The far blade in the pic looks strange at the hub. The near and highest blade looks like the tip may be twisted backwards, and that will get worse as pressure from the wind increases, slowing the blades down. The tip should be angled the same direction as the root (hub area).
The diameter will have to be smaller too. Maybe 42" is what I would try, for no other reason than a gut feeling.
The hub looks OK, but I'm not too picky about that.
Don't expect much until the leaves fall, and the location still won't be very good.
I don't think all hope is lost. I am sort of surprized it made 3V like it is. G- [ Parent ]
And it wasn't whipping around. It was crawling by our collective standards. Wait until you see it with better blades! Scared the poo out of me the first few times.
CmeBREW has a pic that will give you an idea of how it should end up. His are tweaked for his purpose, but notice the root area where it meets the hub. His have a curve after that, which isn't needed. Also notice the tip of the far blade, and its angle. Best pic I could recall. http://www.otherpower.com/images/scimages/3274/leesonpvcblades2.jpg
G-[ Parent ]
That link to the pvc blades were my first version. I trimmed them down thinner to make them go faster here:
However, the diameter of these blades is 6ft. 10 inches. The 12v cut-in for the big DC motor I used for this prop was only 130rpm--- which is Much, MUCH slower than his 620rpm (12v) cut-in dc motor. Even though these blades are quite fast (not as fast as wood though) , they would be nowhere near fast enough for that motor the poster has.
I think he needs to get a better dc motor with a lower 12v cut-in. Also , I think the cogging is significant with his motor and very difficult to start up with a 4' diameter prop even with 5 thin pvc blades. [ Parent ]
The motor could be better. I am trying to get something from what is available, before he gives up. G-[ Parent ]
I could not see his photo of his mill anywhere. How are all of you seeing his photo??
I even went to his 'files' to try to find it, but no photo! No one ever said if his blades are pvc or wood?? I suppose pvc.
I also hope he don't get discouraged. I remember the frustration of only reaching 10 volts (so close, yet SOO far away!) in a fairly big wind with motors similar to that one. Maybe Flux's high speed blade design can get over that cogging well enough and make the extra speed needed. Worth a try. [ Parent ]
The blades on the test hub are far too wide at the root. Looking at them straight from the front, part of the back of the blade is visable. That is simply way too wide to work much at all.
Another look at the 1st photo makes me wonder how close the blades match. The better they match, the faster it will turn with a load.
The 80V with the drill turning it... What is the name plate RPM of the drill? G-[ Parent ]
I am quite confident they will reach charging voltage. I would expect charging to start at about 0.1875 x drill RPMs. The 0.1875 is from the drill test (15V charging voltage / 80V tested). But you never can tell if the motor knows the math! Many of mine do not.
I hope you learn something from it, and have fun. The next one is easier.
Great emphasis needs placed on the current site being VERY bad. It will need to be in a spot with nothing in front or behind. Or higher. I get nothing as soon as the trees bud in spring. Your trees look more dense than mine. G- [ Parent ]
I realize you are in "testing mode" but I have to mention that dangling cable is very likely to get caught in the prop if you don't secure it from flopping around as a big loop. Had it happen myself on a test stand it made a mess and ripped the cable and brushes right out of the Ametek I was testing. I didn't see it happen but the postmortem indicated it had yawed hard and the loop opened and did not follow fast enough and the blade hooked in the loop and the rest was simply physics.
You are coming along nicely. Getting rid of that curl at the root should help it speed wise.
Tom
"Education consists mainly of what we have unlearned."--Mark Twain[ Parent ]
There should be no extra drag with just more wire. Check for one wire touching another.
The bulb is a load, but it is almost a short as far as the windmill is concerned. Bulbs are not much good for testing a windmill.
When charging a battery, no current will flow until the windmill voltage is higher than the battery voltage + diode voltage. No current flow means unloaded.
There should be no current flowing before about 7MPH wind, or it will "stall" trying to make power that is not available in the amount of wind. Things will improve when the battery is connected.
You understand you need a blocking diode? G-[ Parent ]
Careful, now. If you go praising Ghurd too much, between that all the income from his controller he will not be able to get in or out of his shop with his swollen head.
Seriously, tho, he is a great contributor here along with many others, of course.
Luckily his newfound fame and fortune have not significantly affected his humility [YET]!
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