On our trip to Detroit Maker Faire this year we had the chance to make our very own rockets out of nothing more then paper and masking tape. The rockets were then placed on a home made air launcher and fired several hundred feet in the air. It was so fulfilling to both build the rocket and see the look on my kids face when their creation went sailing into the sky I knew we had to make one.
It turns out that this project was featured in Make Magazine Vol 15 and they sell a kit for the project as well.
The best online construction guide I’ve found for this project is located here at makeprojects.com.
The construction of the launcher is very simple. Even if you have never glued PVC or used thread tape the instructions are easy to understand and require a minimum amount of tools. Now getting it air tight is a totally different proposition. The glue joints if done properly should not be a problem so that just leaves the threaded connections.
Tip 1: At least two layers of thread tape on each fitting
Learn from my mistakes on this one. If you only apply one layer of thread tape you most likely will have leaks. In my case the leaks became most prevalent above 60psi..
Tip 2: The soapy water test
This is a well known technique for finding leaks. It was taught to me by my father first with bike tires then with anything that holds air. Mix-up water with a generous amount of dish soap and apply to the joints that should be air tight. Bubbles will be very apparent anywhere air is leaking out.
Tip 3: Don’t be afraid to customize
The basic instructions are great and builds a really nice looking device but don’t be afraid to add your own touches. The instructions suggest wrapping the air chamber in duct tape in case of a failure it will reduce the likelihood of the pieces becoming airborne. With the variety of duct tape available why not add a little character to your project. The electronics are another area that could use a little cleaning up. The instructions leave the batteries and connections exposed. A cheap hobby box from radio shack and some connectors make the whole package look a lot cleaner. This also lets you detach the detonator and makes it less prone to becoming tangled.
This is just the first post in this series. I have made several modifications to this launcher to make it a little safer and more informative for the kids. You may have also noticed the payload chamber at the top of the rocket in the first picture. That has a really neat story and will have to wait for a later article.