Science Buddies: "Ask an Expert"

I making a windmill for my science project it mostly made out of balsa wood, cardboard and toothpicks. I need help though I used three sheets of construction paper to make the fan blades and put it against the fan, the windmill's fan didn't turn at all I think the magnets inside the generator are too heavy for it too spin

but please help I don't know why the fan part of the windmill won't spin
I don't know what to do to make it spin.

Hello Esosa233:
I see that you've created a hypothesis that you'd like to test using a windmill test setup - that's great! Your project sounds very interesting and you should be able to come up with some very good results.

On the problem you mention, that the windmill isn't turning when exposed to wind, it's hard to figure out, over e-mail, what the problems could be. Here's some items you should check:
- Does the rotor turn easily when rotated by hand? You mention that the generator's magnets may be stopping the rotor from turning. For initial tests, you may want to have the windmill rotate freely as connecting it mechanically to a generator will definitely require the windmill to overcome the generator's inertia and magnet forces.
- Are the blades, where they're mounted to the hub, angled against the wind? The choice of this angle is very important and to reduce the test variables, you should keep this angle the same for your different blades.
- This discussion on an earlier Science Buddies forum may be useful to you:

https://www.sciencebuddies.org/mentorin ... 95&p=16548

- It's important that your windmill rotor be balanced and that the blades don't flex when exposed to wind conditions. You may have to try different grades of cardboard or plastic to find a material that's readily available to you, inexpensive, and sufficiently stiff to prevent unwanted bending.

Good luck on your project!

My fan blades are at a 45 degree angle against the wind they don't bend but I'll try cardboard anyways, it doesn't turn easily though its very annoying it's because I used soft metal rods that bend at the slightest touch there weren't any other type of rod there, and only other rod-like thing I have at home is noodles, unless I tape toothpicks together into a pole. So I'm pretty much stuck... Is there any other thing that you guys know that would be in an average house that I could as a pole... the earlier discussion didn't prove much helpful since I have already conducted my research. I'm getting worried because school is starting tomorrow and I don't know when the project is due...

Can I assume that the "pole" you are referring to is the main shaft of the windmill, the long axle that rotates and holds the blades? If so, I think a reasonable choice for a shaft would be a hardwood dowel that can be found in most hardware stores. Various diameters are available and these usually are 24 to 36 inches long, more than enough for your project. The cost should not be that high for just one piece.

Thanks for the dowel idea

I'm building a simple generator for my windmill and after fixing my windmill with a wooden pole instead of a metal one I am having extreme trouble putting magnets on the pole so that one side of the pole would be N while the other side will be S I need to put it so that the magnets in either side of the pole are facing each other equally and their N and S side are facing totally different directions this is so frustrating especially since I don't how to explain my problem , thats the generator I'm trying to build: http://www.eskimo.com/~billb/amateur/coilgen.html

But instead of a nail would be a wooden pole connected to fan blades , I am having trouble getting magnets to stay on the pole I have four high power magnets just weak enough not to break bone, these four magnets are small and cylindrical and split into three smaller magnets. Please I am running out of time the project is due by the end of this week and I haven't started doing my trials. I have cardboard, construction paper, wood glue, duct tape, please help,

Hi,

Have you really looked at the site you provided? The CONSTRUCTION topic has a really good video of the construction process which I would think you could follow:

http://amasci.com/coilgen/generator_1.html

I don’t understand your question. The only possible problem I could see would be the relative orientation of the magnets. I suspect from what I saw the magnets are aligned to they attract each other. You can also look carefully at the DEBUGGING section, which discussed relative magnet orientations.

If you still can’t get your version to work try building exactly the website version. When that one works you can try to incrementally modify it to the version you want.

Good luck!

Barrett Tomlinson

I was able solve my problem, but I need a way to record my information, I planning to do my trials by putting my windmill against a fan for 30 sec. How should I save my information as? Should I save it as average voltage made per second? The median of the volts made under the 30 secs.? The mode? The Mean? Tell me how I should do my trials, my teacher wants my project in by thursday... And also what type of graph would I make according to the information? (I was planning on writing the average voltage made each second, and making a line graph of each voltage made each second)

Hi esosa233,

The data that's meaningful is the total power generated under the different scenarios. A simple bar chart would fine, with a bar for each of the different scenarios.

