If you enjoy this project, then I encourage you to buy my book, Rubber Band Engineer. It's full of more awesome and original projects crafted from household hardware. You can find it wherever books are sold.

This is my take on the compressed air paper rocket launcher. Enjoy!

Intro Video

Step 1: Make the launcher

This launcher works up to 60psi. You can wire in a second 9V battery to get the launcher up to 100+psi. 60psi is enough to achieve spectacular results. Pressures above 60psi dramatically increase the risk of exploding the rocket.

(and by the way, you might want to protect your work surface a bit better than I did)

Built it and it was awsome fun to use. Highly recommended project!
<p>Some safety suggestions.</p><p>Fiber reinforced packing tape instead of duct tape wrapped around all the PVC parts. The fiberglass reinforcing threads are stronger that the fiber backing in duct tape and is much more likely to contain any loose parts. Make sure to tape around every pressurized part including lengthwise and around for all the piping. Still, having the whole thing inside a strong cloth bag would be safer still.</p><p>Not only use a second arming switch in series with the fire switch, but put it on a second cord and only let the adult supervising the launch have it. Lights and buzzers or alarms are a great addition. Even inside a burlap sack a string of red LEDs along the storage pipe and launcher would look good and alert everyone to be extra careful.</p><p>Add an extra 'T' fitting between the storage tube and the valve. Add a 3/4&quot; male thread to it. Using 1&quot; tubing make a short &quot;T&quot; handle about 6&quot; across and 6&quot; upright. You should be able to glue the 1&quot; tubing at the bottom of the T around the 3/4&quot; cap piece. Now you have a removable safety plug. If you have to leave the launcher, the handle should make it easy to unscrew the cap piece and now it is impossible to build pressure in the launcher or fire off a rocket. If already pressurized make the first turn slowly to bleed the pressure off. You may need to rubber gasket to improve the seal. A water house gasket might fit.</p><p>If you are willing to spend an extra $14, amazon among many other places sells an adjustable air pressure relief valve. Add that to the pressurized portion of the launcher and then even if a kid gets over enthusiastic and tries to pump past the limit it will simply vent the extra. Most also can be manually actuated to safely depressurize the launcher without pressing the fire button.</p><p>I have played with one of these but not yet made one. I would like to add it to my list of fun toys.</p>
<p>hi , so i put everything together and have a problem the valve seems to release very slow. No sudden burst of air to shoot a rocket off. Is it a bad valve?</p>
<p>Try a higher voltage, if it doesnt work, then it may be a bad valve/solinoid </p>
<p>exactly what i want. THX\</p>
<p>This is not spam, but a warning. PVC will fail suddenly after a while. This was band member that hurt badly by a T-Shirt launcher explosion.</p><p>See the pictures and never use PVC to hold air, Please.</p><p><a href="https://fundrazr.com/campaigns/1Zs3c" rel="nofollow">https://fundrazr.com/campaigns/1Zs3c</a><br>..</p>
<p>What SHOULD be used then? does CPVC fare better?</p>
No PVC, ABS, CPVC or plastic should ever be used. The cycling to pressure, down to zero, up to pressure, back to zero, makes it fail. It is unsafe to pressure test with air even when new. HDPE can be used, but it has to heat welded, and it cannot be glued. There are lots of metal choices. CO2 tanks, paintball tanks, retired medical or industrial gas cylinders, that used to handle pressures of thousands of pounds, can handle 100 PSI indefinitely. Empty fire extinguishers. Even empty propane tanks and bottles, are designed for pressure, and cycling, up to 250 PSI. One does have to watch for rust or corrosion with disposable tanks, as they are intended to be thrown away before they can rust through. Pressure vessels are also designed to split and vent when do fail, without any risk of shrapnel.
<p>I might end up doing this with lower pressures, like 10-20 psi and nerf darts to make a rifle. At that pressure would it be safe to use a ball valve?</p>
<p>That or large home made pool noodle darts.</p>
<p>i like it!!</p>
<p>i like it!!</p>
