Staff Writer (Updated: 5/10/2016):
Aichi (along with Nakajima and Mitsubishi) submitted their monoplane design to a 1936 Japanese Navy specification (11-Shi) for a carrier-based dive-bomber to replace the aging D1A biplane series. Only Aichi's and Nakajima's submissions were pressed for further development with the request for a full working prototype.
The initial prototype was completed in December of 1937 and first flew in 1938 and fitted with Nakajima Hikari 710 horsepower engines. Despite a poor showing, a second improved prototype was made in an attempt to address issues in stability, strength and power. The second prototype hit the mark and was selected for production over the Nakajima model. This new version from Aichi, now designated D3A1, would feature revised wings of a larger span, improved dive brakes, a 1,000 horsepower Mitsubishi Kinsei 43 radial piston engine in a redesigned cowling and improvements to maneuverability via the lengthening of the dorsal fin.
Standard armament of production models would consist of an assortment of 3 x 7.7mm machine guns. Two Type 97 Light Machine Guns were fixed to fire forward and controlled by the pilot while a single Type 92 Heavy Machine Gun was fitted in a flexible mount in the rear cockpit. As a dive bomber, the Aichi D3A could sport a single 550lb bomb under the fuselage or 2 x 130lb bombs under each wing.
Early "Vals" were flown in limited land-based operations in the Indo-China theater though the rest of the war would see them operating in unison with her Imperial Japanese Navy carrier-based counterparts. D3As, in fact, would end up being responsible for the destruction of more Allied shipping vessels than any other Axis aircraft during the war - such was the reach of this "obsolete" aircraft.
The D3A's were maintained in frontline service up until the Battle of Coral Sea which saw disastrous results for the type - effectively signaling the end of the aircraft's usefulness. Vals, therefore, were systematically phased out from much frontline action as, by 1944, the D3A was simply outclassed by the plethora of American fighters appearing throughout the theater. Many Vals therefore ended up as dual-control, two-seat trainers while some were featured in Kamikaze attacks, the latter focusing in and around the areas of Leyte and Okinawa during the final year of the war.