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Author Topic: Question on tail vs wing icing  (Read 5232 times)

Offline phil-s

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Question on tail vs wing icing
« on: February 18, 2009, 10:20:57 AM »
Starting a new thread because question is very specific. i watched the NASA video that one of the moderators (Jason?) so kindly posted, twice, before I noted the very critical finding that rime ice accumulates on horizontal stabilizer leading edge faster than on wing leading edge BECAUSE (according to the video) the former has a sharper (thinner) airfoil.  This finally explained to me why one might expect tail ice w/o wing ice, and why NASA did its flight tests with simulated ice accretion only on the tail surface. But this begs a further question:

Why does a sharp leading edge accumulate ice faster than a blunt one?

Anybody help me out here? 

Phil



Offline KSYR-pjr

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Re: Question on tail vs wing icing
« Reply #1 on: February 18, 2009, 11:10:18 AM »
Why does a sharp leading edge accumulate ice faster than a blunt one?

It's all relative to the exposed surface area of the leading edge.  My understanding is that since there is less surface area on the smaller leading edge, the building ice will become a larger, more critical percentage of that leading edge faster.   Therefore that airfoil will be negatively affected by the building ice more quickly than the leading edge with the greater surface area (i.e. main wing).

Offline phil-s

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Re: Question on tail vs wing icing
« Reply #2 on: February 18, 2009, 03:09:54 PM »
Peter - That makes sense but (if I recall correctly) the NASA video actually shows both wing and stabilizer leading edges completely covered with ice, with the accumulation on the stabilizer extending maybe twice as far "out" (forward) as the one on the wing. I wonder if the blunt edge creates more turbulence than the sharp edge, thus the blunt edge sheds some of the moisture before it can freeze? Certainly the blunt edge creates more drag. -- Phil 

Offline joeyb747

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Re: Question on tail vs wing icing
« Reply #3 on: February 19, 2009, 06:18:52 PM »
It also has to do with "disturbed" air passing over the tail after it crosses the wings. Most wings have vortex generators on the upper surface that "swirl" the air after it passes over the wings. So, in a sense, the tail is getting "more" air...if you will.