Smooth Going for GTF Allows Pratt to Extend Thrust Rating

Pratt & Whitney’s launch on Tuesday of a 35,000-pound-thrust version of its Geared Turbofan extends the family’s power range by another 2,000 pounds, giving Airbus A321neo customers enough range and payload capability to effectively operate from such hot and high locations as Mexico City and Bogota. Dubbed the PW1135G-JM, the engine gets its extra thrust from leftover development margin extracted from the design of the family as a whole, thereby requiring no hardware or design changes, explained Pratt & Whitney vice president of engineering Tom Prete.

“We’ve been able to hit all our technical metrics and we’ve been able to use some of the additional development margin to add customer value where needed,” he told AIN during the company’s annual “media day” event in East Harford, Connecticut. “The engine will be certified with all the existing redlines, all the existing parameters at the higher thrust level.”

Having built 35 of what it now calls the PurePower engine family, Pratt paid particularly close attention to the concepts of scale reuse, meaning, for example, the engines designed for the Mitsubishi MRJ closely resemble those destined for the Embraer E2 E-Jets. Meanwhile, with the engine used for the Bombardier CSeries, explained Prete, the company did “a large amount of scaling” to arrive at the design for the A320neo. In turn, the engine in development for the Irkut MC-21 represents a “reuse” of the PW1100 designed for the Neo.

“You can rely on scale and reuse to accelerate the development of the newer programs because you already went through a lot of the development learning early on,” said Prete.

At the same time, the use of the geared technology in the PW1000 has enabled further advances in other parts of the engine such as a lightweight hybrid metallic fan. “The fan is the highest efficiency fan in the world,” he added. “So you have a fan that, since it operates at a low speed, is lightweight [and] has very detailed features so it’s very aerodynamic; it allows a very laminar flow, increasing the overall efficiency of the fan.”

That fan efficiency accounts for part of a 15-percent reduction in fuel burn in the A320neo. Scheduled for certification in the second half of this year, the Neo engine—designated PW1100G—has finished 75 percent of its certification testing. Pratt & Whitney announced on Tuesday that it just delivered the first shipset of PW1100Gs to Airbus for installation on the first flying A320neo test article, now undergoing assembly in Toulouse, France.