RAAF Edinburgh Airshow - South Australia - 1980's The Edinburgh RAAF base is surrounded by Market Gardens and OLD Glass Houses. Towards the end of the show the pilots were allowed some fun doing low level sonic booms over the run way. It was very impressive. Unfortunatly one RAAF pilot I think in an F1-11 got carried away and did a low level banking sonic boom over the top of some old market garden Glasshouses. The market gardener claimed extensive damages. The boom would have travelled down the inside of the glasshouse and blown the ends off. The Pilots were still doing some end of show sound offs when I had left the base and was at a BP Petrol Station several KM away and the 3 metre high glass windows were really stressing with the booms.
Like I said earlier it is the size and location of the sonic boom. The boom a round makes is very small and in the vast majority of cases will not break glass. Larger booms can and do.
Before I begin, I do have to admit that I only read pages 1 and 4 so this may have been mentioned before but anyway:
Myth: Any Sonic Boom will break any glass: Busted
However, as Jaime mentioned in the episode, conditions have much to do with the effects. I lived in Brooklyn for several years and every 4th of July just a regular firework exploding would send shock waves echoing up and down the streets setting off car alarms and did occasionaly cause window damage. I worked as a window washer on suspended scaffolds, believe me when I say I had to replace more than a few windows every 5th of July.
Now, a jet flying supersonic over a city would never happen under normal circumstances and I'm not sure it could even be simulated, but still it would be interesting to see the effects of a sonic boom on that test site inside a city (or canyon now that I think about it) rather than the open desert.
Ive been to 2 airshows in the last 3 years where they broke the sound barrier. Once with a Cheetah C (Modified Mirage III) and the 2nd time with an English Electric Lightning. The sonic boom from the Lightning was much louder and felt way more intense. Im sure this is because of the less aerodynamic shape this aircraft has. Likewise, with the FA18s, they are very aerodynamic and the sonic boom is perhaps not as bad as it could be.
Additionally, after one of the airshows, there were complaints from people, who lived on the slope of a rather large hill, with broken windows. This could be because the shockwaves were amplified due the the almost parabolic like shape of the terrain.
Yes, MB used a large variety of glass (shapes and types) however, Large window panes were not seen there. Often, shopping centres, office buildings and even big houses have massive panes of glass, which would surely break easier.
Other thoughts: Atmospheric conditions: (Humidity means more water in the air, possibly making the shockwaves travel better?) The area in which those tests were done looked very dry. I dont know if going even faster would have any effect on the magnitude of the boom?
I thought that the main reason for there being the most obvious damage inside the building is that it was all flat walls allowing the sound waves to bounce off and create the most disturbance. The car had fabric and awkward shapes to absorb the shock wave.
As for the myth, like others said, it said any sonic boom will break any glass and that just wasn't reflected, nor did I expect it to be.
I saw one person sorta hit on this earlier in the discussion, but it looks like it was mostly glossed over. The type of aircraft has a LOT to do with the perceived loudness of the sonic boom, as well as how the energy of the shock wave is shaped. Starting about 35 years ago, aircraft designers started intentionally shaping military aircraft bodies so they would make a "quieter" sonic boom. One way to do this is spread out the boom into a series of smaller booms. They don't break windows (and ear drums) as easily, and people perceive them as quieter. The F/A-18 was designed with this principle in mind. So no matter how low you fly, you're never going to get as much of a boom as you would in a jet designed before engineers cared about such things. For instance, take any Vietnam-era fighter moving at the same supersonic speed as an F-22, and I guarantee the sonic boom from the old jet will be much, much louder.
This isn't really relevant to the busting of this myth itself, but the idea that all sonic booms are created equal is wrong. It has a lot to do with the size and shape of the object. And yes, as the "Ballistic Expert" (hopefully still employed) now probably realizes, even a 50 cal bullet makes a continuous sonic boom until it slows down from friction to subsonic speed.
Related to this, it isn't the 4 engines on the B1-B that make it have a loud sonic boom. It's the size and shape of the fuselage. Its sonic boom would be just as loud if you accelerate to supersonic and then turn the engines completely off.
So I was showing my friend this episode, and he was saying something that was quite interesting. He had another myth about super sonic bullets. He was telling me that if any super sonic bullet hits a rain drop, it would either shatter or explode. But it is only with super sonic bullets
I appologize for the tardiness of this post as I accidentally posted it in the wrong place. xxxx
I was disappointed that the Sonic Boom episode did not give any historical data, when so much is available.
