H-Darreius wind turbines ( VAWT ) !

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This seemed to stiffen the aluminium extension once and for all.

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Ready to rock....6 carbon fibre covered 6,5 mm plywood strips will be added in the upper part to where the tower part bending force is the greatest on the legs.

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I hope this ends the tower nodding when windy.

[MattM]

How about taking video on next run?

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Taken a lot of videos...great way of analyzing stuff.

Yesterday I tested the 3rd prototype blades in the new set up in 7 m/s wind.

The efficiency was ½ of what the bigger blades had on half the wind speed.

Smaller blade/wing has 2 x lift coefficiency and drag....aspect ratio is 5 where as 4th has 8.

10-20 would be decent...even great.

What is funny is that 3rd set of blades rotated 2 x as fast in the same wind speed as the 4th set....without load.

There is something funny happening there I don't just get.

Anyone care to explain me ?

Tower was stiffer...but not tough enough to take 4th blades in to 10 m/s wind.

[topspeed]

Ok...now I found the glitch here....anyone want to take a guess on it ?

[MattM]

So more lift coefficiency or lower aspect ratio reduced efficiency?

My gut instinct would be on this style of VAWT that flat boards with zero angle of attack would work better than an aerodynamic shape simply due to the peak torque would come from the points nearest and furthest from wind origin.  Lenz used drag scoops to draw power from the recovery phase between those two positions.  But nearest those two positions are where the magic happens.  Mind you, at perfect nearest and furthest points everything should be in balance (potential energy peak) so nothing actually happens until you approach or leave those points.

Lower aspect ratio in my thinking would mean less of your arc would be spent transitioning.  I wouldn't doubt that the lower aspect ratio would create more torque at start up but then peak early as rpm's increase.  A higher aspect ratio should give you more arc for the wing in transition.  Lower torque would develop until the rpm's get closer to the drag limit, which would be higher rpm's due to lower drag at the aspect ratio.

I also thought they used the center wing to create a directional center point offset the center of rotation, so the center of rotation is slightly set outwards and perpidicular with the wind.  The offset would not improve airflow, just use torque of aligning to the wind to improve startup as the downwind side would be further from support.

But if I understand you correctly, your results are in direct opposition to my gut instincts.

[topspeed]

So more lift coefficiency or lower aspect ratio reduced efficiency?

My gut instinct would be on this style of VAWT that flat boards with zero angle of attack would work better than an aerodynamic shape simply due to the peak torque would come from the points nearest and furthest from wind origin.  Lenz used drag scoops to draw power from the recovery phase between those two positions.  But nearest those two positions are where the magic happens.  Mind you, at perfect nearest and furthest points everything should be in balance (potential energy peak) so nothing actually happens until you approach or leave those points.

Lower aspect ratio in my thinking would mean less of your arc would be spent transitioning.  I wouldn't doubt that the lower aspect ratio would create more torque at start up but then peak early as rpm's increase.  A higher aspect ratio should give you more arc for the wing in transition.  Lower torque would develop until the rpm's get closer to the drag limit, which would be higher rpm's due to lower drag at the aspect ratio.

But if I understand you correctly, your results are in direct opposition to my gut instincts.

Yes....you have to remember I have an innovation in this which sorta makes a difference (at least I hope so).

I have to go to test fourth time soon...it is getting chilly here again.

I think I know now why the tower was shaking even though I have a less lift coefficient 4th set of blades.

[Mary B]

4 blades, 3 legs, setup oscillation in between supports...

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4 blades, 3 legs, setup oscillation in between supports...

Yes Mary...there has to be a support in between the legs...they bend ever so slightly.

I try once more to get a decent efficiency figure out this.

If not...then I have to wait for a situation with a decent funding to get right kinda axial flux generator....more space, workforce etc.

[JW]

your workmanship is good. you need too understand the 9 by 12 magnet and stator relationship. in that way you can "dial in" a specificity load in real time. And don't forget the potential to make the most electricity.

I spoke to Flux about another WAWT situation his reply, was just because its spinning does not mean its making power.
 

[Mary B]

4 blades, 3 legs, setup oscillation in between supports...

Yes Mary...there has to be a support in between the legs...they bend ever so slightly.

I try once more to get a decent efficiency figure out this.

If not...then I have to wait for a situation with a decent funding to get right kinda axial flux generator....more space, workforce etc.

I am well versed in 3 legged tower harmonics... I have had to help friends add weights to tower legs to damp violent tower harmonics that were literally shaking antennas apart.

This tower had lead weights mounted inside the legs(2" angle iron 1/4 inch thick!) to stop the top antenna from whipping 12" back and forth...

That tower is 3' wide on the face and was 80' tall for the main tower, rotating stub added 20 more feet.

[topspeed]

Yes Mary....damping is the word here...to find right kinda stiffnes that might even counter act the frequency the system is trying to tremble itself down.

[topspeed]

your workmanship is good. you need too understand the 9 by 12 magnet and stator relationship. in that way you can "dial in" a specificity load in real time. And don't forget the potential to make the most electricity.

