Hi,Not being on the NGX beta team, I have to ask the team one thing that came into mind after reading the NGX Brakes thread. Needless to say, the details modelled involving braking and brakes in the NGX create a feeling of respect :). They know what they are doing.So, what I am asking about is the cold soaking phenomenon that can cause airframe icing. Through various mechanisms. One of the most common ones being the one where you land a jet to a warm and humid place with some very cold fuel in the wings. Clear ice is formed on the top of the wing when the water tied to the humid air comes in contact with the cold airframe. Warm fuel is then needed to get rid of this problem.Is it possible to recreate this phenomenon in FSX ?---cold soaked effect:The wings of a/c are said to be "cold soaked" when they contain very cold fuel as a result of just having landed after a flight at high altitude or from having been re-feulled with very cold fuel. Whenever precipitation falls on a cold-soaked a/c when on the ground, clear icing may occur.Even in ambient temperatures between -2 degrees Celsius and +15 degrees Celsius, ice or frost can form in the presence of visible moisture or high humidity if the a/c structure remains at 0 degrees Celsius or below. Clear Ice is very difficult to be detected visually and may break loose after takeoff. The following factors contribute to cold-soaking: temperature or quantity of fuel in fuel cells. type and location of fuel cells, length of time at high altitude flights, temperature of refuelled fuel and time since re-feulling.---rgds,Tero

I doubt it makes sense to go after such things within confines of FSX. We don't even have reliable winds, temperatures or visibility so talking about icing is like asking to have expensive artwork in a subsidized housing unit. :( Not to mention that your "cold soaking" includes element of time - who wants to sit "in FSX" for hours and wonder about ice accumulation. Any such thing is doomed to have more in common with a cheap game than with a serious flight simulation. Folks tend to have very simplistic understanding of aircraft ice which in real life is actually quite a complicated phenomena - just right temperatures and visible moisture are not enough to cause icing - we are dealing with complicated thermodynamics here, way, way beyond what a programmer can do in FSX. I personally am against any serious simulation company to waste effort on such stuff - at least until we first make some quantum leaps in basic weather modeling.

Actually, the problem is somewhat more relevant where the NG is concerned than with other aircraft, as NG 737 models can be prone to the phenomenon unless measures are taken to prevent it. This is because the NG had its fuel tanks relocated from where they are on classic and original 737s, which was necessary when Boeing beefed-up the undercarriage on the 737 NG because they knew it would require additional clearance from tail strikes because of the proposal to develop the 900 and 900ER models. The new fuel tank location means that more of it comes into contact with the upper wing surface than on previous 737 variants, thus the cold fuel can cool the wing and cause the problem. But, and it's a big but...In the event, there are actually guidelines issued by Boeing to prevent cold soaked icing from presenting too much of a problem, which are essentially rules about taking off if one suspects non-environmental icing is present: Basically they recommend landing with less than 9,000lbs of fuel on board, so that the cold fuel doesn't cool the wing surface too much. There are lines painted on the wings of NGs which mark the areas where it is permitted to have non-environmental icing and still go for a take off. The gist of this is, if there is 1.5mm or more of ice on the bottom of the wing, then you may have a problem on the upper wing surface and should inspect it and get it cleared if it is bad. If it is not beyond the painted markings on the wings, and if the control surfaces and leading edges are free of ice and any ice that is present outside of those areas is evenly distributed on both wings (which isn't always the case if the sun is low down and one wing is in the shade), and if it isