Engineering:Yakovlev Yak-46

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Yak-46
Role Airliner
National origin Soviet Union / Russia
Designer Yakovlev Design Bureau
Status Cancelled
Number built 0
Developed from Yakovlev Yak-42

The Yakovlev Yak-46 was a proposed aircraft design based on the Yak-42 with two contra-rotating propellers on the propfan located at the rear. The specification of the Samara turbofans was in the 11,000 kg (24,250 lb) thrust range.[1] Though proposed in the 1990s, production of the Yak-46 never commenced.[2]

Design and development

At the 1987 Paris Air Show, the Soviet Union displayed scale models of several aircraft in development,[3] including a 150-seat aircraft powered by two pusher propfans mounted on the rear fuselage.[4] This aircraft was unnamed at the time, but the Soviets disclosed that the Yakovlev Design Bureau was developing the aircraft.[4] Later in 1987, the Soviet civil aviation minister noted that Yakovlev was building a twin-propfan airliner based on its Yak-42 model.[5] In 1989, Yakovlev planned to test the D-236 propfan engine from the Ivchenko-Progress engine design bureau (also known as Progress, Lotarev, Muravchenko, ZMKB, and Zaporozhye) in flight on a Yak-42 testbed aircraft by the end of the year.[6]

Yakovlev revealed details in early 1990 about Yakovlev's propfan design, which was given the name of Yak-46 and planned to enter service in 1997.[7] The Yak-46 and the Yak-42M, a 4-metre stretched derivative (13-foot; 4,000-millimetre; 160-inch) of the Yak-42 that would enter service in 1994, would have fly-by-wire (FBW) controls, an electronic flight instrument system (EFIS), a supercritical airfoil wing of added aspect ratio, span, and sweep, seating capacity of 150 passengers or more, and new engines with thrust reversal capability. However, the Yak-46 would have two unshrouded propfan engines mounted on the aft fuselage, instead of the Yak-42 and Yak-42M's three aft-mounted turbofan engines (that includes one attached to the vertical stabilizer). Yakovlev also proposed an unnamed interim derivative situated between the Yak-42M and the Yak-46, which would be powered by two underwing engines based on the contra-rotating, integrated, shrouded propfan (CRISP) engine concept. Since this derivative required greater airframe changes, Yakovlev was less sure of its eventual production.

The Yak-46 would hold 150-162 seats in a six-abreast, single-aisle configuration, fly as far as 1,540 nautical miles (2,850 km; 1,770 mi), cruise at a speed of 445 to 460 knots (800 to 850 km/h), and be powered by two Lotarev D-27 propfan engines. The 3.8-metre diameter (12 ft; 3,800 mm; 150 in) propfan engines would have contra-rotating propellers with eight blades in front and six blades in back, have a thrust specific fuel consumption of 0.44 lb/(lbf⋅h) (12 g/(kN⋅s)), and deliver 9,700 kilowatts (13,000 hp), resulting in a thrust of 11,200 kgf (24,700 lbf; 110 kN). The fuel consumption per available seat kilometer of the Yak-46 was 13.8 grams per kilometre (0.78 ounces per mile) per seat. This value compared to 14.5 g/km (0.82 oz/mi) for the Yak-46's underwing engine alternative and 21 g/km (1.2 oz/mi) for the Yak-42M, which was already 35-40% more efficient than the Yak-42. At the time, airline interest but no orders were reported for the Yak-46, but Yakovlev was negotiating to sell 200 Yak-42M planes to Aeroflot,[8] which was then the world's largest airline.[9]

By October 1990, the two versions of the Yak-46 were in competition with the 102-126 seat Tupolev Tu-334, which like the higher-capacity Yak-46 had an interim turbofan version and a final propfan version, to replace hundreds of aging Tu-134 airliners at Aeroflot. To prepare for Yak-46 development, Yakovlev created a joint venture with Ivchenko Progress and the Soviet Ministry of Civil Aviation. Aeroflot would help fund a prototype, which would be built starting early in 1991 if the Yak-46 were selected. Annual production would eventually be as high as 100 airliners and would run through 2005.[10]

