How-to: Building a compressed air rocket launcher

Fun & Games
How-to: Building a compressed air rocket launcher

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Summer is here, and I was looking for something to do with the kids. They raved about how much fun the rocket launching was at Maker Faire in San Mateo, and I wanted to bring a little bit of that fun home. All I needed to do was build my kids the kit version of Rick Schertle’s compressed air rocket launcher that was featured in MAKE Volume 15.

This is a really easy build, and the rockets go amazingly high! How high? That’s a great question that I can’t answer. Why? Because the rockets went so high, that I could barely see them anymore. I guess that’s high enough! If you know a way to measure the height, let me know in the comments. I know of a few ways, but I’d like to hear your suggestions too!

Note: You can build the launcher from Rick Schertle’s plans in MAKE Volume 15. The kit includes a copy of MAKE Volume 15, all the electronics, and the PVC parts cut to length. All you need are a few simple tools, glue, and tape.

What you need:

  • Tape, duct or similar re-enforced
  • Bicycle pump
  • Pliers, channel-lock

Time to build: about 1-2 hours

Difficulty: Easy!

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The kit from the Maker Shed has a few changes that make it more portable. I’m not going to go over every last detail of the build, because they are all in the magazine, but I will cover the changes and some of the modifications that I made to my rockets.

Let’s get started: Build the pressure chamber
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Start by adding the Teflon tape to the reducer fitting and screwing it into the threaded PVC reducer cap. Use an adjustable wrench to tighten.

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Next, using some more Teflon tape and screw the brass barbed fitting into the reducer fitting.Simple!

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Now it’s time to start gluing the PVC parts together. We are going to add the piece we just made to the PVC tee as described in the directions.

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The process is the same at every connection. First wipe the connection with primer. I chose clear, but purple is more common. Now add the glue. Any PVC glue is OK to use. I used “extra strength” but the standard variety is fine too. Make sure to work fast, and give the parts a little twist during the joining process.

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Now glue the 10″ long PVC pipe into the other end of the PVC tee as described in the directions.

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Followed by gluing on the end-cap to the 10″ piece of PVC.

The launching system:
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Start building the launching system by wrapping Teflon tape around each of the 3/4″ male threaded x 3/4″ female slip PVC adapters.

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Attach each adapter to the sprinkler valve, and tighten with channel-lock pliers.

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Take note of the arrows on the sprinkler valve. On the “out” side of the valve, glue a 16″ length of PVC pipe. On the “in” side of the valve, glue a 3″ length of PVC.

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Now glue on the reducer slip fitting on the top of the PVC tee connector as described in the directions.

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Followed by gluing on the sprinkler valve assembly you just made.

Building the improved stand:
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The kit has a stand that is different than described in MAKE Volume 15. It’s more portable, and easier to build. Start by measuring 6 1/2″ from each side of the include 16″ lengths of PVC pipes. Next drill 1/8″ holes completely through the PVC pipes at those locations.

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Now enlarge the holes with a 1/2″ bit, but only on one side of the PVC (this is now the “top side”). Do not drill all the way through!

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Feed 1 end of the included zip-ties into one of the 1/2 holes. Next, use a small screwdriver inserted into the back of the PVC pipe and push the zip-tie up into the other 1/2 hole you just drilled. Sound complicated? It’s not!

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Don’t attach the legs yet! We have to wrap the air chamber in duct tape first. We’ll do that in a bit.

Building the electronics
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Let’s start by building the launch handle. It houses the electronics and allows you to fire it from a safe distance. First, drill an 1/8″ hole in 1 of the PVC end caps, and a 1/2″ hole in the other end cap.

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Solder the (2) supplied wires to the button. I added some heat-shrink tubing for added security.

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Add the button to the end cap with the 1/2″ hole. It’s a little tricky to screw in the retaining nut since it’s a tight squeeze.

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Now feed the wires through the 4″ section PVC pipe. I added a small nut to the wires. It makes it hard to pull the wires out of the handle. Just loop the wires around 2-3 times about 1″ from the end of the PVC pipe. Next, feed the wires through the other end-cap. No need to glue any of these pieces.

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To make the wires look neat, I clamped them in a drill and twisted them together. You can do this by hand, but the drill makes fast work of it.

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1-2 seconds later and I have a nice length of twisted wire! The controller is done. Now lets mover on to the power supply.

Building the power supply
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The power supply is fairly straightforward. Start by soldering (1) red wire from the battery clip to (1) black wire of the another battery clip. I cut my wires a little short and used some heat-shrink tubing for added security.

