we KNOW it is physically possible, so the only question now is who is going to deploy a working system and when?
OK now you can go back to waving the butterfly net.
:)
Doug S.

Hi Harry:
I am glad you share the vision!
yes that is what I am working on. Just finished shooting footage with a Discovery Chanel content provider of a turbine with 19 rotors. The next step is to add a third tower in the center.
Single-rotor turbines are like single-cylinder engines - they work, but more cylinders are better.
Doug S.
Maboomba?

 

Modeling global AWE-seed planting:

Avoid using any other keystroke when placing the single-digit password to open the product. 

 

For printing the note by DS with password of exactly just one digit 7   A global AWE seed

 

 

On Mon, Jan 4, 2010 at 2:03 PM, dave santos <santos137@yahoo.com
C'mon, Dave! You're a micro-balloon designer; you KNOW about mass
limits. 1000' of sewing thread is going to weigh many times what the
miniature kite does; it's drag will be ~ 2 orders of magnitude higher
than the little kite's. You'll have 900' of thread on the ground and
the kite perhaps 50' up, down at the end. There are many kitefliers
out there with extensive knowledge of miniature kites; please ask one
of them for advice before promulgating this kind of stuff.

Dave

Greetings Douglas,
 
 
One advantage about uni-directional (even bi-directional) winds in valleys, it allows for some flexibility in the design of the towers that will carry a driveshaft with multiple rotors. Towers (for omni-directional winds) and electrical generation gear involve high expense. The freedom to revise the design of the tower would allow the "hubs" to be placed at much higher elevation (120m above ground or higher) where the turbines would capture wind blowing at 25% to 50% greater velocity than turbines on towers of 80m.
 
 
There would be scope to install both tower-mounted turbines and cable-suspended turbines at different elevations between mountains . . . the 2-concepts may compliment each other.
 
 
Airborne turbines may be attached to the tops of the mountains for 3-concepts of wind power to co-exist  and operate in the same geographic location.
 
 
Harry
 

---

To: AirborneWindEnergy@yahoogroups.com
From: doug@selsam.com
Date: Mon, 4 Jan 2010 16:34:40 +0000
Subject: Re: [AWECS] ~500 times the blade area for the same power

 

My gut is telling me to request discussion over the SkySails emphatic use of the word "propulsion" which might be great ... or not. They are saying they have for ships a "wind-propulsion system." Perhaps I can change, if some of our group blesses such. For me, I see traction with towing kites pulling the ships along as a wind-for-traction system. I might need reeducation; thanks for a moment on this. What say you?

Hey Dave S:
I asked before if you could please stop the "Doug-this" and "Doug-that".
What you are engaging in is called "shoot the messenger".
I am only relating known facts that anyone can look up regarding drag machines, how inefficient they are, and why. You can choose to verify or invalidate what I am saying, or ignore it.
Try taking me out of the equation and just stick to discussing the facts presented, please.

We in the wind energy community, which let's face it, this group hopes to leapfrog and "show them how it can be improved", spend inordinate amounts of time explaining away the endless procession of drag-based machines that every newbie to wind energy is naturally drawn to. Look at my first machine I drew back in the 1970's (recently patented as "laddermill"). It was a series of kites on a looping path, downwind, then upwind. I had thought I was a teenage genius until I started reading actual literature on wind turbine design, realized I was just another idiot with one more redundant drag machine, except I had taken the ill-fated concept into the sky, and so I quickly adjusted the design to spin (Superturbine(R)) rather than loop. It pays to pay attention to the work that has come before you.

Yes I have to say, on the one hand I have to applaud any effort to think outside the box, and organize any meeting of the minds, and I hate to rain on anyone's parade, but rather please let me try and refocus these active minds. I must have been invited to that conference for a reason. Is the reason so everything I say can be ignored? All I'm trying to do is save you work.

