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30-643: Based on the core of the Ukrainian Progress D-36 turbofan, the D-236 was the first Soviet propfan, and as of 2019 it is still one of only four different unshrouded, contra-rotating propfan engines to have flown in service or in flight testing. The D-236, an engine with unshrouded contra-rotating propellers, was first investigated in 1979 as the powerplant for the first version of the Ukrainian Antonov An-70 . The front propeller

60-505: A Yak-42 for geophysical survey and environmental monitoring. Fitted with large underwing pods containing electro-optical sensors. Conversion as testbed for Progress D-236 propfan engine. Single D-236 (rated at 8,090 kW (10,850shp)) mounted in place of starboard engine, on special pylon to give sufficient clearance for 4.2 m (13 ft 9¾ in) propellers. First flew 15 March 1991. A projected but unbuilt stretched airliner. Planned to be powered by three Progress D-436 turbofans,

90-471: A design powered by three of the new Lotarev D-36 three-shaft high-bypass turbofans, which were to provide 63.90 kN (14,330 lbf) of thrust. Unlike the Yak-40, the new airliner would have swept wings. The first of three prototypes, which was fitted with an 11-degree wing and registered SSSR-1974 , made its maiden flight on 7 March 1975. It was followed by the second prototype, ( SSSR-1975 ) with

120-469: A diameter of 4.2 m (14 ft; 420 cm; 170 in), a takeoff thrust of 10.5–11 tonnes-force (103–108 kilonewtons; 23,000–24,000 pounds-force), and an output power of 8,900 kW (12,000 hp), although it was limited to 7,050 kW (9,450 hp) on this testbed. The Yak-42E-LL testbed aircraft was flown to the 1991 Paris Air Show as a demonstration for the planned Yak-46 aircraft with twin propfan engines. The D-236 test engine replaced

150-456: A failure of the actuator screw jack , causing the aircraft to fatally crash near Mazyr . The type was grounded as a result, not returning to service until October 1984. An export order for seven aircraft was announced in 1982 by Aviogenex of Yugoslavia , but the contract lapsed. The availability of the longer-range Yak-42D variant from 1991 onwards gave rise to a few more export sales, to Bosnia, China, Cuba, and Iran. As of 1 January 1995

180-403: A metal spar , and they had about 45 degrees of twist. The propellers would rotate at 1,100 rpm at takeoff and 960 rpm at cruise . Soviet engineers claimed that the engine would be delivered by 1989 and help Antonov airliners meet the strictest U.S. community noise standards, although they were still working on a solution to lower cabin noise . The gently curved blades were efficient up to

210-558: A single-stage fan with 29 titanium blades and a Kevlar outer shell, which is driven by a three-stage turbine . The six-stage low pressure compressor with titanium blades is driven by a single-stage non-cooled low pressure turbine. The seven-stage high-pressure compressor with steel blades is driven by a steel bladed high-pressure turbine. Since the tradition in the Soviet era was to gradually and continuously improve engines in serviceability, engines went from Series 1 to 3A (depending on

240-416: A speed of Mach 0.7, which led some American engineers to claim that the contra-rotating propeller was not fast enough to be a propfan, and that it was simply an advanced propeller. The propfan/advanced propeller would power an unspecified Antonov airliner and be connected to the D-236 engine, which would be rated at 7,500 shaft kilowatts (10,000 hp). The engine was scheduled to start flight tests by

270-421: A stretched fuselage and new wings. Design developed into Yak-242. Further developed Yak-42M, with two underwing Aviadvigatel PS-90 turbofans. Design evolved into Irkut MC-21 . As of July 2019, 22 Yak-42s remained in commercial airline service. Operators are Izhavia (8), KrasAvia (10) and Turukhan Airlines (4). As of 15 February 2018, eight fatal accidents and one non-fatal incident have occurred on

300-470: A total of 104 seats. In its first year of operation Aeroflot's Yak-42s carried about 200,000 passengers, mainly on routes from Moscow, but also on international services from Leningrad to Helsinki and from Donetsk to Prague , with the type being planned to enter wider service throughout the Aeroflot fleet. On 28 June 1982, however, the tailplane detached from an Aeroflot Yak-42 in flight owing to

