# Can a supersonic aircraft avoid missiles

## What happens when an airplane “flies through the sound barrier”?

When an airplane is traveling faster than sound, it is said to be traveling at supersonic speed. That has not been possible for so long. It was not until the middle of the 20th century that airplanes could reach such speeds.

### How fast is sound?

Sound travels around its source in the form of waves. We can hear this sound within a certain radius, for example when someone is playing an instrument. The sound is not infinitely fast, but moves at a certain speed depending on the temperature. At 20 degrees it is about 333 meters in one second. That is almost 1200 kilometers per hour - 10 times faster than a car is allowed to drive on the motorway! Still, there are things that move even faster. For example, light is faster than sound. That's why you always see the lightning first before you hear the thunder during a thunderstorm.

### How fast does an airplane fly?

After all, a normal passenger aircraft can manage around 1000 kilometers per hour - but that's not enough to fly faster than sound. To do this, it would have to fly at more than 1200 km / h. However, the military uses jet planes that are faster than 2000 kilometers per hour.

### What is the sound barrier now?

Airplane engines are pretty loud. So they generate sound that travels in all directions from the aircraft. If the aircraft is slower than the sound waves, they will fly ahead of the aircraft unhindered. But if the aircraft moves faster than the sound it generates, it pushes the sound in front of it, so to speak. The sound waves cannot escape that quickly. They are compressed, condense and pile up. This is the so-called sound barrier. The sound waves propagate in a cone shape behind the aircraft - you can imagine it like a ship where water collects in front of it at the bow and creates water waves behind it.

### Where does the bang come from?

When an airplane approaches us at supersonic speed, we don't hear it at all at first. The noise is too slow for the plane. But if it flies overhead, at some point it pops violently: all of the collected sound hits us all at once. You won't hear this bang on the plane itself, however, as the plane has long since flown on.

Incidentally, the same effect also occurs with a whip: the cord reaches supersonic speed, displaces the air and generates a bang when the sound waves collectively reach our ears. The whole thing isn't quite as loud as an airplane.

For a while, it was actually believed that the sound barrier was a real wall. The pilots were therefore afraid that the planes would break if they hit the sound barrier. On October 14, 1947, pilot Chuck Yeager was the first person to fly his rocket plane at supersonic speed. His plane survived unscathed.

### The darn Bermuda Triangle

The Bermuda Triangle is a place of mysterious incidents where planes and ships disappear without a trace. But what is really all about the myth of the Bermuda Triangle?

Read more… The darn Bermuda triangle