Carbon Brake Dust - Airbus
Only half a speed-brake
I heard this one from someone I am severly inclined to believe, but spent quite some time looking for a reference (FCOM 2, G2G w/TO perf, FCTM, FCOM blue OEBs ...). PL, can you help?
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carbon brakes
i cannot beleive boofhead pilots .....you sit in the lefthand seat ....oh i will switch on the cooling fans as i have stopped too quickly and i dont give a stuff who i cover with black soot .....where's my allowances tut tut
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Flight Detent
I can't remember where I read this...but, I think it's in the Airbus publication "Getting to Grips with Aircraft Performance".
In any event, it is not correct that the stopping capabilities of the brakes increases with temperature. Airbus also has a publication that explains carbon brakes.
"Wear" is a totally different matter, however. Specific temps for wear rates vary slightly, depending on the vendor (and their engineers, the brake design, etc.), and wear rates improve when the brakes are a little warm.
The 300 degree limitation is for wheel well fires. Airbus design circumvented the need for wheel well fire detection.
It is interesting that Boeing does not believe carbon brakes are appropriate for the 737...but they are looking at using carbon brakes for the new 737 design. (I read this in Aviation Week and Space TEchnology.)
According to Boeing, carbon brakes offer significant advantages...like weight savings...stopping capabilities...etc. But, carbon brakes get hot...and for planes like the A320 or 737, where short ground times are sometimes part of the airline's marketing plan, carbon brakes may not have the cooling times they need for the next takeoff.
Airbus solved this problem with the installation of fans....albeit fans are an option, not standard equipment....most 320's have fans installed. (Buying a 320 without brakes fans is possible, but that's like buying a Cadillac without air conditioning....they normally come with air conditioning.)
So, while the use of fans may be optional (under your airline's SOP), they should be used as per the Airbus SOP or recommendations. And, remember, the temps keep climbing while you're at the gate...peaking around 25 or 30 minutes after the landing.
So, waiting five minutes or so after landing (or just prior to gate arrival) to turn on the fans (as per Airbus recommendation) is a prudent course of action. Depending on the turn time, you still may have the fans running during the next taxi out...turning them off just prior to takeoff.
Fly Safe,
PantLoad
In any event, it is not correct that the stopping capabilities of the brakes increases with temperature. Airbus also has a publication that explains carbon brakes.
"Wear" is a totally different matter, however. Specific temps for wear rates vary slightly, depending on the vendor (and their engineers, the brake design, etc.), and wear rates improve when the brakes are a little warm.
The 300 degree limitation is for wheel well fires. Airbus design circumvented the need for wheel well fire detection.
It is interesting that Boeing does not believe carbon brakes are appropriate for the 737...but they are looking at using carbon brakes for the new 737 design. (I read this in Aviation Week and Space TEchnology.)
According to Boeing, carbon brakes offer significant advantages...like weight savings...stopping capabilities...etc. But, carbon brakes get hot...and for planes like the A320 or 737, where short ground times are sometimes part of the airline's marketing plan, carbon brakes may not have the cooling times they need for the next takeoff.
Airbus solved this problem with the installation of fans....albeit fans are an option, not standard equipment....most 320's have fans installed. (Buying a 320 without brakes fans is possible, but that's like buying a Cadillac without air conditioning....they normally come with air conditioning.)
So, while the use of fans may be optional (under your airline's SOP), they should be used as per the Airbus SOP or recommendations. And, remember, the temps keep climbing while you're at the gate...peaking around 25 or 30 minutes after the landing.
So, waiting five minutes or so after landing (or just prior to gate arrival) to turn on the fans (as per Airbus recommendation) is a prudent course of action. Depending on the turn time, you still may have the fans running during the next taxi out...turning them off just prior to takeoff.
Fly Safe,
PantLoad
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My own feeling is Airbus would not be putting it in black and white if it was just harmless black soot being blown over the ground personnel. I personally give more credit to the people who made these aircraft.
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Look at F1 cars with Carbon Brakes - they need to get some temperature in them for them to work at their best. Airbus brakes regularly exceed 300C on short runways such as ABZ
We turn the fans only if The temps are exceeding 300c and 5 mins have passed - to allow for thermal equalisation across the entire brake assembly. and Avoid oxidation of brake surface hot spots.
