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Ever wonder what it would be like to fly faster than the speed of sound? Let's take a virtual ride on Air France's supersonic Concorde and find out. Luggage stowed, seat belt fastened, eyes out the window, we are ready for take-off. Here we go!
We feel the powerful acceleration as our pilot starts the plane racing down the runway. Each engine creates about 17,260 kilograms of thrust. It's produced by the combination of a normal jet engine and a special post-combustion system. With most jet engines, air is sucked in and compressed (squashed). A mix of air and fuel is then ignited and blown out of the engines to create thrust. With the post-combustion system, the engine's exhaust gases are reheated to increase the speed at which they are blown out. Greater exhaust speed means more thrust.
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In about 30 seconds, we reach a take-off speed of 360 km/h. Now that's fast enough to mess up a few hairdos. We're off! The pilot puts up the landing gear, and we wait for the beverage cart. You can relax because we aren't going to break the sound barrier right away--to avoid upsetting things on the ground, the Concorde only breaks the sound barrier over seas and deserts.
We just plod along at Mach 0.93 for a while. We know how fast we're going because there is a "machmeter" (like a speedometer) on every cabin wall. The numbers jump around a bit because mach speed is a based on the plane's speed and the speed of sound in the outside air. Sound travels faster in warmer air--as the air temperature changes, our mach speed does too.
We're over the ocean now. Prepare for supersonic flight! The pilot turned off the post-combustion system on take-off to cut noise, but now it's restarted. We feel a couple of pulses as the plane accelerates. That's it. We have broken the sound barrier! Because we are travelling faster than sound waves, we are in a zone of complete silence. It's not so quiet on the ground though--anyone below us would hear a loud ear-splitting, window-shattering bang (a sonic boom) right about now. (Actually the Concorde produces two booms--one from the plane and another smaller one when the shock wave is reflected off the upper atmosphere.)
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At Mach 1.7, the pilot turns off the post-combustion system again. We continue to gain speed, and soon we are cruising at Mach 2. That's about 2,200 km/h and you can't even tell! Not only are we travelling darn fast, we are really high too--cruising altitude is between 16,000 and 19,000 meters. That means we are flying in the almost cloudless, stable stratosphere (the second layer of Earth's atmosphere). The sky is an amazing bluish purple. Who knew travelling twice the speed of sound would be so smooth and easy?
Before we know it, it's time to land. Back to "boring" subsonic flight. We feel the engines power down and some braking. The pilot slows us down even more by applying reverse thrust. It actually looks like we're about to take off because the Concorde puts its nose up in the air to land. We touch down at 275 km/h and the braking system quickly slows us down. That's it. Now let's just hope we can find our luggage.
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