The so termed GTF or geared turbo fan engine that will power the first flight of an Airbus A320 NEO (new engine option) jet this morning at Toulouse might not immediately grab the attention of the masses.
But it will help make life quieter for those many millions of people who live near airports or under low flight paths.
It cuts the engine noise nuisance by half. In the social space this may prove far more valuable to Airbus and the airlines that use it than the economic dimension of an initial fuel burn reduction of 15 percent, rising to an intended 20 percent by 2020.
That’s what this GTF engine, termed the Pure Power line by US designer and maker Pratt & Whitney will do in large part for the European airliner consortium together with efficiency contributions from airframe improvements of which the most visible and technically significant are the raked ‘sharklet’ wing tips which have already appeared on current build single aisle A320 family models.
Assuming the weather conditions offer sufficient visibility for the chase aircraft that will observe and record every minute of the first flight of an A320 NEO, it should go ahead this morning.
Toulouse is full of ‘anoraks’, the generally well tolerated term used for aircraft spotters who have staked out their vantage points to see airliner history made, if not heard as loudly as before.
A GTF engine could be termed a radical ‘old’ concept, since it has been around for decades in various forms, none of them until perhaps now, proving to be sufficiently reliable or successful to become commercially useful.
Pratt and Whitney says it has tamed the concept, notwithstanding a ground test failure of a small version of the engine that should fly today on a Bombardier CSeries prototype 110 seat airliner in May.
This is how the engineering website Design Engine eloquently summarises a GTF engine for curious lay readers:
The basic principal behind the geared turbofan engine is the gear box which allows the fan to spin at a lower speed than the turbine and low pressure compressor which in turn creates more thrust while expending less fuel. So in effect, the gear box allows these two separate and distinct components to move at optimum speeds for a greater efficiency thus the end result of 15% less fuel consumption. The new engines have a bypass ratio of 12:1 versus the typical 8:1 of conventional jet engines. This means that for each pound of air entering the engine 12 pounds of the air will bypass the core. In this way the geared turbofan engine will allow the fan to spin at slower speeds then the core turbine. To accommodate this new approach these engines will have larger fans and smaller turbines.
The new engines will have a unique set of issues most notable being a more regular scrutiny of the engines themselves and specifically the gear box for potential cracks and metal fatigue and the larger fan also means that in many cases the engines can not be retrofitted on existing aircraft designs and will more typically be used on newer planes designed with this specific engine in mind.
Airbus has stayed well in the lead over Boeing in the contest to sell new engine technology versions of single aisle jets, with some 60 percent plus share of such sales to date amounting to 3257 jets thus far for the Euro jet maker.
There are a number of reasons for this. Airbus is at lest two years ahead of Boeing in new engine tech sales, which will not at latest word, bring its competing 737 MAX series into service until sometime in 2017, compared to the fourth quarter of 2015 for the NEOs.
But Airbus also does offer an option. As well as the US GTF from Pratt & Whitney it will offer the French American CFM International LEAP engine, which doesn’t involve the geared turbo fan technology, but relies of numerous improvements to a more conventional engine design to the same goals of lowering fuel consumption, emissions and noise, and maintenance costs
The CFM engines are the only ones available on the 737 MAX, just as the current engine from the GE of America and SNECMA of France joint venture is the only engine available on the 737 NG series jets now being made by Boeing.
What else is a GTF engine and why isn’t it part of Boeing’s offerings?
GTF engines are big fat wide looking engines, and the Boeing 737 line, which dates back to the late 60s compared to the late 80s for the A320s, are ground huggers. They sit lower on the tarmac than the Airbus design, which means they aren’t all that easy to adapt to a wider fatter engine. And apart from that, CFM has an exclusive engine deal with Boeing, just as its American component, GE, has exclusivity on the 777 lines.
Boeing also resisted the idea of re-engining the 737 in favour of doing an all new design to replace them, but Airbus, or rather American Airlines, forced it to follow suit when it said it wanted to buy hundreds of new single aisle jets sooner than the US plane maker could come up with a new design.
(American went on the split its order to hundreds of jets from each maker, as it needed to replace a very large but increasingly costly to maintain fleet of McDonnell Douglas MD80 series airliners.)
Earlier this week, in its rolling 20 year Global Market Forecast, Airbus estimated the demand for single aisle airliners as 22,000. That’s a demand that neither Airbus nor Boeing may be able to meet, regardless of what percentage of the sales each wins.
In that sense, the Airbus NEOs and Boeing MAXs foreshadow the rise of a competitor, with most observers naturally predicting this will happen in China within two decades and possibly also in India.