How Do Contra-Rotating Propellers Work?

While most single-piston and turboprop engines generate thrust by driving a single propellor, some engines feature a pair of propellors that spin in opposite directions. This apparatus, which is present on many cargo aircraft, bombers, and some early airliners, is referred to as a set of contra-rotating propellors, which are formally referred to as CRP coaxial contra-rotating propellors.