The best performing turbine blades the home builder could
make are carved timber blades. With timber you can achieve
a near perfect set of blades, but the process is very
labour intensive and requires some timber working skills. Timber is a very good blade material, its flexible and durable, to find
out how more about hand carving timber blades visit Hugh's web site.
There has been some development in
using large diameter PVC pipe as blade material. By
cutting a PVC pipe lengthways and reshaping the leading
and trailing edge with a file, you can achieve a near
perfect blade profile, and the process is so simple
you could make a complete set of blades is an hour.
You would need some large diameter thick wall pipe,
250mm diameter and 10mm wall thickness. A concern it
that PVC is a bit of an unknown for durability. UV light
will weaken the PVC and it may shatter, sending sharp
PVC splinters in all directions, so a safe operating
life of 2 years or less is expected. .
and cord need to be calculated to suit your windmill.
The blade profile is calculated
at stations along its length. The diagramme here also
shows the blade twist
You can download a blade
Its an excell spreadsheet so you will need to have Excell
installed ( part of MS Office ). The formulae used is
based on the work of others, so I cant guarantee its accuracy.
These are timber blades made
to Hugh's instructions by forum member Dennis Latham. A lot of work but good results.
A set of plastic blades
similar to those used on the Air-X range of windmills. They run at a very high speed. Diameter
is 1.5 meters and performance is very poor in low winds. Not recommended for a serious windmill.
PVC blades. These are the
easiest to make for small windmills. You can see the aerofoil
shape in this photo. Diameter is 1.2 meters.
The mini-mills blade is made from one piece of PVC. Diameter is 300mm
Timber blades made with a chainsaw? Another forum member Oz-tules developed this technique as a quick and easy way to rough cut the basic blade shape. Very effective and good results. More details here.
New on the scene are these extruded PVC blades. The blades use a well proven GE222 profile and work very well on turbines 200 to 2000+ watts. Details here.
If you just want to make a set of simple blades
to get your windmill going, click on the image below. It shows
how to make a set of blades from 18mm ply wood that might
not be as good as properly carved blades, but will work well