Icing in X-Plane

[Reece Hunter]

The cold winter hit Norcal (where I live) hard enough yesterday and today that freezing levels were down to 2000 in some areas. Last night, as I was manning Oakland Center, I solicited PIREPs, regarding icing, from several aircraft and several reported clear of ice. It may very well be the case but it occured to me that if the sim does not model icing, pilots would not detect it anyway, either visually (from external view) or with the changed aerodynamic characteristics of the airplane.

 

So then the question: Can you guys tell me if our beloved sim models icing? Please cite your sources. Personal experience with pictures is a valid source.

 

Muchos Gracias!

 

RH

[Peter Larsen 885332]

I don't have ani pics. but i have tried on a few occasions where i had to land due to icing in a Cessna.

The plane couldn't fly and started decending.

[Brandon Huey 998117]

de-icing is simulated as long as the aircraft supports it.

 

not sure what you want to see in the way of pictures, but simply set the weather conditions manually so that you can observe icing and then activate your aircraft's de-icing equipment.

 

did something happen during your flight that the equipment couldn't solve?

[Reece Hunter]

Peter,

 

Thanks for your response. Was full power available to you then? Was there visible moisture in the air when it happened? Rain, mist, snow, etc... and did you happen to note the temperature?

 

Brandon,

 

Thanks as well for your response. You are right, I have seen some aircraft that model de-icing systems. It seems implied then that since de-icing systems are modeled, icing, structural icing to be more specific (ice that sticks to the flying surfaces of your airplanes and changes its flight characteristics to that of a brick) may be also modeled. Thus, my initial question. I am looking for proof that icing is modeled in XPlane. If I see pictures with ice on the wings, I would be fully convinced and impressed

BTW, yes, carb icing is modeled.

 

Thanks to both of you.

 

RH

[Edit: typo]

[Wayne Conrad 989233]

Based on a super-quick test in both X-Plane 8.64 and 9 beta 13, X-plane models:

 

pitot icing

AOA vane icing

prop icing

engine inlet icing

window icing

frame/wing icing

 

The only icing that appears to be visible in the quick tests that I ran is window icing. However, if one is accomeulating, they are all accomeulating, so if you see window icing, you may [Mod - Happy Thoughts]ume the presence of all of the other forms of icing.

 

Deicing is close to instantaneous. There appears to be no differentiation between anti-ice and deice: All icing remedies in x-plane act as deice.

[Keith Smith]

Reece,

 

Head over tothe data input/output window, and toggle the 'icing states' option (if memory serves). Fly into visible moisture with an OAT below 0. Observe the icing figures on the data output. In not too long at all, you'll notice a decrease in RPM (for fixed pitch planes), but more importantly, your wing will become less efficient, and you'll have to increase AOA to maintain lift. Good times!

[Reece Hunter]

Keith,

 

I tried this just now. The data input/output had icing buildup option, as you mentioned, so I turned it on to display ice buildup info in the items that Wayne mentioned below. In addition, the lift and drag coeffecients for numerous wings/control surfaces were also available so I turned those on as well. I set the weather such that there were clouds as high as you can see with heavy precipitation for good measure and set the ground temp to 0F. I fired up my King Air, which appears to be certificatated(did I just pull a George W here?) for flight into known icing conditions, climbed to 20,000 feet and waited for the ice buildup parameters and drag to increase while the lift coefficient decreased. I waited for about 20 minutes and it seemed that the experiment was not going to yield the results I was hoping for.

Then of course it occured to me that the standard lapse rate for temperature (and maybe pressure) may also be modeled. It was simply too cold aloft for ice to form in the airplane. A quick increase of ground temperature verified my hypothesis as the ice buildup figures started to climb and wing efficiency began decreasing. In addition, the airplane other subsystems mentioned by Wayne started to show subtle signs of being affected by the ice buildup. Torque started to decrease in level, unaccelerated flight and airspeed indicator started to creep downwards. I watched for another 10 minutes hoping that the aerodynamic characteristics of the airplane will change drastically before I had to make breakfast for my kids. Alas, the buildup was not fast enough. I did note that once it started, the rate was linear.

I will try again later and post more notes here if you or anyone else is interested.

 

RH

[Ian Elchitz 810151]

I will try again later and post more notes here if you or anyone else is interested.

 

Yes, interested.

[Wayne Conrad 989233]

Had a little experience with icing on one of my Mitre test flights. Chicago weather is nothing like Socal. One of the Mitre rules is "No emergencies," and I can't imagine asking for higher or lower for two reasons: The frequencies are going to be swamped, and they've empasized the importance of the flight profile uber alles. So if I do get icing on a Mitre flight, I will deal with it by cheating it away.

