Blades - Limoux November 2004

Wind turbine construction course at Krug SARL, Limoux, France, 15-20 November 2004

BLADE CARVING PAGE

BLADES

Joris, Serge and Olivier.
We had some nice wood, although rather unseasoned. We did have problems with the tip warping on one blade.
In future it would be better to cut the rough shape out first and then leave the piece to change shape for a few days before cutting the all-important blade angle (drop).

3 metre diameter blade rotor for Limoux workshop November 2004

station	radius (from centre)	chord width	drop	thickness
1	250 mm	200 mm	45 mm	44 mm
2	500 mm	200 mm	42 mm	31 mm
3	750 mm	130 mm	15 mm	17 mm
4	1000 mm	100 mm	7 mm	13 mm
5	1250 mm	85 mm	4 mm	10 mm
tip	1500 mm	70 mm	2 mm	8 mm

Joël cutting the basic shape with a jigsaw. This is rather slow and we mostly used a circular saw.

Joris and Serge mark the drop using a spirit level. This is a good technique if the wood is not flat.

Here Manu and Guillaume use the same trick but with the addition of a nut at the leading edge to bridge over a hump.
They had to add the thickness of the nut to the drop measurement.

Serge and Joël using a vertical spirit level to check drop. Easier to read the ruler.

Joël uses a surform rasp to work the wood. It leaves a rough finish!

Extending the line that marks the thickness along one side of the blade.
On this trailing edge side, the line can only go so far because the piece of wood becomes too thin to mark the full thickness on it.
The calipers set the correct thickness measurement at the next station (in space) and Joël draws the line as far as he can.

Then he draws another line from that point to the end of the leading edge thickness line at station 1.
All the wood above the lines will be cut away up to the new line Joel is drawing.

In the end, what matters is that the blade should be the correct thickness at a point 30% away from the leading edge, and the back should be parallel to the front until it is later carved into a nice curve.