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Guest Rockcliffe

Ice in FS?

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Is ice modelled in FS?I didn't think so but an interesting thing happened this evening while I was flying in realtime weather with ActiveSky wxRE. I had flown the new RealAir C-172SP in clouds for a couple of hours and was on final to land. My speed was 70 KIAS and I had just set flaps 20 degrees. Pitot heat was on. A that point the stall warning sounded and the plane began to pitch. I lowered the nose and added full power. The horn continued to sound as the plane accelerated out of the white arc. At that point I got the "plane overstressed" message. Annoying because this was my first crash in a year or so.This would be unexpected behavior in a Skyhawk. The plane should not stall in that configuration. Wings were level and it was well above any stall speed, on a stabilized decent at the time the warning sounded. Why would the stall continue as the plane accelerated after adding full power? Also, how could the plane suffer a structural failure (of the flaps?) at the same time the wing was stalled?The only real world scenario I can image that would account for this would be if ice on the wings had raised the stall speed. The POH of a real Skyhawk recommends against flaps when ice is present because the altered flow of air can reduce stabilizor effectiveness. I can't imagine a real Skyhawk breaking up so easily because 20 degrees were deployed beyond white arc. Also, the airport was Waterloo, Iowa (ALO) and no freezing temperatures were reported at my altitude.I considered the possibility of wind shear causing the stall. However there was no drop in indicated airspeed thoughout the whole sequence and the stall continued as speed increased.Any thoughts? Was this modelling something real or just a glitch in the program or flight model? Is is aerodynamically likely for a stalled wing to be stressed to the point of failing?

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I have had the same problem with a number of planes, including the RealAir.After taking of from Darlington I had to fly through a cloud layer, and after a while my pitot tube became blocked, airspeed indicator dropped to zero. I kept climbing, but my descent rate dropped and the plane became difficult to control. I got out of the clouds but I couldn't maintain the climb, and although I didn't have a working airspeed indicator, it seemed to me that the plane was close to stall speed, even with full power and level flight. Mixture was OK too.Although this experience was with the RealAir plane too, I have similar experience with other planes. I doubted that FS2002 would simulate wing icing to this level, but it's the only way I can explain this behavour.Maybe there's someone who knows if wing icing is modelled in FS2002 or not.

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Yes, I believe it is. You can't see it accumulate, but fly in clouds with icing conditions enabled and you will gradually lose lift and pitch up, as you experienced.Iced up pitot tubes are also modelled, but unfortunately, carb ice is not. Maybe in FS ACOFBlairCYOW

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Actually, Carb Ice is modelled in FS. THey don't run rough though, just loose power gradually in clouds. Have to be in clouds with icing turned on. The other thing is if you are flying a fuel injected engine there is no carb ice like the new 172. just the old 182 rg has carb heat. there you will see a drop in man. press. Just thought you guys would like to know.Adam

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This is very interresting!I would like to see a definate answere to this wing icing thing. Maybe someont could run a few tests and cruch some nubers to proove this idea?Hell, Maybe I'll just go do it now!!!!!

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Please note references to icing and turbulence in clouds in the FSUIPC module if you are using it. These may help you perform tests.

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Gonna try that too. I've run my tests in the 172 without realizing it's fuel injected.

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I'm back from my flight!!!!I've tested it out, and I can say with DEFINITY that icing IS simulated in FS!!!Here are my findings!Flight= 30nm from CSS3 to CYHUaircraft= C-172 with that new fancy flight model (I forget by who)-----> WITH PITOT HEAT ON!!!Weather= Custom weather, 22 degrees F, Dew point 22, overcast 2000-6000 FT, severe icing, no wind, no turbulence. Cruise:Initial cruise speed, 3000FT, full throttle= 120 Kts15 NM out cruise speed, 3000FT, full throttle= 100KTS5 NM out cruise speed, 3000FT, full throttle= 83KTSLanding with full flaps:approach speed= 65 KTSapproach attitude= between 5 and 8 degrees nose upapproach RPM= beween 1700 RPM and 2000 RPM Takeoff with flaps 0 and full power(immidiately after landing):Ground roll= VERY long, about 3000-3500 FTVr= 65Vertical speed= 300 FPM, and NO MORE OR STALL!Attitude= about positive 15 degreesI think theses finding are pretty conclusive, dont you? Test it out youreselves!!!!

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Thanks for your tests. It's hard to tell whether wing or carb ice is being simulated there. A fuel injected engine would rule out carb ice, but that is in the real world. Who knows how these things are simulated in FS.It would be interested to try a stall series after flying in ice for a while. You would need to try power on and power off stalls, both level and banked, using all different flap settings. Then repeat the tests where icing is not a consideration and compare the results. This should establish whether wing icing is simulated.

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Icing is simulated for sure. Just watch your airspeed drop as you fly through clouds in icing conditions.I don't think carb icing is simulated. I did see the rpm, manifold pressure drop when I applied carb heat, but I didn't see any decrease in engine performance that might have been caused by icing.Carb ice is independent of weather conditions that would cause airframe icing anyway. You can have carb ice when it's 30 Celsius if the conditions are right. Peak carb ice risk is anywhere from -5 to +25 C, depending on the moisture content of the air.

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