A simple solar powered heat engine

In this project we are going to take a heat engine that is normally driven by the evaporation of water, and convert it to solar power.

The “Happy Drinking Bird” is a popular toy often found in science museum gift shops.

While this is a wonderful little heat engine, to keep it working you have to fill the water cup every day. (We will explain how the toy works a little later, in the section called “How does it do that?”).

In our modification, we will eliminate the water, and use the heat of the sun to power the bird. Now the bird can sit in a window sill, and bob as long as the sun shines through the window.

What you need

• One Happy Drinking Bird
• One cup of boiling hot water
• Some black paint
• Some reflective silver paint (white paint will also work)
• A sharp knife

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The first step is to remove the feather tail from the bird. You can do this by scraping the glue off with the sharp knife, but it comes off more easily if the bottom of the bird is first soaked in the boiling hot water for a minute.

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Next, we remove the bird’s hat and the fuzzy coating on the head.

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To do this, we soak the head in the hot water for a few minutes to soften the glue, and then scrape gently with the sharp knife until all the fuzz comes off, along with the hat.

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Now we paint the bottom half of the bird black.

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Then we paint the top half of the bird silver.