Every summer, Qualcomm hosts a Battle of the Schools competition, which gives employees the opportunity to represent their home universities. This year, entries were to be homemade contraptions, and they were judged according to how cool they were perceived to be. Virginia Tech's cannon project tied the University of Michigan for first place. 

The project entailed a pneumatic cannon with valves controlled electronically. When the cannon electronics receive a certain message over Bluetooth, the appropriate barrel fires. On the other side, an Android app uses the phone's Bluetooth modem to send messages to the cannon. This approach allows the cannon to be fired from around a 30-foot range, line-of-sight.

Here is a brief video describing what we'll be making:

We started the project on a Friday night and finished the bulk of by Saturday night. We worked pretty much non-stop, and all had experience working on this kind of stuff. With that said, we'd recommend carving out a whole week if you're working on this by yourself. So now that you're enticed beyond your wildest imagination, let's get started.

Please remember to be safe while building and using this device. You are entirely responsible for what you do with this information.

Step 1: Shopping List

Here's a list of all the parts you'll need: 

Arduino Uno (1x, $29.95 each) 
BlueSmirf Silver Bluetooth Modem (1x, $39.95 each) 
Male Break Away Headers (1x, $2.95 each) 
Solid Hookup Wire (1x, $10.95 each) 
150-psi Inline Sprinkler Valve (2, $11.99 each) 
Bicycle Tire Inner Tube (2x, $3.99 each)
6" x 4" x 2" Project Box (1x, $5.29 each)
SPST Relay (2x, $3.19 each)
Breadboard-Style Prototyping Board (1x, $2.19 each)

2" Diameter PVC
3" Diameter PVC
1" Diameter PVC
2" PVC Endcap
2" PVC Elbow
2" Coupler
3" to 2" Reducer Bushing
1" Schedule 40 PVC Adapter 
3" to 2" PVC Adapter Coupler
2" 45 degree PVC Coupler
Plastic Epoxy
PVC Primer and Cement

You'll also need some tools: 
Soldering iron with solder
Safety goggles
Ear plugs
Solder sucker (unless you're really good)
Wire strippers
Flush cutters (optional, for a professional finish)
Heat gun and heatshrink tubing (optional, for a more durable finish)

Also, please note that you can get ranges up to 350 feet if you are willing to spend an extra $25 on a Bluetooth modem, assuming your phone's hardware also supports that range. The BlueSmirf Gold is also available from SparkFun with a very similar interface. Please note, however, that the pin order is slightly different between the silver and gold models. It shouldn't be too bad to convert from one to the other though.

This is an amazing project *2 thumbs up* ..............my only picky bit is the photo instep two. Your key shows that hardware is red and software is blue but the arduino board is blue :| <br><br>Shouldn't it be red? I'm guessing you refer to it as software because of the programming but the board itself is hardware with software on it. Software is non-physical. <br>Great Project either way
<p>or could you make an iphone app please</p>
<p>is there a way you could make this so that it is powered by the serial monitor</p>
<p>is there a way you could make this so that it is powered by the serial monitor</p>
<p>Great excellent step by step process used a rainbird sprinkler valve only complaint is the cannon is really loud to shoot. Not a bang but a high pitch air horn. I have been doing research trying figure out why its so loud thinking its the valve cause restriction. Ordered a new valve off amazon that has less restriction.</p>
Awesome Project i just have one question i was trying to put the arduino program into my arduino buy i keep getting this error : serial' was not declared in this scope any suggestions?
Right, I see PVC is not designed for air pressure, if use PVC how much limits PSI for safely?
Often PVC has a PSI rating printed on it. There is probably a safety factor built into that number but I would still never pressurize all the way to the rating. Watch for any signs of cracking, especially near anyplace you modified (e.g., drilled a hole) the pipe.
Great Instructable, this app will hopefully save me a month or two of work learning Java.<br>I'm trying to install the app but can't figure it out, I'm not sure what file I should be opening. I have Eclipse and all the appropriate add-ons. I guess the problem is I don't know Java orAandroid development. Besides getting the app installed on my phone I was hoping to change the images. I found the images in the files, will it work if I just replace them with my own images with the same names?<br>Thanks.
Wow! You guys managed to combine my three favorite types of projects! Arduino, Android, and Canons!
I thought I recognized those colors... Let's go!!! HOKIES1!1<br><br>i was just there for a CEED camp 3 weeks ago. all the way from CA!!! i wish we could have done something cool like that while I was there. :(
When you had it at the school you should have filled it with confeti with a backstop of some kind so it rained down on them. Would be awesome to be there during that.
The safety note is *important* and one should not overlook it.&nbsp; While building a Super squirt gun using 4 inch diameter PVC I accidently over pressurized it to 90 psi before I was able to release the quick release valve (but not quick enough!).&nbsp; I heard a boom and I was no longer holding onto anything.&nbsp; The end caps held on by normal pipe glue gave out under the pressure sending a large chunk of it into my face.&nbsp; I broke the orbit of my eye socket and although I have some permanent nerve damage to some facial nerves, I kept my eyesight.&nbsp; (At least now I don't need novocane when I go to the dentist!)&nbsp; My crooked smile is at least an honest smile now.&nbsp; So... the purpose of my life is to serve as a warning to others...<br> <br> Best Wishes and Be Safe.

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