The Japanese Mitsubishi G4M twin-engine "Betty" Bomber makes its maiden flight.
The Mitsubishi G4M was a twin-engine, land-based medium bomber formerly manufactured by the Mitsubishi Aircraft Company, a part of Mitsubishi Heavy Industries, and operated by the Imperial Japanese Navy from 1940 to 1945. Its official designation is Mitsubishi Navy Type 1 attack bomber (一式陸上攻撃機, 一式陸攻, Ichishiki rikujō kōgeki ki, Isshikirikukō) and was commonly referred to by Japanese Navy pilots as Hamaki (葉巻, "cigar", lit. "leaf roll") due to the cylindrical shape of its fuselage and its penchant for igniting after a hit. The Allied reporting name was "Betty".Designed to a strict specification to succeed the Mitsubishi G3M already in service, the G4M boasted very good performance and excellent range and was considered the best land-based naval bomber at the time. This was achieved by its structural lightness and an almost total lack of protection for the crew, with no armor plating or self-sealing fuel tanks. The G4M was officially adopted on 2 April 1941 but the aforementioned problems would prove to be a severe drawback, often suffering heavy losses; Allied fighter pilots nicknamed the G4M "The Flying Lighter" as it was extremely prone to ignition after a few hits. It was not until later variants of the G4M2 and G4M3 that self-sealing fuel tanks, armor protection for the crew and better defensive armament was installed.
Nevertheless, the G4M would become the Navy's primary land-based bomber. It is the most widely produced and most famous bomber operated by the Japanese during World War II and it served in nearly all battles during the Pacific War. The aircraft is also known for being the mothership that carried the Yokosuka MXY-7 Ohka, a purpose-built anti-ship suicide weapon during the final years of the war. Of the 2,435 G4Ms produced, no intact aircraft have survived.