Iranian Chill Thread
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scimitar19
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don't you just love american foreign policy?!
yavar
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yavar
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Scientists Finally Have An Explanation For Why Helicopters Are So Loud
It goes without saying that helicopters are really loud. What’s trickier is explaining why, and finding a way to make the explanation visible to the naked eye.
But researchers from the German Aerospace Center (DLR) say they are the first to provide a visual explanation of the cause for all that noise.
And armed with that knowledge, they’re in a better position to make helicopters quieter and more comfortable, good news for civilian and military pilots and passengers.
To answer the question of why helicopters are so noisy, researchers set up camp in a limestone quarry and pushed skilled pilots to pull off risky maneuvers just 30 feet above the ground.
In a January press release, the DLR explained that most noise comes from the helicopter’s main rotor. As it spins, air pressure drops above each blade, and rises below it (pushing the helicopter up). To even out the pressure difference, air flows around the blade, creating a concentrated vortex. What the vortex meets the next blade, you get a vibration — sound.
The clever bit is how the German researchers found a way to capture that effect on camera.
They took advantage of a common phenomenon: the way air seems to shimmer on hot days (due to changes in air density, which refract the light). Against the right background, that shimmering makes the air vortices created by helicopter blades visible.
Last year, the DLR researchers successfully visualized those rotor blade vortices by flying in front of a rocky background in the Alps, and over fields and meadows.
Recently, they took things to the next level, with a BO 105 helicopter flying in the limestone quarry near Hanover. After setting up 10 cameras at various angles, the team asked the pilots to rock the helicopter just 30 feet above the ground, in front of an exposed rock face.
It paid off: The experiment generated the first 3D images of an in-flight helicopter’s rotor blade vortices.
The DLR says it plans to continue this kind of testing, and the results could help make helicopters quieter and more comfortable.
Here’s a composite of the vortices seen from different angles:
image: https://static.businessinsider.com/image/52f10d0beab8ea5d69c2ff0f-1200/image.jpg
And some photos from the experiment in the quarry:
image: https://static.businessinsider.com/image/52f10d0aecad04491f4a97c4-1200/image.jpg
DLR (CC-BY 3.0)
image: https://static.businessinsider.com/image/52f10d0c6bb3f7257daad56b-1200/image.jpg
DLR (CC-BY 3.0)
image: https://static.businessinsider.com/image/52f10d0cecad044b1f4a97c5-1200/image.jpg
Read more at https://www.businessinsider.com.au/scientists-why-helicopters-are-so-loud-2014-2#A25AMIshcpUSGSQ0.99
^ tarikh khabar 2014
@Hack-Hook
be nazaram amricaeha hamin alan helicopteraye kamsaro seda darand va dar hal stefade hastand
va goya in alman ha ham dar hal sakht modelaye bisaro seda tar hastand .
It goes without saying that helicopters are really loud. What’s trickier is explaining why, and finding a way to make the explanation visible to the naked eye.
But researchers from the German Aerospace Center (DLR) say they are the first to provide a visual explanation of the cause for all that noise.
And armed with that knowledge, they’re in a better position to make helicopters quieter and more comfortable, good news for civilian and military pilots and passengers.
To answer the question of why helicopters are so noisy, researchers set up camp in a limestone quarry and pushed skilled pilots to pull off risky maneuvers just 30 feet above the ground.
In a January press release, the DLR explained that most noise comes from the helicopter’s main rotor. As it spins, air pressure drops above each blade, and rises below it (pushing the helicopter up). To even out the pressure difference, air flows around the blade, creating a concentrated vortex. What the vortex meets the next blade, you get a vibration — sound.
The clever bit is how the German researchers found a way to capture that effect on camera.
They took advantage of a common phenomenon: the way air seems to shimmer on hot days (due to changes in air density, which refract the light). Against the right background, that shimmering makes the air vortices created by helicopter blades visible.
Last year, the DLR researchers successfully visualized those rotor blade vortices by flying in front of a rocky background in the Alps, and over fields and meadows.
Recently, they took things to the next level, with a BO 105 helicopter flying in the limestone quarry near Hanover. After setting up 10 cameras at various angles, the team asked the pilots to rock the helicopter just 30 feet above the ground, in front of an exposed rock face.
It paid off: The experiment generated the first 3D images of an in-flight helicopter’s rotor blade vortices.
The DLR says it plans to continue this kind of testing, and the results could help make helicopters quieter and more comfortable.
Here’s a composite of the vortices seen from different angles:
image: https://static.businessinsider.com/image/52f10d0beab8ea5d69c2ff0f-1200/image.jpg
And some photos from the experiment in the quarry:
image: https://static.businessinsider.com/image/52f10d0aecad04491f4a97c4-1200/image.jpg
DLR (CC-BY 3.0)image: https://static.businessinsider.com/image/52f10d0c6bb3f7257daad56b-1200/image.jpg
DLR (CC-BY 3.0)image: https://static.businessinsider.com/image/52f10d0cecad044b1f4a97c5-1200/image.jpg
Read more at https://www.businessinsider.com.au/scientists-why-helicopters-are-so-loud-2014-2#A25AMIshcpUSGSQ0.99
^ tarikh khabar 2014
@Hack-Hook
be nazaram amricaeha hamin alan helicopteraye kamsaro seda darand va dar hal stefade hastand
va goya in alman ha ham dar hal sakht modelaye bisaro seda tar hastand .
