Tag: sonic boom

Reapproaching Supersonic Air Travel
Before the Concorde even began regular flights, protests over its sound levels caused the U.S. and many other countries to ban overland commercial supersonic flight. Those restrictions have stood for fifty years. But NASA and Lockheed Martin Aeronautics are hoping to make supersonic air travel a possibility again with their experimental X-59 aircraft, designed to have a much quieter sonic boom.
In supersonic flight, every curve, bolt, and bump generates a shock wave, and these waves tend to coalesce at the front and back of the aircraft, creating strong leading and trailing shocks. It’s these shock waves that are responsible for the double sonic boom that rattles windows and startles those of us on the ground. The X-59 reduces its noise by spreading out those shock waves, a feat designers managed with heavy reliance on computational fluid dynamics. They used wind tunnel studies mainly for validation, since iterating designs in the wind tunnel was far slower than working computationally. With the initial aircraft built, the team will now do test flights and, starting in 2026, will fly over the public and solicit feedback on whether the aircraft is acceptably quiet. (Image credit: NASA; via Physics Today)
The sound of the X-59’s sonic boom compared to other familiar sound levels.
April 15, 2024
Challenges of Commercial Supersonic Flight
Years ago as I sat on a plane taxiing at Heathrow, I caught a glimpse of a Concorde out on the tarmac. My classmates couldn’t understand why I was so excited to see that funny looking plane, but even as a high schooler, I was fascinated by the prospect of flying faster than sound.
Unfortunately, there are a lot of challenges to overcome in making supersonic flight widely available — fuel efficiency, cost effectiveness, and sonic boom control, to name a few. This video delves into some of the major issues and touches on some of the recent work at NASA and other organizations studying the problem. Perhaps as new technologies develop and mature we’ll once again see faster-than-sound air travel outside of rocket launches and military jets. (Video and image credit: TED-Ed)
June 24, 2021
Shock Waves in Flight
Schlieren optical systems have been used to visualize shock waves in labs for more than a century, but the technique did not translate well to photographing shock structures outside the lab. But now NASA’s Armstrong Research Center and Ames Research Center have developed a method that allows them to capture highly-detailed images of the shock waves around airplanes while they are flying. This is incredible stuff. Be sure to check out the high-resolution versions on this page, along with more description of the coordination necessary to pull off the photos.
The light and dark lines you see emanating from the airplane are places with strong density gradients. The dark lines are mostly shock waves, with the strongest shock waves appearing black due to the large change in air density. Many of the light streaks are expansion fans, areas where the density and pressure drop as air speeds up.
The goal of this research is to better understand shock wave structures around supersonic planes in order to reduce the noise supersonic aircraft cause when flying overhead. As you can see in the photos, the shock waves at the nose and tail of the aircraft persist far away from the aircraft; these are what cause the twin sonic boom heard when the plane flies by. (Photo credit: NASA; via J. Hertzberg)
August 31, 2015
Schlieren in Flight
Schlieren photography is a common method of visualizing shock waves in wind tunnel experiments, but it’s much harder to pull off for aircraft in the sky. This video from NASA shows off some stunning work out of NASA Dryden capturing schlieren video of shock waves from a F-15B aircraft at Mach 1.38. You’ll notice that shock waves extend off the nose, wings, tail, and other parts of the airplane and extend well beyond the camera’s field of view. It’s these shock waves hitting the ground level that causes distinctive sonic booms. These tests are part of NASA’s on-going research into minimizing the effects of sonic boom so that civilian supersonic flight over land is feasible in the future. When the U.S. government shutdown ends, you’ll be able to learn more about this work at NASA Dryden’s GASPS page. (Video credit: NASA Dryden)
October 10, 2013
Shock Waves in Flight
Schlieren photography allows visualization of density gradients, such as the sharp ones created by shock waves off this T-38 aircraft flying at Mach 1.1 around 13,000 ft. Although shock waves are relatively weak at this low supersonic Mach number, they persist, as seen in the image, at significant distances from the craft. The sonic boom associated with the passage of such a vehicle overhead is due to the pressure change across a shock wave. The higher the altitude of the supersonic craft, the less intense its shock wave, and thus sonic boom, will be by the time it reaches ground level. (Photo credit: NASA)
March 11, 2013
Supersonic
Moving supersonically–faster than the local speed of sound–can cause some awesome effects. Among these are vapor cones (a.k.a. Prandlt-Glauert singularities), shock waves, and, of course, the sonic boom.
September 22, 2010
Breaking the Sound Barrier
The shock waves propagating in front of an Atlas V rocket after launch decimate a rainbow-like effect called a sun dog. #
July 22, 2010