My 1st VAWT failure!

[willib]

i finished this a while ago and never tested it in real wind , wings are about 18 inches tall and same dia..

based on Ed's cycloturbine

[gizmo]

I call it the "Littleford" rotor

Might have a go at it myself this weekend.

[CmeBREW]

Hey guys.

     Very interesting concept Windstuff-ED and Willib. You guys sure take your prototypes serious!! I make mine out of 2x4 pine first--then, when it don't work I can chop it up with an ax and burn it!!

Gizmo, can't wait for you to try that simple design.

I gave up that horizontal dream method I was goofing with. I think I was beginning to go alittle 'mental' when I tried that one. Vawtman was right---how can the wind catch the vortex--if the rotor can't catch enough wind to make the vortex in the first place. I'm doing all right now though-thanks. Nevertheless, I returned to my original design attempt--but this time I put the airfoil shape on the INSIDE instead of the outside. It didn't start at all either, so I turned it at a steeper angle (heres a picture of it laying sideways to show angle of blades):





Needless to say, this did nothing also. This thing just won't start Man! Then it dawned on me--- since these DArriaus type are almost impossible to start, then why fight it. I realized to hook the rotor to a treadmill motor and 'jumpstart' the Dam thing until it will take off. And then the treadmill will BECOME a generator when it gets going. It would only take a simple 'jumpstart' circuit to disconnect and then let it generate power.  And of course, some kind of a simple wind sensor switch.(that goes on and off with the breezes)

Similarly, this is what I have been doing with my little 4'(Passingwind) windmill. Since it is a downwind generator, sometimes I have to 'jumpstart it' to get it to turn into the direction of the wind. And when it gets going, I remove the wire and it begins generating power. It only uses about 10 watts for several seconds each time I have to do this. However, the treadmill the VAWT rotor is hooked to takes 20watts for several seconds each time. But the generator should recoupe that power spent in just the same amount of time.

 Heres the picture of what I did with the VAWT rotor:






Hooked (temporarily) to a 12v battery, it begins going around 400rpm and then because it is out of balance the 2x4 starts swinging back and forth bad so that it still don't take off fully. Also, the breeze just went away for the day just minutes ago when I got to test this for the first time.

I will balance and test the thing tomorrow. (or when there is a alittle wind)

But my big question is: Should the airfoil shape be on the OUTSIDE or the INSIDE? - Or does it even matter? It seems most have it on the outside.

The breeze was seemingly starting to take hold of it, but it was too out of balance right now I think.

After I get it in balance and flip the blades around, I think I will try 18 volts to the treadmill motor and see what 600rpm + will do!  Maybe then it will take off!

I will keep you posted when and if this crazy thing ever takes off !!!!!

[gizmo]

Well I did put together the little rotor using some 1 inch stainless thinwall tube and a few scrap lenghts of zinc. I even made some winglets. It does run, but yet to work out if it running as a drag or lift VAWT. I've mounted it next to my aneometer and will do some data logging over the next week with different wing angles to see what gives the best results.

Glenn

[CmeBREW]

Nice work Glenn! Let us know if the results of a different angle works better.

I did some further testing on my VAWT rotor and the treadmill motor today. Today there are upto 10-15mph breezes. I balanced it better and found out that it does way better with the airfoil turned OUTWARD instead of inward. It spins faster that way. It did not do as good as I had hoped though. I also put my ammeter inline to see the exact power it is drawing for these so-called 'jump-starts' I was doing. It is alittle more than I had quessed due to the drag of these blades.  I have the blades back to 0 degrees as ED said to do--and I can see know that is the only place they should be of the drag is INSANEly incorrect!

Hooked to the 12v battery it starts drawing 36 watts for a few seconds and then goes down to 27 watts steady. The rotor is going about 350rpm.(my best quess)  

The breeze would sometimes take it up to around 400rpm but only for seconds. It still would not take off by itself.

So I then hooked it to two batts in series (24vdc) to speed it up. The draw now was up to 60 watts and it was going between 500-600rpm. Now I can see it take off some with the good breezes (about 15mph) but it would not last too long after the breeze goes back down. Also the location is not that good. But I am certain that in a steady 15mph wind it would keep turning at around 600rpm or so. (no load)

My conclusion is that the DRAG on these blades must be pretty horrible. The straight side of the blade (inward side) must cause ALOT of drag.