On March 15, 1991, Yakovlev finally began flight tests of one D-236 propfan engine on a Yak-42E-LL aircraft testbed, making it the first propfan flight test program led by an individual Soviet aircraft design bureau.[11] The testbed appeared on static display at the 1991 Paris Air Show in June.[12] Like the D-27 engine, the D-236 was a contra-rotating system with an eight-bladed front propeller and a six-bladed back propeller. It had a fan diameter of 4.2 m (14 ft; 4,200 mm; 170 in), a power rating of 8,195 kW (10,990 hp),[13] and a thrust rating of 10,500–11,000 kgf (23,000–24,000 lbf; 103–108 kN). The testbed engine was limited to a smaller thrust, though, because the D-236 was more powerful than the Lotarev D-36 engine that it replaced.[14]

To support the development of its Yak-46 concept, Yakovlev flew a Yak-42E-LL testbed aircraft powered in part by a Progress D-236 experimental propfan engine.

Meanwhile, conflicting reports appeared about the Yak-46 power plant: one article stated that the D-236 would be the eventual engine,[15] but another article said Yakovlev was deciding between a gearless unducted fan, which would yield a fuel consumption of 12 g/km (0.68 oz/mi), and a less-efficient, but now considered more realistic, ducted fan with an ultra-high bypass ratio between 20 and 27.[11] In August, a report stated that the initial version of the Yak-46, now named the Yak-46-1, would have two Progress underwing power plants resembling the International Aero Engines (IAE) SuperFan engine, while the follow-up version, called the Yak-46-2, would again be aft fuselage-mounted D-27 engines.[16] A Soviet aviation publication named the initial engine as the Progress D-627, a quiet, super-high bypass ratio turbofan.[17] Derived from the D-27, the D-627 had ducted, contra-rotating fans and used a differential gearbox.[18] The D-627 had a takeoff thrust of 11,000 kgf (24,000 lbf; 110 kN); its thrust specific fuel consumption (TSFC) at cruise would not exceed 0.5 lb/(lbf⋅h) (14 g/(kN⋅s)) at Mach 0.8 and 11,000 m (36,000 ft) altitude, equivalent to a speed of 529 kn (980 km/h; 609 mph)[convert: invalid option]; and the Yak-46's per-passenger fuel consumption with the D-627 would be 15.5 g/km (0.88 oz/mi). The subsequent version of the Yak-46 would have the same characteristics and performance outlined for the D-27 earlier, but its cruise TSFC after losses would be 0.47 lb/(lbf⋅h) (13 g/(kN⋅s)) at 460 kn (850 km/h; 530 mph) speed. In addition, the Yak-46 would have a planned service life of 60,000 hours, based on an annual average flying time of 3,000 hours.[17] Yakovlev was constructing a wooden mockup of the Yak-46 as of November 1991.[19] By August 1992, it was planning for co-production of the aircraft in South Africa.[20]

As of March 1993, Yakovlev had received one order to develop the Yak-46, which temporarily saved the firm from bankruptcy.[21] In mid-1994, the Progress engine design bureau was looking to create a turbojet derivative of its D-27 to use on the Yak-46.[22] Later that year, it was reported that the Yak-46 would use two Progress D-727 high-bypass turbofan engines, without mention of a propfan aircraft version.[23] In 1996, though, another airliner census still described a Yak-46-1 version with D-727 underwing engines followed by a Yak-46-2 with D-27 aft-mounted engines in a T-tail empennage configuration. Because of engine development issues, neither of the planes would fly before the year 2000.[24]

Specifications

Data from Grazhdanskaya Aviatsiya (Civil Aviation), September 1991.[17]

General characteristics

  • Crew: 2–3
  • Capacity: 150
  • Length: 41[25] m (134 ft 6 in)
  • Wingspan: 35.5[25] m (116 ft 6 in)
  • Diameter: 3.8[26] m (12 ft 6 in) fuselage
  • Height: 11[26] m (36 ft 1 in)
  • Wing area: 120 m2 (1,300 sq ft)
  • Aspect ratio: 10.5
  • Empty weight: 37,300[25] kg (82,232 lb)
  • Max takeoff weight: 61,300 kg (135,143 lb)
  • Powerplant: 2 × Ivchenko Progress D-27 propfan, 110 kN (25,000 lbf) thrust each at takeoff
  • Propellers: 8 fore, 6 aft-bladed coaxial pusher contra-rotating propellers, 3.8 m (12 ft 6 in) diameter