Hack-Hook
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well they used such helicopters when they attacked Bin Laden Compound in PakistanScientists Finally Have An Explanation For Why Helicopters Are So Loud
It goes without saying that helicopters are really loud. What’s trickier is explaining why, and finding a way to make the explanation visible to the naked eye.
But researchers from the German Aerospace Center (DLR) say they are the first to provide a visual explanation of the cause for all that noise.
And armed with that knowledge, they’re in a better position to make helicopters quieter and more comfortable, good news for civilian and military pilots and passengers.
To answer the question of why helicopters are so noisy, researchers set up camp in a limestone quarry and pushed skilled pilots to pull off risky maneuvers just 30 feet above the ground.
In a January press release, the DLR explained that most noise comes from the helicopter’s main rotor. As it spins, air pressure drops above each blade, and rises below it (pushing the helicopter up). To even out the pressure difference, air flows around the blade, creating a concentrated vortex. What the vortex meets the next blade, you get a vibration — sound.
The clever bit is how the German researchers found a way to capture that effect on camera.
They took advantage of a common phenomenon: the way air seems to shimmer on hot days (due to changes in air density, which refract the light). Against the right background, that shimmering makes the air vortices created by helicopter blades visible.
Last year, the DLR researchers successfully visualized those rotor blade vortices by flying in front of a rocky background in the Alps, and over fields and meadows.
Recently, they took things to the next level, with a BO 105 helicopter flying in the limestone quarry near Hanover. After setting up 10 cameras at various angles, the team asked the pilots to rock the helicopter just 30 feet above the ground, in front of an exposed rock face.
It paid off: The experiment generated the first 3D images of an in-flight helicopter’s rotor blade vortices.
The DLR says it plans to continue this kind of testing, and the results could help make helicopters quieter and more comfortable.
Here’s a composite of the vortices seen from different angles:
image: https://static.businessinsider.com/image/52f10d0beab8ea5d69c2ff0f-1200/image.jpg
And some photos from the experiment in the quarry:
image: https://static.businessinsider.com/image/52f10d0aecad04491f4a97c4-1200/image.jpg
image: https://static.businessinsider.com/image/52f10d0c6bb3f7257daad56b-1200/image.jpg
image: https://static.businessinsider.com/image/52f10d0cecad044b1f4a97c5-1200/image.jpg
Read more at https://www.businessinsider.com.au/scientists-why-helicopters-are-so-loud-2014-2#A25AMIshcpUSGSQ0.99
^ tarikh khabar 2014
@Hack-Hook
be nazaram amricaeha hamin alan helicopteraye kamsaro seda darand va dar hal stefade hastand
va goya in alman ha ham dar hal sakht modelaye bisaro seda tar hastand .
shocked to see sadegh zibakalam given 18 month prison sentence... hes my second personal favorite political analyst after mohammad marandi.
apparently he gave an interview to german media saying the protests showed the peoples frustrations with the entire system. and if another referendum was held today, 70% would vote no to a Islamic republic.....
this is a critical moment for the government I think. I think Rouhani said it best when he said something along the lines: just because we chose to live a certain lifestyle 2 generations ago doesn't mean we should be forcing onto others
the biggest threat to irans government are themselves. a handful of really old stubborn ultra conservative mullahs in Qom Will bring about the death if they continue this way. Whats the point of giving out 2 year prison sentences for bad hijab? being the only country on earth forcing hijab on women and angering a huge chunk of the country for something so petty (even the governments own figures say "49%" disagree with forced hijab)
They need to concentrate on the big picture, and at least stop harassing people with petty things. Otherwise were weakening our country and opening up avenues for foreign enemies.
apparently he gave an interview to german media saying the protests showed the peoples frustrations with the entire system. and if another referendum was held today, 70% would vote no to a Islamic republic.....
this is a critical moment for the government I think. I think Rouhani said it best when he said something along the lines: just because we chose to live a certain lifestyle 2 generations ago doesn't mean we should be forcing onto others
the biggest threat to irans government are themselves. a handful of really old stubborn ultra conservative mullahs in Qom Will bring about the death if they continue this way. Whats the point of giving out 2 year prison sentences for bad hijab? being the only country on earth forcing hijab on women and angering a huge chunk of the country for something so petty (even the governments own figures say "49%" disagree with forced hijab)
They need to concentrate on the big picture, and at least stop harassing people with petty things. Otherwise were weakening our country and opening up avenues for foreign enemies.
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