Piasecki H-21 Shawnee
Known variably as the “Shawnee,” the “Workhorse,” or the “Flying Banana,” the H-21 was developed from the world’s first tandem rotor helicopter, a sturdy design that would later be improved upon with the CH-46 and CH-47. The H-21’s inaugural flight occurred in 1945, with formal adoption by the US Armed Forces in 1953 as an assault transport and rescue craft. A total of 213 were produced, before it was eventually fazed out in favor of the Huey and other, more sturdy transports.
 Strategic Air Command & Aerospace Museum. “CH-21B ‘Work Horse,’” accessed September 10, 2018.