The Ilyushin Il-12 (NATO reporting name: Coach) is a Soviet twin-engine cargo aircraft, developed in the mid-1940s for small and medium-haul airline routes and as a military transport.

Design and development

The Il-12 was developed as a private venture by the Ilyushin Design Bureau from autumn 1943 and was intended as a replacement for the Lisunov Li-2, a license-produced version of the Douglas DC-3. Initial studies proposed a 29-seat airliner powered by four 1000 hp supercharged M-88V engines (as used in the Ilyushin Il-4 bomber) and with a pressurized cabin, allowing the aircraft to cruise at an altitude of 6000 - 7000 m, with a range of 5000 km at almost 400 km/h. The aircraft would be fitted with a tricycle landing gear, the first use by the Ilyushin OKB. During 1944, the design was changed, with the M-88B engines replaced by two ACh-31 diesel V-12 engines (each producing 1900 hp at take-off). The plans for a pressurized fuselage were abandoned and the number of passengers reduced to 27. The lower operating altitude resulted in a reduction in the aircraft's range and cruising speed. The Il-12 made its maiden flight on 15 August 1945. It was soon decided to re-engine the aircraft with Shvetsov ASh-82 radial engines, as it was expected to take too long to develop the ACh-31 to an acceptable reliability and time between overhauls for commercial service. The modified first prototype flew with its new engines on 9 January 1946. The Il-12 was found to have problems with vibration during testing, having poor engine out characteristics and requiring a strut under the rear fuselage to prevent tipping during loading due to centre-of-gravity problems. However, factory test pilots praised the quality of the new aircraft, with much better performance and handling than the Li-2, which contributed to the decision to launch the Il-12 in series production. One problem was the use of magnesium near the engines which, in case of engine fire, could cause an uncontrolled fire, damaging the wing structure. This was revealed by a crash of an Ilyushin Il-12 near Voronezh in 1949 which killed all on board, following an engine fire. Subsequently, as a result of the accident investigation, the magnesium was replaced by aluminium alloys and the fire extinguishing system was redesigned. In addition, the aircraft's takeoff weight was restricted to ease the hazard of an engine failure during take-off - this in turn reduced the aircraft's passenger capacity, which was temporary limited to 18. The Il-12 was a low-wing cantilever monoplane, with a single fin and rudder and a retractable tricycle undercarriage. It was powered by two Shvetsov ASh-82FN radial engines, rated at 1850 hp for take-off and 1630 hp at 1550 m, driving four-bladed propellers. The fuselage had a considerable volume, and was equipped with eight rectangular windows on each side. The crew consisted of three and the aircraft could transport 32 soldiers, 32 parachutists or cargo. There was also a civil version, which although designed to carry up to 32 passengers, was limited in Aeroflot service to 21, with normally only 18 carried. At that passenger load, it meant that use of the Il-12 for passenger use was un-economic. A total of 663 Il-12s were manufactured. The aircraft was later improved into the Ilyushin Il-14.

Operational history

The Il-12 was revealed to the public on 1 May 1947, when a group of aircraft participated in the annual May Day flyby over Red Square in Moscow. Performance testing was completed by 20 May, and the first regular passenger service by the Il-12 on Aeroflot began in June 1947. The first regular international use of the Il-12 was on the Moscow-Sofia route in 1948. The Il-12 was used on Aeroflot's services to Paris from 1954. Within the USSR, the Il-12 was placed on Aeroflot's longest route: Moscow-Khabarovsk, with the flight lasting 28 hours, including five refueling stops. From 1956, the Il-12 (modified for use on ice runways) supported the Soviet expeditions to Antarctica. Aeroflot continued to use the Il-12 on some routes until the end of 1970.

Export sales

The first export customer for the Il-12 was LOT Polish Airlines, who placed an order for five Il-12Bs after it was displayed at the Poznan Fair in Poland in the spring of 1948. This was followed by Czech Airlines, who purchased 10 aircraft from 1949 to 1951, TAROM in Romania from 1949, and at least 20 aircraft to CAAC in China.

Variants

Accidents and incidents

Of the 663 Il-12s produced, 56 have been lost in accidents with a total of 465 fatalities.

1940s

1950s

1960s

Operators

Specifications (Il-12)