NASA’s X-59 team marked a significant milestone in March with the completion of a crucial ground test, ensuring the quiet supersonic aircraft will maintain a specific speed during operation. The test, known as engine speed hold, is a key step forward as the X-59 prepares for its first flight later this year.
“Engine speed hold is essentially the aircraft’s version of cruise control,” explained Paul Dees, NASA’s X-59 deputy propulsion lead at the Armstrong Flight Research Center in Edwards, California. “The pilot engages speed hold at their current speed, then can adjust it incrementally as needed.”
While a similar engine test was conducted previously in isolation, the March test integrated the speed hold function with the aircraft’s avionics. This was crucial to ensure all components—software, mechanical linkages, and control laws—worked together seamlessly within the entire system.
“We needed to verify that speed hold worked not just within the engine itself but as part of the entire aircraft system,” Dees said. “This test confirmed that everything is functioning as intended.”
The successful test demonstrated the X-59’s ability to precisely control speed, which is vital for flight safety. The system will help reduce pilot workload during the first flight, allowing them to focus on other critical aspects of flight operation.
“The pilot will be very busy during first flight, ensuring stability and control,” Dees noted. “Having speed hold manage some of that workload makes first flight safer.”
Originally planned for inclusion in an upcoming series of ground tests known as aluminum bird tests, the team opted to test the engine speed hold earlier after recognizing the opportunity to do so while finalizing other systems.
“It was a target of opportunity,” Dees said. “If we can learn something earlier, that’s always better.”
With each successful test, the NASA and Lockheed Martin team brings the X-59 closer to making aviation history with its groundbreaking quiet supersonic technology.