OR if the temps are likely to exceed 500C. Again this would be done before pulling onto stand because you can get quite a cloud of brake dust sometimes, which may cover your groundstaff- they would then be crying off to go home and get changed. We routinley turn the fans on in the after starts whenever the temps exceed 100C and off just as we line up. You must have less than 150c fans on or 300C fans off for take off.
We turn the fans only if The temps are exceeding 300c and 5 mins have passed - to allow for thermal equalisation across the entire brake assembly. and Avoid oxidation of brake surface hot spots.
OR if the temps are likely to exceed 500C. Again this would be done before pulling onto stand because you can get quite a cloud of brake dust sometimes, which may cover your groundstaff- they would then be crying off to go home and get changed. We routinley turn the fans on in the after starts whenever the temps exceed 100C and off just as we line up. You must have less than 150c fans on or 300C fans off for take off.
‘The use of autobrake LOW for normal operations helps to reduce brake wear by reducing the number of brake applications to one, and by increasing the brake temperature to moderate levels. The use of autobrake MED is recommended to reduce runway occupancy, when landing on a short or contaminated runway and when operating in LVPs.’
Carbon brake wear is related to the number of brake applications and to the temperature. hence getting the fans on
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I know carbon nano tubes aren't the same as carbon fibers but...
Carbon nanotubes may be as harmful as asbestos
Carbon nanotubes may be as harmful as asbestos
Ann Fernholm, Chronicle Staff Writer
Wednesday, May 21, 2008
PDT SAN FRANCISCO -- One of the most promising materials for the future of technology, carbon nanotubes, might be as harmful as asbestos if inhaled, according to a new study published Tuesday in the scientific journal Nature Nanotechnology.
Animal studies indicate that these long and very thin carbon molecules could cause a cancer called mesothelioma, which occurs in the lining of the lungs.
"The problem of asbestos was caused when it was released into the air, if it was handled inappropriately or incorrectly. Carbon nanotubes could do the same," said Andrew Maynard, chief science adviser to the Project on Emerging Nanotechnologies in Washington and one of the authors of the study.
"With this information, we should assume the worst, we should think of them as asbestos. But more research might relax that point of view."
Carbon nanotubes, 10,000 times thinner than a human hair, are among the materials many scientists believe will be used to build tiny electronics.
In 2001, IBM made an array of transistors out of carbon nanotubes. In 2004, General Electric created a carbon nanotube diode, and last year, UC Berkeley scientists used single carbon nanotubes to make the world's smallest radio.
Today, the most widespread application is in plastic materials reinforced by carbon nanotubes. Stronger than steel but light as plastic, carbon nanotubes are highly attractive to manufacturers of everything from sporting goods to airplanes. They can be found, for example, in some tennis rackets, baseball bats and bicycle frames.
"I would be very surprised if it is dangerous to use, let us say, a tennis racket or baseball bat containing carbon nanotubes," Maynard said. "But I do not think it is OK to tell people that we think it is safe - we've got to have evidence."
Such products, he said, should go through a number of tests investigating, for instance, what happens when they break or when the surface is rubbed against the ground. He also wonders what happens when the products are disposed of.
"Is there a chance that the nanotubes will enter the environment?" Maynard said.
The main concern, however, is the effect on people processing carbon nanotubes and manufacturing the materials containing them.
At Unidym, a Menlo Park company exploring the possibilities of using carbon nanotubes in such items as touch screens, precautions already have been taken.
"This is what we expected. It fits with the paradigm that long and skinny fibers can cause asbestosis. It does not really matter if they are made of carbon or asbestos. The key is not getting them into the body," said Ken McElrath, vice president for product development materials at Unidym's facility in Houston, which manufactures the carbon nanotubes.
To protect employees from breathing nanotubes, the manufacturing is conducted in closed ventilated systems. People working with the nanotubes also are protected by dust masks with respiratory filters.
McElrath said he found the study to contain some positive news: Shorter carbon nanotubes might not be harmful.
"We are using these kinds of findings in our product design," he said. "We try to stay away from things that potentially cause problems."
The research presented in Nature Nanotechnology used an animal model developed in the 1980s to study the development of mesothelioma, which can be caused by asbestos exposure.
Using this model, the nanotubes were injected into the abdominal cavity of mice, which is lined by tissue similar to the human lung and is a sensitive predictor of mesothelioma. After one week, there was an inflammatory response to longer versions of the nanotubes.
