Amazing: Supersonic planes 'paint' shock waves in the sky
Thursday, October 8, 2015, 4:27 PM - NASA has released stunning photos of supersonic airplanes that appear to be 'painting' shock waves in the sky.
The images are the product of a new technique that's able to photograph the waves that form when an airplane breaks the sound barrier.
According to NASA, the images may one day help engineers identify the regions where shock waves produce the most noise, leading to the development of quieter supersonic planes.
While the technique is new, NASA says the technology involved is anything but.
"NASA researchers in California are using a modern version of a 150-year-old German photography technique to capture images of shock waves created by supersonic airplanes," NASA says in a statement that was released over the summer.
"Over the past five years scientists from NASA’s Armstrong Flight Research Center at Edwards Air Force Base and Ames Research Center at Moffett Field have teamed up to demonstrate how schlieren [a German word for 'streak] imagery, invented in 1864 by German physicist August Toepler, can be used to visualize supersonic flow phenomena with full-scale aircraft in flight."
When sound waves move from an object they deform the air around it, changing the air's density. That changes how light reflects off the object.
Schlieren imagery captures the changes in light intensity in a shadow image. In the past, scientists used scale models in wind tunnels to learn about shock waves.
But advancements in camera technology have brought schlieren imagery into the 21st century and made the new images possible -- and that could lead to big advancements in the development of supersonic planes.
Current regulations in Canada and the U.S. have strict rules about supersonic flight.
Planes typically can't fly over land, but the photographs may help engineers create supersonic planes that meet federal aviation standards.
“Air-to-air schlieren is an important flight-test technique for locating and characterizing, with high spatial resolution, shock waves emanating from supersonic vehicles,” said Dan Banks, Armstrong's principal investigator on the project, in a statement.
“It allows us to see the shock wave geometry in the real atmosphere as the target aircraft flies through temperature and humidity gradients that cannot be duplicated in wind tunnels.”
NASA says the next step is to advance the technology so it can guide the development of future airplanes.