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  #1  
Old 11-11-2019, 10:39 AM
bmarvel's Avatar
bmarvel bmarvel is offline
 
Join Date: Aug 2005
Location: Grand Junction, CO
Posts: 101
Default Icing Heads Up

When we built our -14A I put a short piece of black electrical tape on the outboard leading edge of the left horizontal stabilizer as an ice indicator. Since the surface with the tightest curvature is generally the first to get ice, I reasoned that this would be the likely place. When the black surface started to become white, it was time for Plan B.

As it turns out, we found out there is another location that gets ice first and is much easier to see. In our airplane we stuck with the plans as written and installed the landing lights in the wing cutouts. These in turn are covered with Plexiglas lenses which are mounted on the inner surface of the leading edge wing skins around the perimeter of the cutout.

A few months ago on a trip from Colorado to Oklahoma we had an icing encounter but the first indication was not on the electrical tape. As I turned my head to inspect the tape on the horizontal stabilizer, I noted a dim glow from the left wing landing light area that was clearly visible in daylight. My wife saw the same thing on the right wing.

As it turned out the tiny ridge between the plexi and the wing skin is the smallest radius on the airplane and true to predictions was the first place where ice formed. Each time the landing light pulsed there was a dim glow from that area, giving an early indication of even the smallest amount of ice.

An altitude change solved the problem but I thought this bit of information would be a good thing for the rest of you to toss into your bag of aircraft knowledge for the future.
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  #2  
Old 11-11-2019, 12:13 PM
Bavafa Bavafa is offline
 
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Default

Great to know... thank you for the info and glad altitude change remedied your situation.
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  #3  
Old 11-11-2019, 01:32 PM
lr172 lr172 is offline
 
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Location: Schaumburg, IL
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That is definately the place that accumulates the fastest. On the way to colorado (IFR in VMC), we went through the very top of a cumulus build up. As soon as we went in, it sounded like gravel was hitting the plane. We passed through in about 10-20 seconds. Windshield and wings were covered with a thin coat, but the turbulence area surrounding the light cutouts in the wing had over 1" long pieces of ice sticking out of them. Pretty sure it was SLD and it gave me a new appreciation of exactly how FAST ice can build up. I always thought I had a few minutes to get out of ice and this taught that may not be realistic in all cases.

Larry
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Last edited by lr172 : 11-11-2019 at 01:36 PM.
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  #4  
Old 11-11-2019, 02:01 PM
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airguy airguy is offline
 
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Location: Garden City, Tx
Posts: 5,591
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Quote:
Originally Posted by lr172 View Post
That is definately the place that accumulates the fastest. On the way to colorado (IFR in VMC), we went through the very top of a cumulus build up. As soon as we went in, it sounded like gravel was hitting the plane. We passed through in about 10-20 seconds. Windshield and wings were covered with a thin coat, but the turbulence area surrounding the light cutouts in the wing had over 1" long pieces of ice sticking out of them. Pretty sure it was SLD and it gave me a new appreciation of exactly how FAST ice can build up. I always thought I had a few minutes to get out of ice and this taught that may not be realistic in all cases.

Larry
I've had exactly one case of getting into SLD, and accumulated about 1/4" of ice in less than a minute - really scary how fast it can build up.
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  #5  
Old 11-11-2019, 02:54 PM
lr172 lr172 is offline
 
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Quote:
Originally Posted by airguy View Post
I've had exactly one case of getting into SLD, and accumulated about 1/4" of ice in less than a minute - really scary how fast it can build up.
Curious if you noticed a loss of performance, airspeed, etc. with a 1/4" of ice. I, luckily, have never accumulated that much but am curious how much the plane can take if I ever have an event like that.

Larry
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  #6  
Old 11-11-2019, 03:46 PM
rocketman1988 rocketman1988 is offline
 
Join Date: Jun 2010
Location: Sunman, IN
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Default Ice

Well, I can tell you an acquaintance got into icing conditions in a C182 in northern Wisconsin. It took full throttle to maintain a descent rate for landing. He made the landing, barely. There was a chunk of ice the size of a large softball on the spinner and between 1 and 2 inches of ice on the airframe...

You may be able to find the safety article that he wrote for aopa pilot magazine several years ago to see the photos...

Point is, in these GA aircraft, the winning move is to AVOID the ice; it can build faster than you would believe possible...
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  #7  
Old 11-11-2019, 03:53 PM
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airguy airguy is offline
 
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Quote:
Originally Posted by lr172 View Post
Curious if you noticed a loss of performance, airspeed, etc. with a 1/4" of ice. I, luckily, have never accumulated that much but am curious how much the plane can take if I ever have an event like that.

Larry
None that I could tell, but I didn't use any flaps for landing because it was in the back of my mind.
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Built an off-plan RV9A with too much fuel and too much HP. Should drop dead any minute now.
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  #8  
Old 11-11-2019, 06:35 PM
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rocketbob rocketbob is offline
 
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Location: 8I3
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One of my neighbors has a bit of time flying/evaluating the Beriev BE-200 amphibious firebomber. One day he described how the anti-ice system in that airplane works. It consists of a series of ultrasonic transducers in the wing leading edges that work very well at shedding ice. Would be neat to prototype something and try to test the effectiveness of it on the ground using some cheap ultrasonic cleaner transducers.
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  #9  
Old 11-12-2019, 05:07 AM
Handclutch Handclutch is offline
 
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Location: Bendigo, Australia
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I hadn?t heard the smallest curvature theory before (you never stop learning in aviation) but the best icing indicator I had was the OAT probe on my Twin Comanches - very visible in top LH windscreen and always the first warning. Re rapid build up, only experienced this once in decades of IFR, but in the space of a minute or less a 310 I was flying went from cruising happily at 175 kts to barely making 120 at full power - and shuddering!

Jack
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  #10  
Old 11-12-2019, 08:08 AM
AdamB AdamB is offline
 
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Location: Fremont, NH
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Quote:
Originally Posted by airguy View Post
None that I could tell, but I didn't use any flaps for landing because it was in the back of my mind.
Good call.
You don't want to cause a potential tail stall.
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