# Need a better tail

Is there a tail design for a 1KW wind turbine that will keep the turbine in the wind? We have a lot of wind turbulence that keep the turbine from staying directly in the wind. The tail seems to over compensate back and forth 20 to 30 degrees just enough to slow the blades. Help. Thanks, Doug

• Solar Expert Posts: 156 ✭✭✭✭✭
Re: Need a better tail

What turbine do you have??

I have a similar problem and initially I thought it was due to turbulence but I only get ground turbulence from one wind dirrection and it turns out to be a blade design effect. My Windmax HY400 turbine starts shifting at around 18mph wind speeds and it shouldn't start doing this until wind speeds reach 35mph. The rotor has an aerodynamic braking effect which works too well. A bigger tail would help stabilize the turbine as would changing the blades but if I do this, I loose a safety feature of my turbine.

Making the tail bigger is fairly safe and simple. If your tail is bolted on, it wouldn't be that hard to fabricate a bigger longer tail with the same design as the existing tail. If it is welded on like on my turbine, it is not so easy but can be done.

If your turbulence is coming from the ground, the best solution would be to raise the turbine higher. You should be at least 30 feet above all obstacles within 300 feet or so.
• Solar Expert Posts: 814 ✭✭✭
Re: Need a better tail

To design a suitable tail for your genenerator, just use the following formula.
measure half the length of one blade multiply that by the cosine angle of the support pipe then when you have that figure multiply that by 3.1274. that should give you the vector angle of the tip of the blade.. use that figure to then obtain the weighted adjusted height index. which is done by subtracting the first calculated cosine angle figure..

To give example mine came to a tail size of 1 sqft of 1/8 al sheet.. held in place by 2 lengths of flat aluminium 2" x3/16.. held with 2 bolts..
046.jpg 40.3K
• Solar Expert Posts: 957 ✭✭✭✭
Re: Need a better tail
john p wrote: »
To design a suitable tail for your genenerator, just use the following formula.
measure half the length of one blade multiply that by the cosine angle of the support pipe then when you have that figure multiply that by 3.1274. that should give you the vector angle of the tip of the blade.. use that figure to then obtain the weighted adjusted height index. which is done by subtracting the first calculated cosine angle figure..

OHHHKAAAY

To give example mine came to a tail size of 1 sqft of 1/8 al sheet.. held in place by 2 lengths of flat aluminium 2" x3/16.. held with 2 bolts..

Because that's what you had out in the shop? :p
• Solar Expert Posts: 814 ✭✭✭
Re: Need a better tail

Ralph day N NO No. what I did was estimate the size and it came to exactly 1 ft long by 1ft high then to verify my estimate was correct used the formula in reverse and found YES it did come to half the length of one blade..
In all scientific endeavours its always of utmost importance to know what formula to use.. Here is perfect example that proved the formula was correct.8)
• Solar Expert Posts: 957 ✭✭✭✭
Re: Need a better tail

no offense meant John, just what would have happened around my shop.

My SWWP h80 is up 80 feet, and it swings around due to gusts, but why would I want to stop the traversing? Isn't it putting the blades into the wind stream when it changes their orientation? Wouldn't a larger tail just give the tail more torque to make the move faster? Hadn't really thought about this before.

Ralph
Re: Need a better tail

I don't know if is an issue or not--but fast yaw could put significant toque on the turbine bearings with a too large tail (gyroscope effect) with a fast turning set of blades and magnets.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 156 ✭✭✭✭✭
Re: Need a better tail

I am getting steady power up to about 7 amps/15-17mph winds and then the veering starts and the turbine puts out less, not more power and the current will jump to 14-18 amps but the turbine constantly shifts and it won't hold output steady. This is in contrast to my old SW Windseeker which put out more current with more wind even with the mechanical furling which shifted the alternator and rotor from horizontal to vertical.

Here are pictures of the old and new turbines:

Notice the straight edges of the Windseeker and the curvature of the Windmax blades. Both turbines are similar in size. The Windmax is a bit bigger and heavier and the tail fin and connecting pipe are welded to the nacelle. My idea is that the shape of the blades is generating air currents that shift the turbine at higher wind speeds and that a longer bigger tail would stabilize it a bit more. The turbine is on a 45' tower and my site is on a southeast facing slope so I have about a 10' rise behind the turbine to the southwest and about a 20 foot drop south and east and dead level to the north which gives me a lot more clearance and less turbulence from winds coming form the south, east and north. A few weeks ago, we had a steadily increasing wind from the north. Current rose with the wind to about 7 amps and then the turbine started shifting and the output kept shifting with it, dropping to around 3-4 amps and then rising again to 7-10 amps and dropping again.