Here's what I noticed at that conference. Looking out the window, past my bobbing, handmade, prototype turbine that weighs 30 pounds and produces possibly 3 kilowatts at 50 feet height in a strong wind, I saw something that it seemed nobody else noticed:
A wind turbine.
Yes off in the distance was a white 3-bladed wind turbine, on a monopole tower, powering someone's home or farm.
During that conference, I would guess that this working turbine, in a light wind, produced more power than all the projects being discussed at the conference had cumulatively produced in total throughout their entire combined R & D lifetimes. So of course nobody wanted to notice it. On this basis, it was a potential bubble-burster, best ignored by most, it seemed.
I wondered:
What brand is it?
What power rating?
What diameter?
How is the wind resource here?
How much energy is it making (kWh per day)?
Is it stall-controlled or pitch controlled?
Or does it furl out of the wind for overspeed protection?
Is the furling passive or does it involve active yaw control in response to onboard instrumentation (like recent Chinese turbines)?
Does it use an induction generator feeding the grid directly, running at a constant RPM,
or a permanent-magnet generator feeding the grid through an inverter, implying variable speed operation?

I sought several times to engage people in the room in conversation about this wind turbine operating in the distance.
I had no luck.
It seemed nobody was interested in the turbine in the distance.
It seemed that basically, nobody had even noticed it.
And probably nobody there had anything to say about it anyway, with basically no knowledge of wind energy to work with.

That was when I knew i was not in the presence of anyone with any intimate familiarity with generating electricity from the wind.
There is no way real wind energy people could sit there all day in view of a working wind turbine and not notice it or discuss it.

Please realize that this same basic machine DID feature kites as sails 1000 years ago, when it was used extensively for grinding grain worldwide. When people saw that adding a blade frame shaped like an airfoil netted better performance, allowing the blades to travel much faster and last much longer before becoming tattered, the kite/sails slowly morphed into today's blades.

Now unless you think Leonardo DaVinci's helical parasol helicopter is suddenly going to start replacing all the Hueys and Sikorsky's out there, you might realize that cloth sails and kites are old technology when it comes to modern aerodynamics. A set of fast blades does the same job better, for less total weight, spinning faster, which means you can use a generator of a resonable size or less gearing. That is the simple fact that most of the world has taken hundreds of years to work out.

So all I can ask is once again, please stop with the "Doug-this" and "Doug-that". It is not ME you have to convince, and it is not me stopping you from making any power. It is you who is stopping yourself from making any power. It is tempting to try to substitute Doug-bashing and kite-waving for making any power, but that is not a solution to your problem of no working machine.

No, I am just the one bringing a few facts to the table. I think Joe F. just brought another, when he pointed out how many foot pounds, traveling how fast, your kite lines would have to reel in and out to match the power of a typical 8-foot tower-mounted turbine that weighs perhaps 40 lbs and lasts many years (1 kW).

Stop shooting the messenger and come up with one thing that works besides re-iterating indoors that you enjoy flying kites, or have felt a large amount of pull on the line. Yes there is something there - and it may be more subtle than you realize. Yes kites started aviation, and they morphed into wings, to survive high speeds and constant wear. Connected at a central point, the wings become a propeller or rotor. Yes many have tried cloth-sail (kite) rotors. They take up too much area of the circle (excessive rotor solidity impairs performance), can't travel fast enough to extract energy efficiently, don't hold an airfoil shape well, and quickly fail due to fabric wear. This is 1000-year-old knowledge from wind energy. But don't just take "Doug's" word for it - try picking up a book or two on the subject.

I'm not saying there is anything wrong with kites. That is a mischaracterization, or an attempt to change the subject. I own kites, I fly kites, and i have always loved kites! I have made many many kites as a youth. I was the kite guy in my neighborhood. We even sold the kites we made to others. My patents include kites to help elevate Superturbines(R) in fact, so you are preaching to the choir that kites are good. And I believe kites are great for replacing sails on ships, radio antennas, ariel photography, and a thousand other uses. But you seem to be relying on this group to validate or invalidate the various approaches to wind power through discussion of them, and so I am discussing the specifics, complete with the math, as are others, and it in fact appears that any reality is simply not wanted.

I think I just gotta move on - we in wind energy have found that there is no end to trying to talk would-be inventors out of their drag-based and reciprocating turbine designs, and it seems that the introduction to facts is similarly resisted when we talk of bringing wind energy up into the air.

I say lets stay focused on what will generate useful amounts of electric power at a reasonable cost (lower cost than the status quo).

