Wind Pumps
Today's project was designing a wind-powered water pump!
We discussed the history of harnessing the wind to power machines, from Hero of Alexandria's wind-powered pipe organ in the 1st century A.D. to the wind pumps used in Muslim cultures in the Middle East and Central Asia, to the windmills created by the Dutch (which--I didn't know before--could mill grain AND pump water from the ground!).
The book I mentioned in our discussion today was called Wind Power, written by Ian Graham and published by Raintree Steck-Vaughn Publishers.
We talked about Daniel Halladay, the American inventor of the wind pumps used in farms across America. We talked about the Law of Conservation of Energy, how energy is never created or destroyed, but only changes form--in this case, changing from kinetic energy to mechanical energy, and in wind turbines that power homes, it is also converted to electrical energy.
We talked about converting different kinds of motion using a machine called a crank. A crank converts rotary motion to linear reciprocating motion, and the kids suggested many other machines that are operated by cranks, such as steam locomotives and combustion engines in cars. There are many different kinds of cranks, but the kind we were making today involved wind blowing on the blades of a wind wheel to rotate the driveshaft attached to it. And that driveshaft is connected to another disc which is connected to an output shaft that is held together at right angles to the disc, converting the rotary motion to linear motion.
You can see a great animation of how cranks and other mechanisms work on this BBC page: http://www.bbc.co.uk/schools/gcsebitesize/design/systemscontrol/mechanismsrev8.shtml
Then we started building! This was a much more challenging project than last week's, so the kids worked together in groups. They had a lot of fun doing that, and it saves us on materials.
They cut their blades out of cardboard, while parents helped me cut discs. They used skewers for the shafts, boba straws for the pump, and tiny bits of sponge which is supposed to pump water up into the pump. A lot of kids had to abandon the sponge because they had trouble getting it to pump smoothly up and down, and I was fine with that. Even my sample, which worked reasonably well, wasn't efficient at actually pumping water and more materials may need to be added to the design if you want an actual, functioning water pump. But the main objective of today's class was to teach them about converting rotary motion to linear motion and wind energy to mechanical energy.
I was so impressed by the kids' creative and innovative designs today. That was the real benefit of doing such a hard project--the fact that it posed a lot of problems and complications was GOOD because it got them doing a lot of problem-solving and working together! Everyone had a unique design. One girl gave her output shaft a joint, and to hear her explain proudly how she thought that would help with converting the motion more smoothly was such a treat! She later abandoned that because it didn't work quite how she wanted and flopped a little. But what creativity and ingenuity! I was so proud of her!
Other problems that the children solved creatively on their own were: the horizontal shaft being tilted too much--one group anchored it with another skewer.
Another group found the straw pump was very constrained in the water bottle, so they created a way to allow some horizontal motion for the straw. They actually created a peg-and-slot machine to allow the straw to move. Blows my mind.
Another kid made a paper pinwheel and didn't even bother with the cardboard. I was surprised and didn't think paper would be strong enough. But guess what--it worked great!
Kids tinkered with the length of the skewers, the positioning of the skewers where they connected to the disc, and all kinds of creative ways to hold the pump upright. They were amazing. They inspire me, week after week!
Some kids' projects didn't work, and I always do my best to troubleshoot but occasionally I am stumped. (I'm not a professional engineer--I just do this as a hobby.) So I strongly recommend that anyone who is stumped with their project upload a video or photo to the Curiosity Machine website and get feedback from the professionals there!
Finally, if you want to try this but just aren't in the mood for something so complex, there are some easier wind experiments that teach more or less the same thing. For example, you can attach a pinwheel to a pencil, hang a washer (or another light weight) from the other side of the pencil using some string, and watch as the rotating pinwheel rotates the pencil to pull the washer up. You can find this experiment in the book Experiments with Energy by Salvatore Tocci, published by Scholastic.
We discussed the history of harnessing the wind to power machines, from Hero of Alexandria's wind-powered pipe organ in the 1st century A.D. to the wind pumps used in Muslim cultures in the Middle East and Central Asia, to the windmills created by the Dutch (which--I didn't know before--could mill grain AND pump water from the ground!).
The book I mentioned in our discussion today was called Wind Power, written by Ian Graham and published by Raintree Steck-Vaughn Publishers.
We talked about Daniel Halladay, the American inventor of the wind pumps used in farms across America. We talked about the Law of Conservation of Energy, how energy is never created or destroyed, but only changes form--in this case, changing from kinetic energy to mechanical energy, and in wind turbines that power homes, it is also converted to electrical energy.
We talked about converting different kinds of motion using a machine called a crank. A crank converts rotary motion to linear reciprocating motion, and the kids suggested many other machines that are operated by cranks, such as steam locomotives and combustion engines in cars. There are many different kinds of cranks, but the kind we were making today involved wind blowing on the blades of a wind wheel to rotate the driveshaft attached to it. And that driveshaft is connected to another disc which is connected to an output shaft that is held together at right angles to the disc, converting the rotary motion to linear motion.
You can see a great animation of how cranks and other mechanisms work on this BBC page: http://www.bbc.co.uk/schools/gcsebitesize/design/systemscontrol/mechanismsrev8.shtml
Then we started building! This was a much more challenging project than last week's, so the kids worked together in groups. They had a lot of fun doing that, and it saves us on materials.
They cut their blades out of cardboard, while parents helped me cut discs. They used skewers for the shafts, boba straws for the pump, and tiny bits of sponge which is supposed to pump water up into the pump. A lot of kids had to abandon the sponge because they had trouble getting it to pump smoothly up and down, and I was fine with that. Even my sample, which worked reasonably well, wasn't efficient at actually pumping water and more materials may need to be added to the design if you want an actual, functioning water pump. But the main objective of today's class was to teach them about converting rotary motion to linear motion and wind energy to mechanical energy.
I was so impressed by the kids' creative and innovative designs today. That was the real benefit of doing such a hard project--the fact that it posed a lot of problems and complications was GOOD because it got them doing a lot of problem-solving and working together! Everyone had a unique design. One girl gave her output shaft a joint, and to hear her explain proudly how she thought that would help with converting the motion more smoothly was such a treat! She later abandoned that because it didn't work quite how she wanted and flopped a little. But what creativity and ingenuity! I was so proud of her!
Other problems that the children solved creatively on their own were: the horizontal shaft being tilted too much--one group anchored it with another skewer.
Another group found the straw pump was very constrained in the water bottle, so they created a way to allow some horizontal motion for the straw. They actually created a peg-and-slot machine to allow the straw to move. Blows my mind.
Another kid made a paper pinwheel and didn't even bother with the cardboard. I was surprised and didn't think paper would be strong enough. But guess what--it worked great!
Kids tinkered with the length of the skewers, the positioning of the skewers where they connected to the disc, and all kinds of creative ways to hold the pump upright. They were amazing. They inspire me, week after week!
Some kids' projects didn't work, and I always do my best to troubleshoot but occasionally I am stumped. (I'm not a professional engineer--I just do this as a hobby.) So I strongly recommend that anyone who is stumped with their project upload a video or photo to the Curiosity Machine website and get feedback from the professionals there!
Finally, if you want to try this but just aren't in the mood for something so complex, there are some easier wind experiments that teach more or less the same thing. For example, you can attach a pinwheel to a pencil, hang a washer (or another light weight) from the other side of the pencil using some string, and watch as the rotating pinwheel rotates the pencil to pull the washer up. You can find this experiment in the book Experiments with Energy by Salvatore Tocci, published by Scholastic.
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