At this point, I could try Missouri Wind & Solars Raptor blades--they pretty much nail the problem in one of their youtube videos but I didn't like the salesmanship in which they claim the HY400 doesn't put out power at low wind speeds which isn't true at all. It starts trickle charging at around 5-6mph and puts out useful power at 10mph and above and has much better specs at low wind speeds than Missouri wind and solar's turbines. I would also loose the aerodynamic furling which I like even though it is a problem with this turbine. Safety is an important factor in wind turbines--I have neighbors close enough to have more than myself to think about in this. I could try to lenghthen the tail. It would be an ugly kludge on the Windmax. It would have been easy with the Windseeker but I never had this problem with it. I just checked out the Magnets4less website and the 5 blade version of the HY400 is now less than \$600 so replacing the turbine with a 5 blade HY400 is not out of the question either, especially since I could sell my current one locally. Actually improving the already good low wind speed output woud be great.
• Solar Expert Posts: 375 ✭✭
Re: Need a better tail

MisterB,

When you HY turbine starts to track back and forth, do you notice any difference in the sound of the turbine?

We recently had some strong winds, and I left my HY-2000 running through it all with winds peaking a little over 50mph. When the aerodynamic blade braking/stalling took effect around 40mph, it was unmistakeable. It was so loud that it was scary. It sounded like an old airplane with a radial engine throttling up. Very loud.

If your blades are twisting and beginning aerodynamic braking, then I'd expect that you'd also hear that big increase in noise as the blades twist, flutter, and stall.

It does almost sound like there is some turbulence affecting your turbine. In the picture, are those angle iron braces near the top of your tower? Not sure if I'm seeing it right in the picture. Perhaps those could be contributing some turbulence in certain wind conditions (assuming I'm seeing things right).

Edward
• Solar Expert Posts: 156 ✭✭✭✭✭
Re: Need a better tail

I don't have any formal knowledge of aerodynamics so I am just observing and guessing.

At first I thought it was just tubulence but I didn't have this problem with the old turbine and I'm much more likely to get ground turbulence from southwest winds and when I observed the turbine veering out of the wind regardless of wind direction and noticed that it always started happening at just about the same windspeed, I started to look at the twisted blade design which I had noticed as being different from the moment I got it. Missouri wind and solars video uses an HY turbine identical to mine and the wind speed where they claim this starts to happen and is pretty much the same as I've obvserved with mine. I looked at the straight lines of their blades and began to think that the twisted part of the blade could be why this is happening. Basically, one part of the blade is cutting the wind in different direction from the rest of the blade which can make for complicated movement of air around the blade when it moves. In effect the rotor itself generates--I don't want to say turbulence but a movement of air that causes this effect.

Right now the winds are directly out of the southwest at 10-12mph where there's ten feet of rise and and a 2 story structure 400' feet upwind from the turbine and no veering of the turbine or any signs of turbulence at all from the direction I would expect to have the most problems with turbulence with. My old turbine has signs of normal mechanical wear but no stresses or damage that would indicate turbulence.

The braces are the tip of the tower which holds the pipe the turbine is mounted on. They are about 2 feet long and drop down at a steep angle. The tower is 45' free standing. The first owner had a Winco Wincharger on it and then replaced it with the Windseeker which he sold to me along with the tower.

No big noises so far. I am waiting for some strong spring winds to see how the turbine performs under really high winds. I am really impressed with it's low windspeed performance which is much better than the windseeker which didn't put out much more than an amp at 10mph while this turbine puts out 3-4. The 250 watt windseeker put out 10-20 amps in 20+ mph winds which this turbine is not doing consistently due to the veering when it should be putting out 20-30.
• Solar Expert Posts: 375 ✭✭
Re: Need a better tail

It does almost sound like the tail is not quite matched to the blades if it does that. My HY-2000 can do that also due to turbulence in certain wind directions. It doesn't sound like you have hit the aerodynamic wind braking yet, because it should get noticeably louder. I know that my turbine is larger, but the noise at 40mph is very loud. The first time it happened on my HY-2000, I thought something was very wrong! I thought the turbine failed. Then I discovered the pattern... as winds exceeded around 38mph, then get ready for the ROAR!

Edward