NASA has now flown its strange, needle-nosed X-59 quiet-supersonic jet 25 times.

That is a serious milestone. But the test that could actually change commercial air travel is still ahead.

The X-59 was built to fly faster than sound without producing the window-rattling sonic boom that helped push routine supersonic travel out of American skies. Instead, its unusual shape is supposed to spread those shock waves into a far quieter sound NASA describes as a sonic thump.

According to NASA, flight number 25 took off from Armstrong Flight Research Center in Edwards, California, on August 21. The 72-minute flight reached Mach 1.2 at roughly 49,000 feet.

A chase plane followed the X-59 to monitor it. The chase aircraft’s own sonic booms masked the sound of the experimental jet, so this was not yet the public-facing noise test.

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NASA said the aircraft has already reached its target cruise conditions of Mach 1.4—about 924 miles per hour—and 55,000 feet during the broader flight program. The current work is expanding confidence across the full operating envelope, including slower and lower-altitude conditions.

So far, the jet’s real-world behavior has closely matched the models used to design it. NASA says its handling, stability margins and structural loads have tracked the predictions, with no unexpected instability or excessive vibration.

That is exactly the kind of boring test result engineers want from a one-of-a-kind aircraft.

NASA test pilot Nils Larson described the flights as exciting but uneventful. The team has made smaller refinements between flights, including control-software adjustments and a fix for nuisance alerts that were being interpreted as caution warnings.

The aircraft looks unlike anything parked at a commercial gate. Its pencil-thin nose stretches so far forward that the pilot cannot see through a traditional front windshield.

NASA solved that problem with an external vision system that uses cameras and displays to give the pilot the forward view. The long nose, top-mounted engine and carefully shaped surfaces are all part of the effort to control how pressure waves form and reach the ground.

The goal reaches beyond building another fast airplane. NASA wants to produce trustworthy noise data regulators can use.

NASA’s Quesst mission is designed to measure the X-59’s sound and then fly the aircraft over selected communities. People on the ground will report what they heard and how they reacted.

NASA plans to deliver that response data to U.S. and international regulators. If the evidence shows that the X-59’s thump is tolerable, regulators would have a factual basis for considering noise limits that focus on how much sound reaches the ground instead of maintaining a broad speed-based restriction.

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That distinction matters. A rule built around measurable noise could create room for future aircraft that are faster than sound but quiet enough not to punish everyone beneath their flight path.

The research is moving in stages. The current flight campaign checks the aircraft itself, the acoustic-validation phase will measure the shock waves, and the later community flights will collect public responses under real-world conditions.

NASA is not designing a commercial cabin or selling tickets. Its job is to prove the low-boom concept, document the sound and hand regulators a body of evidence they have never had before.

The current federal rule is blunt. Title 14, Section 91.817 of the federal aviation regulations generally prohibits civil aircraft from operating above Mach 1 over the United States unless specifically authorized.

It also bars flight conditions that authorities know will cause a measurable sonic boom to reach the surface. Those restrictions grew out of decades-old concerns about noise, disruption and property damage.

The X-59 does not overturn that rule by itself. It is a research aircraft, not a passenger jet, and a successful test program would still leave aircraft makers with the enormous challenge of turning quiet-supersonic technology into something safe, efficient and commercially viable.

Fuel use, ticket prices, airport noise, maintenance costs and certification would all remain major hurdles. A quieter boom solves one central problem while leaving a long engineering and business checklist behind.

It is also the problem that has kept supersonic flight over land largely frozen for generations.

The upcoming acoustic-validation phase will use instruments on the ground and in the air to measure the X-59’s shock waves. NASA technical lead Larry Cliatt called that campaign the moment when the tools and methods behind the aircraft’s design finally face their real test.

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Twenty-five flights have shown that the X-59 can fly like the computer models said it would.

Now NASA has to prove it sounds like the future, too.

This is a Guest Post from our friends over at WLTReport. View the original article here.

 

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