Introduction: VAWT Lenz Type. Stage 1. Converting Wind Power to Rotary Motion.
Update April 2012
The first and foremost thing I must to say is that Edwin Lenz deserves every single bit of credit for this turbine design. check out his website below, this build was based on his designs although I added my own outside the box style thinking to the build design and use of unconventional materials. The wings are basically exactly to Edwin Lenz design specs, with a sign design change to suit the materials I used.
I just discovered that the Intro Page has gone missing so I'm doing my best to re write it from memory, plus I want to tell how it has stood up to the weather over the last 3 years and what I would have changed if i was doing it again.
This was built to see how this new unique design compared to various vertical turbines, squirrels cages and savonious types just created to much drag at one side that just lost way too much power leaing you with very little torque.
The Lenz turbine on the other hand produced unbelievable torque, so much that I was unable to stop the axle from turning by gripping the axle with both hand while wearing welding gauntlets i just managed to slow it down, and on one occasion almost got a concussion as i demonstrated how much torque it had
This project was started mid 2009 a continuation of a failed squirrel cage turbine based on a design by Dan Rojas of greenpowersience on YouTube.
At the time I had limited tools and a very limited budget for material and was trying to think outside the box as to what materials could be used.
Unfortunately as a power producing unit its just now up to the challenge and the hash winter of 2010/11 pushed the envelope on the plastic sign board and one of the wings developed a crack along the curve of the wing.
The plywood is still relatively sound 3 years on but is starting to show signs of de-laminating due to moisture penetrating the wood. looking back in hind sight i would have coated the plywood with several coats of resin of some other very water resistant coating.
This design would work well in a warm dry climate, but unfortunately Ireland does not have such weather. the plastic skins on the wings became brittle and split along the tightest part of the curve on the wing in a freak cold spell last year when it reached -20*c, cold enough to snap a spring in my car in 2 places when I discovered a speed hump hidden in the snow.
The rolling design on the stand unfortunately resulted in me engineering myself into a few problems that would have called for a rebuild of the stand, this with a combination of health problems the project sort of dwindled out and finally got moved to a new position right out of the wind and has remained tied up since the skin on one of the wings split. At this point in time the project was shelved due to health problems from old injuries that started to really catch up on my as reached the age of 40, but thankfully I am on the mend and turbine projects are no back on the menu as I now have a fellow turbine enthusiast who is much less skeptical of the Lenz Turbine once he saw it flying in the slightest of breeze.
looking back at the design I would have skinned the wing with metal sheet either aluminium or galvanized steel, it increase in weight would not be a problem as it add to the flywheel affect and help even out the drops in speed when the wind is blowing in gusts. the bearings where rated for 25kg weight would have been able to cope with the additional weight.
Design wise i would have changed the following things if i had to do this again.
I would have gone with a single hub much like the picture that Slezridr posted below ( I have featured his comment) the double hub with and axle between the two using unconventional materials not best suited for my climate made it difficult to get perfectly true and the turbine has a slight tremor when spinning at high speeds.
I would have used allot more sealant and way more waterproofing as the plywood eventually started to get saturated with moisture and the glue starts to leach out and the layers start to de-laminate.
The the vertical axle design made it difficult to harness power without the use of belts of chains (chains do mot like to be mounted on a horizontal axis)
I would have not used plywood and plastic sewer pipe for the hubs and central support axle, I would have gone with metal hubs and a metal axle, My skills with wood at the time of this build was not the best and I feel that i was really pushing the envelope as to the limitations of plywood and plastic, remember this turbine wieghs aout 20kg and can spin at 120rpm, no wonder my 80+ year old parents where concerned about it shaking its self apart.
Over all the build was a success, I am totally sold on the idea of these turbines and will never go back to horizontal or any other type of VAWT. The torque thee turbines produce is just astounding, and yet they are silent and work perfectly with the wind coming from any direction. They seem to have an upper speed limit of about 120 rpm at which point they go into an auto stall so you dont have to worry aout it spinning out of control on a stormy day, I read somewhere that winds needed to destroy one of thee turbines would the kind that would rip the roof of the house first. Also they have no need for a large tower and seem to work perfectly at round level, I had my turbine located in the sweet spot between 2 buildings that created a wind tunnel affect as the air bunched up on the buildings to get through the gap. the bonus of haveing a turbine ar almost ground level means you can work at it and maintain it without the need to climb a tower to grease bearings and do maintenance.
My health is now thankfully starting to improve so I am again starting to scribble new designs for a complete rebuild. The next turbine will be built to a much higher standard as I a much better range of tools and access to a wider range of specialist tools and have also found a source for better quality materials at almost scrap prices.
Although this project has now passed the point where it can be redesigned to produce power, I may have found a possible home for it and it may yet be able to serve another purpose with some slight modifications. so you never know so watch my profile and you may see it being put to a new use.
Thanks for looking I hope you find this Ible a useful reference on your own turbine build.
