Wind turbine Day 8

_ Day 8

Now for the mounting of the blades, I’m thinking that it would be best to support the blades with some thin flat steel. The blades seem fairly strong without it but I also have a healthy respect for the power of the wind so a little reinforcing should help in gusty conditions.

I had originally thought that mounting the blades was going to be fairly easy but there are many things to think about. If I overlap the 3 blades then each blade will be slightly further out than the previous one & I don’t know if that makes any difference to the air flow. Plus should I mount the blades from the very centre nut or have them mounted further out, again another airflow problem. If I mount the blades on some flat steel bar then should the bar be behind or in front of the blade or sandwiched between 2 pieces of flat bar, I need to consider the airflow & do I also need to consider the weight.  Many questions & I also need to think about how to keep the blades at the right angle relative to each other (120 degrees).

Sounds like it’s cup of coffee time again & a good think about what’s best.

It’s very cold today in the workshop, I briefly heard that it was the coldest day on record or something like that, the coffee helped but I need to do some work to warm up.

I’ve made some decisions & I think having the blades meet in the middle would not be good for the air flow so I’m going to mount them on steel bar a bit further out. Sandwiching the blades between 2 flat bars would be overkill because the bar is 4mm thick & it is fairly rigid on it’s own. I’m going to mount the bar at the front of the blade, I would prefer mounting at the rear but due to the 50mm width of the bar & the nature of the curved blade, it would create a large wind pocket on the back that would slow the blade. Even mounting the bar on the front of the blade means that when fixing the blade to the bar the blade will have a tendency to be squashed a bit flatter than I had anticipated. I think next time I will use a narrower piece of flat steel which should overcome that problem.

So I’ve cut & drilled the bar as per the photo & mounted them, they look great.

I’m thinking about adding a few more fixings to keep them at the correct angle to each other, not exactly sure but I’m far too cold to think about it any more today.

This shows the dimensions of the flat metal bar & how it was fixed to the blade.

A close up of the dimensions.

Another close up, don't forget that you can enlarge any of these pics just by clicking on them.

Showing how the blades are mounted to the motor, once I got the angle correct I drilled 4 fixing holes to secure the blades to each other with a few bolts.

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