The Yakovlev Yak-40, an aircraft crafted by Yakovlev, is a regional jet that took its inaugural flight in 1966.
It remained in production from 1967 to 1981, and was introduced to the market in September 1968.
Since 1970, the Yak-40 has been successfully exported to various destinations.
During the early 1960s, Aeroflot, the state airline of the Soviet Union, operated jet and turboprop powered airliners for their international and internal trunk routes.
However, their local services, which operated from grass airfields, still relied on outdated piston-engine aircraft like the Ilyushin Il-12, Il-14, and Lisunov Li-2.
Recognizing the need for a modern replacement, Aeroflot tasked the Yakovlev design bureau with developing a turbine-powered aircraft.
The primary requirement for this new aircraft was not high speed, but rather the ability to operate safely and reliably from poorly equipped airports with short, unpaved runways measuring less than 700 meters (2,300 feet) in length, even in adverse weather conditions.
To meet this challenge, Yakovlev explored both turboprop and jet-powered designs.
They even considered Vertical Take-Off and Landing (VTOL) configurations with lift jets located either in the fuselage or in wing-mounted pods.
After careful consideration, Yakovlev ultimately decided on a straight-winged tri-jet design capable of carrying 20 to 25 passengers.
The engines chosen for this aircraft were the AI-25 turbofans, a new type of engine being developed by Ivchenko in Zaporozhye, Ukraine.
The Yak-40 is an aircraft characterized by its low-winged cantilever monoplane design, featuring unswept wings, a prominent T-tail, and a retractable tricycle landing gear.
Positioned ahead of the wing, the passenger cabin is accompanied by a short rear fuselage that houses three turbofan engines.
These engines are arranged with two mounted on short pylons on the fuselage’s side and the third located in the rear fuselage.
The engines draw air from a dorsal air-intake through an “S-duct” system.
Additionally, an auxiliary power unit is installed to facilitate engine start-up in the absence of ground support, particularly in rudimentary airfields.
The three AI-25 engines are two-shaft engines with a power rating of 14.7 kN (3,300 lbf).
Notably, these engines lack jet pipes and thrust reversers initially.
The fuselage of the Yak-40 is pressurized and boasts a diameter of 2.4 meters (94 inches).
Within the aircraft’s flight deck, the pilot and co-pilot occupy side-by-side seating arrangements.
As for the passenger cabin, it adheres to a standard layout accommodating 24 to 27 passengers in a three-abreast configuration.
However, by switching to four-abreast seating, the aircraft can accommodate up to 32 passengers.
Access to the aircraft is facilitated through a set of ventral airstairs located in the rear fuselage.
The Yak-40, the initial Soviet-manufactured commercial aircraft that adhered to Western airworthiness standards, features a wing equipped with sizeable trailing-edge slotted flaps, but no other high-lift mechanisms, relying instead on the aircraft’s low wing loading to achieve the necessary short-field take-off and landing performance.
The wings meet at the aircraft’s centreline, with the primary spar extending from wingtip to wingtip.
The wings also contain built-in fuel tanks with a capacity of 3,800 litres (1,000 US gal; 840 imp gal).
The aircraft boasts a large fin, which is angled back at 50 degrees to shift the tailplane rearward to counterbalance the short rear fuselage.
The horizontal tailplane itself is not swept.
The maiden flight of the first prototype of the Yak-40 took place on 21 October 1966, marking the beginning of production at the Saratov Aviation Plant in 1967.
Soviet type certification was granted in 1968, paving the way for the aircraft’s first passenger service with Aeroflot on 30 September 1968.
Subsequent versions of the Yak-40 saw improvements and modifications.
In the 1972 version, a tailspin was eliminated, while in 1974, a new version was introduced with an increased non-stop flight distance.
Additionally, the forward door on the right side of the fuselage was relocated alongside the sixth window.
In 1975, the Yak-40 underwent its final upgrade, resulting in a change in the number of cabin windows on the right side from nine to eight.
