Offset angle of the furling tail

I got asked a question that a lot of people ask me, so I thought it worth answering here.

Hi Hugh my name is Bill looking through your book A Wind Turbine Recipe Book I am a little confused with the tail vane lower stop. If the tail is allowed to travel 110 degrees it would seem you would be 20 degrees to far in the opposite direction and the blades would never face the wind squarely. Does the tail come off the lower stop during normal operation? What am I missing? Thanks in advance.”

offset

 

Here is a plan view of the Recipe layout.  The alternator frame is mounted onto the yaw bearing off-centre, in order to create a ‘yawing moment’ that tends to swivel the turbine around sideways to the wind. The tail is deliberately angled a little to the opposite side in order to balance this tendency and to keep the turbine facing squarely into the wind under most conditions.

 

2 offsets

 

The above picture tells a story.  The left hand turbine is the design I used up to 2008.  After that I switched the offset to the other side so the machine furls to the left instead of to the right.  I will skip the reason for this change here, as it is not very important.  But it has been very interesting to watch when there are two machines of the different designs in the same field of view.  They often look like the above picture.

We tend to assume that the tail always points downwind.  That’s what it’s designed to do, right?  But looking at the above picture, this is what you actually see when there are two wind turbines with the same wind direction. The tail vane swings off the downwind direction.  It’s very noticeable when they swing in different directions.

It’s not at all unusual to see 20 degrees error between the tail and the wind direction, and often the difference is larger.  Why does this happen?  To understand it you need to think about the forces on the tail.  Before the blades start turning, the tail acts just like a wind vane, but when the blades are spinning they catch a large thrust force that is centred a bit off the centre of the tower-top yaw bearing on which the machine swivels.  The purpose of this offset is to make the machine move edge-on to the wind and protect itself from overload in strong winds.

The thrust force is counteracted/balanced by the tail, but it moves a bit sideways first.  It’s like a boat settling in the water as you climb in.  The boat settles to get more buoyancy.   The tail needs a bit of an angle to the wind to create the lift force needed to balance the blades’ thrust.  Hence the 20 degree angle in the Recipe design.

I hope this helps explain the logic.  There’s a lot to say about furling systems.  They are very simple in some ways, and extremely complex in reality, but they do the job.

 

Posted in construction, my own projects, Uncategorized | 2 Comments

Dan Bartmann’s batteries

I read this facebook post by Dan Bartmann this morning and felt it was worthy of wider attention:

Facebook always asks me ‘what’s on your mind’. Lotsa stuff that I don’t wanna share. But for now BATTERIES. I’ve read lots about them… how to take care of them, I understand the complicated charge controllers available now etc.

I got mine off ebay 10 years ago… new but sitting on a shelf for way too long before I got them. Today they are as good as the day I got them. They’ve been moody in between.

My only charge controller is a Morningstar Tristar TS60 running a dump load. The dump load was a 4000 Watt heater but since the flood two years ago only about 1000W of it comes on sometimes. Easy fix, not done yet. (just saying the charge control on my battery is mostly about boiling off water and there’s not much electronics involved)

I water the battery fairly quarterly and everytime I do I add way too much. (7 gallons last march)

My low voltage cutoff on the inverter is set to 32 V (because there’s times when I ask my battery for the very last drop)

So why is it that today and recently its cloudy, not windy… I’m sitting at 50V with a tube amp and the internet on and I just ran a well pump for a while and it’s all good? This is a Forklift battery I got off ebay 10 years ago. It probably needs another 7 gallons of water haven’t checked recently.

I think to a battery years are less than dog years (human x 7) I suppose I take care of myself as well as I do my battery maybe a little better. I should live to be 150.

Posted in People | 3 Comments

V3 Power – parts and turbines for sale – job opportunity too

V3 Power From Clipboardhave been teaching courses around the UK and beyond for many years and also offer wind turbine parts and even complete machines for sale.

Job opportunity with V3 Power

We are looking for someone to join our cooperative! We need someone to take on the role of coordinator and be responsible for the day to day running of our co-op as well as to work on our diverse and exciting projects. This is an excellent opportunity for anyone with good organisational skills who is interested in cooperative work and renewable energy. Is this you? We’d love to hear from you if so! Deadline for applications is 3rd September.

V3 Power coordinator job description

V3 Power coordinator person specification

Posted in construction, courses, People, UK small wind scene | Leave a comment

Workshop stories

Here are three stories of recent workshop courses using my designs.  Click on the photos or the country names to find the stories.

One is in Germany, led by Jonathan Schrieber

 

The next is in Greece, led by Kostas Latoufis at Nea Guinea

Both Jonathan and Kostas are good friends and have been here on Scoraig a couple of times.  The third story is from China, and the course here was run by Simon Goess.  Simon has made a start at translating my Recipe Book into Chinese.

Video here.. and more pics… and more

It’s great to see people all over the world having fun making windmills :-)

 

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Wind turbine course in Kildare 22nd August

For bookings and further information please contact:
Grangebeg Camphill Community
Park Lane
Near Dunlavin
Co. Kildare
Ireland
Phone: 045 406050
Mobile: 087 9285140

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Battery storage on the grid

My friend Ian Woofenden has this to say about using batteries on the grid:

Tesla Battery Perspective

There’s been a lot of buzz recently about the Tesla battery. My attitude and ideas toward it are tempered by 30+ years of living off-grid with renewable energy technology and watching the industry progress. There’s plenty to say – my summary looks like this:

* It’s just a battery. Off-grid folks have been living with batteries for decades. They are not magic, and in fact they are often the biggest problem components in renewable energy systems. If you can avoid batteries, I advise you to do it!

