How did so many international suppliers overcome language and other problems in development of the SSJ? A paperless office in Moscow holds the key
Project leader Sukhoi Civil Aircraft (SCAC) has fully integrated the Superjet 100's (SSJ) development with the impressive team of international tier one suppliers, such as Thales (flightdeck), Liebherr Aerospace (flight controls and air management), and Parker (hydraulics).
Design of the SSJ is led from the offices of SCAC in central Moscow, and is being undertaken using fully paperless technology. Sukhoi and most suppliers are using the Dassault Systems/IBM Catia V5 design tool to create a fully integrated three-dimensional digital mock-up, although some - such as production partner KnAAPO - also use Unigraphics software.
The SSJ design effort started with a team of 100 people in Moscow who have undertaken the bulk of the work, but the entire engineering effort for the airframe now employs 1,500, says SSJ deputy chief designer Evgeniy Kovalenko. "We have 600 engineers participating full time directly on the SSJ design based at our offices - excluding systems and partners," he says.
Kovalenko says that some work is also outsourced on a part-time basis to around 400 more engineers from Russian aerospace institutes who are based in Moscow.
"Most of the engineers are young graduates from aviation colleges in Moscow, as well as people from the design bureaux of Sukhoi, Ilyushin and Tupolev." Kovalenko adds that "quite a big role has been played by Boeing through its consultancy support programme".
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Sukhoi and its suppliers have developed a 3D digital mock-up of the SSJ |
Design data for SSJ components is transferred from the 3D model to Sukhoi's production facilities at KnAAPO and NAPO via a network. "The exact measurements are transferred to the production jigs in the plants. Any errors are transferred back to Moscow from KnAAPO and corrected," says Kovalenko.
From the start of the programme, SCAC was eager to accumulate a team of international suppliers and risk-share partners for the SSJ, many of which have formed joint ventures with Russian companies to develop systems for the aircraft. Many Western suppliers participated in the SSJ's joint-definition phase that lasted around 12 months during 2004-5, says SCAC president Victor Subbotin. "Representatives from suppliers worked with Sukhoi designers and engineers in our Moscow office to define the aircraft," he says.
During this phase systems were developed and integrated into a digital mock-up. "When it was completed the representatives returned to their companies to develop and test systems on their own premises, returning to Moscow for occasional progress meetings," Subbotin says.
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"I summoned people together to review problems and find solutions" |
He adds that the international joint definition process - the first of its type on such a scale involving a Russian airliner - took "much effort" because of the cultural and language differences. "I had to bring people together and make it work. The 'language problem' meant there were misunderstandings, but I summoned people together to review problems and find solutions," he says.
Metric compromise
The international effort also ran into the inevitable metric versus imperial measurement issue. Although Russia is a metric nation, Subbotin says that to meet international requirements the airlines insisted on SCAC using imperial units as some maintenance procedures require this.
The SSJ design was frozen in June 2005, and the twinjet is initially being offered in two variants - the lead version, the 95- to 98-seat SSJ 100-95, is to be followed by the 75- to 78-seat SSJ 100-75 shrink. A stretched 110-seat version of the aircraft is being studied.
The SSJ looks conventional, with pylon-mounted engines slung under the wing, low-set tailplane and wing with a 25e_SDgr sweep. The wide fuselage cross-section - it has a five-abreast cabin - means that proportionally it resembles a mini A320.
The cabin cross-section is one of the key areas where SCAC claims an advantage over the competition - the Bombardier CRJ900 and Embraer 190/195 - which have narrower four-abreast layouts.
Sukhoi Aviation Holding director general Michail Pogosyan says the two-plus-three-seat abreast configuration was adopted for the SSJ as "a two-plus-two seat cross-section like that of the E-190 and CRJ900 is not optimal beyond 70 seats. And for regional aircraft the three-plus-three configuration of the A320 and 737 is too big."
So the SSJ follows aircraft such as the DC-9/MD-80/717 and Fokker F28/70/100 - not to mention the stillborn Fairchild 728 family - in having a five-abreast economy layout.
