CAR v2.1 Air Rocket Launcher Build Instructions

These instructions are for the Compressed Air Rocket Launcher (C.A.R.) v2.1.

A downloadable PDF of these instructions is available at this link: CARv2.1Instructions

By following the simple instructions below, you can quickly assemble the Compressed Air Rocket Launcher in about 15 – 30 minutes using just an adjustable wrench and pliers.  A vice could be handy too if you happen to have one available.  Also by using these instructions, you won’t mar the pipes and you’ll keep your launcher looking new for years to come.  Note: When applying teflon tape, make sure you are winding the tape in same direction you are screwing in the pipe fitting.  Usually three to four wraps of teflon tape works best, as your biggest challenge in assembly is preventing leaks.  (You can click on the pictures to enlarge.)

Notice:  If you have any issues with your kit, please email us at:  Whether you purchased directly from us, from the Maker Shed or any other vendor, please communicate directly with us.  We won’t be happy until you have a perfectly working Air Rocket Launcher.  

#1 – Unassembled Compressed Air Rocket v2.1 Kit.  Grab a pair of pliers and an adjustable wrench and then you’ll be ready to go with assembly in about a half hour.

#2a – First, we’re going to assemble the launch valve.  Remove the five parts you see in figure below from the packaging.  In order for the air to flow directly into and out of the launcher, it’s important you assemble everything in the correct direction.  It’s also very important that there are are no leaks in the system.  If there are air leaks, the launcher will not work correctly.  Add Teflon tape to ALL screw-in connections. NOTE: If you purchased the newest version of our kit, it will include a brass 1/4″ Schrader valve.   This 1/4″ valve will do away with the 1/8″ – 1/4″ reducer.  See step 2b below.

#2b – The newest kits will have a 1/4″ brass Schrader valve (shown below on the far right) INSTEAD of the 1/4″ – 1/8″ brass reducer and 1/8″ chrome Schrader valve (shown above on the right).  Everything else is the same, but instead of having five parts for the slide launch valve assembly, you’ll have only four parts.

#3 – Wrap plenty of Teflon tape around the 1/4″ push-fit hose connection.  Make sure you are applying the tape in the direction you’ll be screwing it in as shown in the picture.  Screw the push-fit connector into the “Pressurize” side of the slide valve, hand tight.  It’s the side that has the hex end.

#4 – Add Teflon tape to the 1/4″ brass pipe nipple and screw into the “Launch” side of the slide valve, hand tight. Then add Teflon tape to the other end of the 1/4″ brass nipple and screw on the brass check valve so the arrows on the check valve are pointing TOWARDS the slide valve.  It’s very important the check valve is pointing in the correct direction as indicated below.

#5 – Add Teflon tape and screw the 1/4″-1/8″ reducer bushing into the other end of the check valve and then screw the 1/8″ Schrader valave into the reducer bushing.

#6 – Clamp the 1/4″ push-fit connector, from step 3, in a vice or hold with pliers.  Use a rag to keep it from getting scratched.  Now using and adjustable wrench on the Schrader valve on the end tighten everything down at once.

#7 – Now we’re going to build the pressure chamber.  Locate the 1/2″ steel pipe cap and 1/2″ x 12″ steel pipe nipple.  Put a generous amount of Teflon tape on one threaded end of the 12″ pipe and thread the 1/2″ cap on hand-tight.  Add Teflon tape to the other end and thread the “A” side of the Quick Exhaust Valve (QEV) onto the 12″ pipe.  Using a rag to protect the 1/2″ cap hold the cap with a pair of pliers and then tighten both connections with an adjustable wrench on the QEV side.  you can also clamp the pipe cap in a vice vertically and then tighten with the adjustable wrench.  Before going on… please read Step #7a that we just added.

#7a – We’ve noticed that the rubber diaphragm inside the Quick Exhaust Valve (QEV – the part with the A, R, and P on it) is a bit tight from the factory and it works well to break it in first.  Using a clean stick or long object, gently push the diaphragm down through the “P” side of the QEV.  Then flip to over and push the diaphragm back through the “R” side.  Push it back and forth a couple of times to loosen it up.  Then cup your fingers over the opening of the “P” and “R” side and blow through each side and the diaphragm should easily flip back and forth.  See the two pictures below for details.

Continuing with Step #7…












#8 – Using Teflon tape, screw the 1/2″-1/4″ reducer into the “P” side of the QEV hand-tight.  Then screw the other 1/4″ push-fit hose connected into the 1/4″ side of the reducer.  With your adjustable wrench on the push-fit connector, tighten both connections.

#9 – Now locate all the remaining parts in the figure below.  You’re now going to attach the pressure chamber to the wood stand and finish putting everything together.

#10 – Put the 1/2″ cap side of the pressure chamber through the “key hole” in the small piece of the stand.  Make sure it’s going in the right direction.  Pull the 1/2″ pipe into the slot and then fit the small wood stand piece into the large piece.  The stand is designed to fit snugly.  Make sure everything is in the right direction, and then pound the two pieces together with your hand.  If more force is needed, use a rubber mallet and piece of scrap wood on top to keep from damaging the stand.

#11 – Once the stand is firmly together, slide the QEV toward the center of the wooden stand until it touches the edge of the wood stand.  Put the U-bolt through the two holes around the 1/2″ pipe.  On the other side, slip the washers on and tighten down with the wing nuts.