I spoke to Flux about another WAWT situation his reply, was just because its spinning does not mean its making power.

I need to get more rpm out of the slicker prolifed wing...I am working on it.

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(Attachment Link)

This part is now also fiber glass reinforced.



It is easy to test the better stiffness as Ihave the extra 4th leg left...as it was made to a tripod.

It looks like new after some paint.

[topspeed]

Stiffness was increased by 7x and 5x in other direction.

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That aerodynamical part on top looks quite a bit larger than before.

How did the new torque arm turn out?

Aerodynamical part indeed is a big...that is why it tries to tears the tower down...in each test..... now the legs are 6 times stiffer.




I did some serious balancing too and straightening here...I hope all goes well.

[MattM]

How much offset is there from the center of rotation to your central wing?  I assume some of the wobble you experience comes as your central wing aligns to the air direction.  The larger the offset the more the wobble I suppose.  Any noticeable offset should allow self starting.

Honestly, I assume this is a huge device I gather by its size relationship of the wing to the size of the Dewalt drill next to it.  Has to be big enough for 3kW at least.

[topspeed]

How much offset is there from the center of rotation to your central wing?  I assume some of the wobble you experience comes as your central wing aligns to the air direction.  The larger the offset the more the wobble I suppose.  Any noticeable offset should allow self starting.

Honestly, I assume this is a huge device I gather by its size relationship of the wing to the size of the Dewalt drill next to it.  Has to be big enough for 3kW at least.

Yes you are quite right.

It was so strong in last tests that the system loosened those anchor bolts from the bottom part of the legs....and broke one halogenlight and loosened one ballbearing from
 the housing in the torque arm.

The corrections I made enabled 40% more efficiency but still too low to make any difference...I presume I need to add more resistance...shorten the legs and put little more carbon fibre in the tower.

The chosen generator ( bike hub motor ) may be the biggest culprit in this for the poor performance.

[MattM]

Perhaps you can go for a smaller test prototype version so you can study the results and eliminate the static being generated from the mobile version.  As it is now its not a very practical test subject.  What you have is a very refined version for the wings that I'd assume your final product should look.  But honestly it is so large you really need a sturdy fixed tower for something with potential for that much potential power.  I fear your prototype could hurt you.

Trust me, for s***s and giggles we made a 20+ foot wide rotor out of sheet metal and found it ran out of control and self destructed because it was more a pinwheel than an actual windmill.  When the wind shifted and the sheet metal arms folded like spaghetti noodles, my heart literally stopped because we had no idea how that was going to end.  Luckily the guy holding up the 20 foot plank that it was mounted on was nimble enough to avoid getting hit in the head.  Smaller prototypes are safer.

[topspeed]

Perhaps you can go for a smaller test prototype version so you can study the results and eliminate the static being generated from the mobile version.  As it is now its not a very practical test subject.  What you have is a very refined version for the wings that I'd assume your final product should look.  But honestly it is so large you really need a sturdy fixed tower for something with potential for that much potential power.  I fear your prototype could hurt you.

Trust me, for s***s and giggles we made a 20+ foot wide rotor out of sheet metal and found it ran out of control and self destructed because it was more a pinwheel than an actual windmill.  When the wind shifted and the sheet metal arms folded like spaghetti noodles, my heart literally stopped because we had no idea how that was going to end.  Luckily the guy holding up the 20 foot plank that it was mounted on was nimble enough to avoid getting hit in the head.  Smaller prototypes are safer.

Yes this has turned in to a real sport like the gladiators fought on the arena in Rome 2 000 years ago.

I have fixed all shortcomings I saw in the previous test now. Sadly the weather is not coping...but I just might be able to test it before the blizzard strikes.

[topspeed]

Taking it down in 15 m/s wind was like a decisive fight in opening of the Troy.

[MattM]

Wow.  Glad you didn't get hurt.  It has enough power at that speed to definitely remove limbs.

[topspeed]

Wow.  Glad you didn't get hurt.  It has enough power at that speed to definitely remove limbs.

Yes it rotates much slower than the previous smaller turbines. At 85-100 rpms in 6 m/s wind. Much too slow for the generator that is rated for 170 rpm.

Had the blades been 3-4 meters long and moment arm like 1100 mm it would have been just fine.


Now I have to figure how to make a 1 kw sized turbine generator for 50-80 rpm.

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I realized that I am getting more and more measurable current and power if I increase the load. So i increased the load even more.

Hopefully I can finally measure a decent out put.

[SparWeb]

Pretty soon, ships at sea will avoid this shoreline, thinking there's a new lighthouse there!

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Yes in fact the ships really can see it.

[Mary B]

Like the Christmas movie where the guy wants his Christmas lights to be seen from space LOL

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Like the Christmas movie where the guy wants his Christmas lights to be seen from space LOL

Yes Mary....what I need is more speed to the rotation.

I have made 5 changes to the system. Making new blades again.

[MattM]

Test post for  topspeed

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