Perhaps the most famous is the March 5th, 1962 record setting flights of a B-58 Hustler between LA and NY. Each of the three flights took just over 2 hrs while traveling over Mach 2. "Unfortunately, it had shattered windows as well as speed records, showering offices and living rooms alike with broken glass. Police switchboards from coast to coast had lit up with calls as frightened people reported they had heard a terrible explosion" (http://history.nasa.gov/SP-4221/ch7.htm; Fortune, February 1967, p. 117; Shurcliff, S/S/T, pp. 3-5, 21-38; Dwiggins, SST, pp. 57-62, 69-73, 77-78, 80). It was also reported that the calls were so constant that the flight paths could be tracked based upon the phone complaints.
Considering that the above B-58 was flying at an altitude around 30,000 ft, it would suggest that the size of the aircraft would have more of an impact upon the strength of the sonic boom. This would also explain why the bullet, which has very little mass or size, would generate a negligible sonic boom.
In the 1960's, the largest test aircraft was the XB-70 Valkyrie. (Much of the Concord's background is based upon the research gained through the Valkyrie). The B-58 was considerably smaller than the XB-70, and yet the B-58 did considerable damage across the USA. The actual B-58 which broke the speed records in 1962 and the only remaining XB-70 are both on display at the National Museum of the USAF at Wright-Patterson AFB, near Dayton, OH. It would be worth a trip to the museum as they also have one of the Bell X-1s, an X-3, and an X-15 to name a few aircraft that have broken the sound barrier. There is enough history at the museum to keep you busy for a day or two.
Today, the aircraft most likely to recreate a sonic boom reminiscent of the B-58 (not including the space shuttle, which would be virtually impossible to repeatedly test for the show) is the B-1B Lancer. The top speed of both the B058 and B-1B is reported to be just over Mach 2.
The fastest aircraft in the world, the SR-71A Blackbird, in 1990 set a record between LA and Washinton D.C. in just over 1 hr at a declassified (but most likely lower than actual) speed of Mach 3.2+. However, it flew at an altitude over 80,ooo ft and during the middle of the night, thus reducing any complaints. Wright-Patterson also has a SR-71A on display.
If nothing else, the "myth" needs to be retweaked. I do not believe every sonic boom would break all glass. However, every sonic boom will most certainly do damage. That amout is dependant upon 1) the size of the aircraft, 2) the speed of the aircraft, and 3) the altitude of the aircraft. This would also explain why such a small fighter had to fly so close to the ground to achieve the same amount of damage as a supersonic bomber.
BTW - the outcry from all the supersonic tests done in the 1960's is the reason the USA outlawed supersonic flight in 1971 thus killing any financial viability to any civilian SST like the Concord.
Part of the reason the XB-70 having less of a noise footprint was the drooping wing outer panels which, when lowered in flight, reshaped the shock waves and channeled them through the "tunnel" formed by the wingtips and the engine shroud. A considerable amount of the shock was converted into extra lift increasing the cruise range of the aircraft. One of the most dramatic issues of Life Magazine had the photo sequence from the surviving chase plane of the fatal accident. I'll never forget the way it looked like some wild beast rearing up in it's death throes. It was a cool plane, but I get why it was canceled. It would have been dogfood for Advanced SAMS. Most people have never seen the wings deployed in Super Cruise, but I was able to find a cool photo.
Hey guys I love the show But you forgot to test any buildings that were / are under pressure most high rises are and the windows would be blown out very easily because of the height and internal pressure have fun and blow things up you guys are the best on T.v.
Ironic that they used the Blue Angels as the Angels broke 1.5 million dollars (today's dollars) worth of glass on August 6th 1969 in Kelowna BC Canada. CBC News
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I was there and remember it to this day.
quote:
On August 6th, 1969, Captain Vince Donile broke the sound barrier over downtown Kelowna, British Columbia, and blew out nearly every window for about 8 blocks - or as BlueAngels.com diplomatically puts it - the majority of the windows in the area parted company with their frames.
When I was a kid, I lived on the water in Freeport New York. It was south of Mitchell Field also on Long Island.
