This Propane – Oxygen Cannon & Shock Tube is one heck of a project. Looks great and should work very well, don’t think there is a video of this one in action though.
 “When a stoichiometric mixture of gasses is ignited, it is known as a deflagration, which results in a subsonic pressure wave. The principal behind the shock tube is to use the subsonic wave to compress a mixture of flammable gas and oxygen in a tube of specific geometry so rapidly that the driven gas mixture detonates rather than deflagrates generating a supersonic shock wave. In this particular type of shock tube pressure waves have been generated as high as Mach 7.”