Please visit Edwin Lenz website http://www.windstuffnow.com/main/vawt.htm
Step 1: The Wings
I picked up the plans for this design from www.windstuffnow.com one of the best sites i have found on DIY Vertical turbines.
The plans i used where based one the ones found here http://www.windstuffnow.com/main/lenz2_turbine.htm
The wings are made of the following.
3/4" plywood for the ribs. 9 in total
1" x 1/2" by 1mtr pressure treated timber for the spars. 9 in total.
reclaimed plastic sign boards, 3mm solid type.
approx 300 5/8" No6 pozi wood screws
Approx 300 No6 nickel plated cup washers.
Also used Gorilla glue, Tech 7 adhesive sealant and hard gloss exterior paint.
Step 2: The Ribs, Cutting Out
I first printed out paper templates for the ribs, I trimmed these down to size and prayed the back of them with 3M low tac spray mount.
This allowed me to get the maximum yield from the scraps of 3/4" plywood boards I had.
These where then cut out using a band saw I cut to about 1mm from the lines on the curve and followed the line on the straight edges.
The curves where then finished off on the table sander
Once the ribs where all shaped and finished on the sander I used a fret was to cut out the notches for the spars.
I used a pillar drill to drill the holes to attach the wings to the metal arms of the turbine. Only the 6 of the ribs and drilled, these are the ones used on the ends of the wings.
Step 4: Assembling the Frames.
The spars where then glued in place with Gorilla glue, I used Gorilla glue as it expands into any gaps that are left when you fit the spars.
I also drilled each joint of the wind and used a 1 1/2" wood screw to give the joint extra strength.
PS. a tip to the wise, if you use Gorilla glue where old clothes and disposable gloves, I didn't and ruined a shirt and had glue (and the dirt stuck to the glue) on my hands for about 3-4 days.
Step 5: Painting the Frames.
After the wings where assembled they where given a rough sanding and any holes inthe edges of the plywood where filled, they where then painted with a hard exterior grade gloss paint.
This is a tedious part of the build that you may want to skip and do later but I would advise you to take your time and do it now and do it properly at least 2 coats, the better this is protected from the elements the longer it will last
Step 6: Skinning the Wings.
Now the tricky bit.
Sorry for no pics of this stage.
First I fitted marked out where the screw would be on the ribs and spars, the screw are spaced at 2" intervals. I used a awl to poke hole through the plastic where the screws would go.
I then used Tech7 adhesive along the edges of the ribs and spars that would be in contact with the skin. at this stage only use the adhesive on the straight edges.
Stating at one of the corner edges i fixed the skin in place then clamped the skin to the frame before adding the rest of the screws, each screw has a cup washer this will give good grip on the plastic.
Note: try and find a cup washer that is not cupped to much, I got some brass ones that had parallel sides they cut into the sheet to much when the screw where tightened, I replaced these with the nickel which have a much less aggressive hold.
Once the flat part was skinned I then added adhesive to the curved edge and clamped the skin into position round the curve before screwing it in place.
This job can be done single handed if you have a good set of clamps, a second pair of hands would make this job a lot easier.
Step 7: The Hubs.
To make the hubs I first glued 3 7" squares of 3/4" plywood together with Gorilla glue.
The pieces are glued with the grains of each piece running at 90* to its neighbor.
These blocks where fitted to the wood lathe and turned down so they where a snug fit to the internal diameter of the piece of sewer pipe. A 6mm hole was drilled in the center of the block when it was on the lathe.
I drew up a template for the ends of the hubs where the metal arms would attach. 4 in total.
The pieces where cut and finished as on the wing ribs. 2 of the plates where recessed so that the metal arms would be a snug fit.
These pieces where then Gorilla glued to the hub blocks and the arms fitted and bolted up.
This is one of the hubs fitted with the metal arms.
The arms are 500mm lengths of 20mm x 6mm flat steel bar, I got them from a local steel works who cut them to length for me. the 6 bars cost £3 and is about the cheapest and simplest way to go.
the arms where marked out and drilled on the pillar drill then corners where ground and they where then painted with a rust killing metal primer.
Again I could have skipped the painting until after assembly but the better the job is done the longer it will last.
The picture shows a completed hub and the cross section of the other one.
I used 6mm cup square bolts and nylock nuts and washers to bolt this all together 110mm for the center of the hub and 50mm for the outer edge.
Once the hubs where fitted to the pipe and the ends aligned the pipe was drilled and 2" wood screws where used to attach the hubs to the pipe.
the wings where then bolted in place using 30mm cup square bolts and nylock nuts.
Step 11: First Test Assembly.
The usual story in wind turbine builds , the day you assemble you turbine for testing there is no wind what so ever!
The following day a nice breeze picked up, the turbine self started and was spinning nicely with a lot more torque than the previous build.
But as the wind started to pick up and I found that the increased head load of the new turbine was causing the frame to flex quite badly.
At this point I decided to dismantle the turbine and reinforce the frame. Good job too as the following few days brought a day of seriously strong winds that where strong enough to bring down a tree not far from my house.