Performance

  • Cruise speed: 800 km/h (500 mph, 430 kn)
  • Range: 3,500 km (2,200 mi, 1,900 nmi) with normal payload
  • Service ceiling: 11,100 m (36,400 ft) cruise
  • Lift-to-drag: 18

See also

References

Citations

  1. ↑ Gunston, Bill; Gordon, Yefim (1997). Yakovlev aircraft since 1924. US Naval Institute Press. ISBN 978-1-55750-978-9. OCLC 636698350. 
  2. ↑ U.S. International Trade Commission. Global Competitiveness of U.S. Advanced Technology Manufacturing Industries. ISBN 978-1-4578-2609-2. 
  3. ↑ "Soviet Union displays advanced transport designs". Aviation Week & Space Technology 126 (24): 64–65. June 15, 1987. https://archive.aviationweek.com/issue/19870615/#!&pid=64. 
  4. ↑ 4.0 4.1 "Soviets developing advanced aircraft to upgrade civil, military air fleets". Aviation Week & Space Technology (Le Bourget, France) 126 (25): 20–22. June 22, 1987. https://aviationweek.com/site-files/aviationweek.com/files/uploads/2015/05/aw_paris_1987.pdf. 
  5. ↑ "Soviets doubt new Il-96-300". Flight International (Moscow, Russia, Soviet Union) 132 (4078): 5. September 5, 1987. ISSN 0015-3710. https://www.flightglobal.com/FlightPDFArchive/1987/1987%20-%201623.PDF. 
  6. ↑ Fink, Donald E. (June 5, 1989). "Experimental tractor propfan flight tested on Ilyushin Il-76". Aviation Week & Space Technology (Zaporozhye, USSR) 130 (23): 51. ISSN 0005-2175. http://archive.aviationweek.com/issue/19890605/#!&pid=51. 
  7. ↑ "Yakolev plans propfan Yak-42 derivative". Flight International 137 (4210): 18. April 4–10, 1990. ISSN 0015-3710. https://www.flightglobal.com/flightpdfarchive/1990/1990%20-%200974.pdf. 
  8. ↑ Postlethwaite, Alan (May 9–15, 1990). "Yakovlev strikes back: Propfan and other high-technology derivatives of the Yak-42 airliner (NATO codename Clobber) are planned". Flight International 137 (4215): 61–62, 65–66. ISSN 0015-3710. https://www.flightglobal.com/pdfarchive/view/1990/1990%20-%201347.html. 
  9. ↑ "Catching up". Flight International 139 (4267): 3. May 22–28, 1991. ISSN 0015-3710. https://www.flightglobal.com/FlightPDFArchive/1991/1991%20-%201279.PDF. 
  10. ↑ "TU-134 replacement decision due". Flight International 138 (4237): 28. October 10–16, 1990. ISSN 0015-3710. https://www.flightglobal.com/flightpdfarchive/1990/1990%20-%203108.pdf. 
  11. ↑ 11.0 11.1 Rybak, Boris (May 22–28, 1991). "Yakovlev takes propfan lead: While development of fuel-saving propfan engines languishes in the West, work continues in the Soviet Union where recent fuel shortages have underscored the need for new engine technology". Flight International 139 (4267): 27–28. ISSN 0015-3710. https://www.flightglobal.com/pdfarchive/view/1991/1991%20-%201303.html. 
  12. ↑ "Yakovlev displays propfan testbed at Paris Air Show". Aviation Week & Space Technology (Le Bourget, France) 134 (26): 44. July 1, 1991. ISSN 0005-2175. https://aviationweek.com/site-files/aviationweek.com/files/uploads/2015/05/aw_paris_1991.pdf. 
  13. ↑ "Yak propfan pops into Paris". Flight International 140 (4272): 16. June 26 – July 2, 1991. ISSN 0015-3710. https://www.flightglobal.com/FlightPDFArchive/1991/1991%20-%201738.PDF. 
