Introduction: Cardboard Savonius Wind Turbine

Picture of Cardboard Savonius Wind Turbine

Goal: build a Savonius wind turbine made out of cardboard to see what
works. This is for the turbine only and not the generator itself. The main photo you see is the goal.

The need for a working model grew out of frustration trying to
jury-rig various designs of a Savonius turbine that in the end would
not turn at all in the wind.

Some Initial Botched Designs
Shown below are several botched designs. All four are attached to the drive shaft of a 24-volt DC battery-operated lawn mower. The vertical bar you see is an allthread bar that is attached to the motor shaft. The galvanized metal is half of a dryer vent tube. The first design would turn half way and then stop because of the resistance of the back side of it coming into the wind. I then added a top disk and attached a number of 2-liter soda bottles and some 1-gallon milk jugs to a disk on top. With a stong wind I actually got the mill to spin if I gave it a start. It has to be the ugliest windmill ever.

The second design is all cardboard and looked really sharp. it didn't budge an inch in a very strong wind.

In the third one I added parts of the dryer vent tube to the cardboard mill and that worked a little bit but there was resistance on the back side coming into the wind.

At this point, I decided that I had to go back to the drawing board with a simple model to see what had a chance of working.

Step 1: Materials Needed

Picture of Materials Needed

The following project took me one hour from conception to finish and I
was making design decisions as I went along. I was amazed that it
worked perfectly. I guess it should work perfectly because it is the
design described in a number places. Of course, the coffee can and
soda bottle designs were said to work but didn't for me.


Materials:
a. A large piece of heavy-duty cardboard box
b. 14-inch dowel (or knitting needle, or something similar) to serve as an axis rod
c. 2 small rubber bands
d. Duct tape or electrical tape
e. Hot glue (optional)

What you see in the photograph are the pieces you are going to cut out of the cardboard. You can also see the knitting needle with some rubber bands on it.

Step 2: Make the Vertical Paddles

Picture of Make the Vertical Paddles

Cut 4 strips of cardboard 4" x 10". These will be the vertical
paddles that catch the wind. Cut two rectangular notches in each
paddle. Each notch should be 3 inches long and just wide enough that
the disk will fit in snugly. These notches will be located 1 inch from either side of the ends of paddles.

Step 3: Cut the Top and Bottom Disks of the Turbine

Picture of Cut the Top and Bottom Disks of the Turbine

You will need to cut two disks 10 inches in diameter. Since I flunked kindergarten, I found this somewhat of a challenge. Trying to draw a true circle without a decent compass is tricky. Then after you have drawn it and cut it, finding the true center is also difficult. Here's an easy way to do it.

1. Cut a 10x10 inch square of cardboard.

2. On all four sides make a mark half way between the edges. That mark will be 5 inches from the corners on each side.

3. Use a ruler to draw lines that connect opposing 5 inch marks through the center of the square. Where these lines intersect, that's will be the center of the circle.

4. Use a compass if you have one and jab it into the center and expand it out to end of one of the radius lines. Now draw a full circle with the compass. I'm not sure school compasses are big enough to do this. An alternative might be to get a ten-inch bowl or something like that and lay it over the square and trace the lines. You can also simply eye-ball it and make an arc from the center of one side the the center of the next. You may not get a perfect circle but I don't think this is too critical for the model we are making. In the real thing it may throw off the ballance.

5. Now cut the circle.

Step 4: Draw Angle Lines on the Disks

Picture of Draw Angle Lines on the Disks

Now for a little geometry. Take a look at the first image. Notice that there is an Angle A and sides a, b, and c. Side c is the line that we want the paddle to line up with. Where we draw it depends on angle a. To do a little geometry on this let's cheat and use a web-based right triangle calculator.

Make use of the following url: http://www.csgnetwork.com/righttricalc.html My side b is 5 inches (the radius of the circle) and I chose to make side a 2.25 inches. Accoding to the calculator, this makes angle A 24 degrees. You can play with this calculator by either entering side a or angle A as you experiment with different configurations.

Going with my 24 degrees configuration, make a mark along side a 2.25 inches from the center of the circle and then draw side c. Now do that with the other three radius lines.

After that is done, do the same thing with the other disk.

Notice that there are short cuts in the disk at angle A on each radius line. The pupose of these cuts is dock the paddle to the disks. The cuts should be about a half inch and should follow the path of line c.

Step 5: Attach the Paddles

Picture of Attach the Paddles

1. Double or triple up one of the rubber bands and push it up the axis rod to within about 2 inch from the top. The purpose of this and the other rubber band is to anchor the rod to the disk via friction. The also help to keep the turbine from slipping up and down.

