Hi Boogey
I don’t think there are any Army-related Mitsubishi “Ka-“ designations to find; and I believe the answer lies in the difference between the IJA and IJN procurement systems. In 1932, the IJA adopted a system in which all aircraft designed to an IJAAF requirement were assigned a unique Kitai, or airframe, number at the project stage. The IJN, on the other hand, relied on the manufacturer’s factory designation, or the “-shi” system (which applied to a specification, not a specific airframe), to apply to designs during development. This changed in 1939 when the IJN introduced the Service Airplane Development Program codes, which were manufacturer-specific and assigned to new designs at the project stage.
Mitsubishi apparently stopped assigning in-house designations to Army designs in 1932, when the Kitai system was introduced; and did the same for Navy designs in 1939. In both cases, the need for in-house designations had evaporated, since distinct official designations were assigned at each particular design’s inception and used internally thereafter.
This is, of course, my own observation, but I believe it’s correct.
Blackkite? Anything to my theory, according to Japanese sources? Regards, Harry