The following few pics show the building of the stand and its later upgrade.
Step 12: The Stand.
This is a pic of the stand as made for my first VAWT project, this is being reused but required some modifications to make it suitable for the new turbine.
The stand for my VAWT was made from lengths of old lorry chassis that was in the scrap heap. I was working with what was at hand so i will not give dimensions other than its about 1mtr tall and the base is centered around the axis or the bearings.
The upright beam is 3" x 1" x 6mm channel iron again from scrap.
The cups for holding the bearings are just cuttings of pipe that the bearing where a nice fit for and are welded to the frame.
The stand cost approx £35 to build 2 years ago, this was due to the cost of bearings and a 1mtr length of 25mm rolled steel bar at a time that steel prices where very high.
There is a taper roller bearing mounted in the top cup and a standard roller bearing in the bottom.
The frame was buffed free of flaking rust using a flap disk in an angle grinder and painted with 2 coats of a rust killing primer and then 2 coats of agricultural oxide.
It may not be pretty but it does the job.
Step 13: The Previous Project. Looks Nice But a Epic FAIL Sort Off.
This picture shows the old Squirrel cage type turbine I built a year or so ago from Dan Rojas idea on www.greenpowerscience.com. this link
I posted this pic to show the 25mm shaft in place.
It worked but is not very efficient. just to much drag and was also a bit wonky due to me rushing the job and not having the knowledge or experience of working with wood.
It made a good conversation piece and a nice ornament and that's about all. I had a dynohub attached but it was only producing a few volts 3-4 to be exact. But this proved that it was indeed possible to make my own power.
I learned that the tolerances needed with chain drives where more than I was capable of back then and that chain drives don't like being mounted on a horizontal plane.
I learned to take my time and do things right rather than rushing and botching up things just to be making progress.
[UPDATE April 2012] Just checked Dans site again, still no update on any of his wind turbines, Dan talk the talk OK but fails walk the walk and to take projects to completion, he gets you interested and then just leaves ya hanging none the wiser how the project turns out. but then when you see his wife you can understand why he has trouble focusing for anything to long. ;-)
But seriously Dan I have waited for over 2 years now for you reveal the secret how you where going to control the air intake on you 2 stroke engine to steam conversion using of the shelf parts I copied his method and had it all sitting ready for the secret to be relieved and a waited for over 2 years and still nothing and finally got so fed up looking at the rig that i scraped it so i could put the scrap value into something else. Come on Dan try harder to see things to completion, ps. if you do see this Dan I seriously want to see that project finished.
Step 14: Stand Upgrade.
The bottom bearing was also locked up due to dirt getting into it, I have replaced this bearing and am going to make a simple dust guard to help stop dirt getting into the bearing.
I found some lengths of T section iron in the scrap heap and welded then to the frame the strengthen it.
Once welded I power hosed the frame and primed and painted the new ironwork.
I now plan to use these supports to box in the stand to give me a rain proof enclosure to mount the generator and electronics.
I plan to add some heavy wood sleepers to the base to make it a bit wider and more stable and also help make it easier to be moved out of the way.
This is a close up of the flange that attaches the turbine to the axle.
It was originally bolted on to the axle, but this time I welded it on to remove a little bit of slap that had started to appear in it. An agricultural engineer made this flange for me and the tolerances he used where a bit agricultural too ;0)
The turbine is attached to the flange using 110 mm cup square bolts and nylock nuts.
The roller taper bearing in this cup carries the weight of the turbine and axle, the roller bearing in the bottom cup just keeps the axle centered.
Not the best design but it was what I could build with what I had available.
Its a little awkward if you need to remove it as you have to make sure you don't knock the bolts into the inside of the pipe. But then I don't intend to have to do that often.
I kept the hole in the axle as it will come in useful as part of a locking mechanism I want to incorporate with the design. I want to be able to lock the blades of if the winds get to high or is the turbine has to be moved.
A simple but effective way to keep dirt and grit out of the bottom bearing.
I cut the parallel part out of a Dr Pepper 500ml bottle this was a nice push fit on the bearing cup, I used Tech7 to stick the bottle onto the cup.
the upper shield is the top of a 2ltr drinks bottle split down one side and held in place with duct tape, this is a temporary measure
I did not plan to paint all of the turbine but there was so many blue fingerprints and scuff marks on the plastic I decided to use a paint roller and give the whole thing a coat of paint.
The paint will help protect the plastic from the UV light of the sun, I don't know how well this plastic will hold up to direct sun light.
Once it was painted it no longer has that made from scrap look.
Step 18: Stage 1 Complete
The VAWT assembled and running once more.
The turbine self starts in the slightest wind and runs smoothly and silently.
I have not had a chance to do any to get any stats on rpm in various wind speeds yet
This is stage 1 of my over all project completed.
Cost of overall project to date approx £60 the stand costing about 35 for the costly but needed axle and bearings, the turbine came in around £25 and that was mostly on consumables and fixings.
The next stage is to convert rotational power into electrical power.
I will post an instuctable for stage 2