Author Topic: Dual Rotor (Read 3363 times)

Shadow · « **on:** February 23, 2006, 05:19:51 PM »

I thought this was interesting, had to do with RE,and was a new wind turbine design. But it got skidded off main page immediatly so I'll post it here.http://www.dualrotor.com/

whatsnext · « **Reply #1 on:** February 23, 2006, 10:39:01 AM »

I've always kind of liked his stuff and if you go to his main site he has designs for rotors with seven or eight props. These would be pretty easy to make for yourself, noncommertially of course, just to see how they work out.

John...

willib · « **Reply #2 on:** February 23, 2006, 10:51:52 AM »

I agree it is great idea , his motto is more rotors = more power..

http://www.fieldlines.com/comments/2005/11/19/17944/463/12#12

wdyasq · « **Reply #3 on:** February 23, 2006, 11:28:35 AM »

The 'inventer' posted here and could never answer a few simple questions posed by the more knowledgable folks here. He may have a good product. The website posted showed what looks like a car alternator with a fat shaft. The welding looks a bit clumsy - and that may be a complement.

To give shady charactors ANY promotion in RE will do the same good GM did for diesel engines in the mid-70's. He may have something. I think he does. Except I think what he has is a bag of it in each hand.

Ron

kitno455 · « **Reply #4 on:** February 23, 2006, 11:31:54 AM »

somebody posts this thing every couple months. then somebody points out that you can add 1 foot to each of the blades, and increase the number of poles in the gen by a bit, and achieve the same effect, with only one prop, plus the larger blades will work better in lower winds.

allan

whatsnext · « **Reply #5 on:** February 23, 2006, 11:43:25 AM »

Ron, I'm curious to know what problems you have with these designs. I admit his welding looks pretty bad but I'm not sure why that would be a knock on his ideas. He has built some pretty lage scale machines and if you get past his hype you can see a lot of good reasons why he's doing what he's doing. My only problem is that he keeps refering to this as a seven foot machine when it's really TWO seven foot machines turning one alt.

John..

whatsnext · « **Reply #6 on:** February 23, 2006, 11:57:30 AM »

And everytime I read that statement I think "who cares?". If you are making blades on a production line it's not that hard to make a few more. The thing I like about this design is that, when using a four prop version, you get almost the same swept area with half as much blade weight. This type of machine seems like it would run very smoothly because it would be easy to balance and keeping runout to a minimum would also be a piece of cake. So, while we may not like the messenger, there is no point of walking in lockstep just because it's easy.

John...

jimjjnn · « **Reply #7 on:** February 23, 2006, 12:07:38 PM »

I don't like his prices, tho you could duplicate it for a lot less.

kitno455 · « **Reply #8 on:** February 23, 2006, 12:42:05 PM »

ok- i'll agree with the comment that this makes it easier to use off-the-shelf blades.

i just dont see the value in the repeated claim of 'most power from a 7 foot prop' as if there is something evil about a 7.5 foot prop. lets see, more bearings, more speed, more points of failure, more chewed up air after each successive prop, never turns fully into low winds, etc.

its not about lockstep, its about KISS.

allan

wdyasq · « **Reply #9 on:** February 23, 2006, 12:56:39 PM »

http://www.fieldlines.com/story/2004/4/5/184919/7784

This covers the START of deceptive and misleading advertising. I hate to see folks waste hard earned money on unproven designs.

I don't know - maybe everyone on this site but me has won the lottery and money and honesty is not a consideration. But for me, I like to know if something works - or if it is waste of time.

Not one on here has a VAWT of any size I know of working. I can't see folks trying to build such machines when Sandia labs with MY MONEY and yours failed to overcome the problems.

I can't seem to understand why some folks want to build composite blades. Proper composite bldes will take engineering, a lot of time, molds and layup techiniques beyond the abilities of the average amature builder. Hell - these folks bitch about the cost of epoxy resin over polyester. I doubt many understand the structure of materials but they get mad when someone says, 'be careful, it could be dangerous'.

WE WILL ALL BE EFFECTED WHEN THESE GOOFS CAUSE LAWS TO BE PAST THAT REGULATE HOMEBUILT WIND MACHINES.

Well, I've gone a bit off track here but I HATE deceptive sales practices and lying salesmen - or sales women or sales persons. I hope this product is good and he solves the worlds power problems and gets filthy rich.

BUT- I hope none of us are holding our breath until it happens.

Ron

kitno455 · « **Reply #10 on:** February 23, 2006, 01:09:08 PM »

yeap- thats the thread i was talking about. notice he only stuck around thru about half of it

allan

ghurd · « **Reply #11 on:** February 23, 2006, 01:21:26 PM »

Why not make the shaft 50 times as long, with 4 blades the same diameter?

Maybe 1000 times longer shaft and 80 blade sets?

Either should beat 16/27 total overall effiency, given the swept area of one blade, or using the same (measured relative to wind) area.

