X-59 Block 1: Landing Gear Up, 43,000 Feet and Mach 0.95 Before Supersonic Tests

NASA's X-59 quiet supersonic research aircraft finished the first block of its envelope-expansion flight tests in May 2026, reaching several milestones. It flew its first flight with the landing gear retracted, climbed to 43,000 feet, reached Mach 0.95, about 627 miles per hour, just short of supersonic, and for the first time flew twice in one day. The tests are preparation for supersonic flights in support of NASA's Quesst mission. This video shows the highlights.

Build-up, step by step

A team member explains that flight testing is about building up carefully, not going as fast as you can on the first try. Each test point goes a little higher or a little faster and expands the envelope. They also go slower and lower, which can be more hazardous, and the X-59 has now been taken to its minimum speed. The flight pace grew too: one flight in the first week of Block 1, then two flights in a week, and later two flights in a day and up to four in a week.

Block 1 milestones:

• the airplane flew again, with the landing gear both up and down, and flew well both ways;
• landing gear transitions proved the vehicle's systems in each configuration;
• altitude up to 43,000 feet and Mach 0.95;
• maneuvers such as bank-to-bank rolls and sideslips, which prove the aircraft is safe in its normal envelope, so later, flying around the country, nobody has to worry whether it can roll left and pull hard on the stick. The control room backs the pilot throughout.

What the team learned

The team has flown the simulator for years, and the real aircraft handles much as it did there. The difference is motion: the simulator has none, so now pilots feel the oscillations and vibrations of a real airplane. In performance, the X-59 seems to be going faster and climbing better than even the simulator predicted. The maintenance crew is turning the aircraft around between flights in shorter and shorter times.

Each flight does something not yet done with the airplane, which is the point of envelope expansion. When nothing new is left to do, the airplane is ready. Block 1 expanded both altitude and airspeed to prove system performance and handling and to check that they match predictions, giving confidence to go further, to supersonic flight.

How a flight day works

A test day involves briefings, the flights and debriefings. Before it, pilots and the test team develop how certain maneuvers will be flown, the control room team rehearses in simulations, the maintenance crew completes routine inspections, and the flight test engineers prepare briefings and test scores.

Sources

• NASA, NASA's X-59 Completes Block 1 Flight Test Milestones, NASA Image and Video Library; rewritten in hubnx's own words.