#12 – Grab the red hose and insert one end of it into the 1/4″ push-fit connector on the QEV.  Now, take the other end of the hose and push it firmly into the push-fit connector on the slide valve launch assembly.  Sometimes a slight twisting action as you are installing the tube helps fully seat it.  If you ever need to remove the tube, push inward on the blue plastic section of the fitting and pull the tube out.

#13 – Screw the 1/2″ x 12″ grey PVC tube onto the “R” side of the QEV – HAND TIGHTEN ONLY.  This is the only connector that does not require Teflon tape as it is not under pressure.  The 1/2″ tube is used for launching paper & tape rockets.

#14 – Your launcher is now complete!  In order to tilt the launch tube for angled launches, just loosen the wing nut and pivot the launch tube about the pressure chamber pipe then re-tighten the wing nuts.  The leftover piece of 6 gauge wire is used as wing holder for the Air Rocket Glider.  Step 10 here: Air Rocket Glider Instructions

#15 – To store your launcher, unscrew the grey PC launch tube and insert it horizontally into the bottom hole of the wood stand.  The middle hole is for the (included) 3/8″ launch tube which is used to launch the Air Rocket Glider kit and other fun things.  The included 1/2″ to 3/8′” reducer bushing is used to screw the 3/8″ launch tube onto the “R” side of the QEV valve.  The piece of wire in your kit is bent to hold the wings back into launcher position.  See:  Air Rocket Glider Instructions  for more details.

Cut two pieces of the included Velcro strap into two 4.5″ lengths.  Secure each tube with a Velcro strap going through the three slots in the launcher. Wrap the hose around the launch stand, aligning the tubing with the notches and secure with the remaining piece of Velcro.

#16 Launch Instructions:

Paper and Tape Rockets and Foam Rockets: With the valve in the launch position, there is no pressure within the launcher.  Slide the paper rocket onto the 1/2″ launch tube (larger diameter tube without a thread adapter).  It should be a slight friction fit for the best performance – too tight will turn your rocket to confetti, too loose will hurt performance.  Now slide the blue valve to the Pressurize position (shown in the photo below), and pressurize the chamber.  If pressure does not seem to be building up, slide it back and forth a few times to reset the QEV valve.  Give a countdown, and slide the blue part of the valve away from the launcher to LAUNCH!  You should hear a loud “Pop”.  Test the launcher (without a rocket) before heading out to the field.

After launching, slide the valve back to the PRESSURIZE position only once to re-pressurize.  The QEV valve needs positive pressure coming into it to reset the rubber bladder inside.  This takes a little practice to get it to correctly reset every time. The QEV also needs to stay VERY CLEAN inside in order for the rubber bladder to reseat correctly.  See our Troubleshooting section on how to easily take the QEV apart to check for debris and re-lubricate.  This article in our Science Content section explains how the QEV and Slide Valve work.

Click on the Paper and Tape Rocket Building Template and Instructions here. Also try our brand new NASA Kennedy Space Center Templates here!

Air Rocket Glider (ARG) and Ultra Stomp Rockets® (Made by Stomp Rockets):  Remove the larger 1/2″ launch tube from the outlet of the QEV, and in its place install the smaller diameter 3/8″ tube, complete with the black 3/8″ to 1/2″ adapter and the formed ARG Wing Wire.  No need to thread this in any tighter than hand tight, and no need to use teflon tape here.  If there was a small leak at this joint, it really wouldn’t matter.  When there is pressure in the launch tube, the rocket is only on there for a few milliseconds.  Fold the wings of the ARG, and install onto the launch tube, with the wings between the wire, preventing them from opening.  Now slide the blue valve to the Pressurize position, and pressurize the chamber.  Give a countdown, and slide the valve to launch!

If the Quick Exhaust Valve Leaks:  Sometimes, when using a bike pump, the QEV diaphragm will fail to seal the outlet, and the air will leak out the launch tube with each pump.  There is one super-easy trick that almost always works if the QEV diaphragm fails to seal.  First, with the slide valve in the “Launch” position, complete one stroke on the bike pump.  This will build up pressure in the hose of the bike pump.  Next, slide the valve to the “Pressurize” position.  The sudden inrush of pressure built up in the pump hose will almost always seat the QEV diaphragm.  In fact, the more you launch, the more the diaphragm gets broken in.  Now, pump up the chamber normally. Here’s a video showing the process:

Depending on your bike pump, this usually will automatically happen between launches, as the slide valve seals off the incoming air and leaves pressure in the bike pump hose.  In fact in the video, you will notice that this happens on the last two firings of the launcher in the video.  When the valve is slid from the launch position back to the pressurize position, the residual pressure seals the QEV diaphragm.  I believe that this quick inrush of air is exactly why the QEV works so well when connected to an air compressor.  We really like This Pump, because it’s bombproof when working with kids and the hose screws directly onto the Schrader connector on the launcher slide valve.  It is also serviceable with the O-Ring Re-Build Kit for $3.95.

Connecting to an Air Compressor (shown with our 2.0 version launcher)  Connection is the same for the 2.1 – For Instructions on how to connect directly to an air compressor, rather than using a bicycle pump, click here.   The set-up below works great with the little 3 gallon, 100 psi compressor from Harbor Freight at:   We’ve done hundreds of launches with this set-up with the regulator set at 100 psi.  After about 12 launches, it turns on to re-pressurize.  We had no issues with the QEV sticking and you do of course need electricity nearby for this set-up.