DIY Hot Air Balloon!!

Today we will be doing a project based on the Technology Teaching Standards. Referencing Standard 18 which is: students will develop an understanding of and be able to select and use transportation technologies.

To be more specific we will be working with benchmark B which is vehicles move people or goods from one place to another in water, air or space, and on land

A lighter-than-air aircraft that has been flying the skies since 1783, could not possibly be considered as transportation. Could it? Well, that is where it is interesting. The hot air balloon, which was created by brothers Joseph-Michel and Jacques-Etienne Montgolfier and then flown by Jean-François Pilâtre de Rozier and Francois Laurent d'Arlandes in France in 1783, has not only been used for air travel but also the transportation of products. The first hot air balloon that was flown in America was launched from the Walnut Street Jail, yes a real jail, in Philadelphia on January 9th, 1793, but another Frenchmen aeronaut by the name of Jean Pierre Blanchard.

Hot-air balloons are considered lighter-than-air aircraft because of the way that they become airborne. Every hot air balloon consists of a container for the hot air, usually called an envelope, an area to carry passengers (usually a gondola or a basket), and a heat source. When the heat source is ignited, it starts to fill the envelope with hot air. Because of the heat, the air inside of the envelope is less dense than the air outside of the envelope, lifting the balloon off the ground. This is described by Archimedes’ Principle, which discusses buoyancy and upthrust. By controlling the temperature inside the envelope, the height of the balloon can be altered - increasing the temperature causes it to ascend, decreasing the temperature causes it to descend.

Some materials you will need are some already in your household:

Birthday candles or skinny candles similar to that size

Thin trash can liner

Aluminum foil

Tape

Straws

Lighter

Maker

So the first step to making this hot air balloon is to review the materials we will be using and why. The reason for using the birthday candles instead of a tea light candle is because they are light weight and produce a larger flame, which is what we need. We used a trash can liner because we needed a large mass that was not only light weight but also thin enough to allow to be inflated by the candles.

To first begin with the construction, we will take six straws to form the base that will hold the candles. We will use three to make each of the two rods, by inserting the ends into one another. After the two rods have been created, we will take the tape, in our example we used electrical tape, to tape the straws together to avoid coming apart. Note: if you have bendy straws it would be wise to tape the bend so they will not open or move around, this will avoid your candles moving around and just add more stability.

Now take the two rods and cross them like an ‘x’ or ‘+’, however you want to view it. Once they are even, tape where the rods intersect. Make sure to use enough tape to make sure the cross will not come apart, this will be your base and it is crucial for it to be stable.

Now take your aluminum foil, and draw a square at least 4 inches by 4 inches. Try to have it as even as possible because your candles will be resting on these and need as much room between each candle to avoid too much weight on one side. Once you have a square drawn out proceed to cut the shape out and set it to the side.

Take the crossed rods and your aluminum foil square and lay the square on top of the rods. Make sure the points of the square are resting on top of a straw, this will make it easier to secure later. Now take your maker and make a dot in the free spaces that are not over a straw. It should be the part that bridges to the next straw.

Set the cross to the side, and take the aluminum foil and have one side hang off the edge of a table. Grab one of the candles and hold it over one of the dots you made earlier. Take your lighter and melt the bottom of the candle and stick it to the dot. Then put the flame under the foil to heat the spot up, to allow the wax to pool to the candle. Set the lighter down and pull the foil back onto the desk and press the candle into place. Allow it too cool and harden for a couple seconds before removing your hands. This process may take a couple tries, but the more wax that it melted around the candle the more durable it will be and less likely to be knocked off by accident.

Once all four candles are on, place the square back on the cross just like in step 5. Making sure the points of the square are resting on a straw. Use your tape to attach the points to the straws. Once you feel like they are secure, gently flip the cross over, with the square and candles attached, and tape the aluminum foil to the straws, again securing it.

Now take your trash can liner and shake it out until it is fully inflated. Make sure each edge of the liner can reach each straw without bending the base at a weird angle or ripping the bag open.

Take your base and lay it on the table to keep it flat. Take an end of the trash can liner and attach it to the end of the straw by wrapping tape around the ends. Repeat this until the trash can liner is stretch around the base and secured to prevent it from slipping.

Before we can light the candles, we have to make sure everything stays together and will not fall apart. So take your newly constructed hot air balloon by the top of the trash can liner and just suspend it. By holding it in the air it allows gravity to play a part and see if anything is off balanced or even if the candles will fall off. If it looks like your base is starting to bow down it is okay to secure it with some more tape to make the rods sturdier, again they are straws.

Once it seems like nothing is going to fall off, lay your balloon on a flat surface and orient the candles to stick straight up. Make sure your area is cleared of anything that is flammable, and that you have adult supervision if need.

Now for the BIG moment. Hold the trash liner in the air but not high enough to bring the base off the table. Take your lighter and carefully light the candles. It will take a while for the flames to grow large enough to physically inflate the balloon. But after some time everything will heat up and you have lift off!