Mitsubishi Ki-50 Heavy Bomber
The IJA ordered Nakajima and Mitsubishi to develop new heavy bomber in 1937.
Mitsubishi initiated development of Ki-50 heavy bomber.
A competitor was Nakashima Ki-49, type 100 heavy bomber Donryu.
But Mitsubishi was very busy with improvement work of type 97 heavy bomber which had been just thrown into the Sino-Japanese war.
Development of Ki-50 heavy bombers was canceled at the design audit stage, and development of new heavy bomber was entrusted to Nakajima Aircraft only.
The IJA ordered Mitsubishi to develop type 97 II heavy bomber in 1939.
The flight performance of completed type 97 Ⅱ heavy bomber was superior compared with Nakajima Ki-49 heavy bomber Donryu!! ;D
It is possible to think that the Ki-50 heavy bomber was realized as the type 97 II heavy bomber.
Source : The IJA aircraft perfect guide 1910-1945, Gakken, ISBN4-05-603757-4
Ki-21 Ⅱ ko(a) : early model
Ki-21 Ⅱ Otsu(b) : later model
Donryu mockup, etc.
http://www.ne.jp/asahi/airplane/museum/cl-pln5/donryu-p.html
https://www.youtube.com/watch?v=UO7m2MlxStc