The McCulloch Model MC-4 was an American tandem-rotor helicopter and was the first helicopter developed by McCulloch Aircraft Corporation, a division of McCulloch Motors Corporation.[1] It was evaluated by the United States Army as the YH-30 and the United States Navy as the XHUM-1. The MC-4 was a larger version of the earlier HERC JOV-3 tandem-rotor helicopter and was developed by the McCulloch Aircraft Corporation. The JOV-3 was developed by Jovanovich when he headed the Helicopter Engineering and Research Corporation. The JOV-3 first flew in 1948. In 1949, Jovanovich moved to the McCulloch Motors Corporation, where an enlarged helicopter, the MC-4, first flew in March 1951. It was followed by a similar MC-4C and three evaluation helicopters for the United States Army (as the YH-30). The MC-4C was slightly larger than the MC-4. When the MC-4C was certified in 1953, it was the first tandem-rotor helicopter to be certified in the United States for commercial use. Three examples were evaluated by the United States Army as the YH-30, but the Army's evaluation showed the helicopter to be underpowered. The YH-30 had a steel tube framework with a light metal skin, A single 200 hp Franklin piston engine was horizontally mounted amidships and powered two intermeshing tandem rotors. It had a fixed-wheel tricycle landing gear with a castering nosewheel. No civil or military orders were received and Jovanovich formed his own company, the Jovair Corporation, where he modified the MC-4C as a prototype for a four-seat private helicopter designated the Sedan 4E. The Sedan 4E was powered by a 210 hp Franklin 6A-335 engine. A version with a turbocharged engine was designed as the Sedan 4ES and a more basic Sedan 4A for agricultural use. By 1965 a small number of Sedan helicopters were built. In the early 1970s, McCulloch regained the rights to the helicopter designs. Variants McCulloch MC-4 Prototype with a 165 hp Franklin engine, two built, one for evaluation by the United States Navy. McCulloch MC-4A Variant for evaluation by the United States Navy as the XHUM-1, two built. McCulloch MC-4C Prototype with a 200 hp Franklin engine, one built and an additional three for United States Army evaluation as the YH-30. Jovair Sedan 4E Production civil four-seat version powered by a 210 hp Franklin 6A-335 engine. Jovair Sedan 4ES Sedan with a turbocharged 225 hp Franklin engine. Jovair Sedan 4A Simplified agricultural version. Military designations YH-30 Military version of the MC-4C, three built. (Specifications below) CHUM-1 Two MC-4As for evaluation by the United States Navy, later redesignated HUM-1.
