The H-25 helicopter, also known as the Piasecki HUP Retriever or Army Mule, was a compact, post-war utility helicopter featuring a distinctive tandem rotor design, used by the US Navy and Army for transport, rescue (plane guard), and anti-submarine roles, noted for its sturdy build and versatility from aircraft carriers and land bases. Developed by Piasecki Helicopter Corporation (later Boeing-Vertol), it entered service in the early 1950s with a single radial piston engine and compact fuselage.

Piasecki PV-3 was the first successful tandem-rotor helicopter, developed in the mid-1940s by Frank Piasecki's P–V Engineering Forum. It was famously nicknamed the "Flying Banana" due to its distinctive upward-curved rear fuselage, a design choice made to prevent the two large rotors from colliding during flight. Development and History Origins: The PV-3 was developed under a February 1944 contract from the United States Navy, which designated the prototype as the XHRP-X. First Flight: The proto

US Army Piasecki H-21 demonstration

The Piasecki H-21 Workhorse/Shawnee is an American helicopter, the fourth of a line of tandem rotor helicopters designed and built by Piasecki Helicopter. Commonly called "the flying banana", it was a multi-mission helicopter, capable of being fitted with wheels, skis or floats. | Aircraft Reports - Aircraft Manuals Data and Publications