Manufacturer signals return to tried and tested strategy of developing civil engines based on military technology
Pratt & Whitney is studying a new engine development strategy that would base its next-generation single-aisle geared turbofan (GTF) and a future mid-thrust combat engine around a new common core.
The plan means the GTF, if launched as planned, will benefit from advanced military engine design technology honed through the recently concluded US government-industry Integrated High Performance Turbine Engine Technology (IHPTET) programme, and implemented in engines such as the F119 and later F100s. The initial proof-of-concept demonstrator, due to run for the first time at the end of 2007 initially as a ground-based engine, is based on the PW6000 core and until recently was widely expected to be used by P&W as the basis for the production GTF.
Confirming the move, which signals a return to the strategy that led to the development of engines such as the JT8D turbofan from the military J52 turbojet, P&W director of advanced programmes Simeon Austin says: "We're looking at how we can use that same core for both commercial and military applications." As far as the GTF is concerned Austin says: "The production version is not based on a 6000, it's based around the new core, which we will hope to make use of in other ways. It's a way to address the cost and maximise the benefits."
The initial studies will focus on derivatives of the F100 or F119 cores, depending on the emerging thrust requirements of both the single-aisle projects as well as military programmes such as the naval-unmanned combat air system (N-UCAS). The same core, equipped with an afterburner, would also be aimed at future combat aircraft and growth versions of platforms such as the Korea Aerospace Industries/Lockheed Martin A-50 and Saab Gripen.
The commercial version, he says, would have overall thrust initially in the 18-20,000lb class (80-90kN). "We also have to look at the F135 [the engine for the F-35], though the core would probably be more than what would be needed for these sorts of applications." He adds that there is talk of "very large platforms going forward" for which the F135 could be a "good candidate". In 2006 P&W completed tests on its final IHPTET demonstrator, XTE67-1, having flowed technology through to production F100/119 and F135 engines from this and earlier predecessors such as the XTE65 and 66.
"Through these we've made a number of advances in terms of blade design, vaneless counter-rotating turbines and lightweight low-pressure turbines. We also looked at areas such as advanced augmentor designs that fed into F135 and fan technologies in terms of improved stability designs and lighter structures," says Austin. Other areas of research also included advanced control and cooling systems.
The first component tests of the initial XTE68-LF1 - the first demonstrator planned under the versatile affordable advanced turbine engine programme that follows IHPTET - start this year, with the full-scale demonstrator due to run in 2009.