I don't think per second data is meaningful, only the thirty second total power.

Note:I was unable to find the project description. What's its URL?

Hi I combined your topic with your previous topics. Please keep new posts in this topic by using the "Post Reply" button. This will help the experts keep track of what you are doing.
Thanks!
Chris

Im confused about writing the total voltage, I connect my windmill to a volt meter and everytime the fan turns it displays numbers of voltage like it would say 0.001 one second the next 0.008 or 0.011 it changes per second, so should I add the changes of voltage together so I can get the total voltage made?

I'm assuming you constructed an AC generator as described in the URL earlier in this thread (spinning magnet(s) inside a coil). If not, we need to know what you constructed.

it displays numbers of voltage like it would say 0.001 one second the next 0.008 or 0.011

What scale are you using? I'm guessing that you are using a DC voltage scale and your generator is producing AC. Try utilizing the lowest AC voltage scale and see if you get better readings.

If your reading is still down in the noise (less than 0.01 volts) with the AC voltage scale, we need to know how many turns of wire and how strong your magnets are and if they are alligned so that they alternate between North and South poles as they rotate.

Just measuring the voltage being produced is not an indication of how much power is being produced. You need to somehow measure both the voltage and the current at the same time. One way to do this would be to use a load resistor. If you purchased a 1000 ohm, a 100 ohm, and a 10 ohm resistor, you could measure the AC voltage across the various load resistors and calculate the current and power being consumed. You could then figure out which load resistor was able to take the most power from your windmill generator. You could then determine if you needed larger or smaller resistors or ones in between these values to maximize the power being transfered into the load.

Given that you are on a tight time schedule, it is going to be hard to get a good power reading for what your windmill is capable of producing.

It should be AC the voltmeter's setting is on DCA/ 2ma I think that should be a good reading when I give the windmill a full turn by hand it reads 0.100 or so, but against the fan it reads that low because of how slow it turns, I didnt follow the website's directions step by step I used high powered normal cylindrical magnets not the ones they specified so it makes less electricity yes its AC but how would I get total power made then....
Im pretty sure Im not going to be able to get a resistor on the fact that I really dont know what that is or how it would look like... is there another way I could do it? please hurry its due soon!

The simplest method of measuring power generation for this kind of project involves a resistor. Yes, there are other methods, but coming up with the equipment would be even more difficult.

Is there a Radio Shack store near you? If so, you should be able to obtain a few resistors. See http://www.radioshack.com/search/index. ... stors&sr=1 and subsequent pages. Part # 271-1321 is a pack of five 1000 ohms, 271-1311 a pack of five 100 ohms, 271-1301 is a pack of five 10 ohms, 271-131 is 1 ohms. You should end up spending about 5 dollars plus tax to acquire these if you are near one of these stores.

You have already noticed that the speed at which the blades turn affect the RMS (root-mean-square or short term time average) voltage (electro-motive force) produced by your generator. How many magnetic poles are you using? If it is only two (one north and one south pole that are 180 degrees apart), then you could increase the frequency of the voltage wave being produced by adding another pair of north and south poles (you need 4 magnets) so that you have a sequence of N-S-N-S at 90 degrees. This will double the frequency and for low speeds should more than double the RMS voltage and probably quadruple the power generating capability.

But its a windmill, I made it so that the fan part of the mill is directly connected to the magnets, the heavier the magnets are the harder for the windmill to spin, I tried what you said before these are high powered normal magnets so it turned disasterous, besides if I add more magnets my windmill probably wont spin, my teacher said to just average them out

Thanks a lot I was able to finish my project especially with you guys help, Im really grateful for this site because I wouldn't be able to do a decent project without it!

The thread is a bit old but the information are very relevant. Students can also use some of the ideas in making projects using fans. We will appreciate is you will post the outcome of your project here. You just have to remember the basic principle of all mechanical fans which is the rotating arrangement of the blades and it should be powered by electric motors. Ceiling Fans