Hot Air Ballons

Today we used a plastic garbage bag, a gas cooker, a cardboard box and a hot air to make a hot air balloon. Before we started Euan fetched a bucket of water just in case anything caught fire. It was very windy outside so we had to make the ballon inside.

We opened the top and bottom of a cardboard breakfast cereal box and made it into a tube. This went over the gas burner to act as a chimney. We lit the cooker and kept the flame very small, then put the chimney over the flame, making sure it was not too near the flame.  The gas heated the air and sent it up the chimney, then sucked in cool air from the holes in the cooker.

With one person on either side of the cooker, we held the bag over the cooker and watched as it filled with hot air. When it started to tug, we let it go and it shot up to the ceiling.

We did not put weights on the bottom of the bag so it tipped over quite easily and let all of the hot air escape.  Then the bag floated gentle down to the floor.

 After a while, the bag got too hot and the plastic started to melt. Next time we will try making the bottom a little heavier, and maybe make the opening a little smaller.

All the pictures are on https://picasaweb.google.com/ReeceSwart/20110130_Hot_Air_Balloons_Part_1#.

Carbide Flames

We saw a methane experiment on TV, and we decided to check if it would work with acetylene.

First we needed to make some stuff. We needed a gas generator. We cut the centre out of the lid of a hot chocolate bottle, and glued a plastic funnel on top. Next we took some pipe the builders had left in our garden, and fitted it onto the funnel. The plastic bottle may melt, but glass bottles are too dangerous to use in case they explode.

Next we got the bubble bucket ready. We put a little water into a plastic bucket and added quite a lot of dish washing liquid. Then we put the free end of the builders pipe into the soapy water, and put a brick on top to keep the pipe under water.

The last thing we had to make was a long distance fire lighter. We tied a candle onto the end of a long stick, and lit the candle.

We put some carbide into the gas generator, added some water, and screwed the lid on quickly. Dad said this was the dangerous bit, so he did this part. the carbide in the bottle started to fizz and the gas generator got quite warm, so we put it into another bucket of water to keep cool.

Very soon, the gas started bubbling out of the end of tube under water, and made lots of bubbles. I took the burning candle and stuck it into the bubbles and woosh, we had a great big flame followed by lots of black smoke.

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We took turns lighting the bubbles until it stopped bubbling. The gas coming out of the generator was very smelly.