Entree Design

The hardest part of building a balloon is getting the design correct so that it takes the load and so that you get a nice shape. I spent over 100 hours researching different designs and shapes from various sources including the popular Boland Homebuilt balloons in the US. I have many different design spreadsheets that various members of the US based balloon makers mailing list have supplied for me. These are all excellent but I have found an amazing peice of software that I am using as the base of the balloon design.

The software is written by a French homebuilder by the name of Arnaud Deramecourt. Arnaud has used his software to design the balloons he has built and the same software has been used by a number of other French homebuilders. The benefits of his software are huge. It calculates everything from a few basic inputs. It will even allow for convexities in the panel shape so that you don't get the pucker effect from straight seams, and the software outputs all of the information to files that can be used by cutting tables to cutthe panels for you.

Arnaud has been more than helpful with advice on his software, and help with wire frame modelling of the output models for me. This has been a huge help. Another friend of mine who is a whiz in Autocad helped me to put together the rendered model of the balloon. You can see an picture of the design here.

I say initial because this has 8 full height panels in the model. Upon reflecting and remodelling this myself I have realised this will have a very faceted apperance on the shape because these panels do not have convexities. As such I have redone the design and only have 2 panels with full height at the mouth and the rest have convexities so its a much smoother result.

All of the information I have from the design, including stress loadings and lift charts (all generated from Arnaud's software and verified by independent calcs) was submitted to CASA for information as the project progressed.

I have found the design process to be the biggest learning curve of the process to date. I learnt so much about the load structure of the envelope and how it distributes the weight around that I had no idea about before.