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Next, solder (1) of the remaining wires from the batter clips to (1) wire of the launch controller. The remaining battery clip wire is soldered to (1) wire of the sprinkler valve. The last connection is made by soldering the remaining sprinkler valve wire to the remaining launch controller wire. It may sound tricky, but it’s a really simple circuit. Check out the instructions for more details.

Building the air supply connections
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The first thing you need to do is remove the rubber housing from the air valve.

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I found that using (2) pairs of pliers and rotating them around the valve stem made the rubber come right off. Easy!

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Place the included crimp on one end of the tube, along with the valve stem, and crimp the “ears”. This makes a very strong connection.

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The other end gets attached to the launcher and is held in place with a zip-tie.

Wrapping up the air chamber
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You should wrap the air chamber in duct tape. The PVC is under a lot of pressure, and in the even of a failure, the tape will help contain the parts.

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You can find duct tape in many different colors now. I saw rainbow, camouflage, and even flower patterns. In the end I chose a nice medium blue. Wrap everything in at least 3 layers of tape.

Finishing up

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Now we can add the legs to the launcher. All you need to do is zip-tie them on.
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The final step is attaching the (2) 9 Volt batteries. Tidy up the wires and zip tie them to the vertical section of the launcher, and you’re all ready to go! Wait! You need to make some rockets!

Making the rockets

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My kids wanted to color the rocket templates. The instructions tell you to use masking tape for the rockets. However, you can also use clear packing tape, which allows the colors to show through. Fun!

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Start by coloring in the included rocket templates, followed by cutting them out on the black lines.

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Follow the instructions for building the paper rockets, substituting clear packing tape for masking tape. There are (3) pieces of PVC tubing in the kit that are used for building rockets. This allows (3) people to build rockets at a time. When you are all done, you should have a great looking rocket all ready for blast off.

Launching!

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Place the rocket on the launcher, and pump up the air chamber to 60-75 psi. Then get ready for the count down…3…2…1…blastoff!

Note: Be safe. Stay clear of the rocket launcher when pressurized, and always wear safety glasses.

I took some video of the launch, but the rockets are so fast, go ridiculously high, and it was so too bright out to get any good video. However, this gave me a great idea. Make a rocket out of vellum and put some LED’s in the nose cone for night launches. I plan on doing that this weekend, and I’ll post up some video if it comes out!

Check out my entire flicker photo set here. Don’t forget you can make you own air rocket from plans in MAKE Volume 15, or pick up Rick Schertle’s Air Rocket Kit from the Maker Shed.

50 thoughts on “How-to: Building a compressed air rocket launcher

  1. Rachel Hobson says:

    This looks so cool, Marc! I’ve been wanting to try rockets with my kids, but since it’s been so long since I built one myself, I was unsure of where to even start. Great tutorial and gorgeous pics. I love the tips, too (twisting wires with the drill = brilliant and kinda fancy)

    And *please* do the vellum/LED/night launch – that sounds RAD.

    1. Marc de Vinck says:

      Thanks! I have the LED version of the rocket built, just need the sun to go down!

      Also, my kids built one with glow-sticks (the bracelet version) attached. They should be even better!

  2. Jim says:

    I built my version of this project after seeing the original online. I made a number of mods to the original with one of them as follows: I incorporated the batteries into the launch controller along with a jack in the bottom of the unit. It allows me to unplug the controller from the launch pad giving me a fail-safe to prevent an unplanned ‘ignition’. Also, my pressure chamber is a different configuration and I found that 30 to 40 PSI works the best. At 70 PSI they only go 20 feet high or shred on the pad (Bernoulli’s priniple??). The kids loved this project.

    1. Marc de Vinck says:

      Moving the batteries to the launch controller is an excellent idea. I’m going to have to do that. Being able to disconnect it would make moving it a lot easier too!

  3. Andy Johnson says:

    My best friend Eric informed me that his new best friend is KipKay… he built this rocket launcher from the Weekend Projects podcast. He came over Saturday and we took the launcher to the local schoolyard. Marc is right. This rocket goes high! Whether on 75 pounds or 40 pounds, it makes the rocket soar! We tried to time the hangtime, and it got 8.5 seconds until it got stuck in a tree, and we were done. (only made one rocket!) If you know the exit velocity of the rocket, you can measure the height by using some formulae.

    So if there’s any makers in SLC that need a new best friend… ;)

    We’ll see if I make the Most Useless Machine with him or not!

