The US Air Force (USAF) has reached a significant milestone in its effort to develop a sixth-generation jet engine.
The service has completed detailed design reviews of two adaptive-cycle engine prototypes from GE Aerospace and Pratt & Whitney (P&W). Both engine makers are under contract for the Next Generation Adaptive Propulsion (NGAP) programme, which seeks to develop engines to power future air superiority platforms.
The companies each confirmed their completion of detailed design reviews, with GE Aerospace reaching that milestone on 19 February and P&W passing the mark the following day.
The reviews were completed using comprehensive digital models, with both teams now cleared to begin procuring physical components for full-scale ground demonstrators.
“The significance of this first fully digital review cannot be understated,” says Jill Albertelli, president of P&W’s military engines business. “Digital processes throughout the life cycle are crucial to rapidly and efficiently deliver advanced warfighter capabilities.”
A focus on model-based-systems engineering to develop a new engine represents a “transformative shift” in how advanced propulsion systems are designed and tested, according to GE Aerospace.
The companies are expected to begin testing their ground-based prototypes in the late 2020s. GE Aerospace has dubbed its engine the XA102, while the P&W design is called the XA103.
“GE Aerospace is making great strides with model-based engineering, which has been instrumental in the success of the XA102 engine design,” says Steve Russell, general manager of the company’s Edison Works advanced research and development unit.
In January, the USAF cleared the NGAP programme for as much as an additional $2.5 billion in research and development funding. Both P&W and GE Aerospace are now eligible for up to $3.5 billion in total allocations under the effort.
However, the USAF tells FlightGlobal it does not plan to spend more than $3.5 billion on the prototyping effort, with that amount being split between the competitors based on their designs.
Both NGAP designs are descended from an earlier air force propulsion effort known as the Adaptive Engine Transition Program (AETP). That initiative sought to develop a new adaptive-cycle engine for the Lockheed Martin F-35 stealth fighter, which is currently powered by a single P&W F135 turbofan.
While the USAF chose to shelve the designs and instead upgrade the existing F135, both GE Aerospace and P&W developed working AETP engines – the XA100 and XA101, respectively.
Although those engines will likely never see service, both manufacturers say the technologies developed for AETP are being used to support their new NGAP designs.
The air force is seeking propulsion advancements that will provide a next-generation fighter aircraft with improved range, survivability and thermal management capabilities, plus the capability to power advanced weapons and sensors.
One general characteristic of the adaptive-cycle concept is the ability to combine the cruising fuel efficiency of a high-bypass commercial turbofan with the aerodynamic performance of jet propulsion systems found on modern fighters.
Under the trailblazing AETP effort, the air force sought to improve range by at least 35%, while simultaneously delivering improved thermal management and an 18% decrease in acceleration time.
GE claimed its XA100 would have offered the F-35 20% more thrust and 30% greater range.
