“We never dreamt that it would be this clear, this beautiful.” – said J.T. Heineck of NASA’s Ames Research Center upon taking a first glimpse at the first air-to-air images of the supersonic shockwave interaction in flight. As cool as the images look, capturing them is not easy and took about a decade in the making.
NASA was able to get the first air-to-air photos of the interaction of shockwaves from two supersonic aircraft flying in formation using the schlieren photography technique. These two T-38 aircraft from the U.S. Air Force Test Pilot School are flying in formation at a distance of around 30 feet while traveling at supersonic speeds, which is faster than the speed of sound, creating shockwaves that can be heard on the ground as a sonic boom. The King Air, flying a pattern at 30,000 feet, had to be in a perfect position as the two T-38s went by at supersonic speeds around 2,000 feet below to get these pictures. The cameras had a three-second maximum recording time and had to start filming as soon as the supersonic T-38s entered the frame and snapped their trek through the sound barrier at 1,400 frames per second. The pictures were taken during a supersonic flight series performed, in part, to better understand how shocks interact with aircraft plumes as well as with each other. The images were initially monochrome and are now displayed as colorized composite images.
Aircraft traveling faster than the speed of sound produce shock waves. These waves combine to produce a sonic boom, which is a loud bang. NASA anticipates that its study will help shape the design of the X-59 QueSST, a quiet supersonic aircraft that will begin test flights in 2022. Scientists may be able to improve the X-59 such that it will only make a slight sound when it breaks past the sound barrier using the additional data points. If the research is successful, it may aid in the burgeoning resurrection of supersonic airplane technology: Due to the sonic boom issue, the Concorde, the most well-known commercial supersonic aircraft, was only allowed to break the sound barrier while it was over water. Yet, if the X-59’s quieter technology holds up, it may help save supersonic aircraft from extinction.