  4. insomniakv says:

    A simple way of measuring altitude involves a protractor, a drinking straw, a plumb bob, and 100ft+ measuring tape. Attach the drinking straw to the bottom of the protractor with some hot glue or epoxy. Drill a hole through the origin of the protractor and tie a length of string through the hole with a fixed loop so that the string swings freely. To the other end of the string, attach a weight such as a large nut or a stack of washers. From the launch pad, measure out a distance and have a helper stand there with the altitude measuring device. Site through the straw, holding the protractor upside down with the string falling along the angle measurements, and follow the rocket to it’s apex. When it gets there, put a finger on the string and measure the angle. You now have a right triangle where the distance from the launch pad to the observer is the base, and the angle from the protractor is the angle opposite the altitude. The altitude can then be calculated as the measured distance from the launch pad times the tangent of the angle.

    1. Andy Johnson says:

      This is a great way to measure alt. Just make sure the straw is perfectly parallel to the bottom of the protractor. Come to think of it, I have a surveyors abney level, which is a fancier name for a sextant. I’ll have to grab my 100′ tape and level and more rockets next time.

      I wonder if I can also calc exit velocity this way. (Fill in x in the formula: http://en.wikipedia.org/wiki/Trajectory_of_a_projectile when x is the distance above ground at maximum height.)

  5. Deeg says:

    We made the launcher last summer and it was a huge hit. Our modifications were to make the rockets out of different colored duct tape (instead of coloring the paper). There’s a thin metallic tape that works great for nose cones. You can see a couple of pictures here: http://www.flickr.com/photos/76246285@N00/sets/72157618549675280/

    Our launch button was made from an Altoids tin, complete with safety switch (which originally was put in just for coolness but turned out to be very helpful with young kids around).

    We made a crude altimeter using a short piece of PVC tubing and a paper protractor taped to it. I used it to demonstrate using trig for calculating the height of the rockets. We measured heights of over 200′.

  6. Victor E. says:

    We have a launcher for 2 liter water rockets, but added a compressed air module with a ball valve that can screw into the launcher and convert it to air rockets. Here is a video of Rocket day with a short description from a launch expert:

    http://www.youtube.com/watch?v=TgxpXDl3z0s

  7. Eric Hansen says:

    ok, these instructions seriously suck.  I can’t see how you could publish them and not even give them a try.  The first picture doesn’t even label the contents.  There is not one good picture of the entire assembly.  These instructions are almost designed to make you fail at this.  If you look at 10th picture it says… “Take note of the arrows on the sprinkler valve. On the “out” side of the valve, glue a 16″ length of PVC pipe. On the “in” side of the valve, glue a 3″ length of PVC.”  It does not refer to 1/2″ or 3/4″ nor does it mention the reducer from 3/4 to 1/2.  Since the “in” side is 3/4 its logical to use the 3/4 for the out.  There are many lengths of 13″ tubing in the kit but those are never mentioned in the kit.

    I can’t say how disappointed I am in Make for offering this kit for $40 with such poor misleading instructions. 

    1. Marc de Vinck says:

      Eric,

      Sorry you are so disappointing, we have had nothing but overwhelmingly positive responses from this kit and the instructions.

      Please keep in mind, these are not the instructions for the kit, but are my “tips & tricks” about building the kit. (stated in the first paragraph) It’s the little things that make the build even better. The full instructions are in MAKE Volume 15, and are by Rick Schertle. (and they are great).

      You can read them online for free at (which is also linked from the product page) — http://blog.makezine.com/archive/2008/12/compressed-air-rocket.html

      You will find a parts list with labels, and all your other questions and concerns answered. Read it first, then read my “tips”, it will make the build even easier.

      Oh, and sorry you don’t like my pictures. :(

    2. Marc de Vinck says:

      Eric,

      Sorry you are so disappointing, we have had nothing but overwhelmingly positive responses from this kit and the instructions.

      Please keep in mind, these are not the instructions for the kit, but are my “tips & tricks” about building the kit. (stated in the first paragraph) It’s the little things that make the build even better. The full instructions are in MAKE Volume 15, and are by Rick Schertle. (and they are great).

      You can read them online for free at (which is also linked from the product page) — http://blog.makezine.com/archive/2008/12/compressed-air-rocket.html

      You will find a parts list with labels, and all your other questions and concerns answered. Read it first, then read my “tips”, it will make the build even easier.

      Oh, and sorry you don’t like my pictures. :(

    3. Marc de Vinck says:

      Eric,

      Sorry you are so disappointing, we have had nothing but overwhelmingly positive responses from this kit and the instructions.

      Please keep in mind, these are not the instructions for the kit, but are my “tips & tricks” about building the kit. (stated in the first paragraph) It’s the little things that make the build even better. The full instructions are in MAKE Volume 15, and are by Rick Schertle. (and they are great).

