PowerJet defies its critics with Super perfomance
The PowerJet SaM146 axial-flow, twin-shaft turbofan was selected to power the Superjet 100 in 2003, when it was still on the drawing board.
The programme has proved its critics wrong so far, entering flight test in July at Komsomolsk in Russia and flying at the Paris Air Show in mid-2009. Powerjet is a 50:50 joint venture between Snecma and NPO Saturn of Russia.
Snecma is responsible for the core, control system, transmissions, overall engine integration and flight testing, while NPO Saturn looks after LP section components and engine installation, as well as ground testing.
The core was developed by Snecma, drawing on its M88 ‘hot section’ military engine experience and the DEM21 core demonstrator project – with its six-stage compressor and single-stage, high-pressure turbine with active blade-tip clearance control – and various other modern design features (such as single-piece bladed disks).
The engine’s thrust range is 13,500-17,500lb with a design point at around 90 passengers and a range of approximately 70-120 passengers. First ground test was in July 2006 and first flight test took place in December 2007 on an Ilyushin Il-76 testbed aircraft. Six months later two SaM146 engines powered the Superjet 100 on its first flight.
Jean-Paul Ebanga, who has been chairman and CEO of PowerJet since 2007, said: “Based on all the assumptions of the business plan we are on track and aiming to certificate the engine by the end of the year. The third flight test aircraft is now flying and they have done more than 4,000 test hours with what are effectively production-standard engines, with no problems.
“We started the engine from a blank piece of paper, which gave us the flexibility to optimise the design point. We got the feeling that customers were looking for a quick solution, not a 2016-2020-type solution, so we decided to mix advanced technology and a proven solution to get the same level of reliability as the CFM56.”
Ebanga says the approach makes the engine a generation beyond the CF34 – for example “it is using a six-stage compressor when the CF34 uses a nine-stage compressor to produce the same pressure ratio”.
Another difference is the long nacelle used on the SaM146 – which should make it quieter than the CF34, Ebanga suggests – while it is also designed with generous temperature margins for reliability in hot climates. “We took the CF34 as the benchmark and ensured that we were better on everything,” he said.
With its other main competitor, P&W’s PW1000G (selected to power Mitsubishi’s MRJ), Ebanga said: “I will be very interested to see the real performance in our market segment. The geared fan is a 20-year old concept which P&W has developed for larger engines but when you reduce the fan diameter you increase the penalties of the gearbox versus the benefit gained.”
He added that the gearbox is a “potentially weak link” because it operates very hot and at high pressure. It also adds weight and increases part-count, when the sensible thing is to reduce it.
As to whether the engine is a contender for Embraer’s next regional jet, Ebanga said: “We are 100 per cent focused on the Superjet 100 entry-into-service but further down the road the engines can be used on a different platform.” For now the SJ100 is in direct competition with the Embraer 190.
The Powerjet chairman added: “From a customer standpoint we are already in discussions with some potential customers in the Middle East… regional flights there have a huge potential. During the last Dubai Air Show we were showing the range on a map – this aircraft can reach all the regional market and has a longer range than the competition – it can even go from Dubai to India.”
Techspace Aero Lubrication system
Microturbo Air starter
Hispano-Suiza Electrical Equipment
FADEC (via Fadec International)
Engine control system components
Sagem Engine overspeed controller
Aircelle Thrust reversers
SO France Engine injection upstream filter
Main fuel filter
Snecma Propulsion Solide Mixed flow nozzle (MFN)
PurePower changing the rules
The advance offered by Pratt & Whitney’s ‘game changing’ geared turbofan engine is to allow both the fan and the core to operate at close to their optimum speeds at the same time – which has previously not been possible.
The fan will operate at around one-third the speed of the turbine. Although there is a weight penalty having a gearbox, this is offset overall due to fewer parts. P&W says that it has calculated a fuel-burn improvement of 12-15 per cent over current engines when it enters service in 2013.
P&W vice president environment and technology Alan Epstein said: “With the engine’s geared technology, we expect it to then improve 1-1.5 per cent annually.”
He added that the GTF is “approximately ten per cent shorter in length and five per cent lighter than a conventional design with the same level of technology. There are approximately 1,500 fewer airfoils”.
P&W proved the concept using a PW600 engine with a GTF drive to the fan, undertaking a 400-hour technology demonstration programme – including 120 flight hours on the company’s 747 testbed and Airbus’s A340 testbed (as Airbus was also interested in evaluating the technology).
The company told Arabian Aerospace: “Our analysis shows that the PW1000G is 12 per cent better than a CF34-8 on an Embraer 170, and more than 15 per cent better than a CFM56-5B/7B with tech insertion.”
As to concerns over the gearbox, Epstein responded: “We’ve run the equivalent of 40,000 take-offs on a gear set and you still could see the machining marks from the production process on the gear tooth surface.” He added that the gear system does not use any life-limited parts.
The US engine manufacturer has moved into 12-15 months of detailed design, which will involve making some more key decisions – such as whether to have composite or metallic fan blades. It is on a high after the PW1000G, with a thrust range of 14,000-17,000lb, was selected as the powerplant for the Mitsubishi Regional Jet (MRJ) – it will be designated PW1217G – and then, somewhat more spectacularly, for Bombardier’s new ‘game changing’ CSeries.
Bombardier needed the step-change in engine efficiency promised by P&W to make the CSeries viable in a market niche sandwiched between the Embraer 190 from below and the 737s and A320 family from above.
P&W was able to oblige by offering a version with a larger, 73-inch fan (increased from 56in) and extra low-pressure compressor stage to bump the engine up into the right thrust range (17,000-23,000), as the PW1524G.
Initial run of a PW1000G is scheduled for mid-2010, with certification expected by the end of 2011 and entry into service in 2013 on the CSeries – if it remains on time. The MRJ, which was also due to enter service in 2013, slipped slightly in September and will now enter service in early 2014.
The MRJ is the competitor for CF34 and SaM146-powered regional jets. It has been selected by All Nippon Airways (ANA), which became launch customer in March 2008, but has so far failed to attract another order.
P&W is leveraging the PW1000G’s geared fan architecture to develop an engine for the next generation narrowbodies of Airbus and Boeing. It has launched a technology programme and is “targeting an additional 8-10 per cent fuel burn benefit through advancements in a higher-ratio fan drive gear system”.