Info on Breaking Sound Barrier

[Mr. RF62]

Does anyone know info on what it sounds like breaking the sound barrier??? dBs???? Frequency???

I know, I have too much time on my hands to think.

[Daddy Dee]

I was hoping I'd hear the sonic boom of the space shuttle returning to Florida, but guess I wasn't in the right area.

Used to hear them all the time with aircraft from LRAFB until the Air Force made the pilots drive slower. I sort of miss it.

They are pretty low frequency I'd think, as I remember rattling windows and picture frames. It would also be interesting to know what kind of area around the aircraft is subject to the sound.

[Wrench722]

I thank this can help. Sonic boom - Wikipedia, the free encyclopedia

[Mr. RF62]

Wow, over 200dBs...they don't touch frequency. Could be most frequencies to rattle windows, if you have enough 2kHz and feel it. D.D., I've never heard a sonic boom (live), that would be neat.

[Daddy Dee]

Wrench722,

Thanks for the link. One thing, I had no idea that the crack of a bullwhip is a sonic boom type thing. The tip of the whip is actually traveling faster than the speed of sound. That's pretty amazing.

RF62,

Yeh. I like the way the air force pilots refer to them.... the sound of freedom.

[oscarsear]

I think the sound is relative to the size of the object breaking the barrier.  Where a whip will crack a plane seems to deliver a double low frequency Ba-BOOM.  The pictures of jets at the moment of breaching the barrier are interesting too.  It really appears to be a flat 2 dimensional plane with the jet traveling right through it.

[Mighty Favog]

Used to hear them all the time with aircraft from LRAFB until the Air Force made the pilots drive slower. I sort of miss it.

Yea, I kinda miss the sound of larger prop planes full of passengers going over my house in the early 70's.[:^)] Rememberances of the last seen from American Graffiti when Richard Dreyfus is looking down at the white T-Bird.

[flannj]

I was hoping I'd hear the sonic boom of the space shuttle returning to Florida, but guess I wasn't in the right area.

Used to hear them all the time with aircraft from LRAFB until the Air Force made the pilots drive slower. I sort of miss it.

They are pretty low frequency I'd think, as I remember rattling windows and picture frames. It would also be interesting to know what kind of area around the aircraft is subject to the sound.

I used to hear them as a kid (early and mid 60's) when I lived very close to Lake Michigan. It seemed to happen several times a day. I have always assumed they were flights out of Glenview Naval Air base about 15 miles north of Chicago. I googled and found this arcticle.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19660029125_1966029125.pdf

The last time I heard one was in the months post 9/11. At that time there were always a couple of fighters patrolling the airspace around Chicago and O'Hare. One day a plane wandered into an area it wasn't supposed to be in and the fighters were scrambled? to intercept. I happened to be outside at the time and while I couldn't see the fighter I recognized the sound of BA-BOOM right away, It definitely brought back memories.

It was eventually reported as to what happened but apparently quite a few calls were placed to radio and police stations by people who didn't recognize the sound. Given the nervous atmosphere at the time I suppose that reaction shouldn't have been a surprise.

- Jim

[jtkinney]

Hey Dee,

I heard it for you yesterday[H] Was standing almost underneath it about 6 miles from the end of the runway. Shortly after the double boom you can hear the roar of the wind going by. It sounds like it's jet powered until it slows down to land and gets real quiet. Beautiful sight by the way. I was happy to see it land since one of the astronauts is a friend of my wife's.

[Daddy Dee]

That's very cool. I'd love to see the shuttle land. Thanks for the description.

It's always been somewhat amazing to imagine flying that thing from space and gliding in, dead stick, for landing. No go arounds.

I've heard that it's aerodynamics are only slightly better than a brick.

[customsteve01]

Dee,

At Johnson Space Center here in Houston they have a mock simulator that you can try your hand at the landing. It is very slugish to your comands so it makes most people over compansate and crash. On the second try I was able to get it on the ground in one piece.

I also miss hearing the sonic boom like I remember as a kid.

