In preparation of the “cigar” shape we prepared our tiny sphere project. Now the time has come to put few things together (Mylar gluing & 3D Printing) and try to build something big again.
Starting with a draft we needed to find out how it will fit to our 1200mm Mylar sheet. So I’ve picked that we’ll go with sort of 5 segments and calculated some guideline values to be able to transpose those to a cutting plan.
I’ve been feeling sorry about a waste so came with a cunning plan to fit in more. Hope that picture below will be self-describing.
That all came with ~3m3 volume, so I gave a call to Serge to give me a hand with some measuring & cutting – as always, Serge appeared same day and started helping me instantly. 🙂
We’ve carefully measured a 1/2 template from a carton paper and then used it to draw it on a Mylar.
Situation changed when I finished our current Mylar roll and started with the “new” one. It came to my surprise that it wasn’t actually Mylar on its own but one side Mylar and second rubber! It was significantly heavier, but also stronger. Such a Mylar sheet came with a 220 grams of weight. That meant that 5 sheets would eat out 1kg of our lifting force.
Handling a panic attack I decided that we’ll add one more sheet – making it 6 in a total. Coming back to a calculator, that grown balloon’s volume to 5+m3, making it just a bit bigger then what I thought, but hey!
And couple hours later we had all sheets ready! (2 silver + 4 black ones)
Meanwhile, when working on the balloon itself, I fond out that some sort of gas filling / releasing valve will be needed and started designing one in OpenSCAD.
Finding a right way to make the printer to actually print it, took couple weeks, but result is simply awesome!
Next stage was to glue everything together. Picture below shows a stage where I just finished gluing all 6 slide sides together. This all was quite a story as I’ve run out of Mylar and the new Mylar, which I ordered in advance, came to my surprise with being double sided – rubber & Mylar. Obviously it all came much heavier then what I was initially counting for. Weighting one sheet, it came with 220 grams. That is 4 times more than the original Mylar I’ve been using.
Quick thought came and I’ve decided to add another segment to the balloon extending from 5 to 6. Recalculating our new balloon volume I came to a new value of ~6m3, what is quite a surprising difference to 3m3 with just one segment less which was 3m3. Another proof that humans can’t understand exponential growth.
Flipping whole setting inside out and adding a cap was another interesting task, while we’ve ended up with a nice folded balloon.
We’ve moved to another stage where we started with pressure tests.
Some of those parts, which I was worried about, were unfortunately not good enough, so I asked Serge again to give me a hand on this. Serge suggested to use a Mylar tape to re-cover balloon seems – Ametalin!
I bought one in Bunnings and asked Serge to show me his mastery in its usage.
It took us couple hours to go through all seems, but it was worth it.
We had a QA supervisor to make sure that all works are done in a safe and pet-friendly environment. 🙂
Last part was to install our new valve and all is now ready to go with another Hydrogen filling attempt!
Thank you Serge again and let’s move on to another stage of our project!
That’s a great report, Jan! I envy your team’s collective problem solving skills!
Cheers, R
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