Introduction: Wind Whirler (plastic Bottle Wind Turbine!)
Wind is one form of available energy. This is a simple vertical-axis wind turbine (VAWT) which you can make for no cost in half an hour (or even 10 minutes!) from stuff you already have, then enjoy seeing it spin!
The pictures and videos may be enough for you, but written instructions are here too if you want.
It turns in a light breeze or even by your breath, and in a steady moderate wind it whirls impressively fast!
Wind Whirlers can be decorated so as to illustrate principles of optics and perception.
They can play a useful part in education: in Geography, studying weather; and in other science projects - such as the physics of friction, airflow and angular momentum.
I've demonstrated this quick craft project, in the past several years, with repeated success: as a Youth Group activity; as an Ecology-Centre activity with schoolchildren and in a shopping mall demonstrated quickly to passers-by; and at The Big Tent 2008 environmental festival.
It's fun to decorate your own Wind Whirler, to enhance its visible proclamation that Energy is Free for Everyone! And when poised, whirling, its ever-varying motion helps us to relate to the atmosphere around us, our weather and our environment, in a satisfyingly personal way.
When I've carried one with me as I travel, it seems to be an eye-catching attention-getter that people often have asked me about, leading to interesting conversations.
It also makes use of what's often thrown away - plastic bottles!
Fun - free - decorative - and educational!
Step 1: What You Will Need (and May Also Want)
What you will need:
- a plastic bottle (2 or 3 litre size is ideal; one with straight smooth sides, not bulging or ribbed).
- a paper clip (or piece of similar stiff but bendable wire)
- scissors with a sharp point, or a craft knife
- a marker pen, or crayon - anything to mark the bottle with
That's all you really need!
You may also want:
- a few small beads, to act as bearings, to help the Wind Whirler turn easily and quietly (they should slide easily onto the paperclip/wire)
- a sheet or two of paper (big enough to reach around the bottle) - or a tape measure
- string or extra wire to hang up your finished Wind Whirler
- coloured tape, or paint, or other means of decorating your Wind Whirler
and, to put your Wind Whirler on a pole (as shown at end of this Instructable), also:
- drill and drill bits, 1-2mm or more (to suit wire diameter and any screws you use)
- dowel, straight stick, timber lath or garden cane eg bamboo (must be a loose fit in neck of bottle)
- some screws (cross-head or Phillips screws: ideally, some having a wide flat head say 8mm, some with slender points), for pivots - but you can use a paperclip/wire instead
- some tubing (that the wide screw-head will fit snugly into) - this is not absolutely necessary but it will help stop the screw jumping out of position. You can even make your own tube using plastic from another bottle.
Step 2: Rinse and Dry Your Bottle First
Take the cap off and keep it for later. Remove the label and discard it. Make sure the bottle is clean and dry.
We will cut vanes in the sides of the bottle, and fold them inward. These will catch the wind.
Step 3: Decorating Your Wind Whirler
Even a basic undecorated Wind Whirler glints and flickers eye-catchingly in the light, but it's fun to personalize and add colour! I have put this step here, not last, because if you're adding helical stripes, it is easiest to do this now, before beginning to mark or cut the bottle. Just wrap tape around-and-along the bottle while gradually turning it.
Duct tape, or coloured electrical tape, is good for this: it has longer-lasting adhesion outdoors than some decorative sticky tapes.
Paint can also be used. I've found that 'tester' pots of home-decorating paint are a cheap source of many interesting shades, if you only require a small quantity of each. Emulsion I find adheres well enough to the smooth surface of plastic bottles (if clean), but they could be lightly roughened with sandpaper or a nailfile if need be.
Whirlers with helical stripes (candy stripes, barber-pole stripes) or vertical alternating stripes.
Wind Whirlers can be decorated so as to illustrate principles of optics and perception:
Vertical stripes (especially alternating light and dark) give extra visibility to the spinning motion until they blur at high speed (a photocell could be mounted to monitor rate of rotation).
Helical stripes as they whirl pleasingly produce a strong optical illusion, appearing to ascend or descend (depending on how they're angled and on the direction of rotation of that particular Wind Whirler).
Stripes or patches of colour initially seen as separate become blended colours as whirling speed increases.
I'll be interested to see what decorative ideas, uses and improvements other people come up with!
Step 4: Make a Paper Guide
This helps mark the bottle for cutting. (You could measure using a measuring tape if you want, but I find this way easier.)
Wrap paper around the bottle and trim it to a length that just fits around.
Trim it to a height that covers the cylindrical portion of the bottle (the straight-sided bit) .
A4 or legal-size paper is about right and may not even need trimming.
Now lay the paper flat , and fold it double lengthwise.
Now fold that over again, into 3 equal sections (like a Z). Crease firmly.
Now - open it out and you have 6 equal parts (6ths).
Mark the 12ths midway between the creases (judge by eye),
(Or, just fold the paper double again, before you open it out!)
That's your paper guide made.
Step 5: Mark the Bottle
This is easier to see from the diagram than to say...
