If your local surplus store is fresh out of supercapacitors but you’re just really in the mood to fire stuff at other stuff, check out [austiwawa]’s step-by-step guide to building a thermal cannon. It shoots whatever will fit into a 1/2″ copper pipe, propelled by cut-up matchheads and lit by a propane torch. [austiwawa] demonstrates it by firing an AA battery at an unsuspecting pumpkin. For what it’s worth, we don’t necessarily condone applying this much heat to alkaline cells.
[austiwawa] used a copper pipe for the barrel because it provides the fastest heat transfer. One end of it is flattened and folded over to form the propellant chamber. A couple of packs worth of match heads are tamped down into the folded end with a paper towel serving as wadding. [austiwawa] tosses in his battery, lights the torch, and then runs away.
This whole dangerous contraption is secured to a wooden base with a u-bolt and a couple of pipe straps, and suspended between more pieces of wood with a length of threaded rod for stability and aiming.
We’ll let the safety-conscious readers do our work for us in the comments, but in the meantime, note that this thing is not safe. As [austiwawa] demonstrates, the copper gets brittle and will split open along the folded edge.
But kudos anyway to [austiwawa] for showing shot after shot of the cannon in action at the end of his video. You know where to find it.
If it’s a stronger, more beautiful barrel you’re after, just machine one by hand.