G-

whatsnext · « **Reply #12 on:** February 23, 2006, 01:34:13 PM »

Allan, I agree, "i just dont see the value in the repeated claim of 'most power from a 7 foot prop' as if there is something evil about a 7.5 foot prop." . The claim that this is a 7' machine is moronic. For that reason alone I don't like this guy because, as an engineer myself, I find his claims insulting. That said I see some real possibilties in this design so I don't want to throw the baby out with the bathwater. Doug is trying to create a commertial enterprise which is not what most of us here are trying to do so falling back to KISS is a non issue. Other that the number of blades, which really isn't a complication, this is really no more complicated than the Dan/Scoraig(sp) mill that many of us seem to like.

John.....

windstuffnow · « **Reply #13 on:** February 23, 2006, 01:51:27 PM »

I'd bet you could build one big one ( 3-4 kw ) for 1/2 the price of one of his 7ft'ers... pretty pricey. It seems like to me, with a reasonably new product you'd want to try to sell them a bit cheaper than your well known competition. You actually get quite a bit of hardware for a similar price when you purchase a Bergey or Whisper as well as a business backing that has been around for awhile.

.

craig110 · « **Reply #14 on:** February 23, 2006, 02:12:20 PM »

Sure, you can build one cheaper than buying one commercially, but that is true in many areas of life and yet for most things we buy commercial items. How many people have hand-built their own house just because they could do it cheaper? (I admit risking getting many "I did!" answers from the people here since this board's audience is, somewhat by nature, made up of people who like to build their own things but this isn't representative of the population at large.) For most things, people are willing to pay a premium to get a finished product. If that guy can sell his windmills at the price he is asking, more power to him (no pun intended) as that is free enterprise.

Craig

kitno455 · « **Reply #15 on:** February 23, 2006, 02:17:41 PM »

falling back to KISS is even MORE of an issue for a commercial enterprise. i dont mind replacing the extra bearings in something crazy that i build, i dont want to have to warranty such a thing

allan

whatsnext · « **Reply #16 on:** February 23, 2006, 02:34:33 PM »

Exactly.

windstuffnow · « **Reply #17 on:** February 23, 2006, 04:09:48 PM »

Hi Craig,

I never said I had a problem with him selling them, I simply pointed out that either making a better one ( more powerful - less cost ) or purchasing one that has a good track record plus all the control components that go with it for the same or less cost. Personally I find his turbine quite interesting, I don't necessarily subscribe to the idea but that's only one mans opinion. I think if you believe in an idea strongly enough then you should take it to the limit... what ever it takes!

.

