Dear Friends
Part - 4
As previously mentioned this 4th Part will present and shortly discuss - horizontal rotors, super fans, and sail windmills.
For me it is very clear that there is no one technological design solution to the design and utilization of wind power - several different designs all have their different advantages under different conditions.
I fully agree with what Mr Paul Gipe states in his book "Wind Power" USA 1993 - ISBN 0-930031-64-4:
Rule nr. 1 [for wind turbines]: "They must be reliable"
Rule nr. 2: They must be cost effective"
"Efficiency is important, but is not the sole criteria, for judging the performance of a wind machine"
Section A - Horizontal Rotors:
First of all the question of terminology - these designs are often called VAWT's - "Vertical Axis Wind Turbines". However I prefer to follow the historical terminology and as also presented in the classic treatment of these designs in the rare book:
"Horizontal Windmills, Draft mills" by Engineer and Scientific model-maker Greville Bathe, Philadelphia USA 1948 - and therefore the use of the terms:
"Horizontal Rotors" for these designs and "Wind Turbines" - for the "normal" 3-bladed electrical power generating [HAWT]designs - thereby keeping everything short and simple and non-confusing.
During the 1970's there was a great interest in these designs and much how-to-do literature was published [those who are further interested in this may send me a mail]. In recent years there has been a growing interest - especially for power supply in urban environments etc. I have previously written a paper in 2002 specificly on this subject of "Stealth Wind Turbines" - a link to this will be found on the server.
It is my considered opinion that the different "Helical-screw Vertical Axis Horizontal Rotor" designs from Finland possibly offer the best combination of track record, adaptability, and discrete reliable power production combined with robustness and longlivity.
http://www.windside.com
http://www.shield.fi - makers of the "Aiolos" horizontal rotors
My good friend and colleague Mr Hannu Virtanen - has on several occasions drawn attention to the work of Prof Johnson from the USA discussing the power potential of horizontal rotors - [likewise see the different links on this server]
Also a further interesting paper by three Russian researchers - Gorban, Gorlov and Silantyev - http://mystic.math.neu.edu/gorban/Gorlov2001.pdf - should be studied. An unusual newer German varient of the helical rotor flow-through design can be seen:
http://www.windwandler.de
Perhaps the best modern book of interest for readers of this board - is once again only available in German and is likewise highly recommended:
"Der Savonius Rotor" Heinz Schulz Germany 1989 - ISBN 3-922964-48-6 - available from
http://www.oekobuch.de - for 7.60 Euros
Heinz Schulz is the director of the "Agricultural Technology Institute" in Bavaria, Germany and this book presents fully-detailed drawings for several interesting large and tall rotors. I include as an example an overview of a 3-rotor 4.4 m. model
However nothing beats the work by a good friend from Central Finland - Mr Erkki Nousianen M.CI & M.WT [Master Craftsman-Inventor and Master of Wind Technology] - who has built possibly the world's biggest/tallest home-made horizontal rotor from redundant paint tins from the VALTRA tractor factory.
Section B - Super Fans:
These designs have previously been discussed however the only person in recent times to have designed and produced these models in significant numbers is designer, millwright Claus Nybroe from Denmark:
http://www.windmission.dk
I include a drawing here made from a photograph that I have taken
The smaller drawings show an 11 kW model while the larger drawing shows the hub construction and the placement of the blades from a smaller model.
I am convinced that these type of blades with their stabile power production under many different conditions are a very fruitful path to follow.
Section C - Sail Windmills:
Likewise during the 1970's and 1980's much material was published concerning sail windmill designs - among these I will emphasize the quality and usefullness of the following two books:
"Water Pumping Windmill Book" - Gary Hirshberg - The New Alchemy Institute USA 1982 -
Lib. of Congress - TJ825.H46 621.4´5 82-41-4138 ISBN 0-931790-23-9
"Construction Manual - for 12PU350-12PU500 Windmill" Niek Van De Ven - The Netherlands 1982
This design has been produced in several countries - India, Pakistan and also Afghanistan.
Because of the great relevence of this sail windmill technology [and likewise consider how the good work done by Prof Crome from the TU in Bremen - as mentioned in Part - 2 fits into this picture]; -
Together with other friends and colleagues - during the early winter of 2001 we conducted extensive low-cost hands-on experiments in Central Finland financed from official Finnish development funds into these designs - experimentation with the fabrication of oil-soaked wooden bearings etc. in attempts to "re-discover" the technology.
There was great interest for many sides in this study and several groups of farmers drove down from N. Finland in their pick-ups to further discuss with us.
We were convinced as a result of these experiments that the large quantity of most of the available literature are perhaps lacking - as concerning several significant details of this simple and robust technology. I therefore took a long field-trip to Crete in 2002 - [As yet my paper has not yet been finally finished - However those who are further interested may contact me]
I include some of my photographs shot on that occasion:
Please note the very large power potential, likewise note the construction of the tower construction and turntable design etc.
Finally I will close this 4-Part series of simple blades and rotors by a future further "Diary entry" which will shortly discuss possible future technologies, uses and tendencies in "Rotors".
With best wishes to all - JF