 

On this last Mitre test flight, I got icing too bad for the plane's deicing equipment to deal with. That surprised me. My quickie test above suggested that wasn't possible. It is. Ouch. The fancy starts-with-an-M plane (Meridian? Mirage?) that I'm flying has pretty much every deicing tool in the toolbox, but it couldn't cope. So I used the opportunity to learn how to cheat icing away in X-Plane.

 

At the first sign of icing--really, before the first sign of icing--make sure that every deicing/anti-icing doodad you have is turned on. Pitot heat, prop heat, pneumatic boots, heated wings, window heat, whatever you have. Don't forget alternate air for your engine. Then bring up the weather tab. Be quick--the rules say no pauses, and this is going to cause you to be paused. Click "VFR" to stop the precip. I don't know if that's necessary, but it's what I did and it worked. Then on the lower-left under "temperature at nearest airport," click the middle digit up a few to get a balmy above-zero temperature. You need this to melt the ice off quickly. Now X out of this screen.

 

The ice should drop off quickly now. If you need confirmation that you've gotten rid of the ice, bring up the icing data display (mentioned in previous posts above) to be sure.

 

The weather will go back to nasty at the next xsquawkbox weather update, so keep an eye on that icing and be prepared to cheat again should your plane turn into an ice cube once more.

[Ian Elchitz 810151]

I am saying this as an absolute nobody in terms of authority:

 

First of all - the request for no emergencies and flying the profile for MITRE makes absolute sense.

 

However - if the intangibles of the human factor are something they are looking for, wouldn't a request to change altitudes due to icing by something they would welcome? Obviously calling for an icing emergency is out of line (and certainly will result in you being removed from the network) but asking for a different altitude? Makes sense to me. GA Aircraft and icing at this specific location during this time of year have got to be something they deal with on a regular basis.

 

I'd ask this on the MITRE OPS forum.

 

EDIT: I'd ask this on the MITRE FORUM and do whatever they say. I shouldn't be stating opinions like this without checking with someone first. I really want the MITRE event to be as useful as possible for them.

[Wayne Conrad 989233]

Betcha I'd have to ask on text. There are events in ZLA less busy than this one will be where I've been unable to check in due to frequency congestion. For that reason alone, I think faking the weather is a real solution to icing. Still, I went and asked. It's a good question.

 

(Edited to add): You are exactly right. Requests for altitude change are exactly the sort of thing they're after if it's what a real-world pilot would do.

[Reece Hunter]

Ian,

 

I am continuing to play around a little more with icing. So far nothing new to report other than what has been said in this thread. I talked to a friend of mine who has an instrument rating and has flown into icing conditions several times and one thing he pointed out is that accomeulation is not necessarily linear. He also said that just because you are in icing conditions does not mean you will accomeulate ice on the structure. So I go...huh? He immediately said "substantial and meaningful icing anyway". What he meant was you can accomeulate enough ice on the leading edge of airfoils but if you keep the airplane in level flight, only a small portion of the surface is exposed for the ice to stick to such that it does not accomeulate more to affect the flight characteristics. Then he said that it was the theory anyway.

Will beat up on it a couple more times.

 

RH

[Jeffrey Crawford 978755]

I actually had some bad icing in x-plane 9 last night (It's still in Beta though). I was cruising along oakland center at 9k and suddenly I'm in moisture (I hate that weather changes in a split second business, should be gradual over a few min.) I notice my temp is -6. I verify my pitot heat is on and go on my marry way. (I should have known better, I'm learning real IFR as we speak just didn't expect the sim to be this accurate). anyway I start to hear a different pitch in the engine and I look down and see I've lost a good 1000 rpm, I thought cool it actually is showing that my carb is icing up! I turn on the carb heat, which makes be loose another 700-1000 rpm, and I have to pitch the nose up to keep in level flight. The problem was (I guess) is that it was so cold that the pitot heat could not keep the ice off the ASI and it finally went to zero. I had to use the DME to have an idea of how fast I was going, Then the plane started to become non aerodynamic. I was falling and the nose was up high. I had full power and was still dropping at about 200 fpm. I called up ATC and asked for lower, he could only get me down to 7k I descended and arrived at 7k with about -2 degrees. The weather then cleared up and I could tell it was clear but there was ice on the gl[Mod - Happy Thoughts]! I could not get rid of it by being in clear air, but now I could see the ground so I told ATC that I needed to get lower, but could avoid terrain because I was in VFR conditions. Finally at about 5k I got 1 to 2 degrees C, and the ice slowly went away and I got my power back. The air was clear after that point so I went back up to my cruising alt. at 9000. It surprised me how close this came to real IFR stories that I've heard.

 

I don't remember experiencing this in the X-Plane 8 version.