Technical Difficulties from on Top of the Mountain
2004-08-07
  MacGyver would be proud
When Greg picked me up to go to camp, while loading several tons of welding equipment and scrap metal, I noticed that he had more than thirty 2L bottles of soda tucked away in the back. Seeing that, I was thinking to myself, this is my kind of road trip.

Turns out, all that soda wasn't just to keep me happily carbonated. Instead, it was sprung on me that I would be responsible for constructing some kind of launcher for soda bottle water rockets. Now it turns out that there are tons of web sites and plans for the rockets and the launchers, but mostly these sites are mostly by people with way too much time on their hands, who have created extensive launch systems and constant redesigns of their rockets. Having neither time, nor much hardware at my disposal, I instead needed to think more like MacGyver. What I needed to build was the world's simplest two liter bottle water rocket launcher.

So at camp, the first thing I did was finish drinking a 2L bottle of soda, and then go looking around to see what parts I had at my disposal. Luckily the camp has a fair collection of random lumber, electrical and plumbing supplies; so after passing over boxes of PVC (hey, I'm here to weld, remember?), I collected up an assortment of various kinds of metal pipe. There was some electrical conduit that was small enough, but joining it to anything was going to be a pain. There was some copper pipe, but I suck at brazing, and I didn't see any fittings. Finally I found some black pipe (which wasn't black anymore), that it just happened to fit inside the 2L bottle (very snuggly in fact). There were various lengths, with threads on each end, and a couple of elbows. I also found an odd collection of adaptors that actually hooked up an air-compressor fitting to a 2" pipe. After taking most of the adaptors apart, I had a perfectly good air fitting to half inch pipe adaptor for the other end of my pipe.


(Click for larger version)

What you see is what you get for the most part. The pipe sticks up into the bottle (hopefully a little above the water line), the pipe goes down to the elbow, to another short section of pipe (which was chosen only because it was it already attached to the elbow), which then connects to the adaptor where the air fitting is screwed in. The air compressor hose is attached to this.

Did it work? Could you have any doubts? Of course it did. We'd shove the bottles on there, hook up the air hose (to a el-cheapo compressor putting out about 40lbs of pressure while leaking air through several holes, bent lines, and rotted seals), the rocket would fill up with pressure and then zip it was gone. This kept thirty kids busy for close to an hour; and threw most of these rockets up in the air over 100'. Interesting, a few times, the rocket would stay stuck on the launch pad, but just the slightest tap to the side of the rocket would be enough to send it off. We tried some smaller water bottles that had about the same size neck, but they were like 0.3mm larger and so would not stick. However we did get a fair altitude by having the kids hold onto the neck of the bottle while pressurizing (do not try this at home unless you are as crazy as these kids were).

Oh, and if you study the larger picture close enough, you will notice a flat metal plate at the base of the pipe where it sets on the stand. That plate is there because I had lots of scrap metal with me, a drill, a cutting torch, and a welder. (I was here to weld, remember?) Otherwise it is probably completely superfluous, though it made a nice stop for the bottles, and actually helped provide a pretty good seal plate for starters. If you have a welder, go ahead and put one on. Otherwise, I wouldn't worry about it.

 
Comments: Post a Comment

<< Home
Life in the middle of nowhere, remote programming to try and support it, startups, children, and some tinkering when I get a chance.

ARCHIVES
January 2004 / February 2004 / March 2004 / April 2004 / May 2004 / June 2004 / July 2004 / August 2004 / September 2004 / October 2004 / November 2004 / December 2004 / January 2005 / February 2005 / March 2005 / April 2005 / May 2005 / June 2005 / July 2005 / August 2005 / September 2005 / October 2005 / November 2005 / December 2005 / January 2006 / February 2006 / March 2006 / April 2006 / May 2006 / June 2006 / July 2006 / August 2006 / September 2006 / October 2006 / November 2006 / December 2006 / January 2007 / February 2007 / March 2007 / April 2007 / June 2007 / July 2007 / August 2007 / September 2007 / October 2007 / November 2007 / December 2007 / January 2008 / May 2008 / June 2008 / August 2008 / February 2009 / August 2009 / February 2010 / February 2011 / March 2011 / October 2011 / March 2012 / July 2013 / August 2013 / September 2013 / October 2013 / November 2013 / December 2013 / December 2014 / February 2015 / March 2015 / July 2016 / September 2016 / December 2016 / April 2017 / June 2017 / July 2018 / November 2018 / January 2019 / February 2019 / April 2019 / December 2019 / March 2020 / April 2020 / May 2020 / September 2020 / November 2020 / March 2021 / May 2023 /


Blogroll
Paul Graham's Essays
You may not want to write in Lisp, but his advise on software, life and business is always worth listening to.
How to save the world
Dave Pollard working on changing the world .. one partially baked idea at a time.
SnowDeal
Eric Snowdeal IV - born 15 weeks too soon, now living a normal baby life.
Land and Hold Short
The life of a pilot.

The best of?
Jan '04
The second best villain of all times.

Feb '04
Oops I dropped by satellite.
New Jets create excitement in the air.
The audience is not listening.

Mar '04
Neat chemicals you don't want to mess with.
The Lack of Practise Effect

Apr '04
Scramjets take to the air
Doing dangerous things in the fire.
The Real Way to get a job

May '04
Checking out cool tools (with the kids)
A master geek (Ink Tank flashback)
How to play with your kids

Powered by Blogger