Atlantis H-25 Army Mule HUP-2 Helicopter 48th Scale Model KitDetails: The Piasecki HUP Retriever H 25 Army Mule was a compact single radial engine, twin overlapping tandem rotor utility helicopter developed by the Piasecki Helicopter Corporation of Morton, Pennsylvania. Designed to a United States Navy specification, the helicopter was produced from 1949 to 1954 and was also used by the United States Army and foreign navies. The HUP H 25 was the first helicopter to perform a loop and to be produced with an