NASA has tested a scale X-59 experimental aircraft at speeds of Mach 1.4 to validate its quiet supersonic technology.
In partnership with the Japanese Aerospace Exploration Agency (JAXA), NASA tested the model in a wind tunnel, measuring the shockwaves generated when breaking the sound barrier.
The tests allowed NASA to validate how closely real-world airflow matched predictions from Computational Fluid Dynamics (CFD) models.
The X-59 is part of NASA’s Quesst mission (Quiet SuperSonic Technology), which aims to make overland supersonic passenger flights possible.
The hand-sized NASA X-59 test model
The full size NASA X-59 will be over 99 feet long (30 metres), with a wingspan of almost 30 feet (9 metres). However, the test model used in the Japanese wind tunnel is just 1.6% of the size at around 19 inches from nose to tail.
The aircraft was exposed to airflow matching the jet’s planned cruising speed of Mach 1.4 (around 925 mph).
The series of tests performed at JAXA allowed NASA researchers to gather critical experimental data to compare to their predictions derived through Computational Fluid Dynamics modeling, which include how air will flow around the aircraft.
This is the third round of wind tunnel testing for the X-59 following another test at JAXA and one at NASA’s Glenn Research Center in Ohio.
NASA hailed the test as “an important milestone for NASA’s one-of-a-kind X-59, which is designed to fly faster than the speed of sound without causing a loud sonic boom.”
Lockheed Martin’s Skunk Works has developed the X-59 for NASA’s Low-Boom Flight Demonstrator project. Work on the project has been ongoing since 2016. The first flight of the full size model is expected later this year.
Quesst: Lowering the noise of supersonic travel
When built, the X-59 is expected to cruise at Mach 1.42 at an altitude of 55,000 feet, and is designed to break the sound barrier without the hallmark ‘thump’ supersonic aircraft usually create.
The NASA X-59 does this by disrupting shockwaves to prevent them merging together, reducing the potential for a loud boom.
It could provide a breakthrough to open up supersonic travel around the world. Previous supersonic commercial aircraft like Concorde were banned from flying supersonic over land, limiting routes to over water.
Lockheed Martin writes that the experimental X-59 will help NASA provide regulators with the information needed to establish an “acceptable commercial supersonic noise standard to lift the ban on commercial supersonic travel over land.”
But regulators are moving ahead anyway, at least in the US. In June, President Trump signed an executive order encouraging regulators to fast-track the return of overland supersonic travel, potentially paving the way for lifting existing restrictions.
Supersonic passenger travel makes a comeback… quietly
With the X-59 paving the way for quiet supersonic flight, attention is also turning to commercial players. Chief among them is Boom Supersonic, a US company working towards bringing a supersonic passenger aircraft to market.
Earlier this year, Boom flew its XB-1 demonstrator at Mach speeds with zero audible noise on the ground. In what the company calls ‘boomless cruise,’ the aircraft uses altitude to ensure the sonic boom does not reach the ground.
This technology will be fundamental to its full size passenger aircraft, the Overture. The Overture is planned to have a range of 4,250 nautical miles and a cruise speed of Mach 1.7. It will have a seating capacity of 60-80 passengers.
United Airlines, American Airlines, and Japan Airlines have all placed orders and pre-orders for the Overture.
For now, it seems unlikely that supersonic travel will be viable on a large scale. The aviation industry is overwhelmingly focused on increased efficiency and reduced fuel consumption. The most economical speed for commercial aircraft is in the Mach 0.78-0.85 range.
Next-generation commercial aircraft are increasingly focussed on fuel savings rather than speed. JetZero’s revolutionary new Z4 Blended Wing Body aircraft is also subsonic and seeks to reduce fuel consumption by up to 50%.
While Boom says the Overture will be compatible with 100% Sustainable Aviation Fuel, critics argue that high fuel burn rates may still make supersonic travel environmentally burdensome, even with SAF.