How to Build a Mini Hot Air Balloon

Once the only successful human-carrying flying vehicle in existence, hot air balloons are nowadays used more for leisure activities than for actual transportation.  The basic science behind hot air balloons is the difference in density between cool and warm air.  Air that is heated by the use of a burner or other flame or heating source fills a large fabric bag or envelope and this heated air causes the balloon to rise.  The heated air causes the balloon to rise because the heated air inside the balloon is less dense than the relatively cooler air outside.

The first step in building your own mini hot air balloon is to source something that can act as the main “balloon” or envelope.  You can either use a dry cleaning bag or a small garbage bag.  A bag made out of a non-flammable material is preferred, but as the heat source will be a good distance from the bag, using a plastic bag shouldn’t be too much of a problem.  The main thing you should be aiming for is a bag that is as light as possible.

After you find a bag, you need to make a holder for your heat source, be it candles, burning cotton balls or just a small gas burner.  This holder can be made of a lightweight cardboard – the lighter the better – and attached to the bag with string.  You should be sure that the holder and the heat source sit a good distance (about a foot) away from the bag to prevent it from catching fire or melting.  The easiest heat source to use is a few birthday candles attached to the cardboard holder.  The number of birthday candles that you use will depend on how heavy your whole hot air balloon is and should be adjusted accordingly until your balloon levitates when the candles are lit.

When you finally get your balloon to rise of its own accord after tweaking the amount of heat generated by your heat source and the weight of the whole balloon, you should ensure that you keep an eye on where your balloon flies.  This is because the flames that heat the air in your hot air balloon are a fire hazard and can be very dangerous if your balloon lands on a lawn, tree or roof somewhere.  There’s also a risk that your balloon can catch fire while airborne, which means you need to be even more alert, especially if the material that the envelope is made out of is a flammable material.