330-861: A total of 185 Yak-42 had been produced, including 105 Yak-42Ds. Original production version. Max. takeoff weight 54,000 kg (119,050 lb). Version with modified avionics for use on international use ( mezhdunarodnyye linii – international services). Entered service in July 1981 on the Leningrad- Helsinki route. Long-range version ( Dal'niy – long range) increased fuel. Replaced standard Yak-42 in production. Derivative of Yak-42D with updated, western AlliedSignal avionics , spoilers to allow faster descent and enlarged cabin door to accommodate jet bridge . Also designated Yak-42A , Yak-42-100 and Yak-42D-100 . Yak-42 used as testbed for radar for Yakovlev Yak-141 fighter. Conversion of

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360-536: Is a three-shaft high bypass ratio turbofan currently produced by the Ukrainian Motor Sich company. The engine was developed for the Yak-42 , An-72 and An-74 aircraft and was very advanced when it was first introduced in the 1970s. The engine was designed by Vladimir Lotarev . The first test runs began in 1971, first flight tests followed in 1974, serial production began in 1977. The engine has

390-520: Is flown by a flight crew of two pilots sitting side by side in a flight deck forward of the cabin. Access is via two airstairs , one in the underside of the rear fuselage, like that of the Yak-40, and one forward of the cabin on the port side. Two holds are located under the cabin, carrying baggage, cargo and mail. All of the prototypes had main landing gear with two wheels each, with the first serial production aircraft, four main wheels were introduced. The wing layout underwent considerable revision during

420-531: Is on An-74TK-300 . Data from Élodie Roux, page 158 Related development Related lists Yak-42 The Yakovlev Yak-42 ( Russian : Яковлев Як-42 ; NATO reporting name : " Clobber ") is a 100/120-seat three-engined mid-range passenger jet developed in the mid 1970s to replace the technically obsolete Tupolev Tu-134 . It was the first airliner produced in the Soviet Union to be powered by modern high-bypass turbofan engines. In 1972,

450-586: The Hamilton Standard propeller manufacturing division (and inventor of the propfan concept in the 1970s) of United Technologies was to meet with a Soviet aerospace delegation to discuss involvement in the D-236 project, the engine never made it into service. Only the Tu-334 was built, but it was produced with D-436 turbofan engines instead of propfans. The breakup of the Soviet Union plunged

480-667: The Yakovlev design bureau started work on a short- to medium-range airliner capable of carrying 100–120 passengers. It was intended to be a replacement for the Tupolev Tu-134 jet as well as the Ilyushin Il-18 , Antonov An-24 and An-26 turboprop airliners. While the new airliner was required to operate out of relatively small airfields while maintaining good economy, as many Soviet airports had been upgraded to accommodate more advanced aircraft, it did not have to have

510-526: The 23-degree wing and a cabin with 20 rows of windows instead of 17 in the first prototype, and a third prototype ( SSSR-1976 ) fitted with improved de-icing gear. The Yak-42 is a low-winged monoplane of all-metal construction, with a design lifespan of 30,000 one-hour flights. It has a pressurised fuselage of circular section, with the cabin designed to carry 120 passengers in six-abreast layout (or 100 passengers for local services with greater space allocated to carry-on luggage and coat stowage). The aircraft

540-620: The AI-20DM. The increased noise affected radio communications and crew working conditions, so the propeller testing was quickly ended. An early version of the contra-rotating propellers for the D-236 engine was shown at the Paris Air Show in June 1985. At that time, the propellers had 16 blades with a diameter of 4.56 metres (14.95 ft; 456 cm; 179.4 in). The blades had a glass fiber and carbon fiber composite shell over

570-612: The Soviets revealed that the D-236 was intended for an unidentified four-propfan aircraft. (This aircraft was probably the An-70, which in 1990 was altered to use four Progress D-27 engines instead of the previous quad-engine D-236 configuration.) In total, the D-236 flew 36 times for a total of 70 flight test hours on the Il-76. The D-236 engine also was tested in flight on a Yakovlev Yak-42 E-LL starting on March 15, 1991. The engine now had

600-678: The application). The Series 1 (used on Yak-42D) did not feature any reverse thrust system however, series 1A to 3A were fitted with bucket-type thrust reversers (used on An-72/An-74). The most recent upgrade (after the Soviet breakup) is Series 4A which has been in manufacture since 2002. Improvements included updated curved titanium blades and a built-in reverse thrust device. More advanced blade design along with proprietary wear-resistant and heat-protective coatings have resulted in improved specific fuel consumption (kg/h/kgf) dropping from 0.65 to 0.63. Specified service life has also improved exponentially to 40,000 hours. The current application for Series 4A

