Update April 2012The 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.http://www.windstuffnow.com/main/vawt.htm
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