<p>Our Scout group had one of these lying around, which I very happily inherited and started playing with immediately. Of course, I tried to break it, which I did. </p><p>I have to agree with DanTDM and Masher007 -- and many thanks for the warnings; this can explode and potentially hurt bystanders or operators. </p><p>The device that failed on me was a couple of years old, and worked well until I pushed it past 40psi. Then then end cap blew off and sent shrapnel 40-50'. Thankfully I had laid a thick wool Scout blanket over the unit, so neither me nor my 3 year old son standing nearby were hurt.</p><p>I was operating the device in about 10 degrees Celsius (50 F) and had successfully launched it about a dozen times with 40psi charges, which resulted in flights over 200 feet.</p><p>So, be careful. Wrap the device in a heavy blanket or a shield that will contain any potential shrapnel. I really don't think duct tape is sufficient; it can fail too. This is especially important if the device is a few years old. It was the pipe cap that failed, not the glue, and I think the point of failure was where the inflating nozzle entered the cap; i.e., the hole that was drilled weakened the integrity of the PVC pipe cap.</p><p>A future improvement might be to add a gasket on the inside of the cap with the nozzle so that there is more support around the weak point.</p><p>Super fun project when it works, potentially very not fun when it fails. Take precautions and be dangerous safely.</p>
I believe the addition of a streamer or something may improve visual recognition for students and other observers.
The rockets are pretty easy to see in real life, though it's really quite challenging to capture a paper rocket on video. Streamers might look fun, but I think it would create too much drag. Perhaps a longer rocket would be more visible (and fun!)
Understandable, on both accounts. My experience has been that even paper airplanes which are comparably slow can be difficult to see. As for drag, I also know of the potential for drag in the streamers. Such decorations would involve those types of sacrifices.
A fun idea would be to affix some sort of smoke-emitting device inside the rocket for a realistic trail! Anyone who figures out how to do this will be held in the highest regard. I'll give away a 3-month pro membership, too.
<p>Use a thin piece of paper or saran wrap over the top of the tub and fill the nose cone with a white or colored poweder? The presure from the launch should puncture the barrier, and release the powder as the rocket launches...</p>
Talc coul be your smoke. Perhaps in the nose cone you could mount a a small tapered tune containing talk. A large, relatively, opening in the front that would apply pressure to the talk and force it out a small exit at the back. Just a thought.
<p>I made a few modifications to the original design and used it with my Cub Scouts at a kick off event.. Mostly cosmetic. I used the on/off switches from an old vacum cleaner. Wired in a re-purposed industrial fire alarm. Used about 20ft of wire to launch from a distance. The 1st switch is labeled ARM, it turns on the alarm to alert everyone that a launch is happening. The 2nd switch is labeled FIRE and it launches the rockets. It was a huge success and the kids loved it. The rockets (when sealed correctly) easily would withstand up to 70psi, the max we tested was 90psi, after the kids had all left (safety first). The rockets averaged about 75 yards (had to keep adjusting the launch angle). I had pre-printed rocket templates for them to cut out and decorate. Awesome idea, thanks for the instructable!</p>
<p>PVC explosions are half the fun!</p>
I would really like to make this rocket, but cannot find a solenoid. I searched the itsablast website and could not find one anywhere. i also searched ebay and the internet in general, but only found motorbike starters. Please help.
YOu buy a water sprinkler valve at Lowes or Home Depot for $13.
Hi there,<br> <br> The solenoid is included when you purchase the modified valve. The valve that I used in this design can be <a href="http://itsablast.com/cart/index.php?main_page=product_info&cPath=11&products_id=28" rel="nofollow">bought here</a>.<br> <br> Have fun!
I'm looking forward to running this project with my middle-schoolers!<br> <br> Here's an easy math extension: if launched at 45&deg;, the ballistic trajectory reduces to a simple equation that can give you the average velocity of your paper rocket (ignoring air resistance) as follows:<br> <br> SQRT(Distance x Gravity) = Velocity<br> <br> So if your rocket travels 27 meters: (27m x 9.8m/s<sup>2</sup>)<sup>0.5</sup> = 16m/s<br> <br> If you've got the right math crew, you can also show how the equation yields m/s from m and m/s<sup>2</sup>. Or, if you're using feet, how taking the square root of the distance in feet multiplied by 32 ft/s<sup>2</sup>&nbsp;gives you ft/s
Cool! Exploding rocket!
