Chispito Wind Generator

Step 3 BLADES

Cutting Blades - makes 9 blades (or 3 blade sets) and a thin waste strip.

1. Place the 24" Length of PVC pipe and square tubing (or other straight edge) side by side on a flat surface. Push the pipe tight against the tubing and mark the line where they touch. This is Line A.
2. Make a mark near each end of Line A, 23" apart.
3. Tape 3 sheets of A4 paper together, so that they form a long, completely straight piece of paper. Wrap this around the section of pipe at each of the two the marks you just made, one then the other. Make sure the short side of the paper is straight along Line A and the paper is straight against itself where it overlaps. Mark a line along the edge of the paper at each end. Call one Line B and the other Line C.
4. Start where Line A intersects Line B. Going left around Line B, make a mark at every 145 mm. The last section should be about 115 mm.
5. Start where Line A intersects Line C. Going right around Line C, make a mark at every 145 mm. The last section should be about 115 mm.
6. Mark each line using a straight edge.
7. Cut along these lines, using the jigsaw, so that you have 4 strips of 145 mm and one strip about 115 mm.
8. Take each strip and place them with the inside of the pipe facing down.
9. Make a mark at one end of each strip 115 mm from the left edge.
10. Make a mark at the other end of each strip 30 mm from the left edge.
11. Mark and cut these lines, using the jigsaw.
12. Place each blade with the inside of the pipe facing down.
13. Make a mark along the angled line of the blade, 3" from the wide end.
14. Make another mark on the wide end of the blade, 1" from the straight edge.
15. Connect these two marks and cut along the line. This prevents the blades interfering with the others' wind.

Sanding the Blades
You should sand the blades to achieve the desired airfoil. This will increase the efficiency of the blades, as well as making them quieter.

The angled (leading) edge wants to be rounded, while the straight (tailing) edge wants to be pointed.

Any sharp corners should be slightly rounded to cut down on noise.

Comments

[goldpen]

Good project but the instructions in this page could be a lot clearer, or illustrated with some photos

[Asmodeo]

This weekend, following this instructable, I did a little one, using a Hard disk motor, and 30cm long pvc blades......It was a piece of cake, and, curious about how well It would spin, I took It to the backyard, where We had a 15 km/h wind, steady.... I supported the motor in my hand (ERROR! ERROR!) , at an angle 90° away from the wind, and slowly turned It winward.... There began the wildest 30 seconds of my life!!!The blades took such a spinning velocity in a matter of seconds, that I thought my fingers were in big trouble. Turning the apparatus away from the wind helped...a little...but It was still spinning furiously until "hand brake" was applied (I pushed the blades to a little bush). This saturday I will make a supporting pipe and take some readings. I'll never "bare hand" support one of those again.

[alcubierre]

what formula do you use to get the proper blade size for the diameter pipe that is used? if i wanted to make larger blades for instance, how would i determine how long of a piece i could get out of a specific size pipe and still have it perform well? also, without having to much or to little twist in the blade?

[ciaagent]

here is a link to a site that explains it:
link

[ciaagent]

The diameter of the pipe is 1/5 the length, Example: if the pipe is 50cm long, the diameter has to be 10cm. Hope hits helps :)