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Ilyushin Il-18 I CLAM - medium-range passenger aircraft

In the Design Bureau of S.V. Ilyushin, newly designed aircraft were often assigned numbers of previously created and not built in a series of predecessors. But in this case, Almost ten years later, the experience of the creation, construction and testing of first IL-18 aircraft with piston engines had a significant impact on the design of the IL-18 turboprop aircraft, which, although it retained the name of its predecessor, was essentially1 newly made passenger plane at a much higher technical level, the one widely known.

There were two IL-18s, the first one of them was a 66-seat passenger liner of the same class as Tu-70 powered by four radials. The first prototype flew on 17 August 1946. The original Il-18 was also a four-engined propeller aircraft (Nato ASCC reporting name Clam), also called SPD, was 97ft 11in (29.855m) long with a wing span of 134ft 10in (41.1m). This earlier piston-engined airliner of the same name turned out to be ahead of its time and was destined never to enter production.

According to one story, it was effectively cancelled at a stroke by Stalin when he saw it and asked the designer, Sergei Ilyushin, how many passengers it could carry? He replied, '66 Comrade Stalin, and a planned assault version will carry 90 troops'. Stalin retorted, 'Think what would happen if it crashed. You had better forget about this aircraft'. It was abandoned in favor of Li-2, IL-12 and IL-14 already in production. The designation IL-18 was used again ten years later.

Wikipedia suggested that "First developed as a piston engine powered aircraft, which was based on a Russian copy of the B-29, it later became one of the most prolific turboprop aircrafts in the world. After the piston-powered version was canceled because the competing design used more common parts of the bomber version, it was resurrected in 1965 in its current form." So much for the wisdom of crowds.

In the spring of the victorious 1945, during the construction of the first IL-12 prototype aircraft, S.V. Ilyushin proceeded to design a multi-seat long-range passenger aircraft Il-18, on which it was planned to install four powerful aviation diesel engines of A.Ch. Charomsky’s AC. The new aircraft was supposed to provide transportation of 60 ... 65 passengers at a distance of 5000 km with a cruising speed of 450 km / h at an altitude of 7500 m and be operated together with the fleet of Li-2 and Il-12 aircraft, the parameters and flight characteristics of which are the most fully comply with operating conditions on short and medium-haul airlines. It was assumed that a relatively small number of IL-18 aircraft will fly non-stop flights along the longest domestic and foreign airlines, for example, on such air routes as Moscow - Transcaucasia, Moscow - Central Asian republics, Moscow - industrial areas of the Urals - Far East. At that time, the main movement of air passengers, mail and long-distance cargo was carried along these routes.

In its appearance and many constructive solutions, the new machine resembled the first version of the design of the IL-12 four-engine high-altitude aircraft, but had significantly larger geometrical dimensions and mass in comparison with it.

As on the IL-12, the aerodynamic layout of the wing provided high aerodynamic perfection and flight safety of the IL-18, but the desire to obtain even higher values of aerodynamic quality and cruising speed of flight led to the use of the IL-18 wing with an unusually large, previously not used on OKB aircraft with a geometric elongation of 12, and with a rather high specific wing load of 310 ... 340 kg / m2 for aircraft of this class. This required the creation of the wing to solve a number of complex engineering problems related to achieving the required strength and stiffness of the wing at relatively low weight, providing the required critical flutter speed. The wing take-off and landing mechanization, consisting of Fowler slotted flaps,

In the summer of 1945, after the first flights of an experimental IL-12 aircraft with diesel engines, it was decided to replace the ACh-72 diesel engines on the IL-18 aircraft. But there are no pictures or characteristics of the ACh-72 diesel engine; about this gas-cooled air-cooled engines ASh-73TK with turbochargers TK-19. New engines have already been introduced into mass production under the direction of A.D. Shvetsov and had a takeoff power of 1765 kW (2400 hp) each. The engines powered double-acting four-blade automatic propellers AB-16NM-95.

