On Fri, 2012-06-29 at 16:36 +0000, Joe Faust wrote:
The laws of nature prohibit such a membrane ever being made, unless you
supply energy. Solid electrolytes can pump ions and effectively do what
you want, but the cost and mass is far too high, not to mention other
problems.

Robert.

On Fri, 2012-06-29 at 15:27 -0700, dave santos wrote:
Your reference to Roderick's post made me suspect that you were thinking
of putting the generator outside the tube (a groundgen maybe). The
Altaeros tube is filled with helium and my understanding is that they
use this buoyancy to keep the tube almost horizontal. The drag caused by
the huge lighter than air (LTA) structure will far exceed the drag from
the turbine. Maybe they angle their tube to try to gain extra lift, but
the thing can only support a small turbine anyway, so I cannot see it
making much difference to the it.

Both LTA and pure flygen are concepts I have completely discarded as
impractical. Practical inflated wing kites will be for groundgens and be
filled with air. My concept is like the basic Altaeros shape but far
slimmer. If there is a turbine inside it will be tiny - sufficient only
to power airborne control systems. The advantage of the inflated toroid
is that a wing with a large area can be made without relying on dozens
of tethers.

The gas inside will be air so I see nothing sad about what Joe's stick
represents.


Sure, but ultimately we will need much more aerodynamic kites.

Robert.

Dave,Robert,Doug and all,

Have you an idea about Betz efficiency between a good conventional rotor (roughly 75% of Betz limit,L/D more than 30 at tips) and a rotor like this Inflatable Wind Turbines Pass Laugh Test - Forbes , and also a ram-air rotor (expected L/D about 10 at tips) ?

PierreB

This sounds much more like a municipality governance response.

It's a very interesting idea. Amazing someone finally noticed: if you have a better rotor, try using it on a wind turbine - hello! Just as an airplane might start with a car chassis driving down a road, add wings and a propeller and it takes off, AWE can start where wind energy is already at - a tower, producing (gasp) electricity!
I think the field of developing a better rotor is wide open.

Comparison to known configurations:
Normally, such a downwind turbine would have only two (2) blades on a teetering hub, already a "standard" "alternative" design known to save the cost of a blade and eliminate the cost of pitching hub mechanism and control system.

Here's the downside:
The cost of the blades is a small fraction of a wind energy installation. Starting with the land, permits, taxes, building roads, clearing land, leveling pads, pouring foundations, running underground cables, building a substation, installing transformers, inverters, power conditioning equipment, trucking in rebar, pouring conrete, torquing hundreds of bolts, welding tower sections, bringing in cranes, crews, steel-rolling machines for the tower sections, ladders and climbing safety equipment inside, the nacelle, a huge gearbox running in reverse, on and on and on and on - finally realizing that the blades may be a mere 2% of the cost, and you may be giving up 50% of your income stream if they only produce 50% of the power of a regular rotor, and wear out in a year or two instead of 20 years, the numbers likely don't pencil out.
But I like the idea in general. Seems like a potential AWE component.

Other downsides:
Wannabe newbie wind energy inventors coming in from the vast open intellectual tundra and hinterlands usually start with the same mis-characterization of "the problem". In their minds, "the problem" is how to make energy. In reality, "the problem" is how to dump energy - how do you shut the darn thing off, or tone it down, when your nice, productive, 30 mph wind slowly starts to transition up into the 40's and 50's mph region, at which point your rotor is making say 10 times the power. Not anticipating what "the problem" even is, you watch as your invention receives a dose of reality from mother nature, and your nice new project is blown to smithereens, or your generator is quickly cooked, since you never included overspeed protection or a way to shut it down.

Cloth blades: Well that topic has been discussed a lot here. Back in the 1970's there were quite a few attempts, but so far it's been shown that its better to pack all that cloth into a mold of a proper blade and squirt in some resin to yield a long-lasting, high L/D, 160 mph appliance good for say 20 years of service.

