Friday, January 21, 2011

Flight of the Concorde

I don't know if all you PhysicsBuzz readers at home know this, but today's the 35th anniversary of the first flight of the Concorde.

No, not the world famous folk duo from New Zealand; the fleet of supersonic commercial airplanes that crisscrossed the globe for 27 years. On January 21, 1976, the first paying passengers took a trip on a jet that could travel faster than the speed of sound from London England to Bahrain. These planes were fast, traveling twice the speed of sound. A flight from New York to Paris would only take a Concorde about three and a half hours, a far cry from the typical eight hours it takes most jets. However there was a downside; the sonic booms that come with faster than sound travel.

Because of these booms, the Concorde originally had trouble coming to the United States. At first Congress banned them because of worries over sonic booms, and then once the national ban was lifted, individual airports like JFK in New York barred the sleek planes from landing.

Though they sound dramatic, sonic booms aren't explosions. They are loud roars that objects make when a plane breakes the sound barrier.

When an object moves through a fluid medium, like a plane flying through the air, it has to push that air out of the way. A normal plane would just push the air aside and fly through the space left. However a plane traveling faster than the speed of sound is moving faster than the air can move out of the way. Air pressure builds up along the wing because more air hits the wing than can slide out of the way, collecting into a cone of compressed air that protrudes out from the nose of the plane. If a person is standing on the ground and this front of changing air pressure rolls over them, they've got front row seats to a loud boom of the sonic variety.

A sonic boom is really two noises. The first boom comes when the compressed air first rolls over the listener. The abrupt change from regular pressured air to high pressure is the first part of the rumble. As the plane flies by, the air pressure actually drops below normal. The second boom is air pressure snapping back to normal. The two booms sound like one, because they happen so close to each other.

What does this sonic boom sound like? Believe it or not, you only have to go as far as the circus to find out. When a lion tamer cracks her whip, you're hearing a sonic boom. The end of the whip is moving faster than the speed of sound, and the crack it makes is its own sonic boom.

Supersonic airplanes like the Concorde or the SR-71 Blackbird which can travel at 3.3 times the speed of sound, all have the same kinds of swept back wings to help dissipate the built up air pressure. This was found by trial and error. The first few generations of supersonic airplanes, like the Bell X-1,
had wings that stuck straight out. After more testing and different designs, airplane manufacturers found that having wings that sweep backwards lets the air dissipate the built up air pressure better, reducing drag letting the plane cut through the air faster.

As for the fate of the fleet of Concords, they never really made much economic sense. There was never much demand for them because seats on board were tremendously expensive, in part because they were so costly to maintain. In July of 2000 a disastrous crash at an airport in Gonesse France killed 113 people, marking the beginning of the end of the Concords. The final flight of a Concorde took place on November 26, 2003 from Heathrow Airport to Bristol. Concords now roost only in aviation museums like the Smithsonian's Steven F. Udvar-Hazy Center in Virginia.

Photo Credit: Echo Romeo


  1. Yes, I am well aware that today is the 35th anniverary of Concorde's inauguaral flight. I was a passenger (seat 5D) aboard the Air France flight from Paris to Rio de Janeiro on that glorious day. Thank you for remembering. E.G.D.

  2. I love Concorde !! Miss them lyk hell :(

  3. I really love concord!!! Really awesome concard!