2 Liter Bottle Launcher
Introduction: 2 Liter Bottle Launcher
After over 20 years of service and thousands of rocket launches, it is time to retire my old rocket launcher and make a new one. This device is used in my classroom as part of my rocketry unit. We study rockets and then build and launch pop bottle rockets as a culminating activity. It is run using a portable compressor and air hose connected to the launcher and operated using a ball valve.
This will be a total rebuild using new parts and incorporating a few upgrades that should make it last until my retirement.
Just as a note, you will find a lot of launchers that use a bicycle pump or other ways of creating pressure but I feel an air compressor is the best solution. The main reason is consistency. My students are trying to design the best rocket possible and without a regulated air supply you cannot get reliable data.
Compressed air is dangerous and I don't allow students to launch their rockets. I use between 80 and 100 psi. When I began, I tested some bottles and they burst at 200 psi so I feel I have a good safety margin. I have only ever had one rocket "blowup" on me and that was a result of a cracked end on a used bottle.
Step 1: Materials
* 3 pcs @ 9” x 12” of ¾” plywood
* 1 pc @ 11” x 7 3/8” of ¾” plywood
* 1 pc @ 4 ½” x 4 ½” of ¾” plywood
* 2 pcs @ 2 ½” x 11” of ¾” pine
* 2 pcs @ 2 ½” x 8 7/8” of ¾” pine
* 2 pcs @ 1” x 12” of ¼” aluminum bar
* 1 pc @ 18” x ½” PVC pipe (4 ½” and 11 ½”)
* 1 pc ½” PVC 90 deg. Elbow
* 1 ea. 1/2 in. Lead Free Brass Threaded FPT x FPT Ball Valve
* 1 ea. 1/2 in. x 1/4 in. Galvanized Malleable Iron MPT x FPT Hex Bushing
* 1 ea. ¼ in. MPT air fitting
* 2 ea 1in. 98
EMT Galvanized Strap 2-Hole
* 1/4 in. -20 tpi hex bolts, fender washers and nylon lock nuts
* 3 ea. 2 inch
* 2 each 1 ½ inch
* 2 ea 2” x 3/8” springs
* See step 9 for updated parts and pictures.
* 1 ea 2 1/2" long 1/2" steel pipe
* 1 ea. 1/2 in. PVC Sch. 40 Female MPT x S Adapter
Step 2: Construction
In this step we will build the base and the adjustable platform. Once you have cut your pieces to the sizes listed on the materials list, it is time to assemble the pieces. Locate the centers of the 7 1/2" x 11" and the 4 1/2" x 4 1/2" piece and drill a 1 1/8" and 7/8" hole respectively as shown in the picture. Use a piece of pipe and elbow to hold the two pieces aligned so that the holes are concentric and then glue and screw the pieces together. Next glue and screw the side pieces to the base and the adjustable platform. Do not add the top pieces to the platform at this time. You may choose to add them if you want but I left them off so that I could easily paint all of the surfaces.
One of the upgrades, I have added, is the use of solid pieces of wood for the narrow pieces on the platform. On the old one, I had to replace one of the pieces because it had delaminated.
Step 3: Priming
I first primed all of the pieces with an oil based primer. I was able to coat all sides of all the pieces by either hammering nails into the wood to act as legs or I used a piece of wood with drywall screws as a standoff. I have a stack of these around my shop that I use for various projects.
Another of the upgrades I wanted to give my launcher is a good paint job. If you look at the old one, many of the pieces are starting to delaminate. Even though it is nearly impossible to prevent fir plywood from checking and splitting a good paint job goes a long way in making it last as long as possible.
Step 4: Painting
After the primer was dry, I painted the launcher with exterior latex paint. I also screwed the top pieces onto the platform and just used the wet paint as a glue. 56