Steve

[j-malotky]

The size of the boom is relational to the size of the object. The boom is also directional and can be surprisingly controlled by the pilot.

There is still a few spots in the US where the millitary flies supersonic. The northern part of lake michigan is still one of them.

JM

[Daddy Dee]

screamin in.

[oscarsear]

Here's a dumb question.  If we get this sound evoked when the barrier is broken do we get again, or anything similar when the object decelerates back though the same barrier?

[RichardP]

Here is a photo published (and taken by?) Nikon. Almost surrealistic.

[Mighty Favog]

I don't think so...it just goes back to being noisy in the cabin of the plane.[8-)]

[pauln]

That's very cool. I'd love to see the shuttle land. Thanks for the description.

It's always been somewhat amazing to imagine flying that thing from space and gliding in, dead stick, for landing. No go arounds.

I've heard that it's aerodynamics are only slightly better than a brick.

That image is misleading. For the very reasons you mention, the whole thing has to be perfect the first time. Shuttle avionics are controlled by very complicated computer programs, not "flown" by

the pilot when it lands. The pilot does activate the release of the

drag chute once the wheels are on the ground. They had to fight to get to do that! This was also part of the

computer controlled landing, but the pilots made the administrators

allow them to do it themselves.

This is in the same line as the

original astronauts insisting that there be a window in the early

capsules even though the flight design did not require it. Even with a craft that needs no pilot actions, pilots are just not comfortable without a window and at least one manual control function. The heroic recovery of Apollo 13 was a vindication of the pilot's instincts.

The last few minutes of the original moon landing descent were performed manually because of a problem with the descent program.

[Rockets]

You'd be surprised as to how much sound the Shuttle makes when it's just gliding. I always expected to hear 'nothing', but it's not that way at all....Sounds like a distant jet. The Shuttle, emits twin sonic booms in quick succession, like a double barrel shotgun going off nearby, but EVERYTHING rattles. Even if you're prepared for it, it still scares the hell out of you. It's worse when you forget about the landing and you're backing your truck up in a parkling lot. Talking about crapping in your pants.....[:|]

[Islander]

Here's a dumb question. If we get this sound evoked when the barrier is broken do we get again, or anything similar when the object decelerates back though the same barrier?

The sonic boom is caused by a pressure wave produced when the aircraft reaches Mach 1 (the speed of sound). It's a continuous sound that trails the aircraft like a bow wave from a boat. A listener on the ground hears it as a boom when it passes by, but the sound is travelling at the same speed as the aircraft producing it.

The sound starts when the aircraft reaches Mach 1 and continues as long as it travels at speeds in excess of Mach 1. That's how I understand it, at least.

[dtel]

A few years ago we were watching the late news 10 pm and about halfway through they said the Shuttle was going to land back in Florida and if it was on schedule they would show the landing on the news broadcast. Next they said it will be passing over our area in the next few minutes and you will be able to see it.

We told the kids let's go out in the front drive way and see if we could see it ? We were standing out there for about 5 minutes and thought we missed it, we were expecting something kind of small like a shooting star or a little bigger, they didn't say how close or how big it should look .

About 2 minutes later we seen a small glow in the sky to the West heading toward us, Christy said that must be it, and it was. What happened next left us all standing there looking like this [:|]. When it flew past which only took maby 10 seconds from start to finish it was UNBELIAVEABLE.

It was much closer than we expected, which made it look much bigger. Something we didn't expect was it had sparks and fire with a long trailing tail of sparks, that's what it looked like at least ! I didn't expect it to have sparks and a leave a trail of smoke after it was out of site ! I had no idea that reentry lasted that long and at that low of an altitude ?

After it passed we went back inside to see the news and just a couple minutes later they showed the landing in Florida ! It went from the New Orleans / south Mississippi area to Florida in a couple of minutes !

It was amazing and something everyone should have a chance to see. Ever since that night whenever I hear the Shuttle is going to land I look to see if it's going to pass over us again ! I have never seen it again, although next time I will take some pics or a movie, I will never forget it !