Improve icing physics on aircraft

Perhaps, but there is a lot of custom code in the Kodiak that may implement icing effect differently (I’ll ask the Dev when I can)

Nice to see the results of your first test . I’ll do some when next in the SIM with a selection of stock and 3rd party aircraft. When testing it could be good to do a ‘non-icing’ flight then, keeping all the variables the same, repeat and then note performance.

I think this thread may have unearthed an important regression in the sim: I’d suggest a change in the title to make it clear that - if confirmed by our testing - this is a bug/regression and not simply a request for improvement. That may result in greater community engagement and attention

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Unfortunately I dont have 3rd party aircraft so I cant test it by myself, however all the default aircraft have this same problem.

Icing is very user friendly, I sugest that there should be also settings for icing intensity or realism. In reality aircraft can build up ice so fast, that unprotected aircraft can stall very quickly.

I think that Asobo is aware of this and it is not a bug. It is just another realism feature which was dumped down intentionally to made this sim more usable for the majority of users.

And regarding the topic name I agree. Do you have any idea?

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How about:

‘Regression: icing no longer effects aircraft performance’

(Depending on what a bit more testing on a range of different aircraft types shows)

I don’t think anyone remotely serious about realism of the SIM - and this clearly includes Asobo- would disagree with the idea that icing is an important aspect of aviation. It must just be one of those glitches that arose during all those SUs last year.

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@hobanagerik @CharlieFox00 @FlyingsCool5650

Tagging you all as folk who’s opinions I really value.

Is this apparent regression something you are aware of? Doesnt seem to have garnered much attention and traction.

I’ve been flying around assuming my ice protection was working great…but maybe not!

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I’ll have to check. I try to stay way out in front of ice and most of my GA flights avoid it altogether. Lately I haven’t had much in the way of accumulation to the point where I’d expect it to noticeably effect performance, especially in the phases of flight where I get a little.

Will do some testing later this week.

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As will I next chance I get.

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Cessna 152 icing test

Airbus A310 icing test

As you can see, in both cases, with both aircraft’s fully contaminated by ice, you can even start to climb, no risk of stall at all.

There is no need to turn on carb heat on the cessna as well.

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have you tried icing yet?

I just noticed something odd. I had a quick test, then found out that my assistance option for visual only icing had got enabled for some reason. I switch that to ON rather than visual only, flew through icy clouds at -10F, and no ice accumulation. I then dragged the slider all the way across to one, and in the 172 I am gradually seeing it decay back to 0. It looks like the combination of weather, and altitude I was at was not letting ice build. Similarly I noticed that if the temperature is too cold, the plane defrosts itself. I would have thought that whatever ice had accumulated would remain, rather than gradually be removed.

It wasn’t until I climber to about 10,000ft that I started to see ice accumulate naturally, no matter what cloud I was flying through. I also noticed something really odd. If I dragged the ice slider to 1 I saw my airspeed drop a bit. I dragged it to 0, and it dropped again. Back to 1, another drop.

But I am seeing a reduction in lift when adjusting the slider by hand. Turn on the “Sim Forces” debug:

image

This will turn on visual representation of lift, I believe.

Zero ice

Fully iced

From the external view you can see the plane drop in altitude before the AP recovers. I think the speed drop I was seeing earlier was due to the attitude of the plane changing maybe. When I remove al the ice it noses up sharply, dropping the airspeed.

Other than those blips I see no large changes in airspeed when things settle.

I also looked at drag. I could see that when fully iced, the total weight increases by about 100lbs.

image

image

So ice is having an effect on the weight of the plane.

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I also found out that when your aircraft is parked at the apron without icing conditions and you move your drone camera to the icing conditions, your aircraft will start to acumulate ice which is also very odd.

Regarding the lift, yes the aircraft are difinitely affected by ice in this sim but the effect is very weak and acumulation of ice is very slow, at least according to me.

For your personally are you satisfied with icing simulation in this sim?

I’m not a pilot, so I can’t answer that with any degree of accuracy or confidence. :slight_smile:

I think there are some aspects of the simulation I don’t fully understand. Like should I not see an increase in drag, or parasitic drag when the airframe is iced over. It does seem to show but as you say the effect is tiny.

Looking at “other_drag”, I see an increase from “0.002” to “0.01”. I have no way of knowing whether that is correct. Similarly I see increases in “cd0”. Similarly small values of reduction in life coefficient.

But no real changes in speed. I would have thought that as the airframe ices over, at the same power level I would need a slightly higher nose attitude to maintain level flight, which would reduce speed, but I don’t think I am seeing that. I can see the plane retrim, but the airspeed recovers.

Exactly, you understand it very well.

I’m a professional pilot and as I wrote earlier, our aircraft in icing conditions can be contaminated by ice within few seconds, when the anti-ice is not turned on. Sometimes even with anti-ice turned on it might not be enough to get rid of ice.

