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Post by PhantomWolf on Sept 14, 2008 2:15:29 GMT -4
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Post by gwiz on Sept 14, 2008 4:40:45 GMT -4
Ever been to an airshow? Military aircraft taking off on afterburner 100 metres away? A Harrier hovering? They don't give ear defenders to the crowd.
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Ian Pearse
Mars
Apollo (and space) enthusiast
Posts: 308
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Post by Ian Pearse on Sept 14, 2008 5:10:54 GMT -4
And where the aircraft at full throttle at the point of impact? Unlikely. At full throttle and maximum speed there would have bene very little time for the pilot to make any course corrections to ensure impact. A building, even the size of the WTS towers, is quite a difficult target to hit at high speed. And these weren't experienced pilots, by all accounts. I've stood at the end of 27L at Heathrow while a jumbo has been passing overhead, maybe 300 feet, at full throttle - my hearing is fine.
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Post by Grand Lunar on Sept 14, 2008 7:58:19 GMT -4
Sorry CBB, but common sense and YouTube links are no substitute for science.
Basically, you're digging a hole for you ideas, just as Jack White did:
You're admission of your lack of education and research, as well as simply referring to YouTube videos puts you in the same position as Jack White.
You have no case without the science to back you up. Period.
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Post by Grand Lunar on Sept 14, 2008 8:15:03 GMT -4
The clip provided by PhantomWolf shows the foolishness of this claim of yours, CBB.
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Post by tedward on Sept 14, 2008 8:22:04 GMT -4
Jet planes 10 times louder than rock concerts... www.newton.dep.anl.gov/askasci/phy99/phy99405.htmQuestion: We are a 5th grade class and we would like information about decibel levels. Do you have a list of decibel levels for common sounds? Such as voice, airplane, etc? ------------------------------------------------ Answer: First, remember that the decibel (dB) is a logarithmic unit, meaning that you cannot add and subtract dB like ordinary numbers. For example, an increase of 3 dB is a doubling of the "strength" of the sound, and an increase of 10 dB means that the sound is 10 times as loud; i.e., 70 dB is 10 times as loud as 60 dB. Now for the list: Threshold of hearing.....................0 dB Outdoors, no people or traffic..........20 dB Background noise in a library...........40 dB Ordinary speaking voice.................60 dB Heavy traffic...........................85 dB Power lawnmower up close................90 dB Motorcycle (rider)......................90 dB Chainsaw...............................100 dB Rock music at concert..................110 dB Jet plane takeoff at 100 yards.........120 dBThreshold of pain......................140 dB These noise levels are approximate, and depend on many factors. Noise levels of 85 dB and above are considered potentially damaging over time; for example, workers are not allowed to spend more than 30 minutes per day at 110 dB -- the level of a rock concert! gary e myers ========================================================= What would have been the measured on the day as opposed to an arbitrary figure plucked from the net? To shoot this down, how about you do a study of people who live at the ends of runways and require daily medical attention. Add to that rock concerts but bear in mind some planes are not as noisy as others so some concerts are noisier than planes. Some are just so loud anyway by your reckoning the attendees will all required medical treatment after a few minutes. As as per your snippet copy from the web, These noise levels are approximate, and depend on many factors.So, you need a noise level meter. A few airports and you should have a decent comparison. Something you can test yourself.
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Post by tedward on Sept 14, 2008 8:46:06 GMT -4
Interesting. Do a bit of a search and you come up with info like 767 using a 1.5 mile runway generates the same noise as street corner traffic. Now I also know different engine options are available. With todays environment airliners are made to be as quiet as possible so I do wonder how old that quote is and how valid with the various engine maker combinations and number of engines.
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Post by scooter on Sept 14, 2008 10:15:42 GMT -4
Interesting. Do a bit of a search and you come up with info like 767 using a 1.5 mile runway generates the same noise as street corner traffic. Now I also know different engine options are available. With todays environment airliners are made to be as quiet as possible so I do wonder how old that quote is and how valid with the various engine maker combinations and number of engines. The newer generation high bypass engines are so much quieter than the early turbojets and low bypass fan models. More of a buzzsaw "whine" than the old jet roar. Certainly not enough to cause permanant damage. If they really were so noisy, there would be an awful lot of stone deaf folks living around airports. It's a completely silly argument.
