The 1950s were an era of aircraft innovation. Engineer Frank Piasecki believed that conventional helicopters were not designed to their full potential, so he came up with a unique blueprint that would eventually be known as The Flying Banana. This H-21 helicopter had a long fuselage, two rotors in a tandem arrangement, and its rear slanted upwards to prevent the blades from overlapping.Although the H-21 was initially designed for sub-zero weather conditions, the helicopter honorably served the US Army during the Vietnam War. The distinctive aircraft was mainly used as a troop transportation carrier, but the H-21 was also the mainstay combat air assault force helicopter during the earlier years of the conflict…