The legendary supersonic passenger jet Concorde may have stopped flying in 2003, but researchers haven't given up the dream of making a quieter commercial aircraft that flies faster than the speed of sound.
Last week, the Japanese Aerospace Exploration Agency (JAXA) flight tested and gathered data on an aircraft made according to a low sonic boom design concept at Sweden's Esrange Space Center.
A sonic boom is the noise created by a supersonic jet as it travels through the air faster than the speed of sound. As the aircraft moves through the air it forces air molecules out of the way. This creates waves, which move away from the aircraft. The waves around a plane become increasingly compressed when the plane moves faster than them—unable to move out of the object's way in time, they amalgamate into one big shockwave that trails behind the aircraft. The shockwaves form a cone shape, which makes it look almost like the aircraft has a tutu around its back end.
Sonic booms are really loud and can cause a great deal of noise pollution if an aircraft flies over land.
Developing technology to reduce sonic boom is therefore key to furthering a future with more civil supersonic transport. In 2014, NASA researchers teamed up with industry experts to work on an aircraft design also geared to take the boom out of supersonic jets.
JAXA researchers say their aircraft is designed specifically to reduce both front and rear shock waves as the jet hits supersonic speeds. In order to test the jet, they first lifted it into the air using a balloon launch pad system. When the balloon hit heights of 30 km, the unmanned aircraft separated from the balloon, accelerated to supersonic speeds (over 700 miles per hour) at free fall, and glided over a boom measurement system, which used multiple microphones to measure the amount of sonic boom generated.
Researchers at JAXA hope that analysis of the data collected during this second test phase will help them contribute to lower sonic boom standards for future supersonic civil aircrafts, which would allow them to fly over both land and sea. Previously, due to the extent of the noise, Concorde was only allowed to fly at supersonic speeds over the sea.
If the researchers come up with a solution, we might soon be once again jetting through the skies faster than the speed of sound.