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#11
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PaulaJay1 ) wrote:
I brought it home to calibrate it and found that it read 2 deg high at 25, 45, and 65 deg. How did you calibrate your thermometer for 25 degrees? -- Peter ----== Posted via Newsfeed.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeed.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= 19 East/West-Coast Specialized Servers - Total Privacy via Encryption =--- |
#12
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Both sentences actually. Recent studies of airframe icing have not been
able to produce icing above 0C. (Sorry I don't have a reference). If the static air temperature is above 0C then the water isn't supercooled, so even if the airplane is at or slightly below freezing you won't get ice. The wing's leading edge experiences a temperature increase, not a decrease. I suppose that it is possible to locate the temp probe in an area with a ram temperature rise greater than the wing. In that case, it is possible for the temp guage to read above 0C but still have the static air temperature and portions of the airplane below 0C. That would lead to icing but it is an instrument error not icing above 0C. Mike MU-2 "Peter R." wrote in message ... Mike Rapoport ) wrote: You can't unless your thermometer is wrong. Are you replying to Dave's first sentence, which is: I'd like to know how you get in icing when the temperature is +5. Or his second: I have never seen ice until the the gauge reads 0 or below. Or both? If you are replying to his second sentence, this is contradictory to my understanding that the temperature right at the leading edge of an airfoil could be up to a few degrees colder than the surrounding air, which is why I learned that airframe icing (excluding freezing rain) can occur in air temperatures above freezing. I should point out here that I am simply seeking clarification of your comment, not challenging it (as I look to you as one of the more experienced in these groups). -- Peter ----== Posted via Newsfeed.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeed.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= 19 East/West-Coast Specialized Servers - Total Privacy via Encryption =--- |
#13
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Yes I am comfortable flying in temperatures above 0 and I do plan
accordingly. Although as soon as I see 0 on the OAT then I also plan accordingly. (Like change altitude , turn around, land etc.) "Peter R." wrote in message ... Dave ) wrote: How do you know your guage wasn't wrong? I forgot to include the point of my adding to this thread: I use these experiences (granted that they are somewhat limited to two winters of IFR flying downwind of the Great Lakes, US) of encountering ice above 0c when flight planning a cruise altitude, as well as when making a go/no decision due to ice. Are you implying that you are comfortable that ice will *not* occur above 0c and therefore plan accordingly? -- Peter ----== Posted via Newsfeed.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeed.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= 19 East/West-Coast Specialized Servers - Total Privacy via Encryption =--- |
#14
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Any time air is accelerated, as it is when passing over a small-radius
surface, its temperature drops...so it is entirely possible to accrete ice when the temp is above zero. That's why you look at those surfaces first...OAT guage, struts, lower edge of windscreen where there is a lip rather than a flush surface, etc. That is also why tail feathers begin to accrete ice before the wing's leading edge does. Bob Gardner "Dave" wrote in message ink.net... I'd like to know how you get in icing when the temperature is +5. I have never seen ice until the the gauge reads 0 or below. "ArtP" wrote in message ... On 26 Jan 2004 10:08:44 -0800, (Andrew Sarangan) wrote: For example, right now the freezing level is at 5000 ft, MEA is at 2500 ft, yet we have an airmet Z that goes all way from SFC to 18k. Since the published icing conditions occur from +5 to -20 C, a freezing level at 5000 would mean icing potentially below 3000 feet. The MEA may be 2500 but the normal minimum IFR altitudes would be either 3000 or 4000 feet depending on direction and that is known icing conditions. I am sorry this frustrates you but depending on where you live a big chunk of winter is off limits to small GA aircraft trying to fly IFR. |
#15
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In article , Peter R.
writes: I brought it home to calibrate it and found that it read 2 deg high at 25, 45, and 65 deg. How did you calibrate your thermometer for 25 degrees? I put it and two reference thermometers in the freezer part of the refrigerator. I put them in the full freezer that is about 0 deg F and the digital did not display. Don't know if the battery was weak or the electronics just gave out. I didn't think that this was a problem since the inside of the plane is at least 25deg F G or higher. The 45 deg was the refrigerator and the 65 was outside temperature. Chuck |
#16
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The temperature above the wings and below the elevators could be
slightly below ambient due to the lower pressure. I don't have a number on what the temperature drop is on these surfaces, but technically it is possible to have icing on the lifting surfaces when the ambient temperature is above freezing. Sort of like carb icing in above-freezing temperatures. "Mike Rapoport" wrote in message hlink.net... You can't unless your thermometer is wrong. Mike MU-2 "Dave" wrote in message ink.net... I'd like to know how you get in icing when the temperature is +5. I have never seen ice until the the gauge reads 0 or below. "ArtP" wrote in message ... On 26 Jan 2004 10:08:44 -0800, (Andrew Sarangan) wrote: For example, right now the freezing level is at 5000 ft, MEA is at 2500 ft, yet we have an airmet Z that goes all way from SFC to 18k. Since the published icing conditions occur from +5 to -20 C, a freezing level at 5000 would mean icing potentially below 3000 feet. The MEA may be 2500 but the normal minimum IFR altitudes would be either 3000 or 4000 feet depending on direction and that is known icing conditions. I am sorry this frustrates you but depending on where you live a big chunk of winter is off limits to small GA aircraft trying to fly IFR. |
#17
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This was gleaned form talking to a Phd (meteorology) instructor,
Citation, Super Cub pilot. Water will not freeze until it is 0 C or below. Just because it is 0 degrees or below doesn't mean water HAS to freeze. There is themometer error, but there are also lower pressure areas on the wing/airframe, and due to the lower pressure, the temperature lowers. It is possible to get ice when your themometer reads above zero, but it will be zero or below where the ice is. If you get ice on your themometer and it reads above zero, your themometer is out of calibration. Peter R. wrote in message ... Dave ) wrote: How do you know your guage wasn't wrong? The digital gauge was calibrated when new and the aircraft is about one and one half years old. Is it possible that it slipped out of calibration a degree or two? I suppose. But since every icing article I have ever read states that icing can occur at temperatures higher than 0c, I have no trouble believing that my icing encounters above 0c actually did occur one to three degrees above 0c. -- Peter ----== Posted via Newsfeed.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeed.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= 19 East/West-Coast Specialized Servers - Total Privacy via Encryption =--- |
#18
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This is not about frustration, but about trying to understanding how
FAA comes up with airmets. An airmet is supposed to be issued when moderate icing is expected. If they are issuing an airmet every time there are clouds and freezing temperatures (or even above freezing), then what about light icing? ArtP wrote in message . .. On 26 Jan 2004 10:08:44 -0800, (Andrew Sarangan) wrote: For example, right now the freezing level is at 5000 ft, MEA is at 2500 ft, yet we have an airmet Z that goes all way from SFC to 18k. Since the published icing conditions occur from +5 to -20 C, a freezing level at 5000 would mean icing potentially below 3000 feet. The MEA may be 2500 but the normal minimum IFR altitudes would be either 3000 or 4000 feet depending on direction and that is known icing conditions. I am sorry this frustrates you but depending on where you live a big chunk of winter is off limits to small GA aircraft trying to fly IFR. |
#19
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#20
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On Tue, 27 Jan 2004 20:33:12 -0500, Roy Smith wrote:
When a gas undergoes adiabatic expansion, it gets cooler. There is no doubt that this happens at the leading edges of airfoils, but at the pressure drops we're talking about in any kind of airplane I'm likely to fly is very small. How small is very small? I'm not sure, but I can't imagine more than a degree or two. That is all we are discussing, whether the FAA +5 to -20 is a reasonable range for icing. |
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