Saturday, March 12, 2011

The "Wings of Russia" Sukhoi Super Jumbo

The Sukhoi KR-860 was conventional in its layout
At the 2001 Paris Air Show, the Russian delegation created quite a stir by unveiling a four-engine, double-deck, long-haul airliner christened "Kryl'ya Rossii", or "Wings of Russia". The ambitious project had the Sukhoi OKB designation "KR-860"- KR for "Kryl'ya Rossii" and 860 indicating the passenger load. Design work on the KR-860 began in 1997 under the General Designer, Mikhail P. Simonov who had headed the design bureau since 1983. Already under his direction the Su-27 Flanker family of fighter aircraft had been upgraded and new variants had taken flight. By the time that design work began on the KR-860 project, Sukhoi had already been making its first steps into the civil aviation market with the start of work on the Su-80 utility transport and the Su-38 agricultural aircraft. But an aircraft in the class of the KR-860 was nothing short of a bold leap by Sukhoi. The "Wings of Russia" would rival the Airbus A380 and would be larger than the Boeing 747. The design team had looked at advanced technologies and unconventional layouts such as a flying wing, but eventually settled on a blend of advanced technologies (fly-by-wire, composites) combined with a conventional layout with a double deck fuselage and four turbofans. At each step of the KR-860's design evolution, tradeoffs were made between high technology and innovation and low-risk approaches. 

Note the twin nose gear and unusual cockpit fairing
Although the layout of the KR-860 was conventional in appearance, the Sukhoi team succeeded in achieving a predicted lift/drag ratio of 19.5 (compared to the L/D ratio of the Boeing 747 of 17) via aerodynamic refinements. Large winglets were a part of the design and the smooth lines of the double deck fuselage were unusually broken by a blister-like fairing that housed the flight deck. One of the more unusual features of the KR-860 was its use of folding outer wings to reduced the footprint of the aircraft. Boeing had looked at a similar system during the design of the Boeing 777 and had even built a test article, but eventually dropped the idea as the gain in space at the gate wasn't enough to offset the increased weight and complexity. For the KR-860, though, the folding outer wings meant that the aircraft could use any gate position that could accommodate a Boeing 747. While the main landing gear was very similar to that of the 747 and A380 with two inward-retracting wing units and two fuselage mounted units, the nose landing gear was more like that of the Antonov An-124 Condor transport with twin units. The third unique feature of the KR-860 was its three integral airstairs that were on the centerline of the underfuselage- the forward airstair was ahead of the nose gears, the second one was mid-way down the fuselage where the wings were located, and the third and aft unit was under the tail. Like the integral airstairs on the Ilyushin Il-86, these were meant to reduce the ground support needs for the KR-860. 

Note the folding outer wings and the boarding airstairs under the nose
A variety of powerplant options were evaluated for the aircraft- the most serious contender was the General Electric CF6-80E1 used on the Airbus A330 family of aircraft- Sukhoi was reportedly in negotiations with GE at the time of the KR-860's unveiling at the 2001 Paris Air Show. License production of the engine in Russia was even discussed. In addition, consideration was also given to the Rolls-Royce Trent 800 used on the Boeing 777 and the Pratt & Whitney PW4168 used on the A330. In addition, Russian solutions were evaluated from the Kuznetsov NK-93 ducted fan to the unusual suggestion of using eight Soloviev PS-90 turbofan engines in paired nacelles. This would have been the cheapest solution, but the pair nacelles and eight engines would have been significantly heavier and cost more in fuel consumption. 

The aft boarding airstairs under the tail
The eight-engined variant was considered more appropriate for a cargo variant which had an upward-hinged nose visor like that of the An-124 Condor and the Boeing 747-400F. Sukhoi even pitched this version as a successor to the An-124s operated by the Russian Air Force. The cargo version was capable of carrying up to thirty of the 40-foot rail/road cargo containers. Using four turbofan engines, such a version was claimed to have a cost per mile only slightly higher than that of rail transit. In addition, combi versions were suggested and one of the more unusual variants was that of a flying liquified natural gas (LNG) tanker to connect outlying regions in Siberia planned for oil/gas exploration that lacked suitable infrastructure for conventional transport methods. 

Sukhoi estimated the costs for the development of the KR-860 would be more than offset with its use in cargo transport. Costs depending upon the authority consulted ranged from 3-4 billion US dollars to as high as 5.5 billion US dollars. As ambitious as the KR-860 was, there was simply not enough passenger traffic in Russia to justify an aircraft its size. Sukhoi turned to both India and China which had booming passenger markets to explore risk-sharing partnerships. At the end of the day, though, an aerospace project the size and scope of the KR-860 was simply more than both Sukhoi and the Russian government could handle and with more pressing financial needs, the Kremlin was reluctant to invest in the development of Sukhoi's super jumbo. Russian aviation authorities were highly skeptical of the need for the KR-860 given that most of what might get built would be exported to more robust and booming aviation markets. As a result, the KR-860 "Wings of Russia" program died quietly as Sukhoi shifted its resources to a much smaller aircraft that was needed in Russia to replace the aging fleets of Tupolev Tu-134 and Tu-154 fleets. Though development of the Sukhoi SuperJet 100 had started in 1999, the shift of OKB resources from the KR-860 to the SuperJet program which was formally launched in 2002. 

Source: OKB Sukhoi: A History of the Design Bureau and its Aircraft by Yefim Gordon and Dmitriy Komissarov. Midland Publishing, 2010, p501-503.

3 comments:

  1. Better looking than the 380, this should have been a star.

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  2. Would have been interesting, but highly unlikely any western country, or Asian for that matter, would have purchased due to Russia's quality issues.

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  3. Quality issues? clearly you are out of touch with modern russia. I regularly fly russian planes and have more faith in them than airbus.

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