NASA researchers have been using a tiny aircraft dubbed “Son of Concorde” in trials to assess the impact of supersonic flights on residents.
The tests took place in a wind tunnel in Japan measuring just 3ft by 3ft.
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At present there is a ban on supersonic flights over land as researchers scramble to find new ways to limit the impact at ground level.
The latest tests come after President Trump ordered the Federal Aviation Administration to scrap a longstanding ban on supersonic air travel across the US.
He wants to replace it with a to-be-determined set of regulations that will allow faster-than-sound travel so long as the sonic booms it creates do not breach certain noise limitations.
In an executive order signed in June, Trump directed the FAA administrator to begin the process of repealing a section of the Code of Federal Regulations that prohibits anyone in the United States from flying a civilian aircraft “at a true flight Mach number greater than 1”.
That regulation was imposed in April 1973, at a time when the British and French governments were jointly developing Concorde, a supersonic airliner that had a cruising speed in excess of Mach 2, or twice the speed of sound.
Engineers from Nasa and the Japanese Aerospace Exploration Agency (JAXA) completed the fresh round of supersonic testing using a miniature version of Nasa’s X-59 quiet-supersonic experimental aircraft in the trials.
The campaign was conducted at JAXA’s facility in Chofu, Tokyo.
It assessed how the aircraft’s pressure signature, audible on the ground as a sonic “thump,” will reach people beneath its flight path.
The X-59 demonstrator measures 99.7ft in length with a 29.7-ft wingspan, but the Chofu tunnel could only accommodate the miniature model, which is just 1.62% of the real jet.
Engineers nevertheless subjected the replica to airflow conditions representing the aircraft’s planned cruise of Mach 1.4 – about 925 miles per hour.
By comparing the wind-tunnel data with detailed Computational Fluid Dynamics predictions, Nasa can validate how air will wrap around the jet’s slender fuselage and long, highly swept wing.
Critically, it will also show how its shock waves are expected to behave.
Unlike conventional supersonic airplanes, whose shock waves combine into a single, ground-shaking blast, the X-59’s carefully sculpted nose and chine are intended to separate those waves.
The goal is a brief, low-volume “sonic thump” rather than an ear-splitting boom, opening the door to overland supersonic passenger flight, reports Interest Engineering.
The Chofu tests mark the third time the model has entered a wind tunnel, following earlier runs at JAXA and NASA’s Glenn Research Center in Ohio.
Researchers delivered “critical experimental data to compare to…predictions”, Nasa noted.
The X-59 is the centerpiece of NASA’s Quesst mission, an effort to prove that quiet supersonic flight is technically and socially viable.
Once airborne, the jet will make a series of community overflights across the United States so researchers can gauge how residents react to its muted acoustic footprint.
Their feedback, combined with the aerodynamic and acoustic data now being amassed in wind tunnels and ground tests, will inform regulators as they consider lifting the decades-old ban on supersonic flight over land.
A short history of Concorde – from Live Aid to sonic booms
Concorde was used 40 years ago this week to allow superstar drummer Phil Collins to perform at Live Aid in London on July 13, 1985, then fly to the US – and appear at Live Aid in Philadelphia on the same day. Here is a brief history of the first supersonic passenger-carrying luxury airplane.
Two decades ago the Concorde took its last-ever flight.
It became supersonic in 1969, flying passengers from New York to London in less than three hours.
It was the only aircraft in the British Airways fleet that required a flight engineer.
Concorde needed unsustainable amounts of fuel and created very loud sonic booms.
Then, in July 2000, a horror accident saw 113 people killed when an Air France Concorde ran over a small piece of metal while taking off from Charles de Gaulle Airport.
It caused the tyre to explode and the engine to ignite.
A year after the horrific crash, 9/11 majorly affected passenger numbers.
Ultimately a combination of these events led to its downfall.
By 2003, Air France and British Airways announced they would be retiring their fleet of Concorde planes.
