The Ilyushin Il-40 (Russian: Ильюшина Ил-40) was a two-seat Soviet jet-engined armored ground-attack aircraft. The first prototype flew in 1953 and was very successful except when it fired its guns, as their combustion gasses disturbed the airflow into the engines and caused them to flameout or hiccup. Remedying this problem took over a year and involved the radical change of moving the engine air intakes all the way to the very front of the aircraft and repositioning the guns from the tip of the nose to the bottom of the fuselage, just behind the nose wheel. It was ordered into production in 1955, but only five production aircraft had been completed before the entire program was canceled in early 1956.
- Il-40 – First prototype
- Il-40P – Second prototype and five production aircraft.
- Il-40K – (korrektirovshchik – corrector) – Artillery spotter, three-seater with spotter-navigator in glazed nose cockpit.
- Il-40T – (torpedonosets) – Torpedo bomber, three-seater with navigator in glazed nose with optically flat panels for weapon aiming.
- Il-42 – Late 1960s revival of the Il-40 concept, beaten in competition with the Sukhoi T-8.
- Il-102 – Ultimate iteration of the Il-40/Il-42, with modern avionics and engines, also beaten by the Sukhoi T-8.