what is the difference between modified valve and air actuated valve? and which we use in doing this paper rocket lancher?
If i use a bigger persure chamber and more presure whould i go farther ?
I don't think so. A bigger chamber just takes more time to fill up to the max PSI.
Tanks for the answer.so il just use the regular chamber
This is a wonderful project that worked just perfectly! The kids were very impressed by how far the double launcher worked. <br> <br>I have some troubleshooting I was hoping I can get help with. After leaving the launcher alone for about a month, I tried it out again with some difficulties. Beyond the pressure of 30-40 psi the trigger won't work properly and won't expel the air from the barrel. Only after loosening the trigger from the chamber, will the air escape through the pvc. I don't know if this has occurred before in any of your models, but if so or not, do you have any tips?
Great to hear that! If the trigger won't work as well as before, try replacing the battery. If the battery is low then it won't have the power to activate the solenoid and release the valve.
That was it! The 9v had only 75% of the max charge, which I guess wasn't enough to pull the trigger fully under high pressure. Much thanks! Now I can use this even more!
How is the &quot;modified sprinkler valve&quot; different from a home depot sprinkler valve?
I don't know exactly how to mod a valve, but I do know that the valve is modded to allow the air to escape more rapidly.
hm you need this device to shoot the rocket darn!
You should try a whistle in the cone...
A serious suggestion - put a safety switch in the circuit - perhaps a toggle switch with a flip up cover. This way firing requires three actions ,flip cover, toggle circuit on , press fire button. It's never too early to impress safety on kids<br>Don
That's a great idea! It would be pretty easy to splice in a second switch, perhaps something that only the teacher can control. I like that it allows students to be in control of the launch without the risk of a misfire. Although my safety talk has so far been effective, it is indeed better to be safer than not.
I like the idea of a second switch in series with the firing switch. <br>On the idea of teaching safety and responsibility; assign one student as a safety officer for each team. The safety officer would make sure all students are clear behind the safety line before calling range clear and pressing their button to enable the firing button. (does my military background show with this suggestion?)
You should also think about wrapping the PVC with several layers of duct tape. Overtime the PVC may weaken and the high pressure could rupture the pipe sending possible shrapnel into the crowd. The duct tape would contain any flying debris in the event of a failure. Or you can use metal pipe for the pressure vessel. With kids its always a good idea to be extra safe. Keep up the good work, I love it when kids get excited about science!
I have to agree with THAYRAY. Some of those kids were too close to the launcher. Perhaps a line which every one must be behind before launching. It's no fun going through life with one functioning eye, I know.<br> On the other hand this is really cool and is going into my grandpa projects to amaze the grandkids as soon as my kids make one for us. Maybe they need an instructable on how to make bqabies.
Thanks for the kind words and your concern for the kids. I'll admit that it is difficult to keep kids at a safe distance - everyone wants a good view of the launcher. I constantly remind kids to back up, but your comment gave me an idea for a better solution: I think it would be easy to use a brightly colored rope to create a safety zone around the launcher. I am conducting this project at many schools this week, so I'll try this out today and let you know how it goes.
I bought some thick and bright yellow rope to define a clear safety zone - it worked very well! Kids were even reminding each other to &quot;Stay behind the rope.&quot; I've updated this Instructable with a photo of the rope being used in step 4. Very simple, easy-to-implement solution until I install a second safety switch.
Yeah...the mom in me cringed when I saw the kids so close but other than that this seems really fun! My munchkin is a bit young yet but someday...someday...
It does seem quite dangerous, though so far I've conducted hundreds of launches with no injuries. I thought about excluding some clips from the video because it looks dangerous, but showing true footage has prompted concerned members of the community to voice their ideas for safety improvements :)

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