As a child I once had a few plastic rocket shaped toys that, after being filled with water and pressurized using a tiny air pump, would be launched over our hill and into my grandfather's garden. As time went by I forgot about this enjoyable set of toy rockets. After getting married I began reliving my childhood through my nieces and nephews. I'm just a big kid at heart. Anyway, one day I was thinking of things to do with the kids during the summer when I remembered my little rockets. I searched the internet for "water rocket." To my surprise, there was a wealth of information on how to build your own water rocket. Forget about toys, these things were serious rockets. But, I was looking for something like what I had as a kid so I moved on. Below is an image of what my toy looked like back in the day.
Toy Water Rocket

Bottle Rocket

However, I just couldn't find anything like my old toys. So, after reading several articles about these much more powerful rockets I decided to build one. I figured the kids could prep the rockets, the adults could fire the rockets and everyone would get WET! Well, I found many plans on the internet. Most of these plans used 2 liter pop/soda bottles as the rocket. After studying the plans for some time, I settled on 1 that used wire ties as a release mechanism on the launcher and was supposed to be powered by a bicycle tire pump. I modified the design slightly since the original design required a person to hold it while the rocket was launched. I formed the PVC pipe into an H pastern base thus making it unnecessary for anyone to hold the launcher and thereby improving the safety factor. There were a few problems. First, everyone got tired using my antique hand bicycle pump to pressurize the rockets. Since I had an air compressor I made some minor modifications and was able to eliminate the bicycle pump. The next problem was that the wire tie release mechanism tended to pinch your skin. This wasn't a big problem for the adults, but really was an issue when the kids wanted to release the rocket. The final problem was that to much air could be added to the rocket and thus cause them to "explode." Even with the bicycle pump attached in place of the compressor a used rocket could still explode. So, I was on a quest to find a different release mechanism when I stumbled upon a site that used a press fit of the bottle on the launcher. This press fit acted as a safety value. It would only allow a maximum of about 35 psi to be applied to the rocket before it would release.
First Launch

With this new design, I modified the launcher a final time by fixing the release mechanism and adding a ball valve to shut off the air flow from the compressor. In the above picture you can just see the bottle lifting off above my dad's right shoulder. Check out the stream of water and air blowing out of the bottle. These modifications to make the launcher safer still allowed a simple unmodified 2 liter bottle to reach heights of nearly 60 feet. I told the kids to try to design an aerodynamic rocket using 2 liter bottles on a rainy day when they have nothing else to do. Of course, they always had something to do so we still use plain old 2 liter bottles. We've lost a few from time to time but we always seem to have fun with it. Check out a video of the initial launch.

Back to the Toy

I never did forget about that little toy. I was looking for some other science related parts for my stirling engines one day when I came across a site selling modern versions of the toy water rockets. I was so happy I found them. I bought several packages of them and gave them to the kids. I'm not sure if they destroyed them or not but one day soon I'll have to buy another one for my son. He just needs to be a little older before that day.

Created on 05/27/2010 11:32 AM by admin
Updated on 08/16/2011 11:17 AM by admin