Judged on standard wind energy criteria, the rotor will be compared on the basis of its total diameter. That means the donut, not producing power, counts against the numbers. And that donut is taking up the space where the blade tips should be. The blade tips and where most of the power comes from, so the design starts out by eliminating the part of the rotor that normally produces the majority of the power - hmmm... hope that donut really works well to channel moe power into the rotor, but the rotor is already visibly less efficient than a regular one that is optimized.

Skin friction: that donut is going to spin at 160 mph? at what cost? Ok maybe 120 mph? How much drag is that with all that skin area? Will it hold together against centrifugal forces?

High solidity rotor: less efficient, and slower, losing more energy to wake vorticity, requiring more gearing or a larger generator.

I'd say, in many ways, this design goes back a few hundred years in efficiency to the middle ages.
:)
Doug S.

It has been shown that every extra blade reduces efficiency and the
Winflex uses 6. The large ring will also probably decrease efficiency so
I doubt it exceeds 50% of Betz.

However, efficiency and the Betz limit really do not deserve the
attention they get in wind energy. The wind is free. What matters is the
cost of the machine that harvests it. The inflated ring allows a rotor
with lower mass and this might just produce enough cost savings to
justify itself - but I doubt it.

Before I heard of this scheme I actually considered using an inflated
ring to support blades. One of the problems that might be difficult to
solve is blade flutter. It will also be difficult to make blades with
good aerodynamics. Using 2 tensioned wires to form a blade will not give
you the optimum angle over the whole blade length.

Allowing the ring to double up for protection in strong winds is a
clever idea but it may not be enough. Protection from storms is
difficult. So on balance I do not think Winflex have something that will
survive in the market even if it can win prizes. Who judges these
competitions?

Robert.

 

Harry,
Good ideas. The 3 disk autorotating Sept2500 design type at flyinground.com has disks 1 & 3 linked in the same direction of rotation. The #2 middle disk contra-rotates from 1 & 3 solving lead-lag issues found in single rotor designs. The rotor/disk size differences balance inertial masses & help with the many circulation turbulence issues when using multiple disks.
My question is, does anyone have an opinion whether for simplicity sake have 1 & 3 directly linked like Harry's 'Fly-gen', or will stability & control be maintained through a 2 or 3 way electromagnetic differential, or will complexity be a product of scale?
Regards, db murray

Yes, downstream turbulence is most always a problem in systems like these. For economy/durability & control/recovery reasons I was looking for as compact a multi-rotor configuration as possible. Lowering the angle of attack closer to the line of true wind seemed the right solution to avoid some of the adjacent rotor turbulence & improve on equipment survivability.
I agreed with Doug Selsam when he said in a recent post, "In reality, "the problem" is how to dump energy - how do you shut the darn thing off, or tone it down, when your nice, productive, 30 mph wind slowly starts to transition up into the 40's and 50's mph region, at which point your rotor is making say 10 times the power."
For a kite, if the wind is becoming too strong, only two simple choices exist. Haul it down, or cut the string & hope for a soft landing. If the airborne wind energy conversion system was a large tension net array it is foreseeable that a complete haul down may not possible before some structural failure takes place. If the remaining airborne kite array could be made to free-fly out of harms way, cutting apparent wind speed by moving with the flow, or break into individual flying parts & autonomously land to wait to fly another day, average system life-cycle costs would be sure to drop faster as the technology improves.

For a more informative read about some of the control/stability issues needing consideration for this design type, here is a link to an autogryro stability paper by Jean Fourcade - Longitudinal Stability of Gyroplanes
http://www.asra.org.au/L_Stability.htm

Regards, db murray

-

Hydroelectric storage is also very open to high charging rates.  Since the real need now is not a grid supplement, but peak demand power, I recommend using the wind directly coupled to a water pump to charge a dam or tank, and standard hydro power generators.  The overall cycle is still quite efficient.  The job of hauling water to the upper reservoir could use a long, linear input, well suited to the ability of a kite tether.  In light air, smaller loads would be raised, and in high wind, a higher operating speed would reduce loading on the power stroke.  

