Air Transport World

The fan is the thing: decades of manufacturer expertise mean that a choice between the two A380 powerplant contenders will depend on the little things.(Engines)

Driven by stringent noise targets, the designs of the two engines for the A380 are remarkable not only for the size of their fans in relationship to thrust produced but also for the very shape of the fan blades. No longer straight shafts of metal, these blades swoop and turn with a sinuous grace that looks, well, sort of sexy--or maybe that judgment is just the consequence of staring at too many engines in a full-frontal sort of way.

High-speed turboprop blades, and lately turbofans, have been getting the swept treatment for some time using aerodynamic technology traced to a surge of research in the 1980s triggered by the 1970s oil price shocks. Now, in the newest engines to become metal, full use is made of powerful computers' sophisticated aerodynamic modeling to produce highly efficient fans that maximize the benefit of each cut through the air by minimizing airflow disruptions created by shockwaves on the blade.

From a subjective point of view, the blades of the GP7200 from the Engine Alliance, a joint venture of GE Transportation and Pratt & Whitney, are the most dramatic in shape, although the blades of Rolls-Royce's Trent 900 have similar lines. Mike Terrett, Rolls-Royce president-civil aerospace, says, "For the Trent 900 and the Engine Alliance--both engines--I think that for the first time in history the noise requirement, the requirement for Heathrow, was the design point." Robert J. Saia, VP-GP7000 Program, has a similar take on the design case: "Airbus gave us challenging requirements for engine weight, levels of noise ... The noise challenge was more demanding than the weight."

Potential A380 customers made the noise issue clear to Airbus officials after initial designs had been drawn but before the program was launched officially. The ability to meet London Heathrow's QC4 noise levels was not enough, customers said; they needed QC2. …

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