The Flying Banana
The Piasecki HRP Rescuer—usually called the "flying banana"—was the first U.S. helicopter developed under a military contract. The nickname came from the "bent" fuselage with overlapping tandem rotors at either end, the latter a characteristic of Piasecki helicopters.
The HRP-1 design was the second helicopter developed by Frank N. Piasecki's P. V. Engineering Forum, the first being a single-seat, single-rotor craft.1 A privately built Piasecki demonstration helicopter with tandem rotors-designated HRP-X-flew on 7 March 1945.
The Navy had ordered two XHRP-1 models on 1 February 1944, with the flight-test aircraft delivered in June 1947. The second XHRP-1 was used for static testing. At the time of its appearance, the XHRP-1 was both the world's largest and first tandem-rotor helicopter. The Navy designation HRP indicated helicopter, transport, Piasecki, with the X indicating experimental or prototype.