The HERC JOV-3 was a two-seat tandem helicopter originally designed by Drago Jovanovich at the Helicopter Engineering Research Corporation (HERC). The helicopter first flew in 1948.McCulloch YH-30 MC-4C, Harold A. Skaarup, Alabama Warbird Survivors 2003: A Handbook on Where to Find Them, Writers Club Press, 2002, , pages 98-100
When McCulloch Aircraft Corporation purchased HERC they improved the design for prospective military use and it became the McCulloch MC-4.
References
External links "Cutting 'Copter Costs" , March 1948, Popular Science