Aircraft

Pratt & Whitney is preparing to begin flight testing its GTF geared turbofan demonstrator with Airbus next month after completing the first phase of trials on its Boeing 747SP flying testbed.

The GTF demonstrator amassed 43.5h over 12 flights that demonstrated the handling characteristics and overall performance of the engine up to 40,000ft (12,200m) and Mach 0.85, exploring the full flight regime up to its safe RPM limit at 30,000lb thrust (134kN).

The flight-test programme, which began 11 July, included a robust package of accelerations and decelerations, high angle-of-attack take-offs and other manoeuvres, including wind-up turns, as well as the starter assist and windmill relight capability of the engine.

Phase one focused on short-range aircraft performance in preparation for applying the lessons learned to the Mitsubishi MRJ regional jet and Bombardier CSeries 110/130-seater, both expected to enter service in 2013, and will be powered by P&W's PW1000G GTF engine.

The engine "met our prediction of what the ground to altitude relationship would be" and P&W has an improved understanding of the "geared components in terms of optimising the engine for fuel [burn]", says Bob Saia, P&W vice-president of the next generation product family.

P&W achieved "near double-digit" improvements in fuel burn on the demonstrator and validates the 12-15% improvement P&W hopes to deliver in service. In addition, Saia adds that P&W is "on the path to hit the maintenance cost values we've committed to for All Nippon Airways and Lufthansa", the launch customers for the MRJ and CSeries.

P&W identifies three objectives for the two-month, 75h flight-test programme with Airbus, which is set to begin in the second half of September on the airframer's A340-600 testbed. The engine is scheduled for handover to Airbus before the end of August.

Firstly, it must validate the data from the 747SP testing by repeating phase one conditions. Secondly, it will explore the acoustic characteristics - this was not done on phase one because of the 747SP's louder, old-generation P&W JT9Ds. Finally, "work closely with Airbus" to determine the ideal design for mounting engine components on the pylon to improve the aerodynamic characteristics.

P&W says it is "on track" with its "PurePower" engine family and expects detailed design work to begin when the demonstrator flight testing is complete. The non-geared PW810 engine core will begin ground testing in mid-2009, followed in December by testing for the MRJ's PW1217G and the first quarter 2010 for the CSeries PW1524G.

For the PW1000Gs, twin 40-50h flight-test programmes are planned for the mid-third quarter of 2010 and "a few months later" on the PW1217G and PW1524G respectively.