* Batteries are actually a load on a system, since they are not 100% efficient and they have a standing loss. Adding more battery adds more load (and more cost). If you can grid tie without batteries, you’ll have the most efficient and environmentally friendly renewable energy system. If you need batteries (off-grid or utility back-up), I suggest you keep your battery relatively small, and invest in more generating capacity instead of more heavy metals that need care and replacement.

* It’s not a real product until it has a price tag, a warranty, and a track record.

* Early specs on the product make me scratch my head about whether the engineers even looked at the current renewable energy technology and how their product might interface with existing systems and gear.

* If the grid needs more storage, it is not your problem. Let the utilities solve that issue; they have a sweetheart deal with a profit-guaranteed monopoly – they can figure out any real storage problems. If you think you need storage personally, ask yourself the hard questions — how often and how long do you actually have utility outages, and do you really have critical loads?

* Perhaps the biggest drawback of the media focus on this prospective product is that people will get distracted from a true star of the renewable energy show — photovoltaics. Solar-electric modules are warranted for 25 years of energy production, and just sit on your roof or in your yard making electricity for you. They are ultra reliable, almost maintenance free, and will last longer than many of you reading this will live. My first modules went on the roof above me in 1984 and are still making clean electricity for my homestead.

* Perhaps the biggest benefit of the Tesla hoopla is that people will start thinking harder about renewable energy. Once they realize that this product is not magic, is expensive, and in itself really does very little for the average homeowner, they might start to ask smarter questions and make better energy decisions. Reputable and experienced renewable energy dealers and consultants are getting plenty of inquiries due to the Tesla hype; the wise ones are using the opportunity to help people understand the practical and cost-effective ways to achieve their energy goals. There is no silver bullet that can solve your energy problems quickly, easily, or cheaply.

Ian’s website is here.

In the United States (where Ian lives) they often have a Net Metering arrangement where the electricity they export to the grid is credited at the same value as what they use.  This reduces the incentive for storage.  But even when the exports are “lost”, as in “not credited to the householder”, there is not a big financial case for using a battery.  The latest new battery announced in the UK for example (article here) stores only a couple of kW hours.  Even if used to the full every day this would earn less than £100 over a whole year.  Batteries are expensive and they only last a few years.  Let’s focus on making renewable energy and investing in the equipment that makes the energy.

Posted in People, products/technical, wind systems tutorial | 5 Comments

Estonia workshop

Here are some photos of a recent workshop in Estonia.  They built a 3.6 metre grid tied machine from the Recipes. More galleries are here: ONE  TWO  THREE

“We are happy to report that we have successfully finished another course here in Estonia. Over the last 4 years this was now the 3rd course. This time, however, the project was not only aiming to educate the students to build a turbine, but also the final prouct was important as we had financing also for the tower, cabling and all electronics required for feed-in.

“It was installed in Ruhnu island harbour, on the South coast…primarily open to winds from E to SW. The tower is 12 meters high plus the height of the seawall (approx. 2 meters). We are expecting to see average winds from 5-6 m/s.

“An interesting fact is that the island is offgrid from the mainland in Estonia as it is quite far off. it has 2x150kW diesel generators providing power….and no other means (not even a single solar panel) – until now….now hopefully we can get at least 3000 kWh/year from the new wind trubine.

“Unfortunately, as it is sort of a one-off project, we can not really talk about a reasonable payback period (this is also because, diesel-generated electricity is sold to the islanders at a price which is equal to the price on the mainland). Even if the material cost for the turbine was about 700 euros, the cost of the tower (approx. 2200EUR), cabling and electronics (1500 EUR) and foundation (2000 EUR) costs make the project quite expensive (especially if compared with the price of a solar system).

“All the best Hugh and many thanks for the inspiration that continues to thrive across the globe,

“Madis and Criss from Estonia”

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Secondhand Proven 6kW turbines

Sangster Electrical in Fearn have a number of secondhand Proven 6kW wind turbines available.  Call 01862 832683 for details.

P1040220

Posted in UK small wind scene | Leave a comment

Scoraig wind turbine workshop 2015

P1040145

We built a 2F machine last week here at Scoraig.  There were 6 guys in the crew plus me.

Ghalib, Hugh, Brian, Svend, Brian, Laurence and Lukas.

Some photos of the sunny week.   Thanks to the guys for sharing photos….

Galleries:

Brian Davison,  Brian Falster,  Lukas Myl 

Posted in construction, courses, ferrite magnets, Scoraig | Leave a comment

2.4m machine on test in Greece

Kostas sent me a power curve and a video of a 2.4m machine constructed from my 2005 publication “How to Build a Wind turbine”from the NTUA test site in Rafina . It’s similar to the same size model in my Recipe Book.

“At a point during the measurement campaign, we had some extreme weather conditions and I thought we would not brake the turbine to see what happens. It operated continuously for as long as the extreme wind lasted, which was for more than 48 hours, operating in average wind speeds of 90km/h. The highest wind speed recorded by the anemometer on the meteorological mast during this period was 31m/s.”

robust

I hope soon to be able to publish more performance data from the tests that Jon Leary and I did in 2013.

Posted in performance, power curve data, Video links | 1 Comment