Not sure of the merits of Edward Warner's device, but in 1935 he expressed very strong confidence that his kite-involved complex could take anything nature could through at it:  (click for his full instruction; Rod, you came to mind as I started examining Warner's proposal): 

Linking AWE with Hydro is a good route to early markets. Bob's contribution below adds to the options.
JohnO

---

 

Thanks Joe,
I guess if enough of us are plugging away at a concept space, then eventually we will evolve similar designs by merging known workable parameters and modes.

I'm very encouraged by the recent postings of works by DB Murray and Alexander Bolonkin.

hopefully I'll get a look at the specs of knitted bag extruders today.
http://htmachinery.en.made-in-china.com/product/peTxXUdYYvWa/China-Six-Shuttle-Circular-Loom-SBY-800X6-GII-.html

and find out more about Inflated sausage packaging devices.

It's holidays however.

I don't mean dumping power electrically - yes that can save your batteries from overcharging in an off-grid system, and it is called a dump-load. I'm talking about not melting your generator, which means not melting you generator. So don't melt your generator by suddenly producing ten times it rated continuous power.

Hello all,
I understand what Doug is saying, and I was talking about ways to save your airborne rig, but I want to add to Bob Stuart's idea of banking wind energy in hydroelectric potential energy.
If you live in an area without hydroelectric infrastructure, and lacked fresh water, you could convert your energy into making another type of commodity. Pumping salt water through a desalination plant may add more value in a hybrid system than electrical power alone.
db murray

The wind is free. Generators are not. Long experience in the wind
industry has proven that the best generator economics dictates that
turbines need to start letting wind energy pass once speeds get to
around 10m/s. Storm winds often exceed 50m/s. That is 125 times as much
power. With AWE we can extend the range of useful wind speeds by using
kites of widely different sizes. When storms blow by the only economical
solution will be to dock the kites back on the ground.

Robert.

Earlier June: 

Topic thread dedicated to S. F. Cody matters

You guys need to differentate between the old problems of overspeed protection, the old problem of the intermittency of wind and how to (wishfully) (lead-acid batteries for a cottage?) store wind power to address that, and the temptation to add more generators in lieu of no overspeed protection. Yes some turbines have two generators - one for low winds, one for high winds. Others load a single generator differently. They still need overspeed protection. No amount of generators will get you out of winds that double and triple rated speed.

These are all (very) old topics in wind energy.
In the case of pumped hydro storage, where it exists, it is just as well-employed storing cheap night-time grid power for daytime use. As I have pointed out, a truly cheap way to store electricity might make wind energy irrelevant rather than facilitating it.

None of these topics addresses how to get wind power out of the sky, except maybe pulling a weight uphill using a kite, which sounds intriguing but reminds me of 3000-year-old technology.

All these discussion do is hammer home the point once again that the people wanting to discuss airborne wind energy are not really up to speed on the topic of regular wind energy - discussing the contents of a glass box (known and well-worn topics) as though it is a black box (new and unknown territory).
The black box is AWE, remember?

Rod,
I see a huge altitude range for this kite type plus the control issues, so you are correct in what you are proposing.
Here are links for 2 devices that seem to suit the inherent simplicity of an inflated torus design. New Varieties of Thermoacoustic Engines - http://www.lanl.gov/thermoacoustics/Pubs/ICSV9.pdf a paper by Scott Backhaus & Greg Swift, & Air Muscles by the Shadow Robot Company - http://www.shadowrobot.com/airmuscles/overview.shtml
Food for thought,
db murray

Robert what the heck is someone who knows anything about wind energy doing on this group? Get back over to the regular wind energy group! Nobody here wants to know anything about wind energy. Knowledge of the art is not appreciated like you would think - it squelches 99% of everything people wanna talk about. It's bad enough that one of us is over here.
=:O
Doug S.
(that is my name here)

On Wed, 2012-07-04 at 18:50 +0000, harry valentine wrote:
If they allowed any movement they would catch more wind which could
break them and that would be sadder.

