Wants comment on design idea - Type of bending Y-HAWT

[MACM]

Hi all.

My name is Mikkel and I am living in sweden.  

I am new to the board, but I have been reading a lot lately on Fieldlines.

I want to build my own turbine. Off course I should have started with one of Hugh Piggott's designs or another proven concept, but I am just that young and dumb and it does not fit on my boat ;-) Bear with me.

The idea is this:

An Y-HAWT on a bending rotating axel.

First I thought I might have come up with a new idea, but it seems like Jack Park beat me by 31 years (I am trying to find his books).

Ed Lenz also seem to have been experimenting with sort of the same concept. For this I am glad. If no one had thought of this before I would have scrapped the idea directly.

What I am trying to determine now is how to design the wings  - I need any input I can get.

-    The angle of attack (if any)?

I want the turbine to be self starting. It must be possible to have some of the top rotors to give a torque if they are leaning out of the Horizontal.

-    The profiles of the wings?

My first thought is to use Ed Lenz´s Blade designer and stretch the wing 40%.

As an alternator I will definitely use the PMA and it would be sweet to have Flux´s volt-adjusting controller in the bottom of that.

The first test model is only going to be 2,5 meters tall!! The horizontal axel made from an expired fishing rod (not to many fish left in the Baltic sea anyhow).  

The picture is pure speculation on how big it could be with this principle, but I hope it provides the general idea.

Background:

At home (my sailboat) I have been running a Rutland 913 at the mast top (Not a very bright idea for those of you wondering! - 12 A and the alternator gets to hot and the turbine starts freewheeling and turns the 913 into a screaming monster - witch I fear can explode anytime, but so far so good, Marlec does make a solid machine).

Anyhow - One thing led to another and I soon found myself entangled in thoughts about building a new turbine DIY.   But  I soon realized that I was soon confronted with some paradimes in the traditional VAWT (and HAWT) that I could not combine with my wishes for a new turbine.

[hobot]

I've actually acidently experimented with variation of this design

in flailing frayed cable drives and props on end of too lose shafts

but most illistrative of concept is the rags tied to end of lumber

in trucks to mark a warning in traffic.

Howabout if you put a normal turbine on end of bent post and lead a

cable drive down inside for power drive.

hobot

[electrondady1]

macm , its been a long time since i was n a sailboat but can't you just run a sort of vawt up the  jib line?

i can understand a flexable shaft on land but kind of tippey on a boat!

[Nando]

My suggestion would be a small Pitch controller wind mill on top of the mast, quite and not problems with "screaming" with automatic RPM control.

There are a couple of those wind mills sold in Europe, one in Germany, I believe.

They worth every cent you spend on them.

I have a friend right now in Europe that has placed two of them on the two mastiles of his sail boat.

He is suppose to comeback at the end of 2007 with his boat.

Nando

[ptitchard]

You could try looking at this link for some ideas

http://www.speakerfactory.net/wind_old.htm

Regards

Paul

[Slingshot]

Wow, now that's what I'd call a "hype site".  Claims "world record" power from a 7-foot turbine.  But actually it's seven 7-foot turbines ganged together.  I guess the engine in my car should qualify for some "world record" of 365 HP from a 44-cubic-inch piston displacement.  But wait, there are 8 of those pistons tied to the same crankshaft

A single turbine having the combined swept area of seven 7-footers would be only 18-1/2 feet in diameter, would require less real estate, and would probably be more efficient.

[Titantornado]

I see near the very bottom of that website, is an almost identical design to Mikkel's design.

[whatsnext]

the multirotor machine would take less material to build the blades though and the weight of the rotor would be less for a given swept area so the idea is not totally without merit just because Doug is a bit of a huckster. Lower polar moment of inertia also so I'm wondering why you think a single rotor would be more efficient. The multi rotor is only flat like in the picture when it is in the "furled" position. The rest of the time the rear rotors are above the front rotors so they see pretty clean air. A lot of people don't like Doug so they discount his machine which seems silly to me.

John.......

[MACM]

Tnx for all the comments.

The idea with a "real" Pitch controlled turbine would be sweet, but the main problem is not so much the turbine as it is the brutal movements of the masttop and therefore also the turbine. The classic solution on boats is to have the turbine lower (on a seperate pole) and that works fine on open water - but most sailers (like me) spends 95% of the time in a habor.

The jibline solution is good, but the turbine will still only get half way up in the mast - on my boat that is 6 meters up, versus 12 in the masttop.

MACM

[Slingshot]

I don't know the author of that web page, so I neither like nor dislike him, but your "huckster" comment does sound reasonable when you look at what he's written

Anyway, my efficiency comment was based on the numbers he has actually published - his "world-beating" claim of 6000 watts at 32.5 MPH.  He has seven 7-foot rotors, for a swept area of 25.028 square meters.  Please check my arithmetic, but I calculated a Cp of 0.0625 based on those numbers, which seems pretty low.

A conventional single-rotor machine of that area would only be 18.5' diameter, and would probably have a higher Cp, giving more power for the same wind speed.  And an 18.5-foot conventional machine is actually "smaller" than what he has, when you consider his forty-foot (my estimate) boom that must have clearance to rotate 360 degrees.

Actually, because of the multi-rotor's low efficiency, you could probably build a single-rotor of less area that would make the same power.

Here's a possibility - perhaps the the multi-rotor concept is innovative and has a few advantages on paper that are gradually becoming less and less in practice.  But the well-meaning inventor, because it's his baby, will continue to hype it out of pride.  But claiming "world record performance from a 7-foot turbine" is nothing but a careful twisting of words and meanings.  As most of us with any experience know, and the inventor probably knows as well, it makes sense to rate and compare these machines based on swept area.

One other possibility is that the hype is not aimed at the general public, but rather at obtaining government grants (wasting my money and yours) to continue flogging the dead horse.

By the way, did you notice from the pictures that the blades on this multi-rotor appear identical to those on Southwest Windpower's Whisper 100?  The Whisper 100 has, coincidentally, a seven-foot rotor  Does the multi-rotor machine make as much power as seven Whisper 100s?  No - it does not.  Putting these blades into a multi-rotor configuration has substantially reduced the overall efficiency.

I think Cp of the Whisper (rated 900 watts at 28 MPH) is about 50% higher than the multi-rotor, apparently using the same or similar blades.