Hi DaveS,

"Thanks JoeF, I now see that the torque-tube transmission was mainly adopted by PeterS to serve pendulum stabilization of the WECS, which was an unexpected to me, even though KiteLab did some early short driveshaft designs a decade ago (but moved on to even simpler concepts, by lower part-count and less mass-aloft)."

That’s right, pendulum stabilization of the WECS. In this case, that keeps the loop belt tether to the ground from getting twisted.

A future version might place the connection of the belt loop to the ground well behind the main rotor to provide better horizontal balance when hanging from its pilot kite. That connection point would be aft of the current connection to the pilot kite so as to act as a lever arm. The balance is tricky and requires experimenting. I can think of alternative designs to address that balance problem. I’m thinking of eliminating the torque tube and changing the design.

You claim to have moved on to simpler concepts, by lower part–count and less mass-aloft. Simplicity is very important. But the simplicity must be appropriately matched to the task. So please show me what you think is better and explain why you think so.

" It seems less troublesome fixed-spars would seemingly do the same function better. The gear-box could be at the turbine hub, with fixed stand-off stub spars above and/or below, to equivalently stabilize the WECS. Here we have both a torque-tube and a rope drive combined, as if both are critically needed to meet the low-complexity goal."

I can’t picture what you have in mind. Please draw a sketch so we can see what you mean. Gear boxes tend to be heavy, expensive, and problematic, which is why wind turbines are moving to eliminate them.

"Its not clear how PeterS proposes to base claims for greater simplicity, besides comparing to high-complexity AWES design Makani (the most complex AWES by far of any ever designed). We may have to count irreducible parts to judge comparative design complexity with similar rope-drive AWES like KiteLab and Kite Winder similarity cases, but even if that comparison was passed, it would still be dubious to claim maximal simplicity in AWES design, which requires a quasi-mathematical proof beyond current state-of-the-art."

Yes, as I clearly stated, I am comparing this HAWT Kite to the Makani Kite concept, which is indeed highly complex and quite expensive. The Makani kite is a good example of “high-tech, macho engineering”. I’m showing how basically the same thing can be done using a far simpler and cheaper low-tech design. Can my design be further simplified? I would hope so! Most concepts and devices can be improved with each iteration, and dozens of iterations may be required. It’s my first approximation -- which is intended to convey the basic concepts: combining ram air rotors with a loop belt tether, plus T-Rule pitch control. As far as I know, no one has ever done that before. If you believe that there is a simpler design for an energy kite that can produce more energy for the same cost, please show me. And be sure to include all of the components, including the ground station and any personnel required to operate the kite.

PeterS

Hi DaveS,

"  No, its reasonable, not "perjorative", to make small technical errors, and correct them promptly. Its been a long time since we considered AWES designs like yours, which resemble early KiteLab, etc, work, so our analytics are predictably rusty."

I'm amazed to hear that you considered ram air rotors driving a loop belt, and more amazed that you rejected the concept. Please show me your sketches.

“Recalling old research, the most questionable aspect of your latest paper-design is to put turbines on the rotor for fast load motion rather than just adding a bit more gear ratio to the primary rotor so it can direct-drive the rope-drive. This would both increase overall efficiency and reduce the "contraption" complexity of so multiple rotors and belt-loops.”

A gear box would be much heavier and far more expensive. And step-up gear ratios put more stress on the various components of the kite. You are utilizing high torque which requires stronger and heavier parts. My solution has less “contraption” complexity, especially since the design could be further simplified. Your solution creates a number of problems to solve that my solution inherently solves (some of which I mentioned in my previous Emails on this subject). So you are already off to a shaky start, so to speak. My guess is that your old analyses were incomplete and/or inaccurate. Please prove me wrong.

“Sorry it took a bit of futzing to recall previous AWES analysis for turbine-on-wing groundgen concepts like this one; so much has transpired in the decade since. You would still be welcomed to build an AWES like this one, to test the analysis provided.”

