Originally posted by 91Accord-LX
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Plane crash in NY
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Originally posted by AbsurdNY View PostWow Owequitit you really know your stuff. That was a good read on the facts. I never knew all that. I'm guessing you are in the aviation industry?
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and the de-ice system is time critical also.
in example if you turn it on too early then the ice will just form around the bubble and keep forming around it and the boot wouldn't even be able to break off the ice.
do it too late then possibly too much ice has already build up for it to break off.
so this system has it's strengths and weaknesses.
the heated wings is more practical but just not on smaller aircraft.
but on the bigger airliners or the fighter jets they have a very complex system with a lot of sensors that monitor the wings and the leading edges of the plane and activates and just melts it away.
and plus the plane was a turbo prop. so the ice form's on the blades also. but too a certain point. planes can't handle much weight.
and 1 gallon of water equals about 10 pounds of weight. so a lot of weight on that plane that makes it drop like a ball thrown up and coming back down faster then it's suppose to so..say bye bye to the glid ratio of the plane.
prayers to the people that lost their lives on the plane.
Yes my name is Dang, Don't use in vain
1992 Honda Accord EX (Coupe/Bordeaux/Auto)
1992 Honda Accord EX (Coupe/Bordeaux/H22A MT)
2008 Honda Accord EXL (Coupe/SanMarino/6spd)
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Originally posted by h22sparkle View Postthey should have used the type 4 fluid
http://en.wikipedia.org/wiki/Deicing_fluid
http://mrw.interscience.wiley.com/em...rrent/abstract
Type 4 deicing fluid provides a holdover time of 30-80 minutes after application. They also shear off at some point, which means they leave the airframe. There are also guidelines when to apply each type of fluid.
http://www.gofir.com/general/aircraft_deicing/index.htm
http://www.dow.com/PublishedLiteratu...romPage=GetDoc
FAA Advisory Circulars on Flight in Icing conditions:
http://flight.pr.erau.edu/docs/Aviat...%20ac91-74.pdf
http://flight.pr.erau.edu/docs/Aviat...20ac91-51A.pdfLast edited by owequitit; 02-14-2009, 12:52 AM.
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Originally posted by vietkid_2006 View Postand the de-ice system is time critical also.
in example if you turn it on too early then the ice will just form around the bubble and keep forming around it and the boot wouldn't even be able to break off the ice.
do it too late then possibly too much ice has already build up for it to break off.
so this system has it's strengths and weaknesses.
the heated wings is more practical but just not on smaller aircraft.
but on the bigger airliners or the fighter jets they have a very complex system with a lot of sensors that monitor the wings and the leading edges of the plane and activates and just melts it away.
and plus the plane was a turbo prop. so the ice form's on the blades also. but too a certain point. planes can't handle much weight.
and 1 gallon of water equals about 10 pounds of weight. so a lot of weight on that plane that makes it drop like a ball thrown up and coming back down faster then it's suppose to so..say bye bye to the glid ratio of the plane.
prayers to the people that lost their lives on the plane.
Water is actually 8lbs per gallon, but yes, you are right. They can't handle much additional weight, since they are typically flown as close to max weight as possible (more revenue). It doesn't take much coverage of the fuselage or wings to acrue a large amount of weight. However, the most detrimental part is the affect buildup has on the lifting ability of the wing. 6 grains of salt per square inch can decrease a wings lifting ability by over 30%. Imagine what a large buildup of ice can do. Of course, that is in addition to the weight.Last edited by owequitit; 02-14-2009, 12:54 AM.
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For those curious about all of the "icing" and "deicing" talk, it is relatively simple. Moisture will build and freeze on a surface if it comes in contact with it. You have probably seen it on the windshield of your car during the winter. The same thing happens with an airplane wing, or structure. The problem with airplanes, and the reason it is so critical is that lifting surfaces on an airplane are EXTREMELY sensitive to clean airflow. Clean airflow doesn't have disturbances, caused by imperfect flow around or over ice. Thus, airplanes CAN NOT fly safely with ice or frost buildup on the lifting surfaces. When frozen/freezing moisture builds on the surface of an airplane, this is call "icing." Here are some pictures of what "icing" looks like:
Rime Ice:
Rime Ice forms when supercooled droplets freeze instantly on impact and usually forms crystals along the stagnation point of the airfoil (the point where air neither goes over or under the wing, which is usually right along the leading edge. You can see where it forms in the "Rime Ice" pictures above.
