The wind speed meter runs with the wind, faster when the wind blows harder. By counting the number of turns you can tell how the wind speed changes. It does not matter where the wind blows from, because the rotor is horizontal and the cups will cause it to turn when the wind blows from any direction.
Posts Tagged air flow
All you need is a square piece of plywood any reasonable size, and a post that you can make from a broomstick, a piece of dowel wood, or any square piece of wood, we took a 2×2 centimeter piece of pine, about 5 inches or 12 centimeter long. Drill a hole in both ends to receive the nail, one to nail the post to the base and the other to act as the shaft for the rotor.
The medicine cups you can get at any drugstore, just ask for a few, three is enough, but you may want some spares. We melted a hole in the bottom for the screw instead of drilling a hole. I used a piece of steel wire from a coathanger and heated the end up with a gas flame, but a candle will work also, when the end is hot stick it through the bottom, don’t make the hole too large! You need some supervision by an adult with this!
The coloured sticks are from a craftstore, you can also use medical tongue depressors, they are the same size but not coloured. You should be able to get these parts easily. Drill a small hole in each stick for the screw that holds the cup onto the stick.
The hub is cut from a sun umbrella post, you can use any round or even square piece of wood, in this case cut or sand off the four corners to make it look better. You need to cut a slit in the hub at three locations divided around the circumference of the hub. Just use a small hand saw to make the cuts. You may need some help dividing the circumference by three, but most highschool students can help you, by dividing a circle by its radiius you get six divisions, pick every other division and you have the three you need. They should be 120 degrees apart. Nice geometry lesson …
Note the craft stick has been reinforced by a piece of electric tape, make sure you pull the tape hard around the stick, when you drill the small hole for the screw it does not split because of the plastic tape holds the wood together. The plastic medicine cup has been screwed with a number six self tapping round headed screw that you can buy at any hardware store. The screw is only one quarter inch, or about six millimeters long.
Note that we pulled some coloured tape around the rim of the medicine cups, that will make them stronger and it looks pretty!
Note that the post on the base has a hole in the top, put a nail through the rotor hub and put two small steel washers between the post and the hub, this will lessen the friction and makes the rotor turn more easily in the wind.
The harder the wind blows, the faster the rotor will spin. That way you can tell how the wind changes.
Show it to our teacher and friends and try other projects from this blog.
Oops, add a little light machine oil used for the sewing machine for example, to the centre of the hub and to the nail and washers, it will spin faster. Also leave space between the nail head and the hub, right?
Make this handsome glider plane! You can fly it, show it off to your friends, exhibit it in your room OR make several and build a MOBILE suspended from the ceiling…SPECTACULAR!
Making this glider plane needs a little skill with sawing the slits for the wing and the tail. Maybe you need the help of an older sibling, friend or adult. The materials are around the house or you can get them from a printing business or sign maker, they have plenty of materials around from printing proofs that they can give you. Try it…
The materials you need are a small piece of soft wood, pine wood is best, I would not recommend balsa wood, that is too light for this glider. The wings are made from an old commercial poster, that is usually printed on a plastic/paper like material, and it is strong enough for the wings. The tail is made of ordimary bristol board. You could make the wings also from bristol board if you wish. The yellow stabiliser is just a piece of craft paper, any white printing paper would also work, no problem! And, of course, we use some electrical tape to add colour and fix the wing!
The wooden body has two slits made with a scroll saw. The front slit is about 8 cm long and is cut at a small slope from the front down, draw a line first so that you can see where to saw! This gives the wings their LIFT when the air flows over them. The slit for the tail is 4 cm long and horizontal!
After you slide the wing and tail into the body, put a bead of glue along the edge of the wing and tail where it meets the body, that keeps the parts in place. Also put 10 centimeters of electrical tape before the wing and after, see photo below. The yellow stabiliser must be folded in two and then fold edges at the bottom, glue these to the tail on both sides of the wooden body.