Please show me images of the concepts you are referring to that are like this one. My guess is that they will have only superficial similarities, like your last comparison of the Flip Kite and the Bird Windmill Kite – which are clearly dissimilar.

Thank you for your permission to build and test my own HAWT Kite invention. But perhaps you meant to imply that I would be wasting my time. Please show me images of what you believe would work better, and please explain why it would work better by comparing it with my HAWT Kite. And then I will do the same.

PeterS

Hi PierreB,

"   You mistake Makani's prototype that works with designs that likely should not work. Concerning loop belt the last design is a _likely less efficient_ variant of what Miles L. Loyd describes on a patent JoeF indicates. So loop belt is an old prior art. Makani and some other teams rightly preferred electrical transmission. Keep in mind that AWE tethers are very long, 1 km-range, and loop belt transmission can be very problematic if it is only possible. For other concerns the last designs have many other disadvantages: the swept area is limited with the length of the blades, while Loyd's design uses said "crosswind" flight in order to expand swept area, the plane being like "tip of blade". Moreover HAWT vs VAWT debate is an old debate. HAWT proved to be more efficient. All industrial wind turbines are HAWT. "

" So please instead of providing multiple details and arguing of loser designs, try to improve what is working. Makani's prototypes work, yours even does not exist.  "

The belief that HAWT are more efficient than VAWT is false. It’s one of a great many myths about VAWT, and perhaps the biggest one.

VAWT are inherently more efficient than HAWT. I’ll give you just one point to prove that. Make a VAWT that is extremely large in diameter so that its rotor aspect ratio (height divided by diameter) is extremely low. The wind passing through the upwind blades will have time to speed up again before meeting most of the downwind pass. The downwind pass will capture almost as much energy as the upwind pass. VAWT typically capture 80% of their energy from the upwind pass, and 20% from the downwind pass. So if the downwind pass captures almost as much energy as the upwind pass, the VAWT will capture close to 160% as much energy as a more conventionally proportioned VAWT. Conventionally proportioned VAWT have achieved a coefficient of performance of .45 way back during the 1970’s by using pitch control. 160% times 0.45 is a coefficient of performance of .72. The absolute limit for HAWT is the Betz limit, which is .593, and the best HAWT so far have reached about .50. (VAWT are not subject to the Betz limit, which was design for HAWT.) The difference between .50 and .72 is extremely large. (HAWT designers struggle hard for gains of .01.) So even if the downwind pass is somewhat less efficient than the upwind pass, it is still extremely unlikely that the VAWT’s coefficient of performance would drop below .593. There are additional reasons that VAWT are inherently more efficient than HAWT, but there is no need to go into them unless you would like to learn about them.

Loop belts are an old idea. Ram air rotors are an old idea. But combining them without using a conventional transmission, so as to save weight and complexity, is a new idea.

My HAWT Kite with ram air drive, as shown in my drawing, uses a fixed diameter for the large rotor. But the diameter could be made to expand a great deal. The pitch control will still work. And the shock cord belt loops to the ram air rotors could stretch another 50% to 75%. So the diameter of my HAWT kite could be enormous while still being extremely light. But my focus at present is on lowering the weight, cost, and complexity of HAWT Kites. I’ve figured out my second iteration of the HAWT Kite and I’ll post it when I’m done.

Thank you for telling me that belt loop tethers can be problematic. Please refer me to those studies. If there are problems, I would like to try to solve them.

If I understand you correctly, you are saying that because the Makani kite works, no one should try to improve upon it by using alternative techniques, but should restrict themselves to small, incremental improvements to the Makani kite. That is anti-innovation advice. In my opinion, and with all due respect for you personally,, I consider that to be terrible advice. The Makani kite is inherently a bad design because it is very complex and far more expensive than it needs to be. Your argument is similar to that of HAWT proponents: stick with a winner. But Dr. Dabiri’s research suggests that HAWT wind farms may be headed for obsolescence. In my opinion, the Makani kite is headed for obsolescence. So why back a loser? Don’t get me wrong: I think that the Makani kite is very impressive. But I think that they decided to try to overpower the problem with “high-techness” rather than trying to finesse the problem using simpler techniques.

