So I did some testing the other day of the bottle rocket launcher and it worked so amazingly well! Check it out!
So below I have come up with a few things that I strongly recommend you read and decide if you want to make one of these. My grandfather tried to make this design as safe as possible but If you make this or use this design please know you do so at your own risk. Misuse of this platform can result in serious bodily injury to yourself or others.
Now that is out of the way, the design of 2L soda bottles incorporate a neck ring to facilitate transfer on production/fill lines. We use this as the holding point for our hold down clamp. Seen here it is that U-Shaped bent steel rod being fed into some lined holes in the wall of the vertical part of the platform. The force on the neck/ring and the pin is able to hold down the bottle with a good amount of force. If you notice you need the pin to slide out without too much effort so I used a liner made of some brass tubing I picked up from K & S Precision Metals. The last part of the hold down is its small pull handle made from some singed oak trim and bright pink shock cord.
The next part comes in the form of a trimmed tractor trailer valve stem with the core removed. When combined with a (#4) stopper this becomes the main part of the fill tube. I added some soft silicone tubing to the end to change the height. What’s seen underneath is a hole made with a paddle bit to allow the hydraulic hose and clamp to fit around the end of the brass tubing of the valve stem. The easiest way to do it is to put the tube so you can clamp it down and then use the hole drilled in the stopper as a way to hold it and tighten it up. Just make sure it fits super snug to prevent leaks from backing out the hole drilled in the stopper. The opposite few feet of the cut hydraulic hose line has a smaller trimmed tuck valve clamped to the end of it. I did not remove the valve core here because it needs it to be able fill the bottle with the air from your pump.
Lastly, you will need to drill some holes in the platforms corners to install some large timber nails. This is the safest way to prevent the platform from tilting . I am shown here testing it with a single dog ear pin. Again it is 100% important to make sure it is secure every time. You need to prevent the platform from tilting in your or others direction when you pull the U-pin out. You want to make sure you are in control at all times.
Notes/Saftey: These are to the best of my ability and subject to change.
- You should never over-pressure any plastic bottle as this can lead to failures that could result in serious bodily injury. Again pressurizing 2l soda bottles can be dangerous if you push them beyond limits. So you want to keep the pressure of the bottle as low as possible. In the video I stuck with roughly 50 psi range. This should be a good enough amount for demonstration.
- The plastic can deform over time. So you should always inspect the bottle for signs of fatigue after every shot. You should always retire the bottles regularly before failure and for top performance.
- You should use only air/water as the propellants in the rocket and nothing else. You want to be able to consistently control the pressure inside. You can’t do that safely with chemicals or expanding gases.
- You should never put yourself in the way of a bottle when it has any amount of pumped air in it. If the bottle fails to come off the stopper after pulling the pin you should give it a few pumps of air until it lets go.
- Always use large nails or dogs in the ground to prevent shifting or tilting of the platform. This is always required for safety. Again we do not operate without the platform being secure to the ground.
- Don’t use you fingers to block air hoses or to empty compressed air. This could result in a compressed air injury.
- When launching, care should be taken when pulling the U-pin out of the platform. Higher pressures are also not recommended as it will make it harder to pull and increasing the force needed to pull the pin out of the platform.
- Always use a T-hand or foot pump and never an air tank/compressor to fill the bottle. Again we want to be able to control the pressures inside the bottle and it is way too easy to over pressure a bottle with an air tank/compressor.
- Experiment with different water air ratios but don’t over fill the water in the bottle. If the water gets above the tractor valve/extension it will syphon the water out of the bottle and damage your pump. Excess water inside also shortens the useable life of the hose. They do make valve extension tubes if you want to make it go higher in the bottle or you can use some silicone tubing like I did.
- Inspect and replace the hose as needed.
- Always replace the rubber #4 stopper if it becomes warped, misshapen or damaged.
- Have fun and experiment with different bottle designs!
Thank you for letting me share this design and fond memory with you all.
Please be safe and take care of each other. K
