Ilyushin Il-86D

The Il-86D — the "D" stands for the Russian "дальний", "long-range" — was the project through which the Ilyushin design bureau tried to turn its first wide-body airliner, the Il-86, into a long-haul aircraft without abandoning the existing design. It never entered service: the sources always describe it as a project, and its path ended in the Il-96, a different aircraft that has its own entry in the catalogue.

Origins. According to the English-language Wikipedia, the Soviet cabinet ordered a long-range version of the Il-86 into development on 26 June 1972, and the design was completed in June 1976. The Russian portal "Российская авиация" explains where the need came from: an analysis carried out in the mid-1970s concluded that, by the end of the 1980s, traffic growth on the Soviet Union's long-haul routes would require high-capacity wide-body aircraft in Aeroflot's long-range fleet, because narrow-body airliners had become uncompetitive on the main trunk routes and were being moved to long, thinly travelled lines. At first it was assumed that this aircraft would be a direct development of the Il-86, keeping as much structural commonality with it as possible.

The concept. The same source states that the Il-86D kept the Il-86's fuselage structure, tail surfaces and main onboard systems, and differed only in wing area and in new high-bypass engines with low specific fuel consumption in cruise. That commonality was meant to shorten development, allow series production alongside the Il-86 and simplify maintenance of both types in service; the Russian encyclopedia adds that full unification with the Il-86 would allow it to be certified and put into service quickly. The English-language Wikipedia mentions a marginally extended wingspan, additional fuel and a range of some 8,500 km; the Russian-language Wikipedia credits it with 330 passengers over distances of more than 9000 km. airport-technology.com sums it up as the long-range version, with a larger wingspan and heavier fuel tanks.

Figures that do not agree. The sources disagree on both the engine and the wing. The Russian encyclopedia (the Russian Wikipedia article on the Il-96 as mirrored by dic.academic.ru) places the Il-86D studies between 1974 and 1977, in parallel with the development of the Il-86 itself, with a wing enlarged to 470 m² and higher-bypass turbofans of 20,850 kgf thrust each (about 204 kN). The English-language Wikipedia cites later announcements that a version of the Il-86D with Lotarev D-18 engines had entered development in March 1975, with an empty weight of 147,500 kg, a maximum take-off weight of 300,000 kg, some 150,000 kg of fuel, a wing area of 325 m² and a range of 10,200 km; airport-technology.com also gives it Lotarev D-18 engines. The Russian-language Wikipedia, by contrast, speaks of Il-86V and Il-86D projects studied in the 1980s with British Rolls-Royce RB211-22B engines of 19,000 kgf. With this material it is not possible to say which of those powerplants was final, or whether they were successive stages of a single project; the D-18 version also appears in the catalogue as a separate entry.

Towards the Il-96. The energy crisis of the mid-1970s, with its sudden rise in the price of kerosene, made fuel burn per passenger-kilometre one of the main design criteria. Studies by TsAGI (the Soviet Central Aerohydrodynamic Institute) and by the bureau itself showed that the Il-86D's efficiency could be greatly improved through new aerodynamic and weight-saving solutions. In 1978, building on the results of the Il-86D project, Ilyushin began work on an Il-96 with a T-tail and a higher-aspect-ratio wing with supercritical sections and an area of up to 387 m². That work continued until 1983, when technical progress led the bureau to give up reusing many Il-86 assemblies and systems and to move to an all-new design, the Il-96-300, which first flew in 1988. The Russian-language Wikipedia sums up the lineage in one line: the Il-86D served as the basis for the Il-96-300.

What is not known. None of the sources consulted gives a first flight or a number of aircraft built for the Il-86D, nor its length or weights outside the D-18 version. Il-96-300 figures are not Il-86D figures and are not attributed to it here.