Ilyushin Il-12

The Ilyushin Il-12 (NATO reporting name "Coach") was 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. The new aircraft followed a classical layout for a twin-engine transport, with a metallic structure, monoplane wings, a conventional tail section. One major improvement over the Li-2 design was the tricycle landing gear, which allowed better visibility when taxiing and landing. Initially the Il-12 was designed for 29 passengers in a pressurized fuselage, with projected maximum range is assumed of 5,000 kilometers at a cruising speed 400 kph. The aircraft was to use four M-88B engines already proven in use on the Ilyushin Il-4.

However, during development, the M-88B engines had to be replaced by two ACh-31 diesel engines (each producing 1,500 hp). The plans for a pressurized fuselage were abandoned and the number of passengers reduced to 27. The Il-12 made its maiden flight on 15 August 1945.^[2] It was soon decided to re-engine the aircraft with Shvetsov ASh-82 radial engines with the revised aircraft flying on 9 January 1946.^[2]

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 center-of-gravity problems.^[3] Further problems 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 later revealed by a crash of an Ilyushin Il-12 near Voronez 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.)^[4] However, once these problems were resolved, factory test pilots praised the quality of the new aircraft, which contributed to the decision to launch the Il-12 in series production.

The fuselage of the Il-12 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.^[3] 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.^[3] 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 1949–1951, TAROM in Romania from 1949, and at least 20 aircraft to CAAC in China.

Variants

• Il-12A : Basic passenger version with 27 seats standard, also produced in versions with 6, 11, 16, 18, 21 and 32 seats.
• Il-12B : Modification from 1948, fitted with an improved de-icing system, lengthened nosewheel and a small dorsal fin fillet.
• Il-12D : military transport version for the Soviet Air Force launched in 1948, for 38 paratroops or military cargo to 3700 kg.
• Il-12T : transport version for arctic operations, with a large cargo door on the left side of the fuselage.

Safety Record

Of the 663 Il-12s produced, 17 have been lost in accidents.

Date	Registration	Location	Casualties	Details
01.07.1947	Л1317	Vnukovo	NA	Engine failure, the aircraft lost speed and crashed.
18.12.1947	Л1343	near Krasnoyarsk	7/25	Engine failure, crashed while returning to the aerodrome of departure.
01.09.1948	Л1465	Severny Airport	1/NA	Lost speed on take-off and was damaged due to crew errors
09.09.1948	Л1427	Buguruslan	5/5	Loss of control due to engine failure simulation in a test flight.
12.10.1948	Л1450	near Baku	10/10	Crashed in bad weather.
23.12.1948	Л1731	near Vnukovo	4/4	mid-air collision due to crew negligence
30.7.1950	Л1803	near Karaganda Airport	25/25	Crashed after takeoff due to engine failure.
1952	SP-LHE	Warsaw	NA	Engine fire; written off.
18.07.1952	SP-LHC	Warsaw	0/NA	Damaged on landing
05.10.1952	Л1328	near Leningrad	5/5	Mid-air collision due to gross negligence by air traffic controller[citation needed]
14.06.1953	Л1375	near Zugdidi	18/18	Crashed after wings broke up.
27.07.1953	NA	near Kanggye, DPRK	21/21	Shot down by USAF F-86 Sabre and became the last aircraft destroyed during the Korean War.[5]
28.10.1954	Л1789	Krasnoyarsk Territory	20/20	Struck a mountain.
04.03.1955	Н479	Mezen	4/25	Engine failure and fire resulting in emergency landing on a frozen lake.
26.04.1956	NA	Berlin	3/6	Collided with a church bell tower while landing in fog.
24.11.1956	OK-DBP	Eglisau	23/23	Crashed in a field 12 km from Zurich.
27.10.1957	Н442	North Pole drifting ice station SP-7	1/6	Struck terrain while flying too low.
09.06.1958	Л1364	near Magadan	20/20	Collided with a hill while landing in bad weather.
19.09.1958	Л3904	near Lazo	28/28	Crashed into mountain while trying to make an emergency landing at night in bad weather due low fuel; loss of orientation, violations of the ATC.
01.1959	04249	Mirny Station, Antarctica	0/NA	overran runway; landing gear failure

Operators

 Bulgaria

• TABSO

 Czechoslovakia

• Czech Airlines

 People's Republic of China

• Civil Aviation Administration of China
• People's Liberation Army Air Force

Imported 42 IL-12 airliners from 1950 to 1951 used to airlift to Lhasa during the Incorporation of Tibet into the People's Republic of China. Some were refitted to aerial survey airplanes later. Retired in 1986.

 Laos

• Pathet Lao

 Poland

• LOT Polish Airlines
• Polish Air Force

 Romania

 Mongolia

• TAROM

 Soviet Union

• Aeroflot
• Soviet Air Force
• Soviet Navy

 North Korea

• CAAK

Specifications (Il-12)

Data from The Osprey Encyclopedia of Russian Aircraft from 1875 - 1995^[3]

General characteristics

• Crew: 3
• Capacity: 21^[6]-32^[7] passengers
• Length: 21.31 m (69 ft 11 in)
• Wingspan: 31.7 m (104 ft 0 in)
• Height: 8.07 m ^[8] (26 ft 5⅝in)
• Wing area: 103 m² (1,109 ft²)
• Empty weight: 11,045 kg (24,350 lb)
• Max. takeoff weight: 17,250 kg (38,029 lb)
• Powerplant: 2 × ASh-82FNV 14 cylinder two-row air cooled radial engine, 1,380 kW (1,850 hp) each

Performance

• Maximum speed: 407 km/h (220 kn, 253 mph) at 2,500 m (8,200 ft)
• Range: 1,500 km with 26 passengers (810 nmi, 932 mi)
• Endurance: 4.5 hr
• Service ceiling: 6,500 m (21,325 ft)
  
• Climb to 5,000 m (16,400 ft): 15 minutes

References

Wikimedia Commons has media related to Ilyushin Il-12.

Notes

Bibliography