PeterS

Hi DaveS,

"  Please understand that its hard to make up the large lingering gaps in your AWES domain knowledge by supplemental volunteer effort.You somehow have missed links periodically offered to old KiteLab and other prototypes, many now on the Wayback Net. Its not easy to catch up with so much AWE work. Your best bet is to diligently work thru JoeF's amazing online archives, where you are sure find the many early prototypes diligently documented, to compare them as fairly as possible with your work. They all resolved the pendulum-stability need, but only your design seems to require your specific pendulum stability solution, and without gaining optimal HAWT horizontal axis alignment. "

Just as I expected: You make critical claims based on previous research relevant to my HAWT Kite, but you are not able to supply the evidence to back up your claims. For evidence, I want to see images and analyses of them, not vague descriptions.

Citing the evidence to back up your own claims is your own responsibility, not mine. No evidence; no credibility.

Criticizing me for being ignorant is not a valid substitute for providing evidence for your claims.

I realize that you sincerely believe that you and KiteLab have already done everything that is worth doing. But I don’t share your confidence because I’ve seen serious inaccuracies.

My recent HAWT Kite design does use pendulum stability in its first iteration, and I’m not comfortable with that. So my second iteration will attempt to eliminate that particular kind of pendulum stability. And I think it should be able to keep the large rotor’s axis reasonably horizontal, while further simplifying.

PeterS

Hi DaveS,

“  https://www.youtube.com/watch?v=EgZ-eNpF9d0   “

Please note that their video does not make clear what they are doing. Their website does not translate into English; the translation button is not working. And some of the videos on their website do not play. I can’t find additional videos that clarify. So what they are actually doing is unclear. They seem to still be working through design iterations.

What does seem to be true is that their design requires a transmission on the kite and another transmission on the ground, plus a retraction mechanism with a motor, and that implies the use of a battery. If they are using direct drive on the ground, then their generator needs to be a large, low rpm model, which is quite expensive.

As the design scales up, the weight of the transmission aloft will become excessive. It will have to handle high torque like any conventional HAWT rotor. That would be workable for HAWT on the ground, but not for suspension from a pilot kite.

As the scale increases, the step up ratio will need to increase greatly or the cost of the generator will be very high.

My concept eliminates both of their transmissions or eliminates one transmission and greatly reduces the size of the generator, so my concept should be much lighter and cheaper.

My concept also eliminates their high torque which requires strong and heavy parts. That should result in a further weight and cost savings for my design.

They use a fixed-pitch rotor and blade twist. That makes their rotor more expensive than my main rotor, and heavier, as the size increases.

Whether their main rotor will be more efficient that mine depends upon the degree of wind turbulence. Modern large-scale HAWT are switching to pitch control.

The relatively low speed of their belt loop requires a relatively large pilot kite to keep the tether tight and to prevent the HAWT from pulling itself downward. My belt loop moves very rapidly, which reduces tension, so I can use a smaller pilot kite.

Because it moves relatively slowly, their belt loop puts most of the tension on the driving side of the belt loop. That requires a stronger and heavier belt loop. My belt loop, by moving much more rapidly, distributes the tension to both sides of the belt loop more evenly, which means the belt loop can be thinner and lighter and less expensive, and probably more durable too.

So while I like what they are doing, I don’t believe that their design is appropriate for commercial applications.

If you think that their design can compete with mine, I can’t agree. And please keep in mind that I have only done my first paper iteration. Yet I’m already way ahead of them conceptually.

So now let’s see your analysis of why their kite is superior to mine, if you have one. Or perhaps you are only making the weak argument that their kite is similar to mine because they both use a pilot kite, a HAWT rotor, and a loop belt. If that is all that you are claiming, then I would agree with you.