OK gotta run
"Doug"

Or equivalent measures...
Shall we have up what is being achieved by SkySails
per square measure as they use a kite to replace fuel to move the ships? DaveC, have you run such figures on OutLeader?

DaveC,   The range of power suggested within the 5lb limit is fully consistent with crosswind power of a parafoil in a moderate breeze. My powerful Pansch 12m parafoil is in the 5lb range & a bigger NPW of similar weight also easily develops a few raw kw. What about all our basic wattage calculations of windspeed x area? A thousand watts per sq meter (ideally at but a few oz per sq. m of wing) of swept or stationed area is well toward the low range. Try this- calculate the unit weight to power of KiteShip's OL & you should get a figure far above your 100w per 5lbs, even with its low L/D. Please let the list know what number you get.   I easily flew small kites to altitude exactly as Martin Bondestam describes. A good kite can lift several times its own weight in line. This is easily testable. Another existence proof is how Afghan kites of tissue & bamboo routinely run out thousands of feet of thin cotton line to fight. To show how minimal means can go so high is not irresponsible, but helps level the field for small AWE competitors, a badly needed service.   There is irony for me to advocate & you deny the amazing power of membrane-based lower L/D kites when you are the one who best taught me this lesson. This easily testable reality should badly worry the high-tech composite wing gamblers. A series of open fly-offs can quickly settle what KiteLab has already shown in-house. Makani has rejected an actual fly-off of its ideas v. KiteLab. Selsam might also want to avoid a tug-of-war debacle against lower L/D AWE. A hybrid mix of high & low L/D is the actual AWE system sweet spot.   daveS   PS What Bondestam was demonstrating by launching at sunset is how a night-time inversion develops from the surface as radiative cooling sets in, but the wind continues above & even accelerates as an LLJ, as squeezed from below. Wayne's on the same page.

The subject at hand was kite-based electricity generation, not "raw" power of kites. As you may know, I'm not a strong advocate of using kites to generate electricity; my 30-year career in kiting is virtually all regarding pulling waterborne structures--applying the momentum of wind directly to momentum of the vessel, without converting it to electrical, mechanical, magnetic or any other form of energy in between. This is easily the most efficient use of wind power ever envisioned for any man-made application (and yes, the highest measured thrust/blade area has been for autogyro turbines. And also, yes, thin membrane structures to date have shown higher ROI, in that application) . Which is perhaps why it was instituted into commercial trade so long ago (~6000 years), and continues to be commercially viable today. *

Dave Santos, in addition to getting my name consistently wrong  ;-)  jumps from one to the other ("raw" power to delivered electricity) in order to support his position as the argument trends; Selsam has one thing right, it is not possible to effectively debate a true zealot.

Dave, measure your delivered power. How many watts of delivered electricity per sq meter of kite surface can you achieve, in what wind and at what capacity factor? It can be micro-watts/sq cm or gigawatts/hectare, but put a stake in the sand and defend it.

Default Dave

* A quote from a designer I admire: 

“Sailing involves no thermodynamic cycle and generates little heat.  Sailboats react mechanically to the forces of the wind without any train of energy-losing conversions in the path of action. 

“As a consequence, the theoretical efficiency of transferring the momentum of a moving column of air to the momentum of a boat can be as high as the best windmills, even before windmills perform useful work: close to 60%. 

“Sailing has the highest potential of any means for exploiting the cheap, renewable, clean power of the wind.”
                        —Bernard Smith

Looking at Selsam's late 1970's notarized drawing

and the 1997  Wubbo Ockles   system at some point called Laddermill, but not so termed in his patent,

what would be a tight descriptive term or term-phrase for the Selsam device?     If Doug Selsam is first with a ladder-looking mill worker, then a generic term of ladderMill might be something that would be generic to coin two decades later; generic terms are sometimes capitalized and used to point to someone's product or project.   In current text "Laddermill" points to Ockels use of the term.  But Doug's ladder-like mill seems to have some standing.    Doug, what did you call your device, if anything?    Your notarized note has the title: Auto-oriented Wind Harnessing Buoyand Aerial Tramway  ; did you have any pet nicknames? Did you earlier have a shorter generic term or phrase?  Doug, you have written that you were the inventor of what you see in Ockels "Laddermill"   ... so far, I tend to agree.           Windmills that look like ladders.... laddermill seems generic to me.   But Ockels is welcome to name a project whatever he wishes. But the 1997 patent was claiming full and complete novelty, which does not mean the claim in true.

