NASA's X-59's quiet supersonic research aircraft successfully completed a series of critical tests in which the aircraft was placed through its pace to cruise high above the California desert - all without leaving the ground.
"The idea behind these tests is to direct the aircraft's subsystems and flight computers to make it work properly," said Yohan Lin, chief aerospace engineer at the X-59 at the NASA Armstrong Flight Research Center in Edwards, California.
The purpose of ground-based simulation testing is to ensure that the hardware and software that allows the X-59 to fly safely can cooperate correctly and be able to handle any unexpected problems.
Any new aircraft is a combination of systems, and determining some of the adjustments required to optimize performance is an important step in the flight method of discipline.
"We think we might find something during the testing period that will prompt us to go back and tweak them to work better, especially with certain software, which is what we're going through. So, these tests are very helpful."
Completed testing marks another milestone in the list of events the X-59 will do before its first flight this year, continuing NASA's Quesst mission to help enable commercial supersonic airlines to cross the land.
During the testing process, Lockheed Martin, an engineer and contractor from NASA, turned on most X-59 systems to turn the engine off. For example, if the pilot moved the control rod in some way, the flying computer moved the rudder or other control surface of the aircraft just like in flight.
Meanwhile, the aircraft electronically connects to the grounded computer (X-59) that sends analog signals interprets it as true - such as altitude, speed, temperature, or changes in various system health conditions.
Sitting in the cockpit, the pilot "flys" the plane and see how the plane reacts.
"These are simple drills, nothing is too crazy," Lin said. "We then inject the plane into the fault to see how it responds. Will the system make up for the failure? Can the pilot recover?"
Unlike typical astronaut training simulations, pilots don’t know what scenarios they might encounter, and X-59 pilots mostly know what the aircraft will encounter in each test, and even help them plan to focus better on the response of the aircraft system.
In aircraft development, this work, known as the "Iron Bird" test, was named after a simple metal frame on which the representation of the aircraft subsystem was installed, connected and inspected.
Building such a test bed is a common practice in development programs where many aircraft will be built. But because the X-59 is a unique aircraft, officials think using the aircraft itself is better and cheaper.
As a result, engineers called this series of exercise "Aluminum Bird" tests because that's the metal of the X-59.
Therefore, the "aluminum bird" uses the actual aircraft and its systems, rather than the "iron bird" that tests a copy of the aircraft system on a non-descriptive framework, which in turn means that the test results give everyone a higher confidence in the design and a higher confidence in the design.
Lin said: “This is a perfect example of the old and true motto in aviation, which says ‘test what you fly.
With aluminum bird testing in the rearview mirrors, the next milestone on the X-59's first flight path was taking the plane to a taxi at the airport, close to Lockheed Martin's Skunk Works facility in Palmdale, California, where the X-59 was built. The first flight will follow these taxi tests.
It has been in the X-59's log since the fully assembled and drawn aircraft debuted in January 2024.
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