Building a Solar Balloon

 Probably the cheapest method to fly...

Spending less than 9€ of materials and more than 10 hours of patient we built a 4 meters diameter balloon, the Airbox Solar One balloon was our first solar balloon prototype.

Here you can find how we design and build the Airbox Solar One. 



We are going to design a solar balloon.

We need a pencil, a notebook, a ruler, a compass, a protactor and a calculator... Or an Autocad.

First of all draw the balloon profile to do, in our case is as simple as a circle and a cone of 45 degrees.

After drawing, divide vertically the balloon in two parts and draw lines horizontally (left picture) the more lines, the more precission.

Now decide how many leaves you want to use to do the balloon, if you use a lot of leaves construction is complicated, if you decide few may be the balloon seems a cube rather han an sphere. In our case we use 6 leaves, if the balloon is higer you may use 8 and if is tinier maybe 4 are enough.

Having 6 leaves then divide the perimeter of a circle by 12. Why by 12? because we do half template and we fold the plastic to cut, like kids doing paper dolls. We have to do this calculation for each of the lines drawn in the previous amount step. Now measure the distance between the tip of each line and this is the distance to draw the 1/12 of perimeter in your template.


As in the "ecuator" of the balloon radius are similar we simplify drawing an straight line. To do all the calculations you spend less time than to do medium level Sudoku.

Here you can see the 6 leaves result:



Now we are going to build a solar balloon.

To do it we need plastic, black or dark colors are the best, and the lighstest as you can, normally garbage bags are a good choice (the cheapest ,the best) in our case we are going to use a painter cover plastic coil of 6 micrometer thickness and 50x2m long. It cost around 6€ and is easy to find it in paint stores and department stores. It weights 5,25 gram per square meter. This plastic is transparent and the idea is to darken it with carbono powder. 

Second thing we need is packing tape, in our case 2 cm width. two tapes cost 1,99€. 

We try to solder or ironing the pieces but 6 micrometer is too much complicated for us, maybe we have no techology and/or knowledge to do it. Packing tape is fastest and effective but it increases around 25% the balloon final weight. 

 We also need some tools such as scissors, black tape or similar and permanent maker.


Step 1:

First we need to find 7 meters of floor clear of obstacles to draw the half leaf template with black tape... and red... and at the end with paper tape.


Step 2:

Once finished the template and measured again to check it was ok, next step was to unfold the plastic on the template.


Step 3:

You have to leave the plastic stretched well, we use wine and cava bottles to fix the plastic, but it is optional.


Step 4:

Draw the line to cut and mark aprox every 40 cm and put a number or a letter, is good to do it because when you are going to fix you can see if all is going ok.


Step 5:

Take your time to cut, remember there are two plastics and you only draw on the upper one, Then mark the second one the same mark as first to make easy the fixing part.


Step 6:

After doing Steps 2 to 6 six times now to fix . Surely you have the ironing board hidden somewhere. Finally it is useful. And now we start a patient work of fix the leaves.


Step 7:

We put a 50x10 cm piece of wood on the ironing board to have a hard base. Starting in a tip, conect the numbers of two leaves, put one over the other maintaining between 5mm and 10mm and fix with the tape, we use around 30 cm of tape each time.


Step 8:

Do Step 7 with patience. Be aware with tape, once is fixed there is nothing to do. maintain the tape at a safety distance and take care for accidentally fix. Pay atention to not step the plastic, is only 6 micrometer thickness.

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