Clear Ice:
http://www2.tech.purdue.edu/at/cours...0ice%20alb.JPG (this is the probably the best icing picture here, but is HUGE, so I just gave the link.
This is the worst ice to encounter, because it can do two things. It can either freeze right after hitting the surface, or it can freeze a little longer after hitting the surface. When it freezes right away, it tends to make very odd looking ice sculptures on the wing, often in the shape of a "horn." It can also flow back along the wing, and freeze BEHIND the equipement designed to remove it. Obviously, this is a SEVERE problem, because at that point, you have no way to prevent its accumulation or remove it from the lifting surface. I am looking for pictures of the horns, as I have seen them and know they exist, but the internet isn't helping much. When I find it, I will add it.
You can see in the pictures above how it has a more clear shape, and has clearly run back along the wing, as opposed to just making crystals.
Mixed Ice: Simply a mixture of Rime and Clear Ice.
Deicing:
This is simply the removal of ice accumulations from the lifting surfaces of an airplane, so that it may safely fly. Often, this is done on the ground at the gate, or just prior to departure, so that there is minimal time between removal and takeoff. It is usually accomplished by spraying the aircraft with a hot mixture of glycol (one incredient in antifreeze) that simultaneously removes frost, snow and ice, and also helps prevent if from forming during a certain time (holdover time). This gives the airplane time to get in the air before frost and ice start to accumulate on the airplane again.
Once the airplane is in the air, if it is equipped with deice or anti-ice, it has more protection, because the moisture will approach from the front of the wing. On the ground sitting there, it is subject to having ice or snow freeze on the surface, behind where the aircraft has the ability to remove it. Once the airplane has taken off, depending on the type of fluid, the fluid will start to "shear" and flow off of the wings and lifting surfaces where it was sprayed. Once this happens, the only protection the aircraft has is whatever equipment it was built with to remove ice.
Here are some videos of airplanes being deiced:
Once the airplane is in the air, there are several ways to protect it from ice. The two most common are either pneumatic "deicing boots" simply called "boots" or bleed air heated surfaces. Most large airliners use heated surfaces, while most turboprobs and smaller airplanes use "boots." There is another system that is becoming more common on smaller aircraft (ones that typically wouldn't be able to even fly into icing such as small Cessnas etc) called the "weeping wing" system. This system uses a glycol based solution similar to what is used to deice the airplane, and excretes it through microscopic holes in the leading edge of the wing. This allows the fluid to flow back and coat the wing, adding ice protection in the process. Just as the deice fluid prevents ice formation for awhile, so does this system. Since the fluid ultimately shears and comes off the wing, it just keeps secreting more fluid.
Here is a video of the boots in operation:
You will notice that the ice suddenly disappears, and then you can clearly see the "ridges" that form on the boots as they inflate fully. This is similar to the system used on the airplane that crashed.
Here is an interesting icing video by NASA.
Some more icing videos:
For the record, most icing encounters are usually only a few minutes. Even large airplanes try to either climb through or descend through the icing as quickly as possible. It isn't someplace you want to see as the airplane can easily pick up ice faster than it can shed it, and you never have total protection from ice forming in places that your aircraft doesn't have the ability to remove it. Still, in only a few minutes, you can pick up some SERIOUS ice. One pilot told a story of taxiing to the gate, and all the mechanics were standing around looking at something. After all the passengers had left, the pilots went out to see what was there. On the tailplane there was 11" of solid ice built up, even though they weren't in the icing for more than a couple of minutes.Last edited by owequitit; 02-14-2009, 01:59 AM.
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