2. Push the axis rod down through the center of one of the disks. I suggest that you keep the side of the disk with the angles drawn facing up for easlier alignment of the paddles.

3. Push the rod through the center of the second disk with the side of the disk with the drawn angles facing down. Slid the disk up the rod to within about 8 inches of the top disk.

4. Slide the second rubber band up the rod to within an inch of the lower disk.

5. Push one of the paddles onto upper and lower disks so that the notches on the paddle dock into the angled notches on the upper and lower disks. You might want to temporarily tape the paddle into place from the top and bottom.

6. Mount the other three paddles in same way.

7. Push the rubber band on the bottom up the rod so that it sits firmly up against the lower disk.

8. Now you can tape the paddles more firmly to the lower sides of the disks (the lower sides if you don't want the tape to show. As an alternative, you could use a glue gun to glue the paddles in place. Only do this after you have finished testing the turbine in the wind and are happy with the angles of the paddles.

Step 6: Test the Wind Turbine

Now you can test the wind turbine. Inside the house you can hold up lightly with both hands in front of a fan and watch it turn. You can see that the fan makes the turbine very easily. The outside video, unfortunately, was taken when wind was variable and blowing only about 3 mph.

The two videos that are attached I jury-rigged a setup so that the turbine could stand up by itself without being held. You can use your imagination as to how mount the turbine a little more permanently.

Experiment with different angles for the paddles to see what is the most efficient. I chose 24 degrees. Would 45 degrees work better? How about 10 degrees? You will notice that the smaller the angle, the better the paddle catches the wind on the left side. However, you notices that it also catches it too well on the right side. If you made the paddles 0 degrees, the turbine would sit idle in a strong breeze.

Where to go from here

The turbine, as is, probably could be used to generate a small amount of electricity in a school setting. The trick will be figuring out how to hook a small motor to it. You could also glue magnets to the bottom of the lower disk and then making coils of wire that remain stationary below the turbine.

What I want to do is make this turbine out of plywood and scale it up by double. I will use some of the material shown in the into to this instructable. Specifically, I will use the DC motor, the vertical allthreads bar that will serve as the axis rod, and the clamp I made to mate the motor and axis rod.

It will be interesting what kind of power I get out of the scaled up version. I would like to see if I could light up a series of LED's when the wind is blowing. That would look great at night. I might also try to use the power to pump water up over a waterwheel.

If you build this cardboard turbine, please post lessons learned and additional suggestions.

Comments

MattM370 (author)2017-09-19

just read this, so haven't had time to try it, but...

when i look at the pattern for the top and bottom, i see a square pattern for the "blades" inside the circle. might it be possible to just use two squares? and attach the "blades" offset on the sides? i hate throwing away odd little pieces of material.

i know i have some 1/4" plywood that would make good blades. if i had a couple squares of thicker wood, i could screw the blades into that. should require a lot less cutting. but would it work? as well? or close enough...

rhackenb (author)MattM3702017-09-19

The straight lines inside the round sections of carboard are indicators of the angle the upright blades slide onto. .

pete.sherwood (author)2017-04-01

The one that worked had the ability to pass the high pressure wind through the center to a low pressure fin on the leeward (downwind) side which is a low pressure zone. The Bernoulli Effect or Principle. The failed ones will work, with varying results, if they have a gap or holes near the center of each fin.

zat1991 made it! (author)2016-06-26

Fun to make =) Thanks for the instructables! (and it spins well =)) ->

https://youtu.be/ygLMbCWiT4g)

gfredy_17 (author)2016-04-19

nice toes...

AgoVeli (author)2014-06-12

This idea is very good, not that hard to make and no special curved surfaces neccessary. Now, the next problem is how to water proof it!

dustinandrews (author)2012-07-23

Here is an Inkscape and PDF suitable for laser cutting. Cut blue, etch black.

http://authenticinvention.com/downloads/rhackenb-turbine.zip

If you want to print on a laser printer you will have to move the objects to multiple pages. Sorry, I didn't think about that.

rcisneros (author)2010-08-24

Computer fans don't have permanent magnets, so they won't work without modding them.

oak1780 (author)rcisneros2010-10-18

pretty much all of the computer fans I've taken apart use a permanent magnet mounted inside the plastic fan body. though you do have to mod the fan a little because most have speed control circuits that would get in the way... but it's usually pretty easy to see were each coil attaches to the PCB, stick some wires on those and run em to a rectifier and "Poof" instant generator..

dustinandrews (author)oak17802012-07-23

That mod sounds like it would make a great Instructable!

