This is the first tandem-rotor helicopter certified in America for commercial use. Constructed of a steel tube fuselage and light aluminum skin, the engine is mounted amid ship. The tandem- rotor system has two distinct advantages over the single rotor, good longitudinal stability and a larger center of gravity. Tandem rotor systems are preferred for today’s large cargo helicopters.

McCulloch Aircraft produced two significant designs the MC-4 and J-2 Autogyro after they acquired Helicopter Engineering Research Corp in 1951. McCulloch also produced versions of the MC-4 for the US Navy XHUM-1 (MC-4A) and Army YH-30 (MC-4C) for evaluations testing and research and development although no production orders were placed.

McCulloch Aircraft moved to California in 1946 and was renamed McCulloch Motors. The company soon dominated the chainsaw market. They produced a small two-stroke engine that was also popular in some aviation applications. One company they supplied was Radioplane a producer of military target drones. Owner Robert P. McCulloch later purchased “London Bridge” relocated and reassembled it in Lake Havasu City, AZ. This is one of only two HUM-1’s built, restored by Yanks from 2007-2011.