06/30/2009. Remarks by Johan Visschedijk: "The first of two prototypes of the three-seat B6N Tenzan (Heavenly Mountain) carrier torpedo bomber was first flown in Spring 1941, however, it took over two years of testing before production was approved in mid-1943. The initial production model was the B6N1, powered by an 1,870 hp Nakajima Mamoru 11 fourteen-cylinder air-cooled radial. After 133 aircraft production switched to the B6N2, powered by an 1,850 hp Mitsubishi MK4T fourteen-cylinder air-cooled radial, over 1,100 were produced. Note the antennae along the fuselage, part of the Air Surface Vessel (ASV) radar, used in night attacks."
Read the type remarks on page 12683.