Frost "spikes"?

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AirCanuck
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Frost "spikes"?

Post by AirCanuck »

Right, I have heard of this referenced a few times now as I prepare for my SAMRA exam. Frost spikes or ice needles. A friend emailed me talking about a question he had, stating

"A thin layer of 0.10% and 0.15% frost with spikes underneath the wing will effect an aircraft's climb. It had to do with climb segments. No option to pick an answer that says go deice. It wanted aerodynamic effects."

I have heard a couple people talk about exceptions to contaminated wing rules with ice needles or frost spikes, etc. The ONLY exception I can find is that with cold soaked wings causing frost under the wing aircraft can still depart if their manual specifies rules (seems generally to be at 1/8" frost)

Anyone have any pointers? I've read through the TC guide on ground de icing and as many other documents as I can get my hands on.
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AirCanuck
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Re: Frost "spikes"?

Post by AirCanuck »

A friend just found a document which makes reference to frost spikes, saying that they form at 0.004", which was another number I have seen thrown about. I have seen various statements saying that you can still take off with certain thicknesses.. but never been able to find an actual official source.

Perhaps this is what they were looking for? From the TC "When in doubt" pub on deicing.

"Frost initially forms as individual grains about 0.004 inches in diameter. Additional build-up comes through grain growth from 0.010 to 0.015 inches in diameter, grain layering, and the formation of frost needles. Available test data indicate that this roughness on the wing lower surface will have no significant effect on lift, but it may increase drag and thereby decrease climb gradient capability which results in a second segment limiting weight penalty"

Anyone know much about this?
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Rodz
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Re: Frost "spikes"?

Post by Rodz »

There is a good publication from TC - Aircraft Critical Surface Contamination Training: http://www.tc.gc.ca/publications/en/tp1 ... 10643e.pdf
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shimmydampner
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Re: Frost "spikes"?

Post by shimmydampner »

Sounds just like the kind of pertinent info TC would want flight crews to know. It’s why I always carry a micrometer in my flight bag.
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Lightchop
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Re: Frost "spikes"?

Post by Lightchop »

When in doubt, just spray. Ain't my money.
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Lightchop
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Re: Frost "spikes"?

Post by Lightchop »

Also block growth.
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AirCanuck
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Re: Frost "spikes"?

Post by AirCanuck »

shimmydampner wrote:
Sun Sep 30, 2018 6:46 pm
Sounds just like the kind of pertinent info TC would want flight crews to know. It’s why I always carry a micrometer in my flight bag.
My thoughts exactly. These questions are often so ridiculous. But I know this is one of them...
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455tt
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Re: Frost "spikes"?

Post by 455tt »

AirCanuck wrote:
Thu Sep 27, 2018 10:58 am
Right, I have heard of this referenced a few times now as I prepare for my SAMRA exam. Frost spikes or ice needles. A friend emailed me talking about a question he had, stating

"A thin layer of 0.10% and 0.15% frost with spikes underneath the wing will effect an aircraft's climb. It had to do with climb segments. No option to pick an answer that says go deice. It wanted aerodynamic effects."

I have heard a couple people talk about exceptions to contaminated wing rules with ice needles or frost spikes, etc. The ONLY exception I can find is that with cold soaked wings causing frost under the wing aircraft can still depart if their manual specifies rules (seems generally to be at 1/8" frost)

Anyone have any pointers? I've read through the TC guide on ground de icing and as many other documents as I can get my hands on.
Under-wing frost needles etc. caused by cold soaking have "no significant effect on lift but will increase drag and decrease climb gradient capability resulting in a second segment limiting weight penalty" (according to MC's ATP course text).
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CL-Skadoo!
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Re: Frost "spikes"?

Post by CL-Skadoo! »

When you pass the SAMRA, I assume you're buying everyone on this board a pretty nice dinner
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AirCanuck
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Re: Frost "spikes"?

Post by AirCanuck »

455tt wrote:
Mon Oct 08, 2018 2:34 pm
AirCanuck wrote:
Thu Sep 27, 2018 10:58 am
Right, I have heard of this referenced a few times now as I prepare for my SAMRA exam. Frost spikes or ice needles. A friend emailed me talking about a question he had, stating

"A thin layer of 0.10% and 0.15% frost with spikes underneath the wing will effect an aircraft's climb. It had to do with climb segments. No option to pick an answer that says go deice. It wanted aerodynamic effects."

I have heard a couple people talk about exceptions to contaminated wing rules with ice needles or frost spikes, etc. The ONLY exception I can find is that with cold soaked wings causing frost under the wing aircraft can still depart if their manual specifies rules (seems generally to be at 1/8" frost)

Anyone have any pointers? I've read through the TC guide on ground de icing and as many other documents as I can get my hands on.
Under-wing frost needles etc. caused by cold soaking have "no significant effect on lift but will increase drag and decrease climb gradient capability resulting in a second segment limiting weight penalty" (according to MC's ATP course text).
yeah, I quoted that above - found it eventually. Thank you!
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AirCanuck
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Re: Frost "spikes"?

Post by AirCanuck »

CL-Skadoo! wrote:
Mon Oct 08, 2018 3:05 pm
When you pass the SAMRA, I assume you're buying everyone on this board a pretty nice dinner
Suppose I'd better! I'd rather make it rounds of beer....
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455tt
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Re: Frost "spikes"?

Post by 455tt »

Hope you do well on the SAMRA - good luck!
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FenderManDan
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Re: Frost "spikes"?

Post by FenderManDan »

F me. had this question on saron #6. So this shit shows up on both. Same with the hydroplaning.
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FenderManDan
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Re: Frost "spikes"?

Post by FenderManDan »

F me. had this question on saron #6. So this shit shows up on both. Same with the hydroplaning.
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AirCanuck2
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Re: Frost "spikes"?

Post by AirCanuck2 »

AirCanuck, which exam versions did you have?
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