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Epidemic of cracked windshields in KDEN, explanation unknown
In article ,
"Matt Barrow" wrote: "Kev" wrote in message ups.com... On Feb 17, 11:15 am, Mxsmanic wrote: See http://us.cnn.com/2007/WEATHER/02/17....ap/index.html So what would cause windshields to crack on many different types of aircraft at the same time? It wasn't impact or anything like that. [..] I don't believe the "wasn't impact" part. I lived in Denver for a while, and when the winds whip up, stones fly around. That brought to mind the skit in "Monty Python and the Holy Grail" about things that will float in water, one of them being small rocks. But, ducks also float, and they fly. Airplanes also fly. Therefore, airplanes are small rocks. |
#12
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Epidemic of cracked windshields in KDEN, explanation unknown
Jim Macklin wrote:
How cold did it get in Denver? Aluminum and plastic have different contraction rates with cold. Plastic also gets brittle with cold. Wind flexes wing, which also flexes fuselages, erg---cracks. It can't be as cold as the jets routinely see above 30,000 feet. I suspect the wind was carrying stones or ice chunks or something like that which cracked the windshields. Matt |
#13
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Epidemic of cracked windshields in KDEN, explanation unknown
On Feb 17, 7:09 pm, Blanche wrote:
High winds. Low temps (-15F and up) == very cold wind chill factor. Common misconception. Wind chill only applies to the heat loss of animals. It does not apply to inanimate objects. The only thing wind will do to metal, glass, plastic, etc is help cool it faster to the ambient temperature. Kev |
#14
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Epidemic of cracked windshields in KDEN, explanation unknown
Matt Whiting wrote:
Jim Macklin wrote: How cold did it get in Denver? Aluminum and plastic have different contraction rates with cold. Plastic also gets brittle with cold. Wind flexes wing, which also flexes fuselages, erg---cracks. It can't be as cold as the jets routinely see above 30,000 feet. I suspect the wind was carrying stones or ice chunks or something like that which cracked the windshields. I suspect the the crews turned on the electric windshield heating without proper warmup when it was very cold, and the cracks resulted from thermal stresses in the windows. The cracks were reported to have happened in the air, where flying rocks would be rare, and not on the ground. |
#15
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Epidemic of cracked windshields in KDEN, explanation unknown
"Blanche" wrote in message
... High winds. Low temps (-15F and up) == very cold wind chill factor. I would think that's still balmy and calm compared to the flight levels. I dunno why they cracked. The airlines also don't know, and they have been thinking about this much longer than we have. |
#16
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Epidemic of cracked windshields in KDEN, explanation unknown
Bob Moore writes:
Of course these jet windshields are heated to provide the middle layer of plastic with some flexibility to resist shattering in case of a bird strike at low temps. Should the heating system be turned off and cold- soaking occur(electrical bus turned off for trouble-shooting perhaps), Boeing had a procedure for re-heating the windshield at very low temps to prevent thermal shock from cracking the glass layers. This involved cycling the power switches ON-OFF at one minute intervals for several minutes. Sounds to me as if the temps at DEN were quite low and the flight crews just turned the windshield heat ON and forgot about it. Just one possibility of course..... It sounds logical. Many models of aircraft were affected, though (and in fact Boeing wasn't mentioned--if a Boeing windshield cracks, there's a _real_ problem). Mostly those Brazilian planes and some others. Most were on the ground, not in the air. -- Transpose mxsmanic and gmail to reach me by e-mail. |
#17
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Epidemic of cracked windshields in KDEN, explanation unknown
Blanche writes:
High winds. Low temps (-15F and up) == very cold wind chill factor. Wind chill applies only to people, not things. -- Transpose mxsmanic and gmail to reach me by e-mail. |
#18
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Epidemic of cracked windshields in KDEN, explanation unknown
"Jim Macklin" wrote in message
news How cold did it get in Denver? Aluminum and plastic have different contraction rates with cold. Plastic also gets brittle with cold. Wind flexes wing, which also flexes fuselages, erg---cracks. Single digits below zero. Nothing. Certainly not "rocks blowing around". | I don't believe the "wasn't impact" part. I lived in Denver for a | while, and when the winds whip up, stones fly around. | |
#19
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Epidemic of cracked windshields in KDEN, explanation unknown
"Kev" wrote in message
ups.com... On Feb 17, 5:14 pm, "Jim Macklin" On the other hand, they mentioned 100 mph ground winds, Who is "they"? and that means flying rocks to me. As those are borderline tornado winds, it's more like regular debris. -- Matt Barrow Performance Homes, LLC |
#20
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Epidemic of cracked windshields in KDEN, explanation unknown
"Roy Smith" wrote in message
... In article , "Matt Barrow" wrote: "Kev" wrote in message ups.com... On Feb 17, 11:15 am, Mxsmanic wrote: See http://us.cnn.com/2007/WEATHER/02/17....ap/index.html So what would cause windshields to crack on many different types of aircraft at the same time? It wasn't impact or anything like that. [..] I don't believe the "wasn't impact" part. I lived in Denver for a while, and when the winds whip up, stones fly around. That brought to mind the skit in "Monty Python and the Holy Grail" about things that will float in water, one of them being small rocks. But, ducks also float, and they fly. Airplanes also fly. Therefore, airplanes are small rocks. Tell us how sheep's bladders can be used to predict earthquakes. |
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