Daniel Deacon (author)oak17802010-11-26

they dont!

Science4fun (author)rcisneros2010-12-27

Yes they Do Cisneros. They use a Magnetic RING on the Flywheel.
So it is the MAGNET RING that turns with the Blades.

the Stationary part are the Electronically-Commutated Poles. (3)

But you do have to solder 3 wires on the Driven side of the windings.

This will be a 3 phase output that needs to be rectified with the proper rectifying bridge. for a DC output.

jimengn01 (author)Science4fun2011-10-06

Good morning, I just was wondering once you make the modifications does is generate cogging thus making it harder to start spinning ?

rcisneros (author)jimengn012011-10-06

I tried hooking it up to a little motor. It does turn on the light and the motor was small so it didn't seem to keep it from spinning. The whole thing didn't last though. I'd like to find a way to make a more permanent version.

srsudarshan (author)2012-02-16

What will be the output voltage?

manojkup (author)2010-07-09

How about trying with single round base and 4-8 CDs instead of cardboard for blades!! and it works.. I further modified the model with few more changes and it is sufficient for my project.

m3rk3r (author)manojkup2011-11-16

thx for the idea

rpushkar (author)2011-08-10

THE WAY YOU HAVE PLANED IT WAS VERY NICE

peasehappines (author)2011-05-19

how can i make this power 2 LED lights with 1 motor. what kind of motor should i use

SamanthaKissMya (author)2011-05-02

I might be banned 4 this, this wind turbine looks like a apeice of crap !!

recycledteenager (author)2011-02-21

rhakenb. Thanks! Used this instructable with a scout group. All the models worked and they loved your model. I am going to use wheel to raise a weight next it looks easily strong enough.

Glad to hear that you could make use of the design with the scout troop. Maybe you could post some photos of what they come up with.

itsnotthenetwork (author)2008-10-10

An easier way to get a good circle is to put a tumbtack in the center and tie a small string (dental floss would work good) and stretch it out to the end of the cardboard and tie a pencil to it.

we used to call that a "carpenters compass" exept we used a small nail and a scrap of paper from the edge of a sheetrock bundle. (useful for cutting curved radiuses in a peice of wood with a saw.)

tinkerunique (author)2011-02-03

Need more power ? Simple fix = hook several small turbines together with bicycle chain and a small alternator. OR make a larger turbine and hook it up to the alternator/generator with bicycle chain. These are just a couple simple/quick solutions of many more avail..... Also check out the local library.

tinkerunique (author)2011-02-03

Several options = 1. Hobby store & "Plastruct" sheeting - 2. Fiberglas sheets are purchased OR easy to make ( think 'boat work" ) 3. horizontal blinds

IETMN (author)2011-01-23

dude! this idea is good! would you be nice and send me the pdf file to my mail please? if so: stefymel@hotmail.com
I'll really appreciate if you send the file please!

iamaqtpoo (author)2010-11-28

This is so interesting, thanks so much. My son is 12, he has been speaking a lot about wind turbines lately so I think this will make a few awesome weekend projects for us. We unfortunately live in a not very windy area(Florida is more know for sun...oh well!) but, we will give this a whirl anyway. Thanks again so very much for your efforts, GREAT JOB!

Waren-Neutron (author)2010-09-22

good work !

Waren-Neutron (author)2010-09-22

such a gonna be great job ever

Astha Ag. (author)2010-08-06

I m making it in a science exhibition and i hv 2 submit it on Monday i.e. 9 August. So, will u pls arrange an image with a bulb with it or how to generate electricity from it??? Also, I wanted 2 ask u that about how many voltages can it supply???

rhackenb (author)Astha Ag.2010-08-06

Sorry, I have the wind turbine disassembled now. It never had a generator connected to it anyway. Maybe you can figure out a way to do it yourself.

rapidprototyping (author)2010-08-04

You can make a simple mount for thses light weight prototypes out of tubing placed outside an axel shafting whitch can be driven into the gound . Once the shaft is plumbed if there is close tollewrences between the pipe and shsaft a single steele or ball bearing can be placed atop the shaft this acts as a piviot point and reduces the actions of friction on the rotors whitch will spin freely in a slight breese. Others were working on small gen set made from surplos computer fans others on larger generators5 volts to 12 volts goal being to charge any device 5 or 12 volt or charge 2 AA or 2 AAA batteries

The problem with any small motor like that is trying to physically mount the motor to the blades. Most small motors have a very small shaft to attach to. Take, for example, a fan from a computer. Mounting to that is very difficult.

