Saturday, May 2, 2009

Water Rocket Launcher Construction Tutorial: Part 6

Hello once again, water rocket enthusiasts! We're going to pick up where we left off last week and continue with the next phase of our water rocket launcher construction tutorial. When we left last time we have finished building the PVC plumbing for the launcher base and at this point we need to begin the assembly of the cable tie clamp mechanism.
The cable tie launcher design is a simple and inexpensive design which is attributed to a water rocket pioneer by the name of Ian Clark. We've taken idea and adapted it to our launcher design in a way which we describe below that should make it very easy for anyone to replicate.
The materials required for this installment of the launcher build tutorial are one roll of Duct Tape, a 1.5" diameter hose clamp, and a package of Cable Ties or Zip Ties.
 The first step is to unroll about 8 inches of Duct Tape and place it sticky side up on your work table. Duct Tape is also sometimes referred to as Gaffer's Tape, and frequently mistakenly referred to as "Duck" Tape. In fact, so many people have adopted this incorrect name that a tape manufacturer actually named themselves "Duck" so that they could have instant brand recognition. The Duct Tape pictured is actually Duck brand!
Start placing table ties on the sticky tape, making sure to keep their heads even and the spacing perfectly aligned so the ties are perfectly parallel. Be sure and place the ties onto the tape with the flat side down towards the glue on the tape.
Continue to place cable ties one after another until you have enough to wrap completely around the PVC 1/2" Female-Female coupler on the base tube of the launcher. We know from experience that 17 of the ties we use will make one perfectly even wrap around the PVC coupler. If you use larger or smaller cable ties then you may need to test fit and adjust the number of ties.
A good method is to put about 4 inches of ties onto the tape and then remove any extras when you go to mount them to the PVC pipes.
Here is a closeup of the ties laying flat side down. This is important because placing them the wrong way will cause the launcher to not work.
Slide a rocket or a bottle onto the launch tube and push it all the way down to the bottom where it will seat against the hose washer on the Female-Female coupler. Now, carefully take the Cable Tie mounted Duct Tape and place it on the Female-Female coupler as shown below. The heads of the cable ties should just overlap the bottle "grip" protruding from the neck of the bottle. Make sure to wrap the Duct Tape tightly and as evenly as possible.
Wrap the remaining tape around the cable ties and cut off the tape with a knife or scissors.
At this point, you should have a neatly wrapped group of cable ties. If you used a different size cable tie or a different diameter pipe for your launcher design, you can pull out any extra ties that you don't need, if there are more than the number on your tape to completely encircle the female-female coupler.
This is a good time to neaten up the alignment of the ties, if anything moved while you were assembling the tape to the launcher. A pair of pliars can be used to pull and twist the ties until they are back in perfect alignment.
We opened up an assortment of hose clamps and removed the one meant for 1.5" hose. This one will fit our cable ties perfectly without a not of excess clamp threads protruding. This is just a cosmetic issue and doesn't affect the operation of the launcher at all.
Put the hose clamp over the cable ties and temporarily tighten the clamp until the ties are secure and cannot move around. The cable ties should all be perfectly even now and securely held in place by the hose clamp.
The final step this week is to trim off the excess leads of the cable ties where they protrude from the bottom of the duct tape. This cleans up the look cosmetically, but also keeps the ends of the ties under control. If you leave the ties protruding, they can get tangled in the launcher pull string and create a problem at some point when you are launching.
Be sure and come back next week where we will show you how to use the cable ties to clamp the rocket to the launcher. We will explain how to size the launch collar and explain the pitfalls you may discover.

See you next week!

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