These blades are for experimenting with the blade angle. They are not designed for any "lift" effect. But they are a bit airodynamic since they are taperd a bit out to the ends of the windblades (this helps reduce the "drag" forces on the outer areas of the windblades since they are going faster - even though the angular velocity is the same)..
The plastic is 1/8 thick. I'm not sure yet if it's too thin. If it is, then maby 3/16 or 1/4 would be ok. A fix for the 1/8 blades would be to glue/melt a strip of 1/8 plastic down the middle of the blade.
Note, when I heat the plastic, I do not put it into directly into the flame. I put it into the heated air above the flame. I do not melt the plastic, but only get it hot enough to bend. You might want to practice on some scrap pieces first. I drew the blue guide (melt and bend) lines with permanent marker ink (can probalby come off with some cleaner). Also, some cans are coated with some material, so you may wish to avoid some possible smoke/fumes from that.
As an extra note, it seems alot of modern plastics shrink a bit when heated, so it probably makes it more dense in that area, however, it might make it more brittle as to bending. This is something to think about, so you don't want to be heating your plastic too many times.
I hope the blades are long enough. The are about 12 inches plus the tip angle piece of 1 inch. I figured if they are not long enough to get some rotation going, I made 2 more blades, for either a 3 or 4 blade design if I need more power.
Later, I did round the tips of the blades to about 1/4 inch diameter round.
You need not bend the blades like I did. You can just bolt them onto some anchor/hub at some angle, probably won't be able to adjust the angle if not designed to do so.
Around here, we get some "good winds" about 1 in 5 days on avereage, and sometimes several days straight. It might be a bit difficult to test the blades; probably have to hook a fan up for now.
I understand most people don't have a bandsaw (just like I don't have a drill press), but it is possible to score and break the plastic much like glass cutting, but it takes a bit more practice maby. Table and jig saws are possible, and then some kind of handsaw might work. Still, it seems a dill, especially a "drill press", is something we all should have for making many projects.
It's probably even possible to make some kind of ceiling fan with blades like this. Thats if you have a very slow motor or one where the speed can be effectively reduced by using gearing (including pulleys).
I estimate and have heard blade angles being about 30 degrees at the hub to about 7 degrees at the tips....however I'm not sure if this is meant for blades where the "width" is constant out to the tips or is it aplicable to blades that are tapered out to the tips. And then what is the optimum taper (angle or percentage) for blades that are tapered. I got some good clues about this and a "theory". When the wind speed, which effectively inclues the windblade speed, doubles (2), the output power (ie. from the generator) goes up by 8 (essentially cubed - ie 2 to the 3rd power). At twice the distance along the blade (of fixed width and blade angle) then from any point, that part of the windblade will have 8 times the force, hence it should be half the width. This is my theory for now, and if anyone wants to validate, correct or explain their theory let me know and it would be grealy appreciated by the windpower community. As indicated above this is not an analysis for compound pitch blades...blades where the angle varies along its length, however it might eventually apply slightly.
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pvc wind turbine out of drill 2by doug287720,955 views
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