Recently published test results by NASA confirm that the Space Agency has made an important step towards silent supersonic travel. NASA has been developing a camera system for a while with which they can study the shockwaves produced by aircraft going faster than the speed of sound.
The technology scientists at NASA have been polishing is not a new though. Schlieren (streak) photography was invented by the German physicist August Toepler 1864. It is an exceptional image making process used to depict the flow of air around aircraft (amongst other scientific usages).
To catch a sonic boom
The scientists at NASA’s Armstrong Flight Research Center in Edwards, California attached the high-speed camera system to a B200 King Air plane which was flying at 30,000 feet. Two T-38 supersonic trainer jets were flying just below the B200 at 28,000 feet, over the speed of sound (faster than 682 MPH).
Sub-project manager Heather Maliska praised the pilots of the test flight, saying: ‘The biggest challenge was trying to get the timing correct to make sure we could get these images, (…) ‘They were rock stars.’
The high-speed camera took 1200 shots per seconds of the two jets passing by to depict the shockwaves they generate. Those shockwaves are the sonic booms, which are extremely loud on the ground level, especially when multiple jets are flying close to each other and the waves merge.
‘We never dreamt that it would be this clear, this beautiful.’
Physical scientist J.T. Heineck sums up his enthusiasm about the success of their current test, which is a result of a ten-year development process. ‘I am ecstatic about how these images turned out,’ he said.
Although the raw images coming from the developed camera system are black and white, Mr. Heineck and his colleagues colored them for better visibility.
Neal Smiths, a research engineer gives more details: ‘We’re looking at a supersonic flow, which is why we’re getting these shockwaves. (…) What’s interesting is, if you look at the rear T-38, you see these shock kind of interact in a curve. (…) This date is going to help us advance our understanding of how these shocks interact.’
It is for future supersonic flights!
So why is it important to know about the shockwaves sonic booms generate? Yes, you guessed it, it is especially important because we want to fly faster. NASA and its contracted partner, Lockheed Martin are working on a supersonic aircraft which can go very fast without a sonic boom.
The 247,5 million dollar contract is about to design a plane called X-59 QueSST, a quiet supersonic aircraft. Sonic booms not only cause damage over inhabited areas but they also disturb the animal population on the ground level.
With this milestone achievement, developers got a step closer to reducing the damaging sound effects of a sonic boom to just a low rumble, which can enable overland supersonic flights in the close future. Regarding the agreement between NASA and Lockheed, the X-59 will be ready for its first flights by 2021.