CO2 Dragster Launcher

thingiverse

CO2 Drag racing cars are super fun but launching them without the right equipment is really frustrating. I've designed a simple mechanical alternative to the solenoid launcher used by F1 in Schools during competitions. The launcher has been designed to be almost entirely 3D printed. As far as possible, the parts have been designed to use little or no support material. A few additional items are required. They can easily be obtained from your local hardware store. Here's a video of them in action: https://youtu.be/D-krPo8s80w Quick instructions: The launcher is pretty simple to put together. I've included a general assembly drawing which shows all the parts in place. The trickiest thing for me was finding a suitable spring that had enough energy once compressed to puncture the CO2 cylinder. I eventually found a set of electric fence tensioners at the local hardware store. I've given the dimensions of this spring on page two of the PDF drawings to allow you to source a suitable equivalent. Assembly: 3D Print: Once everything is printed, check the fit and finish. The irrigation tube (which I've included as an STL file in case you can't find a suitable tube) should fit snugly into the pockets in walls A and B. Spring pin assembly: Screw the M5 nuts, washers, spring, and aluminum tube onto position on the M5x100 set screw using the dimensions on the section view as reference. NOTE: Wall B also forms part of this assembly, look carefully at the drawing. Launcher frame: Wall A can be glued in place on the base. Wall B (with the spring assembly) must be screwed to the base because it's necessary to disassemble and reassemble the spring mechanism a few times to get the alignment perfect. I haven't included these screws in the hardware list, but you can use any suitable self-tapping or machine screw. Just drill out the locating holes to suit. CO2 nozzle: Attach the 'alignment nozzle' to 'wall A' with #4 self-tapping screws. Make sure to keep the holes perfectly centered. Place a sharpened nail in the nozzle hole as per the section view and place a small piece of tube from a pen refill (or you could 3D print something) around the nail to keep it from dropping into the tube. Trigger: Match drill the holes for the trigger and pivot with a 3mm dia drill bit. Use an M3x25 screw as a hinge pin. You'll have to determine the best position to attach the pivot to the base. Mine was 30mm from the back, but your spring may be slightly different to the one I used to experiment. It should be just close enough to Wall B to allow you to clip the head of the cheese head into the trigger when the spring is fully compressed. Once you've determined the position, screw the pivot in place on the base. I think that's it. Happy racing! Refer to the photographs or post a question in the comments if you find anything I've left out. Oh, you can also use this launcher vertically to launch CO2 cylinder rockets if you like, use your imagination, be safe and have fun! Oh, also, for you electronics guys and gals, there is provision in the trigger pivot for a micro tactile switch (you can see it in the sections view) for those of you who want to use a digital race timer.