thepelton (author)2010-07-08

I found that a good method of cutting and constructing parts at least for me is to use 1/8th inch birch plywood cut with an Epilog laser. I could probably make a functional one of these wind blade units with it. I'll have to try it.

typenamehere_____ (author)2010-07-08

You may want to test and see how it will do with a similar light-weight cardboard structure, but more designed to catch the wind while reducing drag. Perhaps add 4 more cardboard strips to the inside to give it a z like shape between blades. (the below drawing may be collapsed when I post this, just in case you see only a blob of slashes) | ____ | \ / / \------- | |

medius (author)2010-06-17

Now what is this hooked to that generates power?

rhackenb (author)medius2010-06-21

As I said in the instructable, it is not connected to anything. I was just experimenting with the placement of the blades. Something this small might be able to run something like the motor behind a computer fan.

omonile (author)2010-06-21

what generates the power.And what is the component?

mibbster (author)2010-04-23

How many watts did you second design produe? This is the design with blue things for the sails

beehard44 (author)2010-03-10

I was browsing on making turbine blades out of cardboard, and the regular turbine blade design wasn't that efficient. Stumbled upon this, hopefully it'll give a lot of torque to power my naughty stepper motor....

rockerape (author)2010-02-23

You missed 4 toes  :-)

foxwoodfarm (author)2010-02-07

I used form board that can be purchased at Walmart of craft stores. It is about 1.4" thick and is more rigid than cardboard. It can be cut with a box cutter,  scissors or exacto knife. The foam board is also weather proof for a long time. I made a PVC pipe frame for mine. Sorry I didn't take pictures 

MattM4773 (author)2009-11-16

this is my last comment
i would like to know how u mounted the turbine cos in the steps i didnt see anything about a mount and im not sure how i can present it without one
plz reply soon because its due this friday

rhackenb (author)MattM47732009-11-17

You can see from the two videos that the mounting is jury-rigged.  First of all, the bottom of the knitting needle is sitting in a large nut that has been taped down to the platform the whole thing is on.  The diameter of the nut is large enough to so as not to impede the spinning.  The nut was used to keep the needle from walking off to the side.

For the top I used a wooden paint stirrer stick.  It had a large hole in it and the needle was passed through it before it was inserted through the axis of the turbine.  This stick was sitting on a surface that was as high as the top of the turbine and had a weight on it to keep it steady. 

If you want to make this more professional, take a long strip of light metal such as aluminum.  Bend it in two places so that the top part reaches to the top of the axis and that bottom part reaches to the bottom of the axis.  You are going to have to use your imagination and creativity on this. 

MattM4773 (author)2009-11-12

hello agn lol
umm if i were tp halve or third the dimensions on teh paddles and teh discs
would i be able to instead of teh knitting needle use something like a satay/kebab skewer or would i have to use something different

rhackenb (author)MattM47732009-11-12

The shorter you make the paddles, the less  the surface will be to catch the wind.  If you don't hook the turbine up to a load (generator), it will still spin.  I used a knitting needle because I found one around the house.  You might want to go to a place like Lowes or Home Depot and pick up a thin wooden dowel. I think they sell them in lenghts up to 36 inches and aren't expensive. 

The whole idea of a wind turbine is to do something useful with it, like generate electricity.  A wooden dowel might be more appropriate for adapting it to some sort of small hobby motor.  Also, cardboard is great for prototyping but you might consider something a little more durable such as the kind of material that they use for political campaign signs.  If you are in the US, there are plenty of these left standing long after the election unclaimed.

MattM4773 (author)2009-11-03

if i were to connect this to a motor (dc motor) to produce electricity how would i do this and how big does the motor have to be? cos im doing this for a school project and have to make electricity

rhackenb (author)MattM47732009-11-03

That's the tricky part.  Basically, you have to get a low rpm DC that has a shaft long enough and accessible enough that you can connect your turbine to. It doesn't have to be very big just to demonstrate the generation of electricity.  You only need 2-3 volts DC to light an LED.  Some people are stripping drive motors from things like scanners, printers or old floppy drives.  I've not had much success with these things.  That's why I was waiting to see what you come up with.  BTW, you don't really have to actually hook up the motot to the wind turbine to see if will produce electricity.  Just attach a multimeter to the negative and positive leads of the motor and spin the shaft.

JohnJY (author)rhackenb2009-11-10

Hello rhackenb,
For a school science fair I've built your cardboard design. The problems I've had were minor, like drawing the angles from the center, and not the edge, but all in all the turbine is a success. I will be posting more after experimentation, and will even inform you if a regular windmill, your Instructable, or a design of my own is more efficient for producing energy. 

Signed, 
94 

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