The
Ki-44 Army Type 2 fighter is one of many famous Nakajima W.W. II aircraft.
Far less well-remembered is a higher-powered development, the Ki-44.5 Mk. V Sumo.
Powered by a triple-row Kabuki Chai 23 cylinder radial engine, it was hoped the new fighter would give the IJA an upper hand in the air against the allies.
Flight trials were promising so a limited production order was placed late in 1944.
The timing was fortunate indeed as a new class of fighter pilot cadets was completing their training. The war situation was so dire by this point that the Japanese had been forced to draft even their elite athletes into service.
Upon getting their wings in mid-1945, these new pilots were assigned to fly Ki-44.5 fighters of the 34592nd Home Defense Group (Heavy) which would become colloquially known as the Sumo squadron and their new planes would also be nick-named Sumos.
The Sumo squadron continued to hone their combat training in their Sumos. Unfortunately, this advanced training was primarily focused on mid-to-low altitude tactics which would prove disastrously short-sighted.
After two months of relative quiet, the Sumo squadron was alerted to intercept American B-29s in early August.
The entire compliment of the 34592nd's Ki-44.5 Mk. Vs took flight just as the day was starting, determined to shoot down the Superfortresses.
However, with each pilot tipping the scales at an average of 135 kg, the Sumos' triple-row Kabuki Chai 23 cylinder radial engines were hard pressed to even get into the air, let alone reach operating altitude.
Being unable to get within range of the B-29s, this lack of height also precluded the back-up tactic of a ramming attack.
Luckily, the Superfortresses just flew on, headed for a leafleting mission over Kobe.
The Sumos flew back to base, hoping their lack of punch could be cured by a good tune-up.
This was not to be. Production versions of the triple-row Kabuki Chai 23 cylinder radial engine were manufactured so poorly that even after the war, the Allied Tactical Air Intelligence Units had a difficult time getting them to work. Initially, this was thought to be due to defective recessed cowl-flap actuators but the cause was eventually traced to Japanese ornamental squirrels (
Sciuridae Callosciurinae Iaponica) taking up residence in a turbo-supercharger duct.
No more Ki-44.5 Mk. V Sumos were ever made and the war ended before they could make even a minimal impact. None survive today and most so-called "experts" write off the type as being too heavy to even consider.
Brian da Basher