The planes used to come in off the water, after test flights. There were only three houses on my block at the time. They probably looked like deserted summer homes to the pilot. So they would come in just barely super sonic.
One day some of the sound of the planes engines were audible before the plane got to us. I could hear he was slowing down. He was probably flying at a hundred feet off the ground.
Because I heard him coming and slowing I did not expect to hear a sonic boom. I actually loved them. Ha-ha.
When he passed overhead, there was a very dark shadow cast on me by the plane. Then the screen door that had glass in the top half of the door, was hit with a pressure wave. The glass reciprocated with a white flash, that hit he me.
It almost knocked me to that ground. There is energy in fast moving objects.
Look at a bullet. That fifty caliber round can blow a hole right through half inch plate steel. Probably two plates. If you take a half inch punch, and check the pressures needed to use it in a turret punch. You will see that it requires huge amounts of pressure. And time.
Often a bullet can penetrate metal and still maintain its shape. A soft copper round can penetrate steel and maintain a lot of its shape. This is only possible because the bullet cuts with a plasma ray, not kinetic energy.
I am a welder so I get to see this electrical effect all day sometimes.
That is how an aluminum plane can cut through steel. It is carrying or creating the cutting plasm ray in front of the plane at those speeds. You can see the ray created on the nose of the plane before it hits an object.
Roy Grumman had done tests and found that some sounds move more slowly then others. So even well below the sound barrier, some sounds will cause the effect. On very moist summer days you can also have super sonic effects take place at lower speeds.
If you stand next to a roadway, and just listen, to the cars moving along at 60 miles an hour. You can hear as they approach you the different frequencies. First the high pitch sounds. As they get closer and closer you start to hear the lower pitched sounds. If you are right at the edge you can even experience a slight bit of over pressure and the sudden effect of hearing all the sound from the car at once. When the car is right next to you.
It is even better at race tracks where they run open headers.
Sincerely,
William McCormick
This message has been edited. Last edited by: mod_ivy,
The jet did create a super sonic boom but the reason the glass did not break was because of 3 thing: it had very little surface area so it was harder to break it; the glass on the car and the wine glassses were curved making it harder to break; and lastly on the car the windsheilds have a protective film covering it so that if a rock or some other debris hits it it will not shatter on the driver.
In the curving a bullet (dosent really have much to do with the movie but) i always wanted to know wat happened when the barrel of the gun was bent like in one of the looney toons cartoons.
I think they need to do this test over again (OH, DARN)... they need to create a large, flat vertical glass surfaces (much larger than the tiny window they were using), and then use a bigger supersonic plane with "messier" aerodynamics (like an F-14 or a concorde). An F-18 is too "sleek", it doesn't punch a big enough hole in the atmosphere to do much to you on the ground. Same for the F-16 (I had one fly over me in Omaha, NE, sub-500-ft at full throttle and it didn't do much to me). Actually, pulling a concorde out of retirement for a 500-ft mach 2 flyby would be pretty awesome . (Assuming you can find a pilot with the guts to try it.)
I feel the test was all wrong due to while hunting I climbed I climbed imto the back ohf my truck and took my 270wsm rifel out and laid it accross my jacket and the roof of my truck the barrel was hanging about 6 inches in front of my windshield and pulled the trigger and shattered my windshield.
I have a few words about the sonic boom bullet test. It seems to me that the projectile needs to be producing a loud enough and constant sound while in flight to create a working sonic "disturbance", ie make that bullet whistle while in flight. A few modifications and poof, there you go. That's your problem.
Originally posted by worlds: I have a few words about the sonic boom bullet test. It seems to me that the projectile needs to be producing a loud enough and constant sound while in flight to create a working sonic "disturbance", ie make that bullet whistle while in flight. A few modifications and poof, there you go. That's your problem.
That completely misses the point. A whistling bullet has nothing to do with supersonic shock waves. All objects traveling faster than Mach 1 in the atmosphere create Sonic Booms. What the MBs did was show that the booms are dependent on size and weight as well as velocity. The fantasy that the shockwave from a .50 will dismember or kill you is simply a gantasy.
It clearly demonstrated that the air disturbance caused by the bullet was incapable of breaking anything apart. I'm saying there is little or no sonic "boom" on anything unless the object in flight is emitting additional sound characteristics. I believe this should be tested.
. (Assuming you can find a pilot with the guts to try it.)