Light bomber

After World War I, attack aircraft were typically identifiable by their ability to carry multiple fixed machine guns, automatic cannons and rockets in addition to bombs.

Purpose-built light bombers disappeared from military aviation by the end of World War II, as advancements in propulsion and aeronautical design enabled newer attack/strike aircraft, fighter-bombers, and multirole aircraft types to deliver equal or greater bomb loads while also having superior performance, range and defensive capabilities.

By the early 1930s many air forces were seeking to replace their older biplane aircraft (for example, the RAF's Hawker Hart and VVS's Polikarpov R-5) with more modern and higher performance monoplane designs.

Contemporaneous twin-engine light bombers included the Bristol Blenheim, Douglas B-23 Dragon, Kawasaki Ki-48 ("Lily"), Martin Maryland (also known as the A-22), Lockheed Hudson, Tupolev SB, and Mitsubishi G3M ("Nell").

Twin-engine light bombers were successful when converted into airborne radar-equipped night fighters during World War II; examples include the Bristol Blenheim, Douglas A-20 Havoc (as the P-70), and Dornier Do 17.

Light bombers were selected as a basis for night fighters during this time because early airborne radar systems, used to find and track targets in the dark, were bulky and often required a dedicated operator in the crew; most smaller day fighters of that era were unsuited to such extra weight and personnel.

Types designed before the war as heavy fighters were also frequently adapted as light bombers, including the Messerschmitt Bf 110, Potez 633, Fokker G.I, Kawasaki Ki-45, Bristol Beaufighter, and Lockheed P-38 Lightning.

As World War II progressed, specialised attack designs became increasingly focused on low altitude strafing of surface targets, armed with automatic cannons, heavy machine guns and newly developed rockets; the A-20 and B-25 Mitchell (type-classed as a medium bomber) each had variants with 8 or more forward-firing machine guns for ground strafing missions.

Later variants of the Ju 87 Stuka dive bomber were adapted to the role of ground attack against tanks armed with 37 mm cannon, and the Curtiss SB2C Helldiver (a U.S. Navy dive bomber adopted later in World War II when that design role was beginning to disappear) also was assigned to ground attack sorties using its cannon, bombs and rockets.