How to build a Hot Air Balloon

Building your own Hot Air Balloon!
M.W.Workman

(Here's How)

The first thing you do is start with 18 sheets of Gift Tissue from your local Wal-Mart or Hooks. It cost about $1.79 for five sheets. Each sheet is 20 by 26 inches. Group the 18 sheets into six sets of three.

For each set of three line them up to form a single sheet that will be 60 by 26 inches. Then overlap each sheet with the next by 3/8 of an inch. Use a slight amount of Elmer’s glue to hold them together. Do not use glue that washes out (such as Elmer’s School Glue) because this glue will get soft as the balloon flies (due to moisture released by the burning fuel). Usually it is a good idea to slightly smear the glue along the length of the sheet to increase the are the glue contacts, thus making a stronger connection.

You should now have 6 sheets that are 60 by 26 inches. Stack these directly on top of each other to and pin them together with hat pins. Now it is time to mark the sheets so that you can cut them to make balloon gores (sides of the balloon). The first marking will be for the top of the balloon.

Now you need to mark the bottom of the balloon, the balloons neck. The combination of these two markings will govern the overall shape of the balloon. It is not too critical what shapes you use for these markings, as long as the top of the balloon ends up having more volume than the bottom of the balloon (to ensure it is stable). Also, remember that the perimeter of the mouth of the balloon is equal to 12 times the length of X (shown in next figure).

Now fold the stack of sheets back so that the marked half of the sheets is on top. Be careful to ensure that all 6 sheets are folded in their middles.

Cut the sheets using sharp scissors. Separate the sheets into sets of twos. Glue ONE side of each set. You should end up with three sets of two glued gores.

Now the hard part is when you put these three pairs together so that the seams are all on the inside. If you don’t care about this then skip to here. Otherwise follow this process:

Number the pairs of gores to reference purposes.

Fold the top gore of gore pair #1 down the center to the right. From the side it should look something like this: .

Fold #2 the same way but then flip it over so that the non-folded piece lines up with the top of #1. Like this: .

Now fold back #2 down the center line to the right. Like this: .

Now fold the top of #3 down the center line and to the right. Then flip it over and lay it on top of #1 and #2 (which are now glued together). Glue them together. Like this: .

Now you only have one seam left. Fold over #3 and invert the entire stack of gores so that the balloon is inverted (seams on the inside). The last seam will take awhile to do, since you will have to do it so that the seam is on the inside. Just work your way from the top down folding a little bit inward at a time and gluing it.

Now get some 20AWG wire (or those cheap/thin coat hangers without plastic on them) and make a circle out of it the radius of the mouth of the balloon. Insert the ring and fold the paper of the mouth up around the ring to hold it in place. Fold about 1 inch of paper around the ring.

Now get three coke cans. Take some metal snips or sharp scissors and cut the top of one can off just below the bend in the top of the can. Then cut the bottom and top off of the other two cans.

By force, and bending the cans; stack the cans vertically. Once they are stacked poke holes in the joints of the cans (where they overlap) and insert some fine (24 AWG) wire through the holes (and tie it) so that the cans hold together.

Now poke holes at the following locations around the perimeter of the engine.

Through three equally spaced holes in the top set connect three wires (one for each of the three equally spaced holes) that are about 9 inches long.

While the balloon is upright (have someone hold it) center the engine within the mouth of the balloon and connect the three wires to the ring within the balloon (you will have to poke these wires through the balloon paper). These wires should be evenly spaced around the perimeter of the balloon.

You are ready to fly. On a not-so-windy day (after a rain is best) have some friends hold the balloon up and out. Do not let the wind (or a friend) let the balloon paper get near the engine. Then pour some denatured alcohol into the engine (this isn’t so easy) and then light the engine through the lower set of holes. Usually you can fill the engine up to the lower set of holes. The engine will shortly heat up and soon there will be a 8-10 inch flame coming out the top of the engine into the balloon. Depending on how much the engine weighs and the balloon weighs it will take off in 30 to 120 seconds. If it catches fire then let it fall - DON’T HOLD ON TO IT! This type of simple balloon can go from 2 to 3 miles depending on how cold it is outside and the wind speed.

If the balloon didn't fly then it weighed too much with respect the outside air. So, try these things:

1. use less fuel.

2. use lighter balloon components. For example lighter wire to hold the engine in place, lighter engine cans (aluminum only), thiner layer of glue to hold the paper together, lighter wire to hold the mouth of the balloon open (but not too light or the mouth will collapse).

3. use hotter fuel, such as rubbing alcohol. Isopropyl alcohol is around 20% water and doesn't burn as hot as pure alcohol.

4. try launching on a colder day. Since the lift of the balloon is related to the lightness of it's hot air with respect to the outside air, the colder the outside air the less heat the balloon will need to lift.

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