Tennis Ball Mortar Launcher
The tennis ball mortar is a great project for many reasons: all the materials are cheap and readily available, its construction is extremely simple, and it gives off a nice loud *pop* which the video doesn’t do justice.
Quick and dirty explanation on how it works: The mortar is composed of three sections of Pringles cans duct taped together. The metal bottoms of the top two cans are cut to form baffles, which will focus the force of the expanding hot gas created by the burnt vaporized naptha, onto the center of the tennis ball. Thanks to the near exact match in diameter of the ball and can, the force of the compressed gases is trapped behind the tennis ball for the whole length of the top can.