For me, so far, I think Doug Selsam fully scouped the two decades-nearly later patent by Ockles in such a strong manner that the Ockels patent might be declared invalid, if contested. What say you?

We have two items, at least,  with which to work: 

Selsam's dated and notarized drawings:
1977  On September 20, 1979, Doug Selsam notarized his kite-lifted endless chain of airfoils HAWP system, generic type that would later show in astronaut Wubbo Ockels device called LadderMill described in a patent of 1997. Doug Selsam conceived his Auto-oriented Wind Harnessing Buoyand Aerial Tramway on April 3, 1977.  notes and   drawings.^[28]

US Patent 6072245 Wind-driven driving apparatus employing kites by astronaut Wubbo Johannes Ockels, filed Nov 12, 1997.

Generic term?  And validity of claim by Ockels?

 

Thanks for assitance on this.       Note: Obviously Selsam's 1979 scheme is very different from Selsam's torque-chain of rotors in his serpent device....two separate animals.

 

 

Dave Culp,
Some of that hit on names in on me; sorry. I got used to the following legend:
DaveL :: Dave Lang
DaveC :: Default Dave :: Dave Culp
DaveS :: ds :: DS :: Dave Santos :: COOIP :: Cooperative IP

Still aiming to stay on recent topic, the KiteShip and SkySails and OceanKite and other traction kite systems are with low heat loss during the conversion of wind into the mechanical tugging tension pulling. Some minor tether and wing-body heat is lost; some minor heat in the drawing of the hulls through the water, etc. In the end we approach the Betz limit of conversion; getting from point A to point B by kite tug is as you know from your long experience, and as you bring forward well, is a top winning wind-using scheme sector. And you note that, aside from return on investment (ROI), that fine-tuned autorotating blades would seem to have a high spot in efficency.

Couple of furtherings:
1. Still it would be fun to see what horsepower figures per kite area that SkySails comes up with. One approach is to calulate backwards from regular fuel costing and its lossy horsepower to get the point A to point B in time constraints ...compared with the kite experience.

2. There is a center-of-rotating blade region with low gains compared to the tip region for the rotating-blade kites. How would a refined kiteplane wing in crosswinding compare with a kited autorating circular blade?

3. Then, what would it take to get the winning wing to perhaps have a higher ROI than the parafoil or OutLeader for long-term commercial use, if such a gain over the fabric wings can occur?

4. Finally, there will be some energy cost when wind power is used to do make electricity, regardless of method. But the method of kite tugging hydroturbines has installations, mostly in the small. Minesto http://www.minesto.com/ is not a tugging mode; they "fly" turbines in a paravane. But a kite-tugged hull, perhaps also trailing various auto-gyrating hydroturbines may obtain an efficiency that could bring high ROI. During such operations we could still travel from point A to point B, albeit a bit slower, as we would be carving off some of the energy into electricity. Arrive with charged batteries at point B.

JoeF :: JpF

DaveC,   By "watts" i mean pure physical work, John Borsheim taught me net electrical generation claims are far too fuzzy to trust. AWE is not just electricity, so we should not presume so (as maybe you did).   Bernard Smith is great, but we all make mistakes, his "sailing involves no thermodynamic cycle" quote is misleading. Of course aerothermal physics applies to sails, where do you think much of the lost 40%efficiencycy goes? AoA creates a lot of convective friction heat & pressure heat that radiates infrared. Such questions are like when i informed you lasers do in fact focus, its easy to be wrong.   Physics is zealously debated & zealous debaters usefully debate each other. Zeal is a good thing in AWE & lets hope you are still zealous & continue to debate open questions.   So how many gross watts does 5lbs of OL extract @ ~25 knts?   daveS

Attachments :

skysails techno.pdf

Some SkySails PDF

These are marketing documents; professional courtesy allows me to say no more. Skysails have published neither raw data nor scientific studies. Nor has KiteShip.  ;-)

