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32-676: In 1972, 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

64-424: A square thread or buttress thread is used, because it has the lowest friction and wear. In technical applications, such as actuators , an Acme thread is used, although it has higher friction, because it is easy to manufacture, wear can be compensated for, it is stronger than a comparably sized square thread and it makes for smoother engagement. The ball screw is a more advanced type of leadscrew that uses

96-503: 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,

128-469: 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

160-453: 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

192-446: A hydraulic jack is not limited by the limitations on screw jacks and can be far greater. After World War II, improvements to the grinding of hydraulic rams and the use of O ring seals reduced the price of low-cost hydraulic jacks and they became widespread for use with domestic cars. Screw jacks still remain for minimal-cost applications, such as the little-used tyre-changing jacks supplied with cars, or where their self-locking property

224-446: A jackscrew on a Yakovlev Yak-42 airliner due to design flaws resulted in the crash of Aeroflot Flight 8641 in 1982. The failure of a jackscrew on a McDonnell Douglas MD-80 due to deficient maintenance brought down Alaska Airlines Flight 261 in 2000. A MRAP armoured vehicle being transported aboard National Airlines Flight 102 in 2013, a Boeing 747-400BCF freighter, broke loose immediately after takeoff and smashed through

256-505: A new company named United Aircraft Building Corporation in February 2006. The firm designed the Pchela ( Russian : Пчела , "bee") drone reconnaissance aircraft (first flown in 1990), but is perhaps best known for its highly successful line of World War II-era piston-engined fighter-aircraft. In August 2023, Irkut Corporation rebranded itself as Yakovlev. The Sukhoi Superjet 100

288-481: A recirculating-ball nut to minimize friction and prolong the life of the screw threads. The thread profile of such screws is approximately semicircular (commonly a "gothic arch" profile) to properly mate with the bearing balls . The disadvantage to this type of screw is that it is not self-locking. Ball screws are prevalent in powered leadscrew actuators. Jackscrews are also used extensively in aircraft systems to raise and lower horizontal stabilizers . The failure of

320-417: 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

352-467: 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

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384-855: 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

416-489: Is a Russian aircraft designer and manufacturer (design office prefix Yak ). Its head office is in Aeroport District , Northern Administrative Okrug , Moscow . It is a subsidiary of Yakovlev Corporation . The bureau formed in 1934 under aircraft designer Alexander Sergeyevich Yakovlev as OKB -115 (the design bureau has its own production base at the facility No.115), but dates its birth from 12 May 1927,

448-518: 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

480-405: Is important, such as for horizontal stabilizers on aircraft. The large area of sliding contact between the screw threads means jackscrews have high friction and low efficiency as power transmission linkages, around 30%–50%. So they are not often used for continuous transmission of high power, but more often in intermittent positioning applications. In heavy-duty applications, such as screw jacks,

512-412: Is increased by a longer handle as well as a finer screw thread. However, most screw jacks have large amounts of friction which increase the input force necessary, so the actual mechanical advantage is often only 30% to 50% of this figure. Screw jacks are limited in their lifting capacity. Increasing load increases friction within the screw threads. A fine pitch thread, which would increase the advantage of

544-523: 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

576-527: The Yak-42 with a total of 570 casualties. Data from Brassey's World Aircraft & Systems Directory 1999/2000. General characteristics Performance Related development Aircraft of comparable role, configuration, and era Related lists [REDACTED] Media related to Yakovlev Yak-42 at Wikimedia Commons Yakovlev The JSC A.S. Yakovlev Design Bureau ( Russian : ОАО Опытно-конструкторское бюро им. А.С. Яковлева )

608-590: The day of maiden flight of the AIR-1 aircraft developed within the Department of Light Aircraft of GUAP (Head Agency of Aviation Industry) under the supervision of A.S. Yakovlev. During World War II Yakovlev designed and produced a famed line of fighter aircraft . Irkut acquired Yakovlev in April 2004. The Russian government merged the holding company with Mikoyan , Ilyushin , Irkut, Sukhoi and Tupolev as

640-416: 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

672-400: The force on the hydraulic actuator is accidentally released. The ideal mechanical advantage of a screw jack, the ratio of the force the jack exerts on the load to the input force on the lever ignoring friction is where The screw jack consists of two simple machines in series; the long operating handle serves as a lever whose output force turns the screw. So the mechanical advantage

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704-407: The foundations of houses. A screw jack consists of a heavy-duty vertical screw with a load table mounted on its top, which screws into a threaded hole in a stationary support frame with a wide base resting on the ground. A rotating collar on the head of the screw has holes into which the handle, a metal bar, fits. When the handle is turned clockwise, the screw moves further out of the base, lifting

736-509: The load resting on the load table. In order to support large load forces, the screw is usually formed with Acme threads . An advantage of jackscrews over some other types of jack is that they are self-locking , which means when the rotational force on the screw is removed, it will remain motionless where it was left and will not rotate backwards, regardless of how much load it is supporting. This makes them inherently safer than hydraulic jacks , for example, which will move backwards under load if

768-402: The one illustrated, the jack screws also help align the connectors and overcome the large frictional forces involved in inserting or removing the connector. When unscrewed, they allow the connector halves to be taken apart. Jackscrews in electrical connectors may have ordinary screw heads or extended heads designed as thumbscrews . The idea of incorporating jack screws into electrical connectors

800-480: The rear bulkhead.  The cockpit voice and flight data recorders were knocked off line, hydraulic lines were severed and most critically, the horizontal stabilizer actuator’s jackscrew was destroyed, rendering the aircraft uncontrollable. A machinist's jack is a miniature screw jack used to support protruding parts of a workpiece or to balance clamping forces on that workpiece during machining operations. Aside from their size, these frequently look no different from

832-464: 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

864-469: The screw jacks used to lift buildings off their foundations. Machinist's jacks can be as simple as a threaded spacer with a bolt in it to serve as a jackscrew. The term jackscrew is also used for the captive screws that draw the two parts of some electrical connectors together and hold them mated. These are commonly encountered on D-subminiature connectors, where they serve primarily to prevent accidental disconnection. On larger connectors such as

896-559: The screw, also reduces the speed of which the jack can operate. Using a longer operating lever soon reaches the point where the lever will simply bend at its inner end. Screw jacks have now largely been replaced by hydraulic jacks . This was encouraged in 1858 when jacks by the Tangye company to Bramah 's hydraulic press concept were applied to the successful launching of Brunel 's SS  Great Eastern , after two failed attempts by other means. The maximum mechanical advantage possible for

928-420: 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

960-484: 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

992-475: Was not considered novel in the late 1950s and early 1960s. Some patents from that era show pairs of jackscrews on opposite sides of a multi-pin connector. Another shows a single central jackscrew. These patents mention the phrase "jack screw" incidentally, without asserting a claim to the idea. Jack screws may have either male or female threads, and on some connectors, the genders of the screws as well as various alignment pins may be mixed in order to prevent

Yakovlev Yak-42 - Misplaced Pages Continue

1024-690: Was redesignated as the SJ-100, and the Irkut MC-21 also adopted the Yakovlev name. The company was sanctioned by the Canadian government on 22 August 2023. Screw jack A jackscrew , or screw jack , is a type of jack that is operated by turning a leadscrew . It is commonly used to lift moderate and heavy weights, such as vehicles; to raise and lower the horizontal stabilizers of aircraft; and as adjustable supports for heavy loads, such as

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