For the last few years, much of the buzz in the turbine engine world has focused on the new small powerplants from Pratt & Whitney Canada, Williams and the Honda-GE Engines joint venture to propel the emerging class of very light jets. Now the spotlight has shifted somewhat, to advanced technology aimed at developing state-of-the-art engines in the 10,000-pound-thrust class for a new breed of large business jet.
At previous NBAA conventions, P&WC and Honeywell briefly outlined technology demonstration programs that they indicated might bear fruit sometime in the future as engines for new large business jets and regional airliners in the 40- to 60-passenger category. This week at NBAA’06, Snecma tossed its hat into the 10,000-pound-thrust ring with the announcement of a program to build an engine in that class, and even gave it a name–Silvercrest. This, observers believe, will likely spark interest in new technology for the class among other engine manufacturers while creating an impetus for P&WC and Honeywell to accelerate their development efforts.
At the same time, it appears that airframers planning to launch aircraft requiring such engines will have several options from which to choose. In recent years, a 36-month interval from aircraft program launch and engine selection to delivery of a certified new engine has become the norm. It will be interesting to see whether manufacturers can meet that schedule for engines that will embody an impressive amount of new materials, design and technology.
Ron Rich, director of Honeywell’s advanced aerospace technology, recently previewed his company’s developing large engine technology for NBAA Convention News. The Phoenix firm plans to evaluate a blend of existing and new technology for a family of engines ranging from 5,000 to 10,000 pounds of thrust. The Tech 7000 program is to be patterned on the certified HTF 7000 turbofan now flying on the Bombardier Challenger 300. Rich said the initial effort will be directed toward an engine in the 7,000-pound class to produce a modular core capable of being scaled down as well as up to the 10,000-pound-thrust level. Paramount among Tech 7000 goals is lowered cost of ownership, to be achieved through better temperature-specific fuel consumption and thrust-to-weight ratio, with bonuses of lower emissions and noise.
Meanwhile, in Montreal, P&WC is moving ahead with what was launched four years ago as the Advanced Fan Technology Integrator (AFTI), a technology core demonstrator program that has more recently gained the designation PW800. Last year on the eve of NBAA’05, P&WC president Alain Bellemare said the PW800 “will lead the way back in our reentry to the regional and larger bizjets. It will fill the gap from 10,000 to 20,000 pounds [of thrust].” This year he said, “we have been working on the AFTI technology program for the last three years, and we are now well positioned to support the 10,000-plus-pounds-of-thrust engine market. We believe that there is a market for such an engine, and we continue to invest in developing technologies to be ready for the next generation of large corporate jets and regional jets. We are in discussion with aircraft manufacturers on potential launch opportunities.”
Tech 7000: Green, Clean and Mean
Rich said the Honeywell engine core that emerges from Tech 7000 will have “far more similarities than differences” compared to the production HTF 7000, but will incorporate “green technologies” for cleaner, quieter operation while boosting performance and economy by achieving higher pressures and temperatures for more efficient compressor and high-pressure turbine operation. Rich said a challenge is to strike a balance between higher thermal and pressure values while preserving component reliability and service life by using improved materials. “We’ve already introduced Alloy 10, a powder metal disk alloy in the turbine disk that has demonstrated improved life under higher stress levels and temperatures.” He added that component cooling is being pursued, particularly for turbine blades and nozzles, through cutting-edge internal geometry and thermal barrier coatings.
Rich also cited ongoing work to achieve “very efficient combustion” and hence lower emissions levels, by optimizing “the rich-quench-lean combustion cycle.” He concluded, “The technology has been defined and we have a roadmap of where we’re going. Our interest in the 10,000-pound-thrust size is backed by solid progress in the Tech 7000 program,” with an HTF7000 engine currently running as a Tech 7000 advanced materials demonstrator. The program also seeks improved fan system efficiency to achieve greater turbine inlet and discharge temperatures with a high level of durability.