Dave

Errata note.
Fuller accuracy for the record of dates show here:

1977 April 3, 1977 invention declared. On September 21, 1979, Doug Selsam notarized his kite-lifted endless chain of airfoils HAWP system, generic type that would later show in astronaut Wubbo Ockels' device called LadderMill described in a patent of 1997. Doug Selsam conceived his Auto-oriented Wind Harnessing Buoyant Aerial Tramway on April 3, 1977. On the notarized disclosure of invention was place a date of Sept. 20, while the notary placed the final signing on Sept. 21, 1979.notes and drawings.[28]

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

I realize this is very approximate but based on sailboats both large and small operating downwind, which admittedly are drag devices in your terminology, I think you get about .1 HP/Sq. Ft. at about 20 kts of relative wind. 

Great for support of this thread, Pierre.
Your lead brings more of same from SkySails:
Five documents are linked off
http://www.skysails.info/english/information-center/press-lounge/documents/information-skysails/
or in case that breaks, here is a TinyURL for same:
http://tinyurl.com/docsSkySailsLIFT

Wind propulsion sounds good to me. Particularly if you pursue a hybrid approach where energy storage and or diesel is used in an integrated way to take care of situations where wind isn't viable.

On Tue, Jan 5, 2010 at 1:35 PM, dave santos <santos137@yahoo.com Were you talking to me? Please use my correct name. Hi, I'm Dave. Just Dave.

This is an interesting re-take on recent events. There were no
non-electrical generation papers, presenters nor guests at the recent
Chico conference (I was a fully-paid spectator, not a guest). Despite
my (and other's) credentials in the field, none were invited to
speak--there was zero wind transport content at the conference. There
has similarly been (approaching an asymptote at) zero content on this
list regarding transport applications of kites. This is all right with
me, but please stop playing this game of "everybody's welcome here;"
this is and has always been about generating electricity, not about
wind-powered transport. Mind you, I'd appreciate it if you keep it
that way; kite boating has quite enough online outlets, with real
experts, thanks. You can get a taste on my website if you
like--kiteship.com
I'll leave the knife slipping ever so softly between ad-hominem ribs
in your oh-so-kind remarks and just relate that I think I'll stick by
one of the country's top physicists as opposed to your opinions on
this one, Dave. Perhaps look up "thermodynamic cycle?" Of course any
mechanical system dissipates heat--one in equilibrium dissipates *all*
the energy involved, eventually as heat. Further, the Betz limit
involves no "lost efficiency;" it simply relates the maximal
efficiency possible in an open system (unconstrained airflow). Close
the system and we can talk about "lost efficiency." In the meantime,
the Betz limit *is* "100% efficiency." By definition. Thermodynamics
is actually a science, folks, it's not a collection of opinion pieces
on the internet. I get a pain I cannot locate when I hear people
talking about "beating Betz." Simpler to just embrace perpetual motion
and be done with it.

JoeF says:

That's my point, Joe. There is no "conversion." That would involve,
for instance, thermodynamic cycles. There is no "conversion" in
sailing; the momentum of the wind is imparted directly to the momentum
of the hull; the entire formula involves only momentum--mass and
velocity. There's no gearing, there's no conversion of wind's momentum
to mechanical motion (blades) -to rotary motion (shaft)-to electricity
(generator)-back to rotation-back to mechanical motion-back to the
water's momentum (for instance). Further, there are no transmission
losses--your ultimate consumer is tied to the other end of the kite
string (or attached to the bottom of the mast in a conventional
sailboat). Yes of course there are inefficiencies; the point is they
are small--smaller than any other scheme for gathering and applying
wind power. That's why I said in my earlier post that sailing has "the
best" efficiency; I did not say "perfect" efficiency, and neither did
Smith.

It just pains me to hear concepts adding "improvements" like
generators and batteries to sailing vessels. Why would I take a system
with near perfect efficiency and use it to drive a hopelessly
inefficient and expensive auxiliary system? Have any of you run the
numbers on just how many batteries it would take to equal the 110,000
hp of a single big container ship?

Dave