The Asahi D4Y1 Model 11 Suisei (Judy) was delivered for service in 1942 to replace the aging and out of date Aichi D3A1 (Val) carrier based dive bomber which had been in service since 1939. The D4Y carried a single 550 pound bomb in an internal bomb bay and could be fitted with two wing attached 120 pound bombs. Having the bomb load inside an enclosed bomb bay kept the airframe extremely clean and allowed for the high rate of speed which this aircraft could achieve.
The D4Y1 series was powered by a series 601 inverted V 12 cylinder water cooled engine which was built under license from Daimler Benz and produced 1200 horse power. This engine proved to be under powered so it was modified in the D4Y2 series to produce 1400 hp. For the later model D4Y3 and D4Y4 series the engine was replaced, this time by the very powerful and reliable 1,560 hp Mitsubishi Kinsei 62 14-cylinder twin row air cooled radial engine. The D4Y3 and D4Y4 had an operational range of 1600 miles and a top speed of 356 MPH.
The D4Y series of dive bombers were extremely fast for this type of aircraft and some were even converted to night fighters and had success against the high flying B-29 bombers later in the war
2,038 D4Y1 though D4Y4 variants were produced from 1942 through the end the war.