Hatsukaze engines were produced in very large numbers, as the powerplant for the license-built
Bücker Bü 131 Jungmann variants that were the standard primary
trainers for the
Imperial Japanese Navy and
Imperial Japanese Army. The naval version of the engine was designated GK4, the army version as Ha47. The
Hatsukaze Model 12 was the power section linked to a
compressor to create a primitive
jet engine called a
motorjet; the resulting
Ishikawajima Tsu-11 was intended to power
Yokosuka MXY7 Ohka Model 22
flying bombs. The standard Hatsukaze Model 11 engine was modified at a Navy arsenal by replacing the propeller drive shaft and engine front crankcase cover with a step-up gearbox. The gearbox increased engine output shaft RPM at a 1:3 ratio. At engine speed of 3,000 rpm, the compressor section was operating at 9,000 rpm. The compressed air was then ducted into a combustion chamber where a liquid fuel was sprayed and burnt. The heated compressed air then exits through the tailpipe providing static thrust of . It is likely that about 1/3 of the total thrust was contributed by adding the combustion chamber aft of the compressor. The Tsu-11 was also selected to power the
Yokosuka MXY9 Shuka ("Autumn Fire"), a trainer intended to prepare pilots for the Mitsubishi J8M rocket-powered interceptor. Neither of these aircraft entered service, however, as their development took place too late in the war. ==Variants==