Now, with the bottle upright, wrap your paper guide around your bottle again, and holding it firmly (or taping it in place), use a marker pen or crayon to make dots at each 12th of the way around... both top and bottom of the paper (lined up straight!). This may be easier for two people to do... one holding, one marking.
You can draw the vertical lines in if you want (down the side of the bottle).
Only alternate verticals (6 lines) will be cuts; the ones in between will be folds.
And from the top and bottom of each vertical line, mark a horizontal line 12th of the way around.
(Go either clockwise or anticlockwise; but always the same way, whichever you choose.)
Step 6: Start Cutting
Remember, only alternate verticals (6 lines) will be cuts; in between those will be folds.
From the top and bottom of each line, cut a 12th of the war around the curve of the bottle.
Go either clockwise or anticlockwise; but always the same way, whichever you choose.
Step 7: Finish Cutting
There are 6 vanes to cut (each with one long vertical cut and two short curved cuts); then you're done cutting. (Breathe a sigh of relief!)
Step 8: Folding the Vanes
Bend each cut vane inwards. The bend should be midway between vertical cuts you made. Press the plastic inwards and fold it double (right over), so it touches the inside of the bottle. Pinch hard, making a sharp crease all the way from top to bottom. Then ease that vane back, so its inner edge points toward the centre-line (axis) of the bottle.
Do the same for all six vanes.
If you could cut your bottle through, it should be like this: see the turbine shape!
Step 9: Piercing the Cap
Again, this is a step it's best for adults to do for smaller children!
Place the cap on a piece of scrap wood, and be careful it doesn't slip.
Use a sharp-pointed blade of scissors, or craft-knife, or drill, to bore gradually through the cap.
Go slow and steady!
Once there's a tiny hole, you can widen and neaten it from either side (turning the cap over).
it should be 1mm or 2mm diameter; just wide enough for the paper-clip/wire to pass through, without being tight.
Step 10: Making the Axle
Open up a paper-clip so it looks like a shepherd's staff (with a hook-over or loop at the top). Adults, please do this for small children.
Make the straight bit as straight as you can. This is good for developing dexterity! Pass the pointed end down through the hole you made in the cap, then thread on a couple of small beads. Push them right up into the cap.
Make a sharp bend or two in the wire, for the beads to rest upon and not slip off or jam.
Make sure to keep the angles of the wire well within the cap, as the bottle's neck will also have to fit in there without the wire rubbing on it.
The main line of the wire, from loop down through cap and beads, should be as straight and kink-free as you can make it, for smooth easy turning. Hold the wire axle up by its loop and check the cap spins freely.
Step 11: Now Hang It Up and Enjoy!
You can use string or extra wire to hang it up.
I've found it best not to use the 'hook' of the axle itself to directly connect to a support, as the whole Whirler-including-axle needs to be free to swing sideways as a unit when the wind blows. If the axle is too rigidly fixed to a support, the bottle alone swings, and friction may increase, or the axle may be bent.
Yours may work first time, or it may need some adjustments to the axle (straightening) or to neaten the hole in the cap (if there are points catching as it rotates).
Testing the 2 Wind Whirlers I made indoors earlier, outdoors:
(I slightly adjusted the twist in the axle, swapping the caps of the two Whirlers between tests).
test 2 - comparing noisiness versus ease of turning
Step 12: An Alternative Twist (sound Effects!)
The direction of twist and the exact shape of it determine the sound.
The extra friction will act as a brake, so there's a trade-off between sound or ease and speed of spin. Your whirler may need a higher windspeed to start it spinning.
Which way your Wind Whirler rotates depends on whether you cut the vanes to fold in clockwise or anticlockwise.
The hole in the cap is never completely even, and also the cap's inside surface often has moulded ridges in it. If you hold the Wind Whirler up by its axle, then turn it by hand or blow it, you may hear, feel and see the 'clicking' vibration it makes.
This means the Wind Whirler can be experienced also by people with sensory impairments.
Step 13: Other Way Up!
For stability and durability in strong winds, or for use to deter birds from seedlings, or just for fun, you may want to mount your Wind Whirler on a pole.
The bottle is up-ended to do this.
The plastic at the bottle's base is thicker and harder to pierce than the cap, so a drill is really necessary (and some way of steadying the bottle and drill to get a really central hole).
You can use a paperclip or wire axle as before, putting a spiral twist in it to wrap around a stick or insert in the end of a cane.
Alternatively I've found that a slender screw threaded into the base of the bottle, resting in the cross of another screw, can serve as a low-friction pivot. The lower screw can be pressed into the end of a bamboo cane, or screwed into a dowel or timber which has had a pilot hole drilled in its end.
You may want to put a length of tube up around the lower screw so as to hinder the upper screw from jumping off too easily.
You could make such a tube from part of another bottle's side, wrapped around and tightly taped with duct-tape, or bound with wire or string; or use any convenient offcut of metal or plastic tubing; or just use the hollow of a bamboo cane.
The bottle's neck, a loose fit on the support pole, provides an additional fairly low-friction bearing that keeps the Wind Whirler upright (full on to the wind) even in strong winds and so maintains its efficiency. These can really hum round fast!