Broken Glass or Broken Myth? Talk about it here!

DCFM

Congratulations Adam for getting to fly with the Blue Angels!

You guys have to know that your rifle 50 cal test was flawed. It was not even worth testing the way you did it.

You guys have to know that the bullet breaks the sound barrier immediately out of the muzzel. As the bullet passes the glass you had up it is already supersonic. So the test is bunk.

Also, the trio should be careful when they modify bullets. They are creating wild pressure problems inside the chamber of the weapon.

If you guys need help, let me know.

Ballistic Expert: Sonic booms are produced continuously for the entire period of time a projectile is supersonic. It doesn't matter where they put the glass, because a .50BMG projectile is going to be supersonic for a very long distance.

And to be perfectly accurate, the bullet becomes supersonic within the barrel.

As mentioned in other posts, the sonic boom is always there as long as the object is supersonic. It doesn't just happen when the object passes through Mach 1.

I was on an aircraft carrier many a time when an F-14 would fly by at Mach 1.4 at 100 ft. It would shake the whole carrier. 100,000 tons of steel. That's a whole lot of energy.

I remember reading in (I think) "Early Supersonic Fighters of the West" by the British aviation writer Bill Gunston- the Royal Canadian AF had just gotten Lockheed F-104 Starfighters, and a flyby was made at a new airport (again i think)in Toronto- the jet was just transonic as it flew by the new terminal and it seriously broke a bunch of windows. Apparently, sonic booms are very powerful just at barely Mach 1 or so, where even though the plane isn't supersonic, the airflow around parts of the plane is.

I think if they were to test the same sonic boom test using the jets only changing one part, since the jets cant go super sonic under 500ft they should build a 100 ft tower or bigger then put the glass on the tower and test it.

Not an expert: if you google sonic boom..and view the images of a plane traveling slower than the speed of sound and then accelerating faster than the speed of sound in an instant....you'll see the air expansion cone formed... i feel if they performed the tests in that manner they would definitely get different results at the lowest legal distance

I lived in Idaho as a kid and we heard sonic booms from jets all the time. One day a sonic boom shattered both lenses of my brother's glasses while he was lying on his bed reading.

I don't know what kind of glass the lenses were made of, but this was 1964 or so, and he was about 11, so maybe they were tempered? And they were probably fairly thick.

The glass stayed in the frames, but was cracked so badly that you could hardly see his eyes. Scared him to death, to the amusement of his little sister (me

At a local air show near where I live, there was reported damage to multiple locations. This can be read in our local newspaper archives. Air show took place June 2005. Reported damage included was to windows, doors, and some other household items. Here is a quick clip of the news article and the link to read the actual article.

" AIR SHOW IS BLAMED FOR DAMAGE Wed Jun 22, 2005

Akron resident Shirlene Kisak's home just happened to be in the path of MAPS Air Museum's Aero Expo 2005 last weekend. Kisak and a few others say they had minor damage to their homes, wh... more... "

Link is bottom right of page in the archive section.
http://akronohio.planetdiscove...&aff=1100&Submit2=Go

i have a feeling that the actual reason that the glass ware and the car windows were not busted by the sonic boom and the PLATE glass window was (and/or were in the case of the other instances mentioned here) is that sound waves in air are very much like fluids and that the sonic boom just FLOWS around the curved glasses and the curved car windows and actually had the oppurtunity to build up pressure agianst the plate glass window. but that is just how i see it.

Like I posted in the other forum, I lived in Cape Canaveral and Orlando, and had broken windows in both my house and car when the space shuttle would land. It didn't happen each time, but there were a few occasions

quote:

Originally posted by WhackyPlague:
Ballistic Expert: Sonic booms are produced continuously for the entire period of time a projectile is supersonic. It doesn't matter where they put the glass, because a .50BMG projectile is going to be supersonic for a very long distance.

And to be perfectly accurate, the bullet becomes supersonic within the barrel.

No they are not. The boom is created when the projectile breaks the trans-sonic boundry. Once the barrier is broken that's it. After that all you see is the bullet disrupting the air ahead and behind it.

Yes technically the bullet transcends the barrier in the bore. But it is when the projo exits the muzzle is where you get the boom.

