Rolls-Royce confirms it is throwing its hat into the ring for the U.S. Air Force’s Adaptive Engine Technology Development (AETD) program, which aims to demonstrate potential fuel-saving features for sixth-generation fighters as well as future bombers and other tactical aircraft.

“We did put in a bid for the adaptive engine technology program, and this is currently in source selection with the Air Force,” says Mark Wilson, chief operating officer of Rolls-Royce’s Liberty Works advanced development organization in Indianapolis.

The AETD will build on advances in the Air Force Research Laboratory’s (AFRL) Advent (Adaptive Versatile Engine Technology) program, and take it to a pre-full-scale engineering manufacturing development level.

Even though the Air Force has pointed out that the technology program is aimed at future platforms, the fuel-saving potential of the initiative, added to the larger size of the proposed demonstrator, has sparked some concern in political circles that it could form the basis for a competing engine for the Lockheed Martin F-35 Joint Strike Fighter.

The sole engine for the F-35 is the F135 produced by Pratt & Whitney, which is also competing for AETD. General Electric, which was formerly in partnership with Rolls on the canceled F136 – the alternate F-35 engine – also is bidding for AETD.

Advent is being used to develop a suite of technologies for variable-cycle architectures to reduce fuel consumption by up to 25% and increase range by 30%. In addition to standard high- and low-pressure flows, Advent architectures add a third stream of cooler air flow that will be used for high power extraction and better thermal management, as well as reducing installed drag and improving inlet recovery.

AETD is expected to go beyond Advent in terms of efficiency and power, and unlike the smaller cores used in the initial effort, will be based around a larger core sized more for future projects such as the U.S. Navy’s F/A-XX and the Air Force’s F-X sixth-generation fighters. The fact that this size requirement also matches that of the F-35 is why AETD recently triggered questions in Congress.

Responses to AFRL’s request for proposals were due May 31, and Phase 1 contracts for two rival engines are expected to be awarded in August. The outline milestones will include initial concept evaluations by February 2013, compressor rig tests in 2014, fan and core tests by mid-2015 and full engine tests as early as 2016.

AETD’s close links to Advent make progress with the original fuel-saving initiative even more important, according to the contestants. On Advent, Rolls is “getting ready to test the core this year,” Wilson says. The engine-maker completed fan rig tests at AFRL in late 2010 and has completed more than 250 hours of operability and other tests on the fan. A full engine test, combining the low- and high-pressure spools, is set for 2013. All hardware for the core is “in place, and in the process of installation and assembly,” he adds.

Rolls and GE are also competing on the closely linked Highly Efficient Embedded Turbine Engine (Heete) program, which is demonstrating extreme high-pressure-ratio core technology aimed at lowering fuel burn by up to 35% compared to current engines. Geared more toward future mobility, reconnaissance and transport platforms, Heete is an adjunct to Advent and part of the Air Force’s Versatile Affordable Advanced Turbine Engine program. “We have a compressor rig which will be tested this year, and we will get data from that this year,” Wilson says.