Building a Lego-powered Submarine 3.0 - balloon and compressor

It was a lot of fun building the Lego-powered submarine. I started working on it again this morning, but have only done some simple paintwork and photographs so far. I hope to get back to it and build the pressure balloon soon for christmas, as that's my deadline for getting everything done.

It takes only a few common household supplies to build your own Lego-powered submarine, and it'll be ready in hardly any time at all. Just be sure that you weigh the risks before taking it for a spin—plastic isn't exactly known for its buoyancy, after all. And what's more, don't forget to grab a life preserver if you plan on tackling a deep sea voyage.

So there you have it: a balloon-powered LEGO submarine that can dive up to 12.5m, goes up and down with a push of a few buttons, and is safe for use by a novice. I hope you can use this knowledge in your projects—I'd love to see what sort of contraptions you come up with!

Overall, I really liked going through the process of designing and engineering a Lego submarine. I think all the best engineering problems are solvable in this fashion, starting from basic components and working your way up to a solid, practical solution.

Our submarine was now functional, but there was nothing doing. Fins pinned the balloon in place allowing it to drift around the kitchen table rather than rise towards my roof.

Awhile back, I wrote an article on how to build a Lego-powered submarine . I had a bunch of fun with it and decided to build another one for the LEGO club at my daughter's school. I called it the Submarine 3.0. Well, this time I am improving it with some new features, like a mini-compressor, a balloon to enhance the design of the sub and make it easier to achieve neutral buoyancy. And again (we are big fans of repeat here), all parts used were entirely from Legos, or if none was considered useful, found outside of the house or in our recycling bin.

That concludes all of my LEGO submarine projects. I've had a blast building all of them. Thanks for reading and following along in the journey! I hope you found the mini-biography of my LEGOs extensive enough, and that the final project came together just as you had envisioned.

I'd wanted to make a few tweaks to the system. I had an Arduino and an LCD display from another project that I never got around to completing and thought I'd integrate that into this boat. This would allow me to control a lot of the internal workings and monitor how much air was left in the balloon, where I was located, how deep/high/fast I was going.

Using a pressure difference between a large and small air chamber, we can power a piston that pushes water through a tube, creating an upwards force on the submarine.

I never thought about putting a balloon inside a tank and pumping the air out to propel it. But now that I have, I understand why this works. This is something that a child's mind can figure out on their own, and it means they'll spend more time playing and less time worrying about how to get it to work. Let them have fun with it!

This is a fun little project but can be cumbersome to construct. If you would like a good printer friendly version of the instructions please do not hesitate to request it via the comments section as there are very few instructions uploaded online that do not require an account with any site.