D3A development benefited from industrial growth and experience with the D1A before the war in China placed heavier demands on Japan's resources. Competing designs underwent extensive prototype testing against a requirement for dive speeds above 240 knots. A longer dorsal fin strake corrected directional instability, especially in the dive, and the resulting aircraft approached fighter-like maneuverability. Engine development continued, with the second version reaching 1,300 horsepower at takeoff in 1942. Its greater weight still allowed a power-to-weight ratio close to the Zero's. Stronger engines existed, but insufficient production prevented them from filling the wider gap in aircraft power.
Notable Point · 1:27:10-1:30:48
D3A testing fixes instability and meets a demanding dive requirement
Prototype testing resolves the D3A's directional instability, while engine development maintains performance as aircraft weight increases.