09/30/2008. Remarks by Johan Visschedijk: "The model 48 was a military version of the civil model 42 and utilized the rotor and other dynamic systems of the model 47 H-13 Sioux. Pictured is first of two XR-12 prototypes ordered by the USAAF, s/n 46-214 and 46-215, they were redesignated XH-12 in 1948.
A third enlarged prototype, model 48A, ordered as XR-12B, was flown as the XH-12B on November 21, 1949, serialed 46-216. An order for a production batch of thirty-four R-12A-BEs, s/n 47-491 to 47-524, was cancelled in 1947. Ten YR-12B evaluation aircraft were ordered, s/n 46-217 to 46-226, before delivery they were redesignated YH-12B in 1948."