Il-66 / Il-72 - SST Projects
The first of the Soviet aircraft designers, who began the development of supersonic passenger aircraft, was VM. Myasischev. It was in OKB-23 that the first scientifically grounded requirements were formulated for the devices of this class and engines for them.
In 1960, shortly after the decision to close OKB-23, the development of such machines was attempted to be deployed in the Ilyushin Design Bureau. In March of the same year, Sergei Vladimirovich, in a letter to the Deputy Chairman of the Council of Ministers of the USSR, D.F. Ustinov proposed to include in the pilot construction plan a steel supersonic passenger airliner, which later received the designation Il-66.
In April, S.V. Ilyushin appealled to the government with a proposal to include in the pilot construction plan a supersonic steel passenger aircraft IL-66. Informing about the preliminary design data of this machine, he wrote: "Fifteen years of experience in passenger aircraft and four years of experience in working on a cruise missile gives us reason to present a technical design of a supersonic Il-66 aircraft in Q3-1963 and begin flight tests in the second half of 1965. The aircraft should be designed to carry 60-100 passengers for a range of 7300 km with a flight speed three times higher than the speed of sound."
Preliminary calculations suggested that the projected aircraft would be economical. Several variants of the power plant were considered, including a combined power plant with turbojet engines and ramjet engines. The choice of the preliminary scheme of the aircraft was strongly influenced by the triangular wing prevailing at that time and the arrangement of the engines on the tail part of the fuselage. Calculations showed that the aircraft, designed according to the "duck" [ie, canard] scheme and accommodating from 60 to 100 passengers, would have a technical range of 7200 km with a speed three times higher than the sound one (according to other data 7300 km). The entire cycle of creating the aircraft was supposed to be completed in five years.
Apparently, the results of research in this direction, obtained in OKB-23, "settled" only in TsAGI and Tupolev Design Bureau. Only this can explain such high performance data, which went against the technological processes mastered in Soviet factories. Even from the standpoint of the 21st century, this was a very bold project, largely based on the emotions of the developers. After all, to implement this project in the country in the early 1960s, the necessary resources were not available.
Not surprisingly, the designers revised the basic parameters of the car in the same year and in the next project reduced the speed by almost 1000 km/h. This allowed choosing as the main structural materials aluminum alloys, abandoning the steel structures.
As a result, the calculations showed the real possibility of creating a supersonic passenger aircraft (SPS), which was designated Il-72, capable of transporting from 40 to 60 people for a distance of 4000-4500 km at a speed corresponding to a number M = 2.2. The project was discussed at the technical council of the enterprise in the beginning of 1961, but it received further development.
The design of such an aircraft required the solution of numerous technical problems in the selection of the final aerodynamic scheme, the type of power plant, the study of questions of heating and cooling the structure, and many others. However, the huge loading of the OKB specialists by other numerous and urgent works did not allow further development of this technically difficult topic.
Unfortunately, it has not been possible to restore the image of this project yet, and it is only possible to guess about the layout of the aircraft. The reason is simple. In the same year, sketches of a similar machine were made in the Tupolev Design Bureau. The designers used the results obtained during the design of the strategic combat vehicle Tu-135.
One of the most difficult problems in creating a supersonic liner is the choice of engine. By 1960, TRDF RD16-17 and RD-17-117F were under development. The most advanced and suitable for ATP was a two-circuit NK-6 take-off thrust of about 20 tons. It was for this engine that the Tu-135 was developed. Apparently, the circumstance related to the continuity of the projects of passenger and combat vehicles, did its job, and the leadership of the civil air fleet supported Tupolev. At the same time, it was necessary to create the engine NK-144, which, as it turned out, was unsuitable for ATP due to high fuel consumption.
The ending of the history of the Tu-144 is well known. The IL-66 project is interesting in that it reflects the view of the Ilyushin school of designing aircraft of those years.
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