Bottle rocket launch pad and nozzle

thingiverse

<b>WARNING!! Use this at your own risk! Predicting structural integrity of 3D printed parts is challenging, so use with caution and wear protective gear, especially safety glasses, to protect yourself from debris in case any parts fail.</b> Update 30/06/2017 Added a thread-less version of the nozzle in STEP format, allowing you to create your own threads if you have a different bottle type. The cavity is 30mm wide and 13mm deep at the outer edges; there's a 2mm chamfer at the bottom, making it 15mm deep at the nozzle. Update 28/6/2017 Forgot to include the base structure (called housing)! Sorry, now it's added! This improvised experiment aims to create a fun water rocket launch pad and nozzle using a compressor or bike wheel pump without Gardena connectors. The release mechanism features a rotating "locking ring" where you can connect a line for remote triggering. The system only works with the attached nozzle. To build the air pressure connector, cut off the air valve from an old deflated bike tire. I use the type with a car tire valve for ease of use. The water connector has a restriction valve to block air pressure from entering the water hose; however, I haven't tried this one yet as my prototype didn't work, and I've changed it to the version that's now online. The base has three "arms": one for air pressure, one for water supply, and the third is prepared for any potential use. Why not connect your soda stream CO2 bottle? Or simply drill out the hole in the middle and add your creation – there's already a channel inside so you only need to drill about 1 cm. The system uses various O-rings; I bought a box of different sizes, but I'm not entirely sure which one is best everywhere. I suggest buying a bunch of different sizes and trying them out. The one between the base and the nozzle is critical and depends on how much pressure you'll use – too tight means no liftoff. Regarding fins: The nozzle has fastening with 3mm wide gaps for fins, allowing a sheet of Depron or similar material to be used as fins. I didn't include STL for fins as the shape in the picture is totally wrong; they're too small and don't make the rocket fly straight. Try making fins of different designs and see what works best – ensure they're not too strong, as the idea is that the fins should break before attachment to the nozzle. If you have fins made from a strong material, use a wood pin to lock them in place. This is highly experimental, but I decided to release it once I got the prototype working; it does work for air pressure, and the water connector is still in progress. You'll need to attach an external valve to control the water flow. The principal should be to first fill with water, then air pressure, and finally pull the line to release.