"This is a very important study; it is very well done. It shows that you do get an inflammation that is similar to asbestosis. What is not known yet is the long-term effect," said Vincent Castranova, involved in the nanotoxicology research at the National Institute for Occupational Safety and Health.
Also unclear is how this experimental model for mesothelioma translates into reality. Scientists do not know under which circumstances these long carbon nanotubes will form a breathable dust, or whether this dust will work its way into the lung.
"Here we run out of information," Maynard said.
Meanwhile, Castranova recommends people working with carbon nanotubes follow National Institute for Occupational Safety and Health guidelines for working with engineered nanomaterials, which involve the use of respirators and special filters to clean the air.
Carbon nanotubes may be as harmful as asbestos
Carbon nanotubes may be as harmful as asbestos
Ann Fernholm, Chronicle Staff Writer
Wednesday, May 21, 2008
PDT SAN FRANCISCO -- One of the most promising materials for the future of technology, carbon nanotubes, might be as harmful as asbestos if inhaled, according to a new study published Tuesday in the scientific journal Nature Nanotechnology.
Animal studies indicate that these long and very thin carbon molecules could cause a cancer called mesothelioma, which occurs in the lining of the lungs.
"The problem of asbestos was caused when it was released into the air, if it was handled inappropriately or incorrectly. Carbon nanotubes could do the same," said Andrew Maynard, chief science adviser to the Project on Emerging Nanotechnologies in Washington and one of the authors of the study.
"With this information, we should assume the worst, we should think of them as asbestos. But more research might relax that point of view."
Carbon nanotubes, 10,000 times thinner than a human hair, are among the materials many scientists believe will be used to build tiny electronics.
In 2001, IBM made an array of transistors out of carbon nanotubes. In 2004, General Electric created a carbon nanotube diode, and last year, UC Berkeley scientists used single carbon nanotubes to make the world's smallest radio.
Today, the most widespread application is in plastic materials reinforced by carbon nanotubes. Stronger than steel but light as plastic, carbon nanotubes are highly attractive to manufacturers of everything from sporting goods to airplanes. They can be found, for example, in some tennis rackets, baseball bats and bicycle frames.
"I would be very surprised if it is dangerous to use, let us say, a tennis racket or baseball bat containing carbon nanotubes," Maynard said. "But I do not think it is OK to tell people that we think it is safe - we've got to have evidence."
Such products, he said, should go through a number of tests investigating, for instance, what happens when they break or when the surface is rubbed against the ground. He also wonders what happens when the products are disposed of.
"Is there a chance that the nanotubes will enter the environment?" Maynard said.
The main concern, however, is the effect on people processing carbon nanotubes and manufacturing the materials containing them.
At Unidym, a Menlo Park company exploring the possibilities of using carbon nanotubes in such items as touch screens, precautions already have been taken.
"This is what we expected. It fits with the paradigm that long and skinny fibers can cause asbestosis. It does not really matter if they are made of carbon or asbestos. The key is not getting them into the body," said Ken McElrath, vice president for product development materials at Unidym's facility in Houston, which manufactures the carbon nanotubes.
To protect employees from breathing nanotubes, the manufacturing is conducted in closed ventilated systems. People working with the nanotubes also are protected by dust masks with respiratory filters.
McElrath said he found the study to contain some positive news: Shorter carbon nanotubes might not be harmful.
"We are using these kinds of findings in our product design," he said. "We try to stay away from things that potentially cause problems."
The research presented in Nature Nanotechnology used an animal model developed in the 1980s to study the development of mesothelioma, which can be caused by asbestos exposure.
Using this model, the nanotubes were injected into the abdominal cavity of mice, which is lined by tissue similar to the human lung and is a sensitive predictor of mesothelioma. After one week, there was an inflammatory response to longer versions of the nanotubes.
"This is a very important study; it is very well done. It shows that you do get an inflammation that is similar to asbestosis. What is not known yet is the long-term effect," said Vincent Castranova, involved in the nanotoxicology research at the National Institute for Occupational Safety and Health.
Also unclear is how this experimental model for mesothelioma translates into reality. Scientists do not know under which circumstances these long carbon nanotubes will form a breathable dust, or whether this dust will work its way into the lung.
"Here we run out of information," Maynard said.
Meanwhile, Castranova recommends people working with carbon nanotubes follow National Institute for Occupational Safety and Health guidelines for working with engineered nanomaterials, which involve the use of respirators and special filters to clean the air.