630-416: The design process, with the first prototype being built with a wing sweep of 11 degrees and the second prototype with a sweep of 23 degrees. After evaluation, the greater sweep of the second prototype was chosen for production. Early aircraft had a clean wing leading edge with no control surfaces, and plain trailing edge flaps . This changed in later aircraft, which were fitted with leading edge slats , with

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660-400: The end of the year. However, the engine didn't fly until it was mounted on an Ilyushin Il-76 testbed in 1987. By June 1989, it had accumulated 50 hours of flight tests on the Il-76, now traveling at speeds up to Mach 0.75 with good efficiency. The D-236 used the gas generator of the 8,500 kW (11,400 shp) Lotarev D-136 turboshaft engine, but added a planetary gearbox to drive

690-603: The propellers. The Lotarev D-136 debuted earlier in the decade on the Mil Mi-26 , the world's most powerful helicopter in production. The D-136 itself had a core that was based on the Lotarev D-36 , a 6,500 kilograms-force (14,000 pounds-force; 64 kilonewtons) static thrust turbofan that entered service in the previous decade and powered the Antonov An-72 , An-74 , and Yakovlev Yak-42 Soviet airliners. A model of

720-541: The propfan testbed aircraft was displayed at the Paris Air Show that month. The Ilyushin Il-76 with the D-236 engine was also flown to the Hannover ILA 90 airshow, with the engine now having eight blades on the front propeller and six blades on the back propeller. The Soviets claimed the D-236 had a true aerodynamic efficiency of 28 percent and a fuel savings of 30 percent over an equivalent turboprop . In addition,

750-683: The right-sided D-36 aft engine that normally was used on the Yak-42 aircraft. The Yak-46 would have a base capacity of 150 seats, a range of 1,900 nautical miles (3,500 km; 2,200 mi), and a cruise speed of Mach 0.75 (460 kn; 850 km/h; 530 mph; 240 m/s; 780 ft/s). The D-236 finished testing on the Yak-42E-LL testbed before the end of 1991. In addition, the Soviet Union considered using D-236 propfan engines on these publicly proposed aircraft: Although in November 1991,

780-466: The same ability to operate from grass strips as Yakovlev's smaller Yak-40 . The requirement resulted in the largest, heaviest and most powerful aircraft designed by Yakovlev. Initial design proposals included a straight-wing airliner powered by two Soloviev D-30 turbofans and resembling an enlarged Yak-40, but this was rejected as it was considered uncompetitive compared to Western airliners powered by high bypass ratio turbofans. Yakovlev settled on

810-626: The successor states into financial troubles, which prevented further development of the D-236 and aircraft that would use that powerplant. One post-Soviet aircraft would eventually enter service with propfans, but the Antonov An-70 aircraft would instead use the Progress D-27 , which was a larger, more powerful, and more advanced propfan engine. Related development Comparable engines Related lists Lotarev D-36 The Ivchenko Progress D-36 (also known as Lotarev D-36 )

840-424: The trailing edge flaps slotted. Two engines were mounted in pods on either side of the rear fuselage, with the third embedded inside the rear fuselage, fed with air via an " S-duct " air inlet. An auxiliary power unit (APU) is also fitted in the rear fuselage. No thrust reversers are fitted. The aircraft has a T-tail , with both the vertical fin and the horizontal surfaces swept. The first production aircraft

870-484: Was completed on 28 April 1978, with the first scheduled passenger flight, on the Aeroflot Moscow- Krasnodar route taking place on 22 December 1980. Production was at first slow, with only 10 flown by mid-1981. Initial aircraft were fitted for 120 seats in a three-plus-three arrangement. This was soon changed to a first class section with two-plus-two seating, and a main cabin with 96 seats, giving

900-556: Was tested on the Antonov An-32 military transport aircraft in 1980, as the An-32's normal Ivchenko AI-20 DM engines had about half the rated power of the D-236. However, the anticipated improvements in takeoff performance and noise reduction did not materialize. The noise at cruise speeds reached 115 to 120 decibels, which was even higher than the noise levels produced by the lighter Aerosila AV-68DM propellers typically attached on

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