Jörg and Cheyenne are challenged to build a Rubber Powered Cannon! Jörg is particularly excited about the maximum carnage they are going to be able to create! Cheyenne sets about building the wheels, framework and crank for the cannon whilst Jörg sets about doing the science behind the rubber! Historical cannons had the huge advantage of being made from metal and using black powder as a propellant, surely Jörg and Cheyenne's machine won't even come close to the real thing?