PeterS

Hi DaveS,

"  Expect the ample proof you want, of AWES concepts similar to yours, to progressively emerge in due time, rather than imagine you can enforce a quick deadline.

KiteMotor1, from 2007, for example, really is a closer comparison than Makani, but undue emotional impatience for the documentation does not count as a principled refutation.

Keep in mind you never noticed the AWE race, and it was us who contacted you first. We set no deadline for you to catch up on your research homework, nor should you set a deadline to become informed."

A search of the AWES site and the Internet finds no KiteMotor 1 from 2007, just references referencing each other.

You didn’t invite me to do anything; JoeF did. Goodness! So now you are trying to pull rank instead of supplying evidence. If you want to get rid of me for expecting you to back up your claims with evidence, as any responsible researcher should, then please do so.

I have no idea what you are talking about when you claim that I didn’t notice the AWE race, or why you think that matters even if it were true. Are you trying to guilt trip me out of asking for evidence?

I have no deadline in mind. When I see your evidence, I will decide whether it is credible. Until then I will assume that it is probably not because you are being evasive. No evidence; no credibility. That is the way science works.

PeterS

Hi DaveS,

"  Yes, if JoeF made first contact with you, it represents the same welcome from the AWE community. We work as a team finding and welcoming new folks like you.

As the new guy, you missed a large mass of AWES prototype work that we followed closely over the years. You are not asked to believe in hearsay information that such work exists in abundance, just asked to patiently review the work over time. We'll help you catch up. Similarly, if you are making claims for designs we have not seen fly yet, don't worry about undue credibility, focus on the work itself, to help us believe in it. It takes time to do it right, either way.

We look forward to seeing your prototypes fly with everyone else's, and hope your concepts stand in pending historic fly-off rounds and future energy markets. "

Thank you for supportive comments.

PeterS

Hi DaveS,

"  Its agreed that KiteWinder is not intending to scale up its concept. Like your similar-enough HAWT AWES, it will not scale greatly. It remains a suitable COTS baseline for you to try to beat in small-scale testing.  "

You made the claim that my HAWT would not scale previously, so I asked you for the limit expressed in kW. You neglected to answer,  yet you repeat your claim.

“Your challenge in AWE is not to insist your paper designs are superior a-priori, but to ready them for testing.”

When I claim superiority, that is my hypothesis to be tested. I’m discussing what seems to be its potential. The first step is to evaluate a series of iterations before trying to build anything. Most inventors make the mistake of building too soon before they have adequately analyzed the problem and the solution. Often, that locks them into a too early version in the series of iterations.

“ No one should rely on AWES claims that have no prototypes available for testing.”

That’s reasonable. So who is relying on what claims? Please note that you are making negative claims about my paper concept that have no prototypes available ford testing. So you are doing precisely what you insist no one should do. Why not do what seems more sensible: First help the concept to mature through iterations by offering helpful suggestions.

“  Please feel welcome to visit the World Kite Museum, to directly evaluate the AWES prototypes in their collection for similarities to your "birdmills", including fly-off privileges at the beach nearby.”

Why are you going off topic to discuss “birdmills”, whatever they are? I’ve seen the Museum’s website but they don’t seem to include any energy kites, so I don’t know why you are recommending them. If they have energy kite prototypes, they don’t say so. So if you believe they do, please show me the kites that are similar to my “birdmills”.

“ You could also acquire a KiteWinder to test against.”

KiteWinder provides no data in English, so there is nothing to compare. My finances would not enable me to buy one or travel to Washington just to fly one. When they supply power data, design data, durability projections, and costs, then I could use that to compare.

“ All wind tech claims are subject to third-party test-engineering validation. How vain to depend on convincing anyone otherwise.

No matter how many times I tell you I’m trying to get help to do testing, you criticize me for not testing. Besides, the subject at hand is my HAWT Kite concept. Apparently, immediately after seeing the first iteration are you already criticizing me for not testing it? Do you think that might be just a wee bit hasty?