I will stake my ammunition business on this information

quote:

Originally posted by Ballistic Expert:

quote:

Originally posted by WhackyPlague:
Ballistic Expert: Sonic booms are produced continuously for the entire period of time a projectile is supersonic. It doesn't matter where they put the glass, because a .50BMG projectile is going to be supersonic for a very long distance.

And to be perfectly accurate, the bullet becomes supersonic within the barrel.

No they are not. The boom is created when the projectile breaks the trans-sonic boundry. Once the barrier is broken that's it. After that all you see is the bullet disrupting the air ahead and behind it.

Yes technically the bullet transcends the barrier in the bore. But it is when the projo exits the muzzle is where you get the boom.

I will stake my ammunition business on this information

Sorry, you're wrong.

I hate to use Wikipedia, but it's easy, so:
http://en.wikipedia.org/wiki/Sonic_boom
"Since the boom is being generated continually as long as the aircraft is supersonic, it fills out a narrow path on the ground following the aircraft's flight path, a bit like an unrolling celebrity carpet and hence known as the boom carpet. Its width depends on the altitude of the aircraft. [2] The distance from the point on the ground where the boom is heard to the aircraft depends on its altitude and the angle α."

Sonic booms are not a single event. They are produced continuously.

A sonic boom at the Air Force Academy Graduation: May, 1968: Fifty thousand dollars’ worth of windows shattered—appropriately enough during graduation exercises at the U.S. Air Force Academy in Colorado Springs. Injured: fifteen persons. The culprit: an F-105 flying at an altitude of five hundred feet.

when everyone is done deciding when a sonic boom is generated and you should also do some research into FLUID DYNAMICS because that is how air acts. study how wind affects buildings and you will start to see. the biggest concern for window problems in a skyscaper is the on the leeward side where the windows are sucked out of their frames. the next area of concern are corners on the windward side where the pressure is the highest.

HAHAHAHAHAHA!!!!!!!!!!!!
WHAT TRIGGER WORDS???????
FLUID DYNAMICS???
BLOWN????

I don't think Adam ever had a reason to be embarrassed , during the first near vertical take off from the runway , my flight suit would have needed some serious cleaning as well.

Did he ever think in his life he would get paid to be a passenger in a blue angel jet? Like he said " It just doesn't get any better."

i bet it was sucked! but i know no other way to discribe what happens on the leeward side of buildings.

HEHEHEHEHEHHEHEHEHEHEHE!!!!!!!!!!!!!!!!!!!!
IT WAS!!! IT WAS!!!!!
i know what the trigger word was.

quote:

Originally posted by WhackyPlague:

quote:

Originally posted by Ballistic Expert:

quote:

Originally posted by WhackyPlague:
Ballistic Expert: Sonic booms are produced continuously for the entire period of time a projectile is supersonic. It doesn't matter where they put the glass, because a .50BMG projectile is going to be supersonic for a very long distance.

And to be perfectly accurate, the bullet becomes supersonic within the barrel.

No they are not. The boom is created when the projectile breaks the trans-sonic boundry. Once the barrier is broken that's it. After that all you see is the bullet disrupting the air ahead and behind it.

Yes technically the bullet transcends the barrier in the bore. But it is when the projo exits the muzzle is where you get the boom.

I will stake my ammunition business on this information

Sorry, you're wrong.

I hate to use Wikipedia, but it's easy, so:
http://en.wikipedia.org/wiki/Sonic_boom
"Since the boom is being generated continually as long as the aircraft is supersonic, it fills out a narrow path on the ground following the aircraft's flight path, a bit like an unrolling celebrity carpet and hence known as the boom carpet. Its width depends on the altitude of the aircraft. [2] The distance from the point on the ground where the boom is heard to the aircraft depends on its altitude and the angle α."

Sonic booms are not a single event. They are produced continuously.

Stake your ammo business hmm? Looks like you own someone 1 business then.
Now. At some military ranges, you have the line, then you have a trench. The trench is a concrete lined hole that people sit in to change and mark targets for people shooting.
Then the bullets travel over head (remember that this is 100+ yards away) you hear a little crack.
That crack is the sonic boom, not the report of the gun.