I trust that a lot of the people here would have basic engineering skills and ideas. So my question is that how would I be able to make a bolt action potato cannon with a combustion chamber? I've got a couple basic ideas but I don't have a clue on how I'd make it so the only exit point for any air or projectile is the end of the barrel. One of my classes at school asks for a project that involves mechanical (the bolt action) and electrical (the ignition for the combustion chamber). I'd love if a heap of people were to comment links of videos or sites that could help me out or maybe even think of an easy way to incorporate the bolt action yourself. It just needs to be air tight so no air can escape from any holes needed for the bolt action part of the build.
Also, if someone can help me work this out or if I can work it out I'll be happy to upload photos of the build and a video of the bolt action reload and the cannon firing at targets as well!