Pratt & Whitney has lost out again on a second key contract to develop next-generation engine technology for future fighter, bomber and transport aircraft.

The US Air Force Research Laboratory awarded separate contracts to General Electric and Rolls-Royce for the work, which calls for developing the next leap in high-pressure ratio compressor systems, active flow control inlets and exhausts, with its focus on engines in the 20,000-35,000lb thrust (89-156kN) class.

The AFRL rejected bids by P&W and Honeywell to win the so-called Highly Efficient Embedded Turbine Engine (HEETE) contracts.

The announcement comes one month after P&W was named as the sole losing bidder for the AFRL's Adaptive Versatile Engine Technology (ADVENT) programme, again selecting GE and R-R to each develop separate demonstrators by 2012. The ultimate goal is to introduce a family of new military engines by the end of the next decade.

P&W's loss of both ADVENT and HEETE means it must devote internal research and development funds to keep pace with its rivals after production of its latest generation fighter engine - the Lockheed Martin F-35 Joint Strike Fighter's F135 - runs its course.

The air force is seeking to take advantage of new leaps in propulsion efficiency, with the objective of designing a new engine that can reconfigure itself in flight to maximise fuel efficiency in both subsonic and supersonic modes. Achieving this goal will require the ability to design an engine that can vary the ratio of air bypassing the engine core by a factor of two during flight.

With ADVENT, the new engine core will essentially be derived from designs of next-generation commercial powerplants, allowing the military to leverage the latest advancements in combustors and low-pressure turbines.

The HEETE project is necessary because the commercial technology stops short of the military's requirements for next-generation compressor systems, with the contract aiming to prove that a "quantum leap" in high-pressure compressor systems is possible. If the three-year project proves successful, the AFRL would seek to integrate HEETE's more advanced compressor systems into the new engine cores developed under the ADVENT project.

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Source: Flight International