On May 16, 2024, General Atomics Aeronautical Systems, Inc. (GA-ASI) completed durability testing for its new 200-horsepower heavy fuel engine at its El Mirage, California, flight facility. The Heavy Fuel Engine (HFE) 2.0, featuring a new GA-ASI-designed gear box and dual brushless generators from General Atomics Electromagnetic Systems (GA-EMS), is designed to bring the engine and all ancillary components to 2,500 hours between scheduled overhauls and greatly increase maintenance-free operational periods.

“Our HFE 2.0 engine is now the best heavy fuel engine in aviation,” said GA-ASI President David R. Alexander. “Hats off to our Internal Research and Development team whose ingenuity and technical sophistication inspired the HFE 2.0 program, allowing us to develop a more reliable and durable engine that also addresses diminishing manufacturing sources for aviation heavy fuel engines and components.”

The final durability test simulated a full 2,500-hour engine life operating the highest flight loads that could ever be seen in the field. The test included conditions simulating 1,250 full power take-offs and climbs to high-cruising altitude, and over 200 hours of cruise in a worst-case generator loading conditions.

The HFE 2.0 engine is being considered by the U.S. Army to become the fleet replacement for the current 180-horsepower engine used on GA-ASI’s Gray Eagle Extended Range (GE ER) Unmanned Aircraft System (UAS). HFE 2.0 is also the cornerstone of the modernized Gray Eagle 25M (GE 25M) UAS currently being produced under a U.S. Army-funded program to support future Multi-Domain Operations (MDO) UAS missions.

GA-ASI and its affiliate General Atomics Europe partnered with global leaders in high-performance engines — supported by propulsion technology innovator Cosworth — to develop an engine with increased horsepower, durability, and reliability. GA-ASI also brought in GA-EMS to design and build the engine’s dual brushless generators, which will dramatically reduce field maintenance and with the same Size, Weight, and Power (SWaP) of the existing brushed generator, will deliver over 50 percent more electrical power for new payloads and mission capabilities.

Final 150-hour qualification testing is scheduled to be completed in September followed by certification from the U.S. Army.