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Post by tedward on Sept 14, 2008 10:55:31 GMT -4
Interesting. Do a bit of a search and you come up with info like 767 using a 1.5 mile runway generates the same noise as street corner traffic. Now I also know different engine options are available. With todays environment airliners are made to be as quiet as possible so I do wonder how old that quote is and how valid with the various engine maker combinations and number of engines. The newer generation high bypass engines are so much quieter than the early turbojets and low bypass fan models. More of a buzzsaw "whine" than the old jet roar. Certainly not enough to cause permanant damage. If they really were so noisy, there would be an awful lot of stone deaf folks living around airports. It's a completely silly argument. Yes, it would help if CBB would understand this. Maybe even find out what the expected noise level is for the engines fitted. Then what would be the observed noise by the people he/she claims should be deafened.
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Post by scooter on Sept 14, 2008 11:30:44 GMT -4
There are serious limits on the noise "footprint" of departing (and arriving) jetliners in many communities. CBB needs to research "noise abatement" as applied to the airport environment, among other things. Not that jets today aren't somewhat loud, they just are not, literally, "deafening", or anywhere close to it. Many older aircraft simply cannot operate at these airports due to their operating noise. Re-engining and modifying older jetliners to continue life as quieter freighters has also been a big industry. (727s, DC-8s)
CBB, your "deafening" argument is thoroughly defeated.
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Post by tedward on Sept 14, 2008 12:37:11 GMT -4
Its quiet day so the noise abatement comment tickled that gland that says "I remember when...." Anyway. Concorde. Cause quite a stir in the US when it started flights. Linky to 1975 hansard (uk parliament)Then a shufty on chapter 3 type aircraft Aircraft noise paper from the International Civil Aviation Organization. Still trying to find a definitive chapter 3 levels and how they are measured that appear to apply to the plane mentioned. Or maybe I will not bother. Time for tea. BTW, came across this PDF. LINKED DIRECTLY, so beware. Not large but there we go. interesting reading
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Jason
Pluto
May all your hits be crits
Posts: 5,579
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Post by Jason on Sept 14, 2008 14:03:29 GMT -4
Well, at least you said it first. okay, you can say it second Very well. With your permission: "cbbrooklyn can't explain much."
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Post by jaydeehess on Sept 15, 2008 19:07:05 GMT -4
Pick me. For several years I lived under the flight path of aircraft using a runway at an international airport. As I said I worked at the airport, it took me all of 15 minutes to get to work. When planes were taking off over my house and one was in the yard it was difficult to hear another person's conversation however it was just as loud as a passing city bus on the street in front of the house. Now the bus was 75 feet away and the plane 1000 feet away so yes the plane generated more sound, BUT in my yard the two were just as loud!
Now in the winter, at 35 below, they were significantly louder. Tell me CBB, any guesses why that would be. Let's see your "common sense" shine!
Of course we did not try to have BBQ parties outside in January. I was young and foolish at the time but not that foolish!
Let's see, what other experience can I relate that is relevent. well I was on the wing of an idling DC3 while my friend refueled it. We later learned that they are supposed to shut the engines down but that if they can get away with it then at 40 below they will leave them running. THAT was louder than the various jet passenger aircraft flying over my house, much, much louder. In that case I could tell my friend was speaking because I saw his mouth moving. He says he was yelling at the top of his voice. I heard nothing that could even be remotely distinquished as human speech. In my back yard, with passenger jets overhead, if one raised one's voice you could be heard.
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Post by jaydeehess on Sept 15, 2008 19:10:03 GMT -4
By his logic I should be deaf. I used to work on the glide slope electronics which are located only a few dozen feet from the runway. I was there, finished my work on several occasions, and having been informed by ground control that I would not be able to take my vehicle onto the runway to get back to the office for some time , I would sit outside and watch various aircraft , 727, 737, 747, L1011 take off. That's at considerably more throttle than landings. Any singed skin? No, why would there be? I said I was at the Glide slope equipment building that sits off to the side of the runway. I did not say that I was sitting ON the runway. I do not recall the exact distance from the edge of the runway but it is approx 50-60 feet. Here's a picture of one. You see the runway just beyond the building.
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Post by frenat on Sept 15, 2008 22:05:32 GMT -4
I go to work every day by driving around a miltary runway where 707s (JSTARS) take off. The road goes right by the end of the runway. I actually open the windows just to hear them. There are also plenty of F-15s doing pattern work with 90 turns on afterburner and only about 500 feet or less overhead. Extremely loud but not damaging. I usually open the windows when I see them going overhead as well. I know my hearing has not been damaged as it is tested every year as part of my flight physical.
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