  14. ↑ Abidin, Vadim (March 2008). "ОРЛИНЫЙ ГЛАЗ ФЛОТА Самолет радиолокационного дозора и наведения Як-44Э" (in Russian). Oboronnyy Zakaz (Defense Order) (18). http://www.ozakaz.ru/index.php/articles/15032008/229-n2011-03-28-0338. 
  15. ↑ Norris, Guy (May 22–28, 1991). "Commercial engines". Flight International 139 (4267): 23, 26. ISSN 0015-3710. https://www.flightglobal.com/pdfarchive/view/1991/1991%20-%201299.html. 
  16. ↑ Lenorovitz, Jeffrey M. (August 26, 1991). "Coup hits as Soviet aerospace industry fights funding and operational problems". Aviation Week & Space Technology (Moscow, Leningrad, and Kiev, USSR) 135 (8): 24–25. ISSN 0005-2175. https://archive.aviationweek.com/issue/19910826/#!&pid=24. 
  17. ↑ 17.0 17.1 17.2 "Yak-46 airliner profiled". Central Eurasia: Baltic and Eurasian States: Interstate affairs. FBIS Report FBIS-USR-92-023: 94–96. September 1991. March 5, 1992. https://hdl.handle.net/2027/inu.30000028648115?urlappend=%3Bseq=368. 
  18. ↑ Kravchenko, Igor Fedorovich; Stepanov, Igor Yuvenalievich; Khustochka, Alexander Nikolaevich (2010). "ГП 'Ивченко-Прогресс': на пороге создания двигателей нового поколения" (in Russian). Dvigatel (Engine) 5 (71): 20–22. http://engine.aviaport.ru/issues/71/page20.html. 
  19. ↑ "Yakovlev banks on new transports to ensure design bureau's survival". Aviation Week & Space Technology (Moscow, USSR) 135 (20): 50–51. November 18, 1991. ISSN 0005-2175. https://archive.aviationweek.com/issue/19911118/#!&pid=50. 
  20. ↑ Velovich, Alexander (August 12, 1992). "Dual carriageway". Flight International 142 (4331): 57+. Gale A12511834. ISSN 0015-3710. 
  21. ↑ Kalinichenko, Natalya; Privalov, Aleksandr; Krizhevskiy, Pavel (March 15–21, 1993). "Problems of privatization of aircraft companies viewed". Central Eurasia. FBIS Report FBIS-USR-93-045: 67–69. April 10, 1993. https://hdl.handle.net/2027/inu.30000028466971?urlappend=%3Bseq=525. 
  22. ↑ Taverna, Michael (June 1994). "Russian engine industry in turmoil". Interavia (Moscow, Russia: Aerospace Media Publishing) 49 (579): 26–28. ISSN 1423-3215. 
  23. ↑ "Commercial airliners directory". Flight International: 54. October 26 – November 1, 1994. ISSN 0015-3710. https://www.flightglobal.com/FlightPDFArchive/1994/1994%20-%202621.PDF. 
  24. ↑ "Airliners of the world". Flight International 150 (4552): 70. December 4–10, 1996. ISSN 0015-3710. https://www.flightglobal.com/pdfarchive/view/1996/1996%20-%203242.html. 
  25. ↑ 25.0 25.1 25.2 Taylor, Michael J. H. (1996). Brassey's World Aircraft & Systems Directory. London, England, UK: Brassey's. pp. 242–243. ISBN 1-85753-198-1. OCLC 33079608. https://archive.org/details/brasseysworldair0000unse/page/242. 
  26. ↑ 26.0 26.1 (in Russian)Aviatsiia I Kosmonavtika -Moskva- (6). 1995. June 1995. ISSN 0373-9821. https://e-libra.ru/read/224921-aviaciya-i-kosmonavtika-1995-06.html#1649010862. 

Bibliography

External links



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