Air rockets!

So this past weekend I built an air rocket launcher with the kids.  I got the plans from MakeZine and got the parts from the local hardware store and from Amazon.  I modified the plans a bit, and generally used them as guidelines and used what I could find in the hardware store and made a few improvements along the way.  I added a schrader valve directly to the air tank and also added a pressure gauge so I could dial in the pressure for each launch.

The valve is the same sprinkler valve as in the plans.  I used two 9 volt batteries in series with a momentary switch on a long wire for the release.

The results were great.  We turned many heads in the park when we were launching.  With each launch I turned up the pressure to see how high we could send the rockets.

A few burst because of the high pressures.  The rockets we made did not have tape all the way around the tube body, leaving a spot for the rocket to burst.  The next batch of rockets we make will be taped all the way around to avoid this failure mode.  It was a lot of fun and fairly inexpensive at ~$20-30 for the total build.   The sprinkler valve was the most expensive part at $12 from amazon, the rest was the pvc and the gauge.  I had a handful of 9 volt batteries around, had the pvc primer and cement from an old plumbing repair a few years back and dug the switch, cross connect wire and small piece of perfboard out of the junk pile on my electronics bench. I may rebuild the trigger switch to be a nice hand held thumb switch or make a box to hold a plunger type switch, but those would just be for show, it works great now.

And a quick change of the rocket launcher tube and I have all the makings of a nice potato cannon, but that'll be a project for when the kids are a little older.  The rocketry was fun, but who doesn't like shooting stuff with a cannon you made your self?  I can't wait to bring this out in a few years with a new front end for launching projectiles instead of rockets.