Saturday, April 25, 2009

Water Rocket Launcher Construction Tutorial: Part 5

Welcome to the 5th installment in our water rocket launcher design tutorial. This week we are going to combine the pieces we have built thus far and we will see the launcher starting to take shape. In our previous installments, we have created a launch tube and a launcher base which we will be joining together and completing the core of our launcher.
To join the launch tube with the launcher base, we will need to cut another length of 1/2" PVC pipe to connect them together. A length of approximately 4 inches will be sufficient. This measurement is really not critical and was picked based on aesthetics alone. Feel free to tweak the dimension to suit your particular tastes. The dimension is up to you, or you can simple copy our design as shown.
The new piece of PVC you have just cut will become the interconnection between the base and the launch tube as shown. The new section goes between the 1/2" PVC elbow on the base and the 1/2" female-female coupler on the bottom of the launch tube. The parts are assembled as illustrated:

If you want to at this point, you may glue the sections together and allow the glue to cure. The launcher plumbing at this point will be complete and you can sit back and admire your good work.
Now that you have finished your launcher plumbing, we will share with you a technique we have devised many years ago to insure that this launcher design will not leak. What we are going to do is add a redundant backup seal to act as a secondary barrier for leaks at the base of the bottle.
A second purpose of the seal is to provide a flexible mounting base for the nozzle which will allow the cable ties we will be adding later to firmly hold the nozzle without excessive force or stretching.
You will need to make a trip to the hardware store and pick up a pack of replacement washers which are used in garden hoses. The pack we have purchased contained two different styles, flat washers and large round washers that resemble o-rings. For this build we decided to use the o-ring style, but the flat washers also work well. We have used the flat washers in the past with great results. Whichever you can find will work.
 You will simply take one of the hose connector washers, and slide the washer down the launch tube until it rests on the bottom of the launch tube firmly on top of the female-to-female connector at the bottom. This is one of the reasons which we installed this connector on the design.
As you can see, the hose connector washer will rest at the bottom of the launch tube at the position where the nozzle will seat.
The launcher is now double sealed against leaks. As seen in the image below, the nozzle is sealed internally bu the o-ring installed on the launch tube using our simple method and the nozzle is also sealed by the hose connector washer pressed between the nozzle and the connector at the base of the launcher.
There you have it! A super reliable water rocket launcher design. The only things we have remaining to do is to add the cable tie rocket clamp and fabricate a nice stable base for our launcher.
Be sure and come back next time when we will be bringing you our very simple technique for installing the cable ties on our launcher.
See you next time!

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