willib · « **Reply #18 on:** February 23, 2006, 04:16:07 PM »

~~~Comeon feel the noise ~~~

oops wrong KISS.

kinto i have to dissagree i think you couldent get more simple than selsem's idea..

and with the idea out there , no one says it cant be coppied for personal use.

i think using my new hub ( front ) from a front wheel drive car , is a perfect match , it allready has the hole for the main driveshaft

vawtman · « **Reply #19 on:** February 23, 2006, 05:15:20 PM »

I didnt see or missed where the customer testimonials where if any.Also I wouldnt want to be a bearing in that alternator.Im wondering if it was mounted in a swirly wind area if it would act like a vawt and they dont work.Kidding but wouldnt the blades overcome the tail?

kitno455 · « **Reply #20 on:** February 23, 2006, 05:28:37 PM »

i really hate that band

of course you can get more simple. add 1 foot to the blades, and lose all the extra parts. less bearings, less hub, less long shaft, fewer fasteners to loosen, etc. seems simple enough.

allan

wiredwrong · « **Reply #21 on:** February 23, 2006, 05:30:33 PM »

thats Quite Riot isn't it?

Drives · « **Reply #22 on:** February 23, 2006, 05:51:57 PM »

Go to this link, subscribe, and read the past few years. You will find out all you want to know about Doug.

http://groups.yahoo.com/group/awea-wind-home/

wdyasq · « **Reply #23 on:** February 23, 2006, 06:42:42 PM »

Gee Dean,

You don't want them so sick they can't post here anymore......

Ron

whatsnext · « **Reply #24 on:** February 23, 2006, 09:07:59 PM »

Once again I'd have to disagree with you. It isn't just adding a foot to the blades. To double the swept area of a normal prop you would need to increase the blade length by a factor of 1.4, not just add a foot. To compete with a four prop version you would need to double you blade length. There are no more bearings in this design, just two, exactly the same number as the Dans machines. There are potentialy clear advantages to a machine like this most importantly being lighter overall blade weight for the same swept area in low winds. Plus, the rotating weight is far closer to the hub. A machine like this would seem easier to acheive good dynamic balance also. Plus, you only cut a long shaft once, how is a shorter shaft any less complicated? And, it seems to me, loose fasteners can be blamed on poor balance and design as much as failure to tighten them. I'm not going to argue that the progessive furling of a machine like this is superior to a more normal Dan type unit because I have not built and tested both designs I just think it's an avenue worth exploring instead of just writing it off without good reason or because you don't like the guy who thought of it before you did.

John...

paradigmdesign · « **Reply #25 on:** February 24, 2006, 11:29:44 AM »

I couldn't dissagree with his idea more. This guy is a disgrace to wind technology. Being that all of the power has to go through the shaft of a turbine, it is smart to keep it as short as possible, not make it as long as possible.

Have any of you guys seen the renderings of his "meggawatt" designs? They would require like 20 billion dollars in carbon composite (which you can't get anymore), instead of just building bigger blades, like all the other companies with real enginers are doing. The only thing that this thought callas has done is get higher rpm's from a rated power, which helps keep the diameter of the PMG's a little smaller.

This has to be by far, the most unsafe, least economical, wind turbine design I have ever seen. We have all just wasted some time talking about it.

paradigmdesign · « **Reply #26 on:** February 24, 2006, 02:50:07 PM »

So you think it is a "good" idea to stick your blades on as long of a shaft as possible? Granted it is not as simple as "adding a foot to the blades", but it is a hell of alot simpler than adding more props to a shaft. I am using a 2" diameter 12" long hardend solid steel shaft for my 5k genny, and I am still not that comfortable with it. Longer shaft = less safe.

Not to mention the fact he started out with 7 blades on a shaft. Why would he go from 7 blades on a shaft to 2? Is it because it is economicially retarted to have a shaft that is 10 times longer than your blades? Or is because the carbon composite racing dirve shafts(well all carbon composite) that he used to use are extremly hard to find now.

I am niaeve about many things in the wind turbine industry, but there are so many things wrong with this design, it actually makes me angry.

oztules · « **Reply #27 on:** February 24, 2006, 03:53:50 PM »

you need to get out more.

There are plenty of standard windgenerators in pieces on the ground from time to time

There are better ones, there are worse ones, there are ones that don't even work at all.

All have their place in the scheme of things. Something can be learned from all of them. It is sad to see such vitriol spewed forth on an alternative..... or is it the person you object to rather than a different design.

I suppose you reserve your most squalid thoughts for people like the wright brothers. Fancy putting the elevators on the front, damn them for wing-warping instead of using elevators, boo hiss they used a propellor not a jet engine. where does it stop.

Any idea deserves critique, most ideas have something laudable within their scheme. What does no compliment to the critic, is damning a design, because of the designer him/herself.

Just because Danb makes one doesn't make it the worlds best (i,m sure he has as many skeletons on the drawing room floor as the rest of us), just because I make one doesn't make it the worlds worst.

We still play with VAWT, we still fiddle with plastic blades... they all have their place in the world.

In this thread I've witnessed the very worst of scientific evaluation where nothing short of hate mail would describe some peoples "objective "critical analysis of the design.

It would do us all some sobering good to stick to the true arguments with respect to this design, not the credentials of the designer.

disappointed............oztules

whatsnext · « **Reply #28 on:** February 24, 2006, 06:43:03 PM »

And I'm guessing, based on your moniker, you have a design or engineering degree from a real university someplace so that all your critisisms have some valid technical points instead of you just shouting out questions? His design does not use a shaft that is "as long as possible" it's just long enough to allow the rear blades to get clean air in low wind conditions. You say "I am niaeve about many things in the wind turbine industry, but there are so many things wrong with this design, it actually makes me angry". How can you be both naive yet all knowing at the same time? And does everything that you disagree with cause anger? Many of us here see this design as very simple and can seperate the design from the designer. The fact that you can not tells us all something very important about your critique.

John

paradigmdesign · « **Reply #29 on:** February 25, 2006, 04:35:34 PM »

First of all, I would like to apologize for my 2 posts yesterday. I was in a very bad mood and probiblly should not have been sharing my thoughts. And your correct, that I should seperate the design from the designer, and that does weaken my argument.

As for being "all knowing", you do not need to be (and I'm not) all knowing to see a very large engeneering error, as with the selsam multi-rotor systems. The design simply does not make sense from any cost perspective that I can see.

Expecially in larger designs, the shaft and bearings become a major cost of the turbine design. Most of the designs on this site and others take advantage of wheel bearings from auto's. That gives them a cost advandge because the wheel bearing is such a mass produced part that they come very cheaply. When your design requires 8 carbon composite racing drive-shafts to acheive a 5k output, it starts to loose the point. The only advandage to his design is it uses a slightly smaller diamerer genny due to the higher RPMs of the smaller diameter props.

Slingshot · « **Reply #30 on:** February 27, 2006, 02:00:28 PM »

Doug has a patent, and I think he mentioned being under government contract to develop his concept. Possibly one of the requirements for receiving continued funding is to develop and offer a commercial product. It could be that he doesn't really care whether we buy it or not

As for the claims of "record power from a 7-ft turbine", that's just salesmanship. The real "size" of the turbine is the boom length plus blades - that's how much circular real estate one takes up when installed.

solarengineer · « **Reply #31 on:** May 04, 2007, 01:07:17 PM »

Actually it is quiet riot

lmao

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Author Topic: Dual Rotor (Read 3363 times)