“  Good luck building and flying your first AWES prototype, to duly prove your claims,  "

Thank you. It’s good to know you’ve got my back. Although, come to think of it, I have yet to see a single positive comment from you about my HAWT Kite concept, even though it contains new ideas.

PeterS

Hi PierreB,

" In wind energy the current winner is the 3-bladed ground-based tower we know. As I study AWES I do not stick with the winner. And also I support Gabor Dobos research on un-tethered AWES using wind gradient. This research is far to be the current winner. But in my opinion it can become a winner as a different source is harnessed and specific means are engaged.

In the other hand I cannot have knowledge about all components of AWES. So it would be possible to discuss about tether material, about generators, about kites, about VAWT vs HAWT, etc. But I prefer thinking about the whole."

Me too. You may recall that I wrote a paper a few years ago about twin tethered kites in the jet stream, and that paper also mentioned dynamic soaring in the jet streams.

“ The debate about VAWT vs HAWT is an old debate. VAWT and HAWT have been built for a long time. HAWT won.”

There is growing evidence that HAWT have not won – that they are only temporarily in the lead.

Actually, VAWT have not been built for a long time. Much less research has been done on VAWT than on HAWT. In the 1970’s, the Giromill cycloturbine VAWT equaled the efficiency of the best HAWT, but no further cycloturbine research was done in the US because the Department of energy decided to focus primarily on HAWT. There was not a technical justification for that choice. The choice seems to have been political because a lot of investment in HAWT had already taken place. So very little VAWT research was funded, and what little was funded usually went to research on eggbeater Darrieus rotors, which are inferior to cycloturbines.

“ As I am a lesser builder than persons and companies who invented and built wind turbines I am confident about the work they made. But you can try to prove VAWT is more efficient by building a prototype with reliable data or complete simulation, not only two or three parameters. “

Sorry, but I don’t know what you mean by “not only two or three parameters”. What are you referring to?

“ But why trying to prove it, trying to make AWES in the same time? “

You seem to be suggesting that I am doing too much at the same time. Is that correct? If so, the answer is that all WECS are related and all need to compete and be compared. As I mentioned above, like you, I am interested in all areas of WECS. My arthritis often prevents me from building things, so I use the time to invent new concepts.

“ Concerning drive-rope as DaveS mentions https://www.youtube.com/watch?v=h0IlGMW4E2o Kitewinder represents a loop belt transmission. But tests and studies about such a transmission should be made with different tether length and power values in order to conclude if it is more or less efficient than flygen and electrical cable, taking account of crosswind flight, keeping also in mind that lighting is required. Proving loop belt transmission is not an easy task. Proving both loop belt transmission and VAWT superiority is a huge task. Words claiming superiority are not enough. A proof of concept or a complete simulation is needed. “

I agree. Only long term testing can provide conclusive evidence. But there is no use testing something unless it looks like it’s going to be better than what exists. So if I think that something looks better, I say so, and I explain why I say that so that others can evaluate my opinion. I am willing to defend my ideas in open debate based on evidence. That is part of the normal scientific process.

“ In my opinion your thinking is a linear thinking about some component + some other component, while a more appropriate thinking should be about the problems to resolve and the means that are engaged."

I don’t regard my thinking as linear. Quite the opposite. I try to make intuitive leaps to new configurations that have the potential to work better than what exists. And I’ve done it dozens of times. That is systems thinking. I focus on linear thinking when comparing and contrasting details, where a step by step procedure is necessary. If you disagree, please show me what you consider to be my linear thinking by quoting me. My guess is that you may be generalizing from a single instance of an analysis where I am indeed using linear thinking because it was necessary to do so. Then please show me an example of your doing systems thinking. And finally, please explain the purpose of your comment. Are you attempting to teach me how to improve my thinking? If so, why?

PeterS