A groundgen based system could also be made to retract easily.


They are usually either lying, or have not tested their equipment in
severe conditions.


Ice formation can give turbines trouble. It will probably also be a
problem for kites. Pity, because as you say, it is a high value market
that could help give AWE a boost.

Robert.

Dave North & company had told us they planned on "crashing kites for a couple of years". Just saw an article on their characterization of the problem, and their approach. Interesting that they see as an advantage over private companies, not having to develop a product that actually works for anyone. Hey that doesn't stop private companies either!
http://phys.org/news/2012-07-electricity-air.html

Dave,
Firstly, your sketchbooks are very impressive.

What you describe below may also work on Rod's ring kites. It seems predictably strong, lightweight things are the basis for many of the game changing ideas.

Flying Plaza looks great! I found 2 links that are somewhat related to Rod's work and Tomas Saraceno's Flying Plaza. The 1st is about early NASA project history - http://history.nasa.gov/SP-4308/ch9.htm , and the 2nd is MATSYS - http://matsysdesign.com/2009/page/2/ , Andrew Kudless' amazing site. Unlike the early NASA protocol for photographic documentation, there is dancing in Andrew's work. The color photos help too.
db murray

NASA: National Aeronautics and Space Administration

A technical manager for the Apollo project that brought the man on the moon tells his story within NASA and IBM.

"NASA never built a rocket, NASA never built a spacecraft, NASA never built a computer, they found it, managed it, but the industry built it. I believe that industry deserve credits then anyone does…."

We were all in it together: The Apollo Program
http://www.youtube.com/watch?v=7QC5cT7QpdM

I like the part where they copy Makani in noting (making a big deal of the well-known fact that) the blade tips make the most power of any part of the blade, so then their kite is suddenly supposed to represent the blade tip, or the part of the blade making the most power.

Sure it's true that the tips sweep the most area, and certainly make the most power, especially per unit weight, since the tips are narrow and thin, do not support the rest of the blade, and sweep the most area.

I just don't quite see how they extrapolate that their kite represents a blade tip, as opposed to any other part of the blade. I mean, I'm not quite catching the connection between identifying the blade tip as the part that produces the most power, with how the kites, whether carrying propellers, or pulling a string such as NASA is doing, is then equal to this blade tip.

I mean it's one thing to wish your kite was equivalent to a blade tip, but where's the evidence?

Given that the thrust force of the kite is pulling on a small capstan, I'd say it's acting a lot like a blade root. Slow travel, requiring lots of gearing. You have a fast kite and then find a way to translate that fast speed into slow speed. That's back to where a regular big blade was in the first place - slow rotation needing a gearbox - you still need to add a gearbox, so how is it that you can claim to be acting like a high-speeed blade tip, when you have thrown away the speed and gone back to slow rotation, high torque? And you have introduced more complexity and a cycle that adds more intermittency, and uses power during a portion of its operation, throwing away steady-state power while adding more expensive and complex systems. And unless the kite is traveling at 120-160 mph constantly, it's going slower than a blade tip anyway.

I guess it doesn't sound so sexy to say "our kite acts like the portion of a blade about 2/3's of the way out from the root" - no bumper-sticker there...

It seems to me that every new team purporting to change the face of wind energy (let's see how many thousand have come and gone at this point?...) wants to fixate on some simple, already-well-known-to-those-in-the-know aspect of wind energy, such as the well-known fact that most of the energy comes from the tips, as "evidence" that they have "cracked the code".

The unsaid part is the implication that the industry as it exists is populated by stone-age drones who never noticed that the blade tips make the most power, and that it is only the fresh insight of a highly-educated superior mentality, newly applied to a previously dumb industry, that has revealed some simple new insight that was previously overlooked, as though they are saying:
"Hey all you wind energy "experts" - guess what? Your power is coming from your blade tips and we are going to eliminate all the other useless stuff - you guys are kind of stupid not to have noticed what we see!".