On August 17, 1946, the crew, led by the leading test pilot V.K. Kokkinaki, made the first flight on this plane. His flight rating was high. During tests, it was found that the take-off of the aircraft is simple. Take-off and escape into the air proceeded calmly. When climbing, the plane was stable; balanced by trimmers, it walked without heavy loads on the controls. In horizontal flight, a balanced plane went in a straight line with abandoned control at speeds from 250 km / h to maximum. Longitudinal control over loads was pleasant, ailerons - easy. Planning proceeded calmly. Landing the plane was simple. In the run the plane was stable and had no features.

The testers and the comfort of the passenger cabin were highly praised. The noise in the cockpit when the engines were running was significantly less than on the Li-2, S-47 and IL-12 aircraft. In the area of working engines it was possible to calmly, without raising a voice, to conduct a conversation with a neighbor. The heating system in winter provided normal, room temperatures throughout the cabin.

In the fall of 1946, the pace of factory flight tests of the IL-18 slowed down. The reason for this was the lack of high-altitude engines ASH-73TK with turbochargers. And without ASh-73TK engines, a comprehensive factory flight test program for the Il-18 prototype could not be completed. Nevertheless, factory testers continued to study the features of the aircraft, to identify its strengths and weaknesses.

The aircraft IL-18 with engines ASh-73 and propellers AV-16NM, according to its flight data, was a promising aircraft. A five-fold safety margin of the aircraft guaranteed flight safety in severe weather conditions. With a total flight weight of 42,500 kg, the IL-18 could make a long flight with three working engines with climb, and with a flight weight of 3,600 kg, flight in horizontal mode with two working engines.

If the Il-18 suffered from its engine problems, it proved to be docile, stable, quiet and much more comfortable than the Li-2 and Il-12. It had enough power margin to fly in case of failure of one or two engines. Nevertheless, the production of the Tu-4 dominated that of ASh-73TK engines, which in addition were not economical enough for civilian use. In addition, the Il-18 seemed too big for the expected traffic: in other words, he was perhaps too far ahead of his time, so he was abandoned. Trials ended in mid-autumn 1946. On August 3, 1947, at the head of the convoy of IL-12 passenger aircraft, the IL-18 prototype aircraft was demonstrated at an air parade in Tushino, while guiding a formation of Il-12. He served in 1948 and 1949 to tow the heavy glider Il-32: it was indeed one of the few powerful enough aircraft in the USSR to do so. Then the IL-18 participated in various test programs. In the years 1948-1949. equipped with a special device, it was used as a towing vehicle for the Il-32 heavy transport and landing glider. Occasional flights continued until the early 1950s, before being scrapped.

By the mid-1950s it became clear that aircraft with piston engines did not satisfy the rapid growth of passenger traffic. There was a need for airplanes with greater passenger capacity and with a higher flight speed than piston aircraft had, that is, with greater productivity. By this time, a technical opportunity appeared. Fundamentally new gas turbine engines (GTE) were created and mastered, which then had two varieties - turboprops and turbojets , which were already used on military aircraft.

Maximum take-off weight42,500 kg (93,700 lbs)
Unladen mass28,490 kg (62,810 lbs)
Length29.86 m (97.97 ft)
Height9.4 m (30.8 ft)
Wingspan41.2 m (135.2 ft)
Wing area140 m² (1,500 sq. Ft)
Wing loading, unladen203.5 kg / m² (41.68 lbs / sq. Ft)
Wing load, take-off303,571 kg / m² (62,176 lbs / sq. Ft)
Engines4 star motors Shvetsov ASh-73TK
Unit power1,765 kW (2,400 hp, 2,367 hp)
Thrust / mass ratio, takeoff0.17
Thrust / mass ratio, empty0.25
Cruising speed450 km / h (280 mph, 240 kts)
Range6,200 km (3,800 mi, 3,300 nm)
Operational ceiling10 700 m (35 100 ft)
Maximum speed HA565 km / h (351 mph, 305 kts)

Il-18 I CLAM Il-18 I CLAM Il-18 I CLAM Il-18 I CLAM Il-18 I CLAM

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Page last modified: 17-11-2019 19:08:25 ZULU