My next experiment with this will be to make a new set of blades with the airfoil shape on BOTH sides of each blade to greatly reduce drag.

Hopefully, I can make the rotor so that it will 'take off' with only one 12v battery, because 60 watts is way too much power to spend for 'jump starting'. If the rotor was more arodynamic, it could spin faster on the 12v battery alone and take less than 27 watts and hopefully take off.

I also see that I need a better location to test this than at ground level at the corner of a house. The small wind gusts stop and go too much and only last 4 or 5 seconds. The rotor can't keep going.

Any more advice is always appreciated. As Vawtman said, the DRAG will make of break ya.   -This time I think it broke me-- but only for alittle while!  -Thanks.

[tecker]

That's why I like to think of VAWT cycles  the Drag can be enormous but regaging the last 180 degrees is fun  .You can use a shield on the upwind side if you have prevailing winds . This will let you test the drag coefficients of the down wind cycle .Of coarse the real beauty of a Vawt is the lift that accents the drag . There is a lot to be done on the VAWT  that is not going to be in a public form like this one .

[CmeBREW]

I agree Tecker--that is the amazing and beatiful thing about these Vawts--that is, the confusing lift that accends the drag- especially on the opposing side to the wind. I am just beginning to learn and they really are fascinating.

I also have GREAT NEWS--- I finally got the thing to at least start turning BY ITSELF in the correct direction!!!. (And it KEEPS slowly going in the right direction in a low breeze!)

This is what I've been working for all week.

I believe I am learning some good things about shape and DRAG, by good ol'trial and error. (basic stuff) -I like PACWIND's Vawts. I think the best way to go is using the DRAG method to start these rotors and have the shape as much as possible into the airfoil shape so that it will then proceed into a fair amount of LIFT and increase RPM's for much more power. Pacwind makes no secret about that with their VAWTS. In fact, you can see it in the photos on their website. These things really DO put out ALOT of power and they are perfectly silent. When I tested mine yesterday going almost 600rpm hooked to two batteries, it made NO sound at all. Therefore, this is the direction I am now pursuing, since I am already getting good results. Here is what I done:







As you can see I went back to the PVC halfs- but this time on three blades instead of two. I now believe 3 is much better for starts than 2. The winds catch BOTH sides of each blade. Notice the positioning of the PVC. I mounted it more toward the inner side to try and keep somewhat of an airfoil shape on the OUTSIDE of each blade---hoping it will, after it gets rotating good enough, produce LIFT and reach higher RPM's. Getting the rotor perfectly straight up and down is MEGA important for easy starts in a breeze. I put my level on top of the center part to get it very plum. Without that center like that, it is impossible to know where perfect plumness is.

Unfortunetly, today has only had nothing but little breezes under 10mph. But it is starting to turn on its OWN many times in these breezes and slowly keeps turning about upto 60rpm!. I know there are still plenty of DRAG issues, but I am certain this thing is going to start by itself and begin turning faster and faster when a decent wind gets here. Hopefully tomorrow. I will keep you posted.

To get some REAL power though, my next one is going to be 6 feet diameter and 3 blades that are 3 feet long each!! I can't wait to make and test that baby real soon!!!

[vawtman]

Glad your having success but on the future turbine you would be better off with 6ft height on a 3ft diameter.

 Keep brewin

[CmeBREW]

One last comment:

     I finally got some decent little breezes today (15mph or so) to test the changes I made a week ago. I thought sure they would work better, but they did not go any faster than only 120rpm. The PVC  round shape on the front is WAY too much drag. In fact, I can see now, all I did was convert it into a DRAG rotor which is not what I want. I want to acchive LIFT and go at least 400-500 rpm with thinner blades!. I even tried extending the arms twice as long--making it 6.5 feet diameter. It made no difference either---It only turned half as fast-- but without the PVC fronts at least. Of course, it started up easy on its own, but only turned slowly.

So its back to the books and research. I swear, on paper, it looks like it should've worked though. It freaks me out to no end. I don't even see how in the world the 'teardrop' shape could work either. Next time I am going with 4 blades and they will be much wider and longer.    -Thanks.

[vawtman]

My guess is this why everybody gives up.Keep on truckin brew