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For those who don't know, a sonic boom is the bang you hear when a jet plane breaks the sound barrier. For all of you who have never seen the sound barrier, feast your eyes on these pictures.

Actual photos of the sound barrier:



This phenomenon only happens at the instant an aircraft breaks the sound barrier.



And it literally appears like the aircraft goes through a wall.



I hope you find these pictures as fascinating as I did.

 

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Re: Sound Barrier

Very cool. Being there...and seeing/hearing, that is quite a treat. I've had the pleasure and it was a great experience.
 

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Re: Sound Barrier

If you want to get technical, what you're seeing, at the moment when the craft exceeds the speed of sound, is the aircraft catching up to and passing the pressure wave it creates as it plows through the air.

At subsonic speeds, the pressure waves (i.e. sound waves) travel faster than the plane, including in the direction of travel. As it crosses th speed of sound, the waves pile up on top of each other at the nose of the plane (and other forward-facing surfaces) and form a shock wave.



That shock wave is a region of extreme variation in air pressure, which is visible due to moisture in the air. Just wanted to point out that the planes are not passing through a physical barrier, per se, but rather the "cloud" is a phenomena that forms around the plane--a visualization of the airflow characteristics around the craft. If the pilot maintained the proper speed, the "cloud" would remain indefinitely around the plane.
 

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Re: Sound Barrier

[quote author=dmention7 link=topic=71561.msg1259253#msg1259253 date=1173491886]
If you want to get technical, what you're seeing, at the moment when the craft exceeds the speed of sound, is the aircraft catching up to and passing the pressure wave it creates as it plows through the air.

At subsonic speeds, the pressure waves (i.e. sound waves) travel faster than the plane, including in the direction of travel. As it crosses th speed of sound, the waves pile up on top of each other at the nose of the plane (and other forward-facing surfaces) and form a shock wave.



That shock wave is a region of extreme variation in air pressure, which is visible due to moisture in the air. Just wanted to point out that the planes are not passing through a physical barrier, per se, but rather the "cloud" is a phenomena that forms around the plane--a visualization of the airflow characteristics around the craft. If the pilot maintained the proper speed, the "cloud" would remain indefinitely around the plane.
[/quote]

You never know what you are going to learn on the internet! Great info for my future trip in a fighter jet!
 

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Re: Sound Barrier

very cools pictures. that is quite fascinating indeed.
 

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Re: Sound Barrier

A fighter jet can create that vapor cone without actually breaking mach 1 (the speed of sound). Compare this first video of an F-18 doing a subsonic flyby versus this second video showing an F-14 actually exceeding the speed of sound. You can hear the F-18 approaching and there is no sonic boom, even though the vapor cone does show, whereas the F-14 is completely silent until it passes, and then the sonic boom passes over.

Legally, planes are not allowed to exceed the speed of sound over land during air shows and such, so you usually see (and hear) a supersonic flyby only in those videos shot over the ocean from an aircraft carrier demonstration.

Those are still awesome pictures of the B1 and the Blues Angels F-18. Imma grab them for my physics class!
 

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Re: Sound Barrier

[quote author=kendalf link=topic=71561.msg1259804#msg1259804 date=1173541907]
A fighter jet can create that vapor cone without actually breaking mach 1 (the speed of sound). Compare this first video of an F-18 doing a subsonic flyby versus this second video showing an F-14 actually exceeding the speed of sound. You can hear the F-18 approaching and there is no sonic boom, even though the vapor cone does show, whereas the F-14 is completely silent until it passes, and then the sonic boom passes over.

Legally, planes are not allowed to exceed the speed of sound over land during air shows and such, so you usually see (and hear) a supersonic flyby only in those videos shot over the ocean from an aircraft carrier demonstration.

Those are still awesome pictures of the B1 and the Blues Angels F-18. Imma grab them for my physics class!

[/quote]

I was on a friends and familty day on an aircraft carrier (I was like 11 at the time). The USS Constellation...prior to it being moth balled (I don't belive it's still active).
 

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Re: Sound Barrier

[quote author=kendalf link=topic=71561.msg1259804#msg1259804 date=1173541907]
.... even though the vapor cone does show, whereas the F-14 is completely silent until it passes, and then the sonic boom passes over.
[/quote]

Watched several shuttles pass over my house, the most recent maybe a month ago when it landed it Fl. The boom comes about a minute after it passes. Cool.

Great pics & writeups.
 

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Re: Sound Barrier

[quote author=kendalf link=topic=71561.msg1259804#msg1259804 date=1173541907]
A fighter jet can create that vapor cone without actually breaking mach 1 (the speed of sound).

[/quote]

True. When an aircraft approaches transonic flight, 0.9 mach or so, portions of the aircraft have airflow that is supersonic. This will create the cloud seen in the pictures if atmospheric conditions are right. It is a common misconception that the picture must be taken exactly when the aircraft's true airspeed is supersonic.
 

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Re: Sound Barrier

Nice find.
 

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Re: Sound Barrier

Thanks for all the interesting feedback/input. Couple of questions:

1. Do the pilots hear the sonic boom?
2. Do they feel a vibration or jolt?
 

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[quote author=RB link=topic=71561.msg1260694#msg1260694 date=1173586269]
Thanks for all the interesting feedback/input. Couple of questions:

1. Do the pilots hear the sonic boom?
2. Do they feel a vibration or jolt?
[/quote]

My guess would be no. Since the sound is actually behind them.
 
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