Fly Damnit

Sonic Boom / Sound Barrier

“A sonic boom is the audible component of a shock wave in air. The term is commonly used to refer to the air shocks caused by the supersonic flight of military aircraft or passenger transports such as Concorde (Mach 2.03, no longer flying) and the Space Shuttle (up to Mach 27 - Note, this high number is largely due to the high altitudes, therefore low air pressures, that the space shuttle flies at).”
Source: Wikipedia

How does it happen?
It happens when a plane or an object is moving in air above certain speed. When an object is moving slowly, the air infront of it slides aside smoothly. This is because air particles vibrates giving “warnings” ahead. A sonic boom appears when an object moves so fast that it gets to the air without warning. That means the object or plane hits the air .

You can also try this in the water. When u place the tip or ur finger in a calm water. You can see the water ripple. As u move your finger, you can always see a ripple infront of your finger. But if u move your finger fast enough, the water will splash.

That’s when sonic boom appears. But only this time its in the air. At sea level with ideal conditions, the speed for a sonic boom is 761 mph. Mach 1.

The sound of a sonic boom depends largely on the distance between the observer and the aircraft producing the sonic boom. A sonic boom is usually heard as a deep double “boom” as the aircraft is usually some distance away. However, as those who have witnessed landings of space shuttles have heard, when the aircraft is nearby the sonic boom is a sharper “bang” or “crack”. The sound is much like the “aerial bombs” used at firework displays.

In 1964, NASA and the Federal Aviation Administration began the Oklahoma City sonic boom tests, which caused eight sonic booms per day over a period of six months. Valuable data was gathered from the experiment, but 15,000 complaints were generated and ultimately entangled the government in a class action lawsuit, which it lost on appeal in 1969.

Critical Speed
Critical speed is when a part of the plane reaches Mach 1 while the other part is still below Speed of sound. This is possible because of the shape of the plane. Since it has the curve over the wing, that part is more likely to hit Mach 1 before any other parts. That is why you see “Clouds” over the side of the Jet.

What is that visible cloud around the jets?
That is actually visible moist as a result from pressure change. This does not happen in supersonic speed but in a transonic condition, where some part of the plane is passing Mach 1. Because of the shape of the plane (chamber and stuff) not all places have the same airspeed. Therefore there is difference in pressure. This difference in pressure condenses the water in the air as the jet passes these waves. So u get visible moist.

Images (not taken by me, for educational purpose only):

End of part 1..