The Yak-40 is a multifunctional jet plane designed in the Soviet aera to act as an airliner for secondary domestic routes. Aircraft Yak-40 is intended for the passenger and cargo-passenger airlifts on the feeder lines. The aircraft can be used in passenger, cargo and cargo passenger versions. The passenger salon can accommodate 32 - 36 seats with high level of comfort. Two jet engines are fixed on the sides at the back of the plane's fuselage, and a third is located inside the tail wing. The plane's small specifications allow it to land on non asphalt landing strips and operate at airports located up to 2,500 meters above sea-level and at high temperatures. Yak-40 is considered to be one of the best civil aircraft in Russia that combines comfort and reliability. More than 1000 Yak-40 aircraft and its versions were produced in Russia before 1981.
Yak-40 was the first and the only jet powered airliner in its class in service in large numbers anywhere in the world, preceding the ERJ-135 and 328JET by three decades. Design of the Yak-40 resulted from a mid 1960s Aeroflot requirement for a replacement for the thousands of Lisunov Li-2s (Soviet built DC-3s), Ilyushin Il-12s and Il-14s (2-engines prop liners) that were in service during the fifties. Aeroflot attached great significance to the Yak-40 program, as the aircraft was intended to operate regional services that accounted for 50% of Aeroflot's passenger traffic.
Its development began in April 1965. A.S.Yakovlev (after whom the design bureau is named) led the Yak-40 design team, and first mention of the program's existence was released on October 21, 1966, when the first prototype made its maiden flight. The type entered production in 1967 and entered service with Aeroflot in September 1968. The type went into production in 1967 and entered service with Aeroflot in September 1968.
As early as 1971, the US refused to grant a license for the sale of Yak–40 commercial jets in the US. US companies were anxious for sales and the Soviets want, in exchange, to sell their YAK–40 small jet, and helicopters in the US, plus US participation by a US firm in equipping a Soviet integrated aircraft production facility and joint design and development of a new and advanced commercial aircraft. The US Government made an airworthiness agreement required for the sale of Soviet aircraft contingent on purchases of US aircraft. UA policy, moreover, puts tight limitations on participation of US firms in the design or construction of an integrated aircraft manufacturing facility in the Soviet Union and precludes joint design and development of aircraft. The US tried to get talks underway on a bilateral airworthiness agreement for certification of the YAK–40. However, the Soviets’ primary prospective partner in selling the aircraft, Rockwell International, pulled out of the deal in 1974.
Production continued until 1978, with 1011 built by the Saratov aircraft factory, of which 125 aircraft were exported to 18 countries. Apart from airliner use, a number are in service as corporate or government transports with a VIP interior. Yak-40 became the first in the world jet aircraft for the feeder lines and first of the Soviet aircraft were obtained the certificates of the airworthiness of Italy and FRG.
The Yak-40 can take off and sit itself down on unpaved airfields. An APU and built-in stairs allow autonomous operation at remote airfields. Simplicity and reliability of the craft, three jet engines and auxiliary power unit in airframe stern post, low sweep wings of unusually large area, landing gear with powerful shock absorption system and large diameter wheels ensured taking off about a kilometer long rough airstrip.
On the external layout Yak-40 is the monoplane with the cantilever low wing, which is retracted by three-strut landing gear with the nose steadfast and rear arrangement of engines. The Yak-40's most noticeable design feature is its trijet configuration, with three specially developed Ivchenko AI-25 turbofans. The three jet engine layout was chosen for increased redundancy and good short field, hot climate zone and high altitude performance, which is very important in many areas of Russia like Siberia, Far East, Caucasus, Urals etc. The unswept, high aspect ratio wing is also designed for good field performance. The comfortable sealed main cabin with soft seats, air conditioning, ventilation, toilet, dressing room and built-in stairway were a nice present for local routes passengers.
Initially the aircraft was produced with a takeoff mass of 14,7 t and the number of places 27. The flying range it was 710 km (with the reserves of fuel) more lately they approached the release of the improved version with a takeoff mass of 16,1 t and the number of places 32. During this modification it was possible to increase flying range. The aircraft take-off mass and fuel capacity were increased up to 17,2 tons and 6 tons correspondingly that ensure range of flight up to 2500 km.
To provide regular flights in European airspace Yak-40 aircraft is now equipped with the following additional instrumentation that ensures meeting BRNAV RNP-5 zone navigation requirements: satellite navigation system GPS; flight collision avoidance system TCAS; early ground proximity warning system SGPWS. Yak-40 aircraft meets "International civil aviation convention" Volume 1, Chapter 3, Appendix 16 Requirements on noise level.
Optionally, the passenger salon can be rearranged in different lay-outs to enhance comfort for VIP category with special place for Number 1 Person. After the political changes of 1990, the Yak-40 was quickly received as the Russian Biz Jet. Several companies in Russia, among them energy and machinery plants, continue to employ some Yak-40 as corporate jets. At organization VIP flights the YAK 40 (saloon) is optimum for transportation from 3 to 4 VIP passengers with service on the first class accompanied by no more than 10 person with business service during flight. Average flight airspeed on a route varies from 450 up to 500 kilometers/hour. Optimal decision is to order the plane of the YAK 40 on flight distance from 1300 up to 1800 kilometers.
At present time the efforts are taken for flight airworthiness support and life time increase up to 40 000 flight hours, 35 000 flights and service life up to 38 years with time intervals between repairs up to 18 years. A.S.Yakovlev Design Bureau is fruitfully proceeding in improving Yak-40 flight performance taking into account market demands in aircraft of that type.
The aircraft became famous for its speed, comfort and reliability. Unfortunately, this type of aircraft is now obsolete, and Russian aviation industry has recently unreasonably stopped modernization of the aircraft, although no complete substitute is available yet.
- Yak-40D - equipment of aircraft by two additional fuel caissons, which make it possible to increase the total maximum capacity of the repaired fuel to 6 tons. Equipment of aircraft by the system of the centralized servicing with the discrete fuel gauge for measuring the quantity of fuel in the additional caissons and control of the centralized servicing. Aeronavigational equipment for the flights on the international air lines is established.
- Yak-40DTS - truck and sanitary version;
- Yak-40K - cargo-passenger version with the maximum payload in the purely cargo configuration 3200 kgf
- Yak-40 "Kalibrovshchik" - version for the functional check of the ground-based radio-range beacons
- Yak-40 "Akva", "Liros", "Meteo", "Fobos" and "Shtorm" the aircraft - meteo-laboratory
- Yak-40 - REO and Yak-25 - flying testing laboratories and checking radio-electronic equipment
- Yak-602 - flying testing laboratory of Czechoslovak engine M-602
- Yak-40TL the proposed version with the engines Of textron-Lycoming LF507-1N (2[Kh]31,1 kN, 2[Kh]3180 kG)
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