It is possible that the design thinking for the SSJ's fuselage cross-section was influenced by the fact that early on during its studies into the regional market, Sukhoi had discussed a link-up with Alliance Aircraft - the company founded by ex-Fairchild managers that proposed the "StarLiner" family of 55-110 seat regional jets to compete in the same market sector as the 728. These plans came to nothing, leaving Sukhoi to go it alone.
In a typical single-class layout, the SSJ 100-95 can accommodate 95 passengers five abreast at 32in (81cm) pitch or 86 passengers in a two-class layout with 78 economy five abreast and eight business-class seats four abreast.
SCAC also claims a technological advantage with the wing. Both SSJ variants will share the same 27.8m (90ft) span, 84m2 (900ft2) area wing, the final design of which was frozen last year after six major revisions had been worked through.
Cruise speed
However, SCAC still has margin to tweak the design to improve performance. The wing, which incorporates slat and single-slotted flap high-lift devices, is optimised for a Mach 0.78-0.79 cruise speed. Although conventional in appearance, construction and configuration, the wing is superior in design to the wing of the SSJ's nearest rival, the E-190, SCAC says.
"Aerodynamically the wing has quite a clear advantage over the E-190," says Maxim Litvinov, who is head of the SCAC general design directorate. "It has been developed with a more advanced method of aero design than Embraer used."
Litvinov says that SCAC has operated a special development programme to improve local aerodynamics. "For example, unlike the E-Jet, the SSJ's main landing-gear wheel bay is fully enclosed, making the fairing smooth and reducing drag."
The SSJ's aerodynamic design has been undertaken by a core team of 19 people at its Moscow office. This comprises five people who conduct calculations, five working on performance, and nine who are working on control laws for the fly-by-wire system.
Another 30 people are involved from external organisations - for example at the windtunnel centres at TSaGI near Moscow and SibNia in Siberia. The former has provided input for high-speed performance and wing geometry while the latter was used for low-speed tests.
In tandem with the windtunnel work, computational fluid dynamics (CFD) software has been used to study airflow behaviour in the most complex external areas of the aircraft - for instance to analyse flow around the engine nacelles and thrust reversers. Once this is established using CFD, then a series of validation tests are undertaken using the windtunnel.
Although Russia has amassed considerable experience in successful use of advanced construction materials (titanium, aluminium alloys, composites), very little is found on the SSJ. "We intentionally excluded carbonfibre as it would make the aircraft too expensive, so we've manufactured the aircraft from traditional materials," says Pogosyan.
Russian suppliers
The aluminium alloys employed in the SSJ airframe are sourced from traditional Russian suppliers. There is no aluminium lithium or other welded aluminium alloys in the SSJ airframe, apart from in some hydraulic and fuel pipelines.
Subbotin adds that it was advice from Boeing that also steered them away from advanced materials. "They advised us to reduce risks, which is why we adopted traditional materials. This may change in the long term - we could adopt composites or aluminium lithium. We have identified areas where the material could be changed - the wing, for example. But a switch would require a large amount of additional testing."
The SSJ does not have any titanium in its wing and fuselage, although the engine pylons incorporate a thick titanium frame. There is also some titanium in the Messier-Dowty-built landing gear. The involvement of Alenia Aeronautica in the SSJ could signal the opportunity for an early move in the direction of composites. The Italian company has extensive experience in this area - it is producing major carbonfibre subsections for the 787 - and the company has identified this as an area where it can bring its expertise to bear.
"We could be able to introduce new materials into the aircraft by the end of the decade," says Alenia Aeronautica's senior vice-president strategies and business development Carlo Logli.
Construction of components for the SSJ development aircraft is under way at the two plants in Siberia, and Subbotin says that final assembly of the first flying aircraft is due to begin at KnAAPO in Komsomolsk-on-Amur next month. "The first aircraft should be handed over to the flight-test department in September and fly by year-end," Subbotin adds.
He also says that four SSJ 100-95s will participate in the flight-test programme. Russian certification is expected at end of 2008, with EASA approval due by the end of the first quarter of 2009.
Click here to see the Superjet 100 family specification
Source: Flight International
