How much ice?

[carusoam]

Icing and aerodynamics are very interesting when combined with dynamics...

1) The end effects of disturbed air flowing around the wing tip kept ice from forming there?

2) The rivets on top of the horizontal stabilizer are showing another pattern of disturbed air flow?

3) Ice sticks to the spinner up until the spinners radius increases the centripetal force too much?

Thanks for sharing the photos and experience...

Best regards,

-a-

Edited January 22, 2017 by carusoam

[bradp]

Remember that the AOA gauges are not useful for a contaminated wing. L\D ratio and critical AOA may be significantly and negatively impacted by icing accretion.


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[aviatoreb]

1 hour ago, bradp said:

Remember that the AOA gauges are not useful for a contaminated wing. L\D ratio and critical AOA may be significantly and negatively impacted by icing accretion.


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I disagree - They are still useful - as long as they are resistant to ice they still can read angle of attack.  I got the heated angle of attack probe so that it will still give me a reading of angle of attack.  

However I agree with the spirit of what you said - the critical angle of attack will become shallower as the wing becomes contaminated -so what was the critical angle of  attack will no longer be the stall point, but it will happen sooner.  I still find the concept of knowing what is the specific angle of attack and perhaps having the ability to adjust accordingling to be more useful than just not knowing.

That said - best not to be there.

[Bennett]

I disagree - They are still useful - as long as they are resistant to ice they still can read angle of attack.  I got the heated angle of attack probe so that it will still give me a reading of angle of attack.  
However I agree with the spirit of what you said - the critical angle of attack will become shallower as the wing becomes contaminated -so what was the critical angle of  attack will no longer be the stall point, but it will happen sooner.  I still find the concept of knowing what is the specific angle of attack and perhaps having the ability to adjust accordingling to be more useful than just not knowing.
That said - best not to be there.

The Dynon SkyView system offers a heated AOA probe which I had installed. Never had any ice in the DOVA, as I think any ice would have been a huge problem. The weight of ice would have been critical, and the wing was fully flush riveted and designed for laminar flow to the degree possible. She was legally IFR because the manufacturer said it was (even though Rotex did not certify the engine for IFR). The LSA rules are somewhat loose in applications. The reason I mention this is that I believe (hope) that Dynon glass panels (complete IFIS systems) just might be allowed into our Mooneys in the next few months. Should that actually happen, if might make sense to have the optional heated AOA installed, even if the accumulation of ice would effect the accuracy of the AOA.


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[aviatoreb]

1 hour ago, Bennett said:

The Dynon SkyView system offers a heated AOA probe which I had installed. Never had any ice in the DOVA, as I think any ice would have been a huge problem. The weight of ice would have been critical, and the wing was fully flush riveted and designed for laminar flow to the degree possible. She was legally IFR because the manufacturer said it was (even though Rotex did not certify the engine for IFR). The LSA rules are somewhat loose in applications. The reason I mention this is that I believe (hope) that Dynon glass panels (complete IFIS systems) just might be allowed into our Mooneys in the next few months. Should that actually happen, if might make sense to have the optional heated AOA installed, even if the accumulation of ice would effect the accuracy of the AOA.


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I would consider that dynon if it available

but  have the alpha system aoa with heated probe and voice annunciations "getting slow", etc

interestingly it is a great ice detection tool.  As you know I have inadvertent tks so I am supposed to not be in ice / get out!

anyway the alpha systems probe is a narrow sliver that sticks out of the bottom of the wing.  So being narrow I assume it gets ice even easier and faster than the wing. 

So if I leave the heated probe OFF then any ice - even a tiny bit clogs the pressure holes in the probe and the aoa thinks I stalled in level flight even at say 150+ias.  So I get an aural "getting slow" and stall colors on the aoa due to ice long before I can see anything on the wings or windshield.  Plus I use tks preemptively just in case anytime I'm in a winter cloud - so there is the problem of how do I know if I'm in light icing if the tks is easily handling it?  That's the worry with a preemptive tks system / how do you know so you can get out?  Well now the aoa can tell me.  So I can react immediately say by changing altitude plus now turning on the aoa probe heat the aural will clear and stop saying getting slow.  This has happened to me twice in the last two years when there was not supposed to be ice Abd I otherwise would not have known there is ice.

i consider this a feature not a bug.

[kortopates]

2 hours ago, aviatoreb said:

I disagree - They are still useful - as long as they are resistant to ice they still can read angle of attack.  I got the heated angle of attack probe so that it will still give me a reading of angle of attack.  

However I agree with the spirit of what you said - the critical angle of attack will become shallower as the wing becomes contaminated -so what was the critical angle of  attack will no longer be the stall point, but it will happen sooner.  I still find the concept of knowing what is the specific angle of attack and perhaps having the ability to adjust accordingling to be more useful than just not knowing.

That said - best not to be there.

+1

In fact, NASA provides some good quantitative data on this showing only a couple minutes of all kinds of icing (Clear, Rime, Mixed) all reduce the wings max AOA down to about 2/3's of a clean wing.  For the GA example they provide, the clean wing max AOA is about 19 degrees, then with just a couple minutes of icing exposure it drops to about 12 degrees. after that point, another 20 minutes of typical exposure reduces the max AOA only a bit more (11 degrees rime to 8 degrees critical with clear). The key point is that just a couple minutes of exposure can double the drag, reduce the max lift by 25-30% and reduced the critical AOA by about 8 degrees. All this good data in in the online NASA icing course. And it points out among other things its useful to know were 8 degrees less (or more) AOA is from normal critical AOA is on your display so you can keep a healthy margin away till landing should you find yourself with a contaminated wing emergency. 

Edited January 24, 2017 by kortopates

[N201MKTurbo]

On ‎1‎/‎21‎/‎2017 at 8:44 PM, thinwing said:

I don't think so!

Actually done it...

[thinwing]

5 hours ago, N201MKTurbo said:

Actually done it...

Cold fingers?

[N201MKTurbo]

30 minutes ago, thinwing said:

Cold fingers?

Whole arm! You have your armpit shoved through the window. 

i have landed looking through the ice window. That should be part of the instrument check ride.

 

Before anybody starts thinking I'm a fool, this all happened back in the eighties. My chicken factor has gone way up sense then.

Edited January 24, 2017 by N201MKTurbo

[tigers2007]

The reason I mention this is that I believe (hope) that Dynon glass panels (complete IFIS systems) just might be allowed into our Mooneys in the next few months.

I called Dynon yesterday and spoke with a sales rep regarding a separate matter but I asked about the future of Skyview or even their autopilot with the D10A in a Mooney. He made it clear that it would be very complicated for either of those to be integrated into our aircraft due to the certification costs. Specifically, it was rather simple to add the Mooney, Maule, etc to the EAA C172 STC for the D10A as the application is nearly identical no matter which aircraft it is in. In regards to an autopilot, the certification procedure is much more aircraft specific and rather expensive. He didn't think the Skyview replacing the six pack instruments would be happening anytime soon too.


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