I have not heard one of them say: "3000 years of wind energy experience eliminated the ideas of reciprocating cycles in the first thousand years, as the Chinese were the last to persist in the pursuit of using downwind thrust for power and reciprocating-cycle turbines over 2000 years ago."

Now that might show a little more awareness of where they fit in to the actual advancement of the art, as it actually exists.

Or how about:
Wind turbines get most of the power from the tips so our rotors have no airfoil at the root.
(That's how I make my blades lately - why bother with the root? The root of my blades exists only to support the tips and contributes almost no rotation power) I think wide blade roots are usually a big waste of material that makes turbines too expensive - a fixation on "efficiency" as relates to the swept area, not the cost of the machine. (beat that circle to death!)

What about:
"Wind turbines lose a lot of power at the actual end of the blade, due to tip losses. Our kites suffer from a doubling of these tip losses since our kites have two (2) tips, doubling the most inefficient part of the blade."

Or how 'bout:
"Wind turbines get the most power from the part of the blade near the tip, but our kites don't go quite that fast so our kite is more like being about halfway out on a regular wind turbine blade."

Nah, none of that stuff fits on a bumper-sticker, which is where science is at nowadays. If it doesn't fit on a bumper-sticker, it won't fit in most peoples' brains... Especially "scientists'" brains!

he he he - shoot, I need to get back to making windmills!
Beep -= ahhh Roger that - we have a liftoff! ...beep...
crackle crackle ...one... giant....step... crackle fuzz fuzz

Attend - SXSW Eco.In Austin,for KiteLab!

 

PierreB

A lifted looping ladder: 

The two-loop lifted loop of drag wings

Issued on Feb. 7, 2012: 

The project here reported reminds me to the Wubbo Ockel's laddermill concept that has been abandoned.

The Italian carousel concept is quite different, it is based on exploiting the cross wind motion: two transverses and two dead phases, like the endotermic engine with two opposite pistons, but in three dimension.

The graphs here could help

http://kitegen.com/tecnologia-2/kite-gen-carousel/
http://fuoripista.webs.com/dalletorrieolicheagliaquiloni.pdf

However, that version has been momentarily put aside, due to the high development cost. Now the yo-yo 3MW version is being developped and built. Also in that case there are two transverses, but not the dead phases, instead there is the retraction phase.

For more information ask the kitegen.com staff

Work crews sometimes have several people standing around a hole, while one person actually is digging, which we think is funny. The bureaucratic solution of course is to add more people standing around watching, right?

I know in my own case there's only one thing stopping me from building all sorts of flying wind turbines: time.
Any of these proposed devices has to be built, and then tested to see if it even acts as planned, as a start. High-throughput experimentation suggests building at a smaller scale to work the bugs out of any concept.

Most of what is proposed here is buildable. There's really nothing stopping at least a trial development of any of these concepts except a lack of determination and probably enough free time to sit there speccing out every component and building working prototypes.

Design
Build
Test

It's one thing to draw an idea on 2-dimensional paper, where the machine acts exactly the way your pen travels across the paper. In real life there is no pen to tell the machine how to act, it will act the way it acts. That's the rub.

Personally I don't think an assembly of a committee of kite luminaries will necessarily result in any success for AWE. Find out how many actual breakthroughs came out of the GE Ecomagination Challenge, for example, or the Masdar Challenge. I'd say proably zero useful ideas will emerge from both. Find a success story from ARPA-E. What is it? They had an assembly of experts! They all applied their minds to the problem! Where's the result? Quick before your beachside home is underwater! noooo Mr. Bill!

Committees. Bureaucracy. Stagnation involving lots of hype and wasted effort that leads nowhere. Most breakthroughs that big involve some determined individual. Too big of a break from the past to be developed by the incremental adjustment process of a committee.

Someone just has to understand what they are doing and be able to ignore the combined ignorance of any group of people, no matter how accomplished in their own right the members of that group might be.

If someone is going to make a breakthrough, then they will do it, and it will probably fly in the face of what any committee would approve.

Not tryin' to throw water on the idea or anything, but I'm just sayin'...