Bottle Rocket

thingiverse

Still printing this to test if it fits 1.5L bottles with a flattish base perfectly, just tape it on securely. I remixed it and made it hollow from here https://www.thingiverse.com/thing:858319. You might want to add some manual supports around the stepped edge inside for better stability. My print had some minor stringing but nothing major to worry about. The main cone doesn't need any supports at all. The nozzle I remixed from here https://www.thingiverse.com/thing:13898 required some serious tweaking to get it right, even after I modded the rear thread to be smooth. The fins were almost separate initially, so I had to make some adjustments. Instead of using a 1/4 NPT compressor quick release, which might not be readily available in most households unless you own a compressor, this nozzle is designed to use waste Schraeder valves from tire centers cut out of wheels and discarded. Then, you can simply screw on a bicycle pump for effortless operation. The valve just push fits into the rear section, so make sure to put some water in first, but not too much. Then, push in the valve and pump until it flies off with ease. Try varying the amount of water as there will be an optimal level that works best for you. Too much water gives longer thrust but more initial weight, which cancels out, while too little water won't take it far at all. I'll upload photos of the whole thing assembled once I finish printing the nozzle section. By the way, I also added a step inside the threaded end to accommodate a rubber washer for better sealing. This should work with any standard 3/4 plumbing or hose fitting tap washer. Just make sure the threads are strong enough to handle it securely. The valve diameter hole goes straight through to the bottle, so it should be a reasonable jet. If I get some spare time, I'll add a taper there to smooth out the flow even further. But hey, it's just a toy, right? PS: The valve in the photo is complete, but you need to cut off the rounded end before using it. If you recover scrap valves from tire depots, they will already be cut off when they remove them from wheels. Last EDIT: I've printed and test flown this with great success! With a compressor attached to pump the pressure in fast, about 6 feet of old galvanized guttering as a launch slide, and just a cupful of water, it flies well over 100 feet. I'll upload the video soon once I figure out how to do it, and my kids are absolutely loving it!