Have you always wanted to build your own hot air balloon and watch it float delicately in the night sky? Know that this is a simpler and cheaper project than you might think! This guide will show you how to make a mini hot air balloon out of a plastic bag, a few straws and some birthday cake candles.
Steps
Part 1 of 4: Getting Started
Step 1. Find a thin plastic bag
The best are the thin and cheap ones that are generally used for the garbage can. You should choose a transparent or translucent one. Don't use the black ones, as they are too heavy. Alternatively, you can use those that cover the clothes when you pick them up from the laundry; if so, get one that covers the skirts and remember to close the top hole.
Do not use plastic bags from the supermarket; they are too small and heavy
Step 2. Check that the bag has no holes by placing it in front of a small fan
Make sure that the opening is in front of the fan, make sure there are no gaps and turn on the appliance. The bag should inflate like a balloon. If nothing happens, there are likely holes in the sides. Identify them and plug them with small pieces of masking tape.
Step 3. Check the weather forecast if you have decided to fly the balloon outdoors
The day should be cold, because the balloon will not blow up on a scorching day. Make sure there is no wind - even the slightest breeze could prevent the balloon from flying. The best times are sunrise and sunset, when the weather conditions are more stable.
Cold, high-pressure winter days are best for flying a hot air balloon
Step 4. Choose a large, empty room if you have decided to fly the balloon indoors
You can always do the experiment inside the house too, but make sure there is plenty of space, you also need to eliminate curtains and carpets; there shouldn't be carpet either. If the balloon lands near these materials, it could start a fire. The garage or school gym is great places to let the ball fly.
Step 5. Keep a bucket of water or a fire extinguisher nearby
Since you will have to work with fire, you have to ensure safety. If you are a child, ask an adult to help you in this project of yours and to always be present in all its phases.
Part 2 of 4: Making the Basket
Step 1. Cut out a 10 cm square from aluminum foil
This will constitute the basket of the balloon; remember that the edges of the tinfoil may be sharp, so be cautious.
Step 2. Mark four points inside the square with the help of a marker
Each dot must be located 2.5 cm from the corresponding corner. Later, you will put a candle on these points.
Step 3. Take two of the candles used for birthday cakes and cut them in half
This way you will not weigh down the balloon, which will fly more easily.
Step 4. Remove some of the wax from two halves of the candles to expose the wick
At this point, you will find that the wick of two of the four half candles are not sticking out of the wax. Break off the ends of these to get rid of the wax and free the central wick. Eventually you will have four mini birthday candles.
Step 5. Melt the base of each candle and glue it to the aluminum foil, right at each point
Let a few drops of wax fall on the dot; when you have obtained a small "puddle", place the candle on it so that it adheres well. Wait for the wax to harden and repeat the process for the other three candles.
If you are a child, ask an adult to help you with this step
Step 6. Fold the edges of the square up 5-10mm to make a basket
During these operations, be careful not to bump the candles, as they would come off easily. This way, each drop of melted wax stays inside the square of foil.
Part 3 of 4: Building the Structure
Step 1. Measure the opening of the bag
Lay the ruler crosswise and note the length of the opening. This allows you to know the length that the sticks must have for the structure.
Step 2. Make two sticks with straws respecting the measurements taken in the previous step
To fix two straws together, make a small incision on the bottom of one and insert the edge of the other; then block the joint with a piece of duct tape. Continue like this until the stick is the same length as the opening in the bag.
If you are using collapsible straws, cut the "accordion" part
Step 3. Make a cross or an "X" with the two sticks
Find the center point of both and overlap them.
Step 4. Secure the sticks with tape
Do not use too much, to prevent the balloon from being too heavy. The best tape to use is clear school tape, while paper tape is too heavy.
Step 5. Alternatively, you can use balsa sticks
You can buy some pretty thin ones at art and home improvement stores. They generally have a square or rectangular section; cut them to the desired length and put a drop of wood glue in the center of each. Now you can stack the sticks to make a cross or an "X". Wait for the glue to dry.
- Try to get the thinnest sticks possible. The lower the weight, the more successful the flight of your balloon will be.
- Don't buy the wooden spinets; they are not made of balsa and generally have excessive weight.
Part 4 of 4: Assemble the Elements and Fly the Balloon
Step 1. Place the candle basket on top of the straw frame
If you look at the piece from above, the candles should be between each stick. This detail is very important, if the candles were exactly above the arms of the "X", the heat would burn or melt the straws. Furthermore, the weight would be poorly distributed, interfering with the flight.
Step 2. Secure the basket to the frame with tape
Take a piece of tape and place it under one of the "X" arms. Press it against the bottom of the basket and repeat the same operation for the other three arms.
Step 3. Secure the bag opening to the frame
Secure one corner of the bag to the end of a straw using duct tape. The opposite corner of the bag is attached to the opposite end of the "X" arm. Repeat this for the other two corners and ends of the structure. Eventually, the opening will have a square shape.
Step 4. Attach a long piece of string to the frame and grab the opposite end
You can also tie it to a table, chair or fence. This detail is very important; if you neglect it, the balloon could escape you and fall out of your reach. Choose thin, light twine, such as sewing thread.
Step 5. Place the balloon on a flat surface and hold the bag over the candles
Try to keep it as soft as possible; the help of a friend could be invaluable at this stage and the next.
Step 6. Light the candles
Be very careful not to push or bump the candles or ignite the bag. For this you should use a long lighter; if you are a child, ask an adult to do it for you.
Step 7. Hold the bag tightly until it fills with warm air and can stand up straight on its own
It will take about a minute.
Step 8. Let go of the bag
It will not take off at first, but after a few moments it will begin to lift off the ground and fly. Remember to hold the string or attach it to something sturdy. The balloon will sway in the air as long as the candles are lit.
Advice
- Depending on the size and total weight of the balloon, more candles may be needed.
- Consider using a biodegradable plastic bag in case you lose your balloon for good.
- The larger the size of the bag, the greater the amount of hot air that can be contained; as a result, the flight will also be better.
Warnings
- Be careful not to melt the balloon as you fill it with air.
- Always follow safety procedures when using fire and have water or a fire extinguisher handy.
- Stay away from trees, curtains, or dry grass when making this project.
- Remember that the balloon could catch fire and fall back to the ground.