Small unprotected GA aircraft in icing conditions can fall like a rock. In this sim you can fly your Cessna 172 in CB clouds for hours and drink your coffee at the same time.

I think there is no need to provide with more proofs that icing simulation within MSFS is not simulated correctly and does not represent and risk for a virtual pilots at all.

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I had a quick poke around in the SDK documentation. There are references to anti-ice dotted about, but only a single icing one.

icing_scalar

With this value you can scale up or down the effects of icing on the plane. This will affects the effect of icing on lift and on the weight.

The default value is 1.0 (100% of the effect).

The 172 already has this set to 1…actually scratch that, it doesn’t have it set at all! But its possible that a “default” setting doesn’t actually need to be set at all if you are happy with the default. So the scalar is still set to “1” even if not explicitly listed.

I might have a play later to see if it can be set to 200%, for example.

The accumulation rate was definitely reduced. I’m not sure about the effect though, and whether its impact was reduced. There was a time when your windshield would get iced over in 5-10 seconds.

Just tried this in the steam 172, in the “[FLIGHT_TUNING]” section of “flight_model.cfg”:

icing_scalar=3

I get a huge change in VS when flipping between no ice detected, and fully iced.

Level flight at 3000ft @ 138kts.

image

Flip to fully iced, and I’m in a 1500fpm decent:

image

Trim could not adjust fast enough. When I pulled back on the yoke I stalled, and went into a spin.

The amount of ice I can now load up has increased as well, so I’m pretty sure that scalar is doing its job!

No ice:
image

Fully iced:
image

Lift has dropped right off, with huge changes in the graphical representation.

No ice:

image

Fully iced:
image

I don’t think we can affect the rate of accumulation, but we can certainly mess with it’s effects.

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That is very nice to see, that this sim is capable of simulating this! That is exactly What I want to see when flying with unprotected aircraft in severe icing enviroment.

Otherwise there is no point of avoiding icing enviroment when it cant really end your flight. No need to turn anti-ice swtiches ON either.

Thank you for your time and testing which you have done!

However guestion remains, how is that possible, that we dont have it like this in the “normal” version of the sim?

I would suggest to also add some slider or options for realistic, normal and light icing.

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I suppose it would be one of those things difficult to simulate accurately, as no one in their right mind would voluntarily fly into those conditions to find out.

All I did was change a 1 to a 3, assuming for a moment that the setting being missing equates to 1. I have no idea whether that is realistic, as the numbers are effectively arbitrary, but it certainly gives you a new found respect for icing conditions.

Without being able to adjust the rate of accumulation, all you can do is make that number larger so that’s it’s effects are felt sooner. But that would lead to a disconnect between the visual icing, and the icing effects. Too high a number, and you might have very little visual icing yet fall out of the sky like a rock.

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You are absouletly correct, however you can find yourself involuntarily in icing conditions, it happend to many aviators and it will happen to many due to the poor weather briefing, overconfidence and so on.

Simulator should simulate all hazards and danger which can happen to you during flight in my opinion.

I dont like to compare but xplane got this right, they find the way how to simulate it, so you have to think twice before flying into the icing enviroment.

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That’s good to know!

I’m going to have a play around with

on the C208.

At least with this knowledge we can all tweak our own aircraft so that icing is actually a hazard. (But we shouldn’t have to, it should be correct ‘out of the box’)


I’m going to tweak the C208 icing scalar so that as a bare minimum it cannot stay airbourne with icing. I’ll do this as shown below:

  • Full power[2397ftlbs torque], no anti-icing, clean configuration, min weight
  • AP on
  • Icing conditions with 1 for the aircraft airframe ice accumulation value in dev console
  • Gradually increase the scalar until stall or unable to maintain altitude

I’m really curious to test both the efficacy of the anti-icing system and the effect lowering flaps has within MSFS.

Is anti-icing just magical (making you immune to icing in MSFS), or is it more realistic?

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I wonder whether the rate of ice accumulation is affected by several factors like real life (Meteorological conditions, Angle of Attack, Aircraft configuration etc.) or if it is just flat rate?

Because if it’s flat rate, that’s something else we could do with being improved too.

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Agree that the evidence is there that icing needs improvement. Not sure we can call it a regression as it was probably never well modelled in the first place!

Great job @hobanagerik :ok_hand:

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I was able to get varying amounts of icing as I played with temperature. Watch the numbers on the slider for icing, vary the temperature, and see how the rate of increase changes. I couldn’t find a way to pin that readout so every time you click away from it to change the weather it closes, but I’m pretty sure the rate change as I made changes.

I may have been doing something wrong, but I couldn’t get icing to start happening until I was about 1500ft up, no matter what temperature, and cloud height I set.

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