Step 12: Final Preparations...

At this point, you should have a full envelope and a completed blimp frame. Find the frame's center of mass -- it should be just behind the battery -- and line that up with the central crease in the envelope ( it comes nicely folded). Now lower your envelope until it's touching the four pylons; anchor it and make sure it's symmetrical around the long axis. Take four velcro patches and press them firmly onto the envelope, directly above the pylons, so that you can sort of pinch the velcro on the mylar onto the corresponding patch on the pylon. Do this for each pylon, and the frame should be securely fixed to the full envelope.

Now, the moment of truth. Release the anchors, keeping one hand on a string at all times. If you're lucky and you kept the weight down (my frame is just under 130g, you can get by with 140g), the whole blimp will slowly rise up. If it does, congratulations! Add some payload to get to your desired buoyancy and take to the skies.

If your blimp fails to rise, do not give up hope. It took me six months to get my blimp fully airborne, you shouldn't feel bad if you don't get it right the first time. Weigh your frame, and do whatever you have to get it 130 grams. If that doesn't do it, your gas is contaminated with air, and you need a fresh run with a better seal between your tube and envelope. Make sure there is no gas leaking from your reaction vessel or tubing.

On an unrelated note, my envelope as seen below is speckled and partially translucent because I spilled some lye solution on it, not because of some error committed by the envelope manufacturer. I'm an idiot. Don't be an idiot.
<p>Can something be sprayed onto a plastic wrap skin, to help hold in the hydrogen gas? I'm trying to keep it light, but don't want the gas to leak out too quickly. Really cool project.</p>
<p>Do you have any idea how much weight (gram) the blimp can lift ? </p><p>Thanks</p><p>Sam</p>
You blimp looks awesome, only the code is without any doubt the most incomprehensible code I have ever seen! I can't make heads or tails from it. Could you explain the how te code works? I really like the 433 MHz set I got, but I haven't found a clear code that I can adapt to my homemade rover. <br> <br>Thom
Darn, I have been trying to figure out your code for quite some time, IT-IS-SO-SIMPLE, I have tried to use virtualwire but then I can't use the servo library (they hate each other). Thanks for sharing it!
when I first read the title I accidently read &quot;Hydrogen bomb.&quot;
Nice work on this project! I had the same 433 Rx Tx units and could never get them to communicate properly! Definitely one of the best troubleshooting sections I've read!
this soo reminds me of the hindenburg. tho to be fair, hydrogen had nothing to do with the explosion. zinc paint(?!) was the problem. <br>very cool project. <br>tho 433mhz might not be legal in USA, but even a toy car with arduino could work
You are my hero. I have tried filling a smaller blimp with hydrogen in the same way, but using only very small amounts of lye (five attempts with no success). I would love to build a setup like this some day, especially one using a hydrogen fuel cell for power. One question: does the water buffer remove any steam or water vapor from the hydrogen entering the envelope? I always worried about getting water in it. Thanks for a very informative 'ible.
You're right to be worried about water vapor. It will only be a problem if you let the reaction get too hot, which will make it start steaming or even boil if it gets out of hand. If you make sure it doesn't get more than a little warm ( I dunno, 75 deg F), the water vapor will be negligible. If you're really worried about it, you could try running the gas through a percolator to cool it down before it enters the envelope (meaning some of the vapor would condense out). The buffer I have is mainly to prevent any water in liquid form that bubbles up from getting close to the envelope. Don't give up on lye!
Awesome. Love the chemistry lab details and the troubleshooting section.

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