Brumby
Major
Air International April edition highlighted in its article the targeted engine upgrade for the F-35 is towards 2025.
The announcement by GE Aviation on February 27 that its XA100 variable-cycle fighter engine design had completed—to the satisfaction of the US Air Force Research Laboratory (AFRL)—the detailed-design process under the US Air Force’s Adaptive Engine Transition Program (AETP) means GE is cleared to manufacture all the parts required to build and test XA100 engines. David Tweedie, GE Aviation’s general manager for advanced combat engines, told AIR International that the detailed-design process involved GE passing “a staggered set of detailed-design reviews (DDRs) over the course of time. That activity was concentrated in 2018.” GE completed the last of the detailed-design reviews before the end of last year, “so at this point there are no further customer DDRs planned as part of the baseline programme. Now we are pivoting to focus on getting the engine manufactured and tested. It’s time for the engineers to put their pencils down, for parts to come in, and let’s go get the data.”
In completing the detailed design of the XA100, according to Tweedie, the company has moved on to a new phase of development from the primary technology-development effort in which it has been involved for the past 12 years to design and mature a variable cycle fighter engine based on an adaptive cycle fan design. Its XA100 design having been approved by the US Air Force, GE has now embarked on the final push to complete Phase 1 of the two-phase AETP programme. This push represents the final maturation of adaptive-cycle fan engine development to the point where an XA100-sized engine can be placed quickly—and with very little technological and design risk—into volume production if required, said Tweedie.
This final push will involve GE Aviation manufacturing the parts needed for three complete XA100 engines that it will build and test by 2021, and GE testing the three engines fully and providing the resulting data to the AFRL. Also, highly importantly, throughout the process the company will be required to demonstrate to the satisfaction of the US Air Force Life Cycle Management Center (AFLCMC, which is overseeing the AETP programme) that GE can reliably manufacture the quantity and quality of parts needed for volume production of the XA100 should the US Air Force decide it requires that. Along with Pratt & Whitney’s XA101 variable-cycle engine, GE Aviation’s XA100 is one of two adaptive-cycle fan engine designs competing for what may eventually be a decision by the US Air Force to order just one variable-cycle fighter-engine design into production based on the service’s findings from AETP Phase 1. In 2016, the AFLCMC awarded each of the two companies a $1 billion, five-year R&D contract under AETP Phase 1 so the US Air Force could choose a potential winner from the XA100 and XA101 and order it into production during the first half of the 2020s. As finally became clear publicly in mid-2018, the US Air Force specifically had in mind a potential decision to re-engine the Lockheed F-35 from about 2025 onwards, partly as a result of the known thermal-management challenges the F-35 has today in combination with its existing F135 engine. To that end, the AFLCMC specified that not only must the XA100 and XA101 fit the space within the F-35 that the F135 occupies today, but it also required the competitors’ variable-cycle engines to demonstrate a 10% maximum thrust increase over the F135, along with a 25% fuel-efficiency improvement and the capability to give the F-35 a 20% range increase.