      You can read them online for free at (which is also linked from the product page) — http://blog.makezine.com/archive/2008/12/compressed-air-rocket.html

      You will find a parts list with labels, and all your other questions and concerns answered. Read it first, then read my “tips”, it will make the build even easier.

      Oh, and sorry you don’t like my pictures. :(

    4. Marc de Vinck says:

      Eric,

      Sorry you are so disappointing, we have had nothing but overwhelmingly positive responses from this kit and the instructions.

      Please keep in mind, these are not the instructions for the kit, but are my “tips & tricks” about building the kit. (stated in the first paragraph) It’s the little things that make the build even better. The full instructions are in MAKE Volume 15, and are by Rick Schertle. (and they are great).

      You can read them online for free at (which is also linked from the product page) — http://blog.makezine.com/archive/2008/12/compressed-air-rocket.html

      You will find a parts list with labels, and all your other questions and concerns answered. Read it first, then read my “tips”, it will make the build even easier.

      Oh, and sorry you don’t like my pictures. :(

    5. Marc de Vinck says:

      Eric,

      Sorry you are so disappointing, we have had nothing but overwhelmingly positive responses from this kit and the instructions.

      Please keep in mind, these are not the instructions for the kit, but are my “tips & tricks” about building the kit. (stated in the first paragraph) It’s the little things that make the build even better. The full instructions are in MAKE Volume 15, and are by Rick Schertle. (and they are great).

      You can read them online for free at (which is also linked from the product page) — http://blog.makezine.com/archive/2008/12/compressed-air-rocket.html

      You will find a parts list with labels, and all your other questions and concerns answered. Read it first, then read my “tips”, it will make the build even easier.

      Oh, and sorry you don’t like my pictures. :(

      1. Anonymous says:

        I did manage to build the kit and it works, but it would be great if there were instructions in the box, so you don’t have to figure out…oh, maybe I can download them. What if someone actually wanted to build someting without using their computer? Also, the instructions in the magazine don’t match the parts included with the kit, so it doesn’t seem fair to tell people, oh, just look at the magazine. I’d love to see some instructions in the box that are labeled and match the hardwear provided. 

    6. Marc de Vinck says:

      Eric,

      Sorry you are so disappointing, we have had nothing but overwhelmingly positive responses from this kit and the instructions.

      Please keep in mind, these are not the instructions for the kit, but are my “tips & tricks” about building the kit. (stated in the first paragraph) It’s the little things that make the build even better. The full instructions are in MAKE Volume 15, and are by Rick Schertle. (and they are great).

      You can read them online for free at (which is also linked from the product page) — http://blog.makezine.com/archive/2008/12/compressed-air-rocket.html

      You will find a parts list with labels, and all your other questions and concerns answered. Read it first, then read my “tips”, it will make the build even easier.

      Oh, and sorry you don’t like my pictures. :(

  8. tensegritydan says:

    Great guide! But the “What you need” list is quite incomplete: soldering iron, solder, drill, 1/8″ bit for wood/plastic, PVC glue, 2x 9V batteries

  9. Salil Phadnis says:

    Great photos and tips. I found these helpful in addition to the make magazine instructions. Thanks.

  10. Vincent Ryan says:

    I am doing a science fair expirment comparing co2 and compresed air. i was wondering if there were pros and cons to the use of compressed air verus the CO2

  11. Vincent Ryan says:

    I am doing a science fair expirment comparing co2 and compresed air. i was wondering if there were pros and cons to the use of compressed air verus the CO2

  12. J Bratton says:

    You skipped this step in your process, now I have to go buy a new fitting.

    2c. Glue the 2″ male slip x 3/4″ female slip PVC reducer bushing into the tee on the pressure chamber.
    I did not realize this until I got to the part where I have to build the base and realized I had already used the required PVC.

     Also, would it have been too difficult to include some Teflon tape? 

  13. vastu consultancy says:

    Great work! That is the kind of information that are supposed to be shared around the web. Shame on Google for no longer positioning this put up higher! Come on over and talk over with my web site . Thank you =)

  14. guteg says:

    i do 120 psi. it is safe on mine and goes much higher

  15. Tamoni says:

    I am a 50 year old grandmother and this was a piece of cake. Mostly, I looked at the picture and used common sense. My grandkids love this rocket but I did find the small 9volt batteries wore out . I converted to 2- 9 volt lantern batteries and used alligator test leads. (for easy on and off disconnect). I also bought a 18 volt air compressor. Same one that matched my cordless drill. It shoots high enough you can barely see the rocket. I also made an attacment for the water rocket. Remember to glue all pieces good. we did have a blow out at 100 psi. This was easily fixable with a proper glue time. Iwant to makea dual launcher but not sure if you can use the same chamber. let me know if you have any tips

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