Production of the Yak-40 ceased in November 1981, with the Saratov factory having manufactured a total of 1,011 or 1,013 aircraft.
By 1993, Yak-40s operated by Aeroflot had transported 354 million passengers, serving as a crucial component of the airline’s domestic operations and flying to 276 destinations within the country in 1980.
Furthermore, the Yak-40 achieved international success as it became the first Russian/Soviet aircraft to receive flying certificates from Italy and West Germany.
Its global presence was demonstrated in 75 countries, including the United States, where orders for the Yak-40 were placed. Variants Yak-40 The first production model. Yak-40-25 Military conversion with the nose of a MiG-25R and SRS-4A Elint installation. Yak-40 Akva Military conversion with nose probe, pylon-mounted sensors, a fuselage dispenser and underwing active jammer pods. Yak-40D With non-stop flight distance enlarged. Yak-40EC Export version. Yak-40 Fobos Military conversion with two dorsal viewing domes and a removable window on each side. Yak-40K Cargo / convertible / combi version with a large freight door. Produced in 1975–81. Yak-40 Kalibrovshchik Military Elint conversion with a “farm” of blade, dipole, and planar antennas Yak-40L Proposed version with two Lycoming LF507-1N turbofans, a joint program between Skorost and Textron (now Allied-Signal) Lycoming The original design would have had a slightly swept wing. Yak-40 Liros Military conversion with nose probe carrying air-data sensors. Yak-40M Proposed 40-seat stretched passenger version. Yak-40 M-602 Flying testbed with a Czechoslovak M 602 turboprop installed in the nose. Yak-40 Meteo Military conversion with multipole dipole antennas and fuselage dispenser. Yak-40P Yak-40L with large nacelles projecting ahead of the wings. Yak-40REO Military conversion with large ventral canoe for IR linescan.
Lateral observation blister on right side. Yak-40 Shtorm Military conversion with multiple probes and sensors on the forward sidewalls. Yak-40TL Proposed upgraded version, to be powered by three Lycoming LF 507 turbofan engines. Yak-40V Export version powered by three AI-25T turbofan engines. Yak-40MS Experimental upgrade with two Honeywell TFE731-5 turbofan engines by SibNIA. STR-40DT A proposed twin-engine composite-wing derivative along the line of TVS-2DTS, also being developed by SibNIA. Endorsed, but not supported by Yakovlev. Specifications Yak-40 Crew 3 Capacity 32 passengers Length 20.36 m (66 ft 10 in) Wingspan 25.0 m (82 ft 0 in) Height 6.50 m (21 ft 4 in) Wing area 70.00 m2 (753.5 sq ft) Aspect ratio 9:1 Empty weight 9,400 kg (20,723 lb) Max take-off weight 15,500 kg (34,172 lb) Fuel capacity 3,910 L (860 imp gal; 1,030 US gal) Powerplant 3 × Ivchenko AI-25 turbofan engines, 14.7 kN (3,300 lbf) thrust each Performance Maximum speed Mach 0.7 (IAS) Cruise speed 550 km/h (340 mph, 300 kn) at 7,000 m (23,000 ft) (max. cruise) Range 1,800 km (1,100 mi, 970 nmi) Service ceiling 8,000 m (26,000 ft) [27] Rate of climb 8.00 m/s (1,575 ft/min) Sources Yakovlev Aircraft Since 1924 – Bill Gunston & Yefim Gordon. OKB Yakovlev, A History of the Design Bureau and its Aircraft-Yefim Gordon, Dmitriy Komissarov & Sergey Komissarov. Soviet Aircrafts Illustrated-A.S.Yakovlev. The History of Soviet Aircraft from 1918-Vaclav Nemecek. Soviet AF Fighter Colours 1941-45-Erik Pilaeskii. Soviet Combat Aircraft of the Second World War, Vol 1, Single Engined Fighters-Yefim Gordon and Dmitri Khazanov. Early Soviet Jet Fighters, The1940s and early 50s-Yefim Gordon.
