03/31/2015. Remarks by Johan Visschedijk: "An all-metal version of the Spencer S-12 Amphibian Air Car was developed by the original designer, Percival Hopkins "Spence" Spencer, and on November 30, 1944, the first RC-1 Thunderbolt Amphibian, registered NX41816, made its first flight with Spencer at the controls. The aircraft was displayed in St.Louis, Missouri in December and by the end of 1944 Republic had received 1,972 civilian orders for the airplane.

The aircraft was also demonstrated to the USN and USAAF. Both services were impressed with the design and on February 19, 1945 the USN granted Republic the rights to use the name Seabee for the civilian version. The Army placed a large order for the aircraft, to be used for air-sea rescue operations under the designation OA-15. In September 1945, following VJ Day, both the Army and Navy canceled their orders. The OA-15 Seabee was the last USAAF aircraft to use the OA designation, which was dropped when the US Air Force was formed as a separate military branch in 1947."