After gluing the second elbow to the Tee, I pushed the "mouths" of the elbows flat onto the table to try to get them as parallel as possible. If they aren't parallel, it will be very hard to fit this Tee assembly onto the rest of the launch tube. inch pressure PVC turned out to be the best size, and it really works well. The parts are easy to find and the pressure rating far exceeds what the kids can pump the systems to. I have clearly neglected this post in the 4+ years since I originally wrote it. Parts, prices, and availability have changed since then. I always knew this was likely to happen, but I figured it would be more useful for a time than not.

PVC Primer is usually purple and both stains and dissolves like crazy. It also smell bad. Be careful with it. Put down a drop cloth and wear old clothes and do this work in a well ventilated area (like outside). There always seems to be a little bit of primer left on the lip of the can, blot it up with paper towel so you don't spill it! Prime both parts that you're joining, and then apply glue to both parts to be joined. You want enough glue that you see it pushing out of the connection, but not so much that it drips or runs. Do not prime all of the pieces first - they're only likely to get grimy while you're glueing. Only prime as you go. Tip: It is often very useful to insert a non-glued piece into an elbow to help get the angle right for the other side of the elbow that you are gluing. The student holding the button should keep his/her trigger finger off of the button until the final countdown is initiated. The button is sensitive and can easily misfire.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. I made a very detailed video on how to build a launcher, but since it is such a long video, I made this tutorial as well since seeing the steps one at a time is sometimes easier. If you have any questions, more than likely they are in this video. Or if you just prefer video instructions, take a look here: This side is harder to get exactly right, but since I am using it for the valve stem, it doesn't have to be perfectly parallel with the frame tubes.

A final update here: we had two launch events and the new launchers were wonderful! they upped the fun factor by like 3-4x! Thanks so much for your work here! Never allow anyone to put their face near the launch tube. Air expelled from the tube, if forced into someone's nose or mouth, is powerful enough to cause the lungs to rupture. This is very serious. Tell your students about this and they will be frightened enough to never get near the tip of the launch tube.I usually refrain from interfering with students' designs, however if a student has created a poorly built fuselage I will step in and help them. Making a new fuselage after attaching everything else can be a hassle. Hold the pieces together firmly for 10 seconds while the glue sets. If you don't hold the pieces pushed together, they will push apart!

Very similar indeed! If you'll notice in my pictures I had a _small_ accident with the primer (and lost many of the numbers on my square). My would kill me if I brought that stuff anywhere near the dining room table, protective covering or not! ;D High volume launchers don't require as high of a pressure to get good results. This is a great option for kids where 20-30 pounds is just about the limit of what you can do with a bike pump. Insert your threaded connections all the way and glue them in place to ensure that the desired alignment/angles/seal is achievable once glued. Twist the parts as you insert them. This really does help to ensure that everything is evenly glued. Just make sure they're pointed in the right direction when you're done. The glue does not take long to dry. Hold the parts together for about 10-20 second - they will try to push apart! After that the parts should be pretty solid, but hold off on high pressure for a day. Have a countdown before each launch as a way to alert people in the area (and to make each launch more exciting!) Drill a hole in a the 1.25 inch PVC cap for the button. The size needed will be different for whichever button you use.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. If using an electric miter saw, we found it best to put the PVC in place, start the saw off of the PVC, bring the saw down through the pipe, and then leave the saw down until the blade has stopped. Otherwise the blade could chip the pipe. I have some clean up tasks to wrap up, but I wanted to post you some of our testing analysis, event layout, and some other fun little things as you have been so great in assisting us and making such a great writeup in the first place! Use a couple of layers of tape here. Cover everything plastic, especially the straight pipe (the elbows and such are a bit stronger, but no guarantees here). Don't skimp - think of the kids! The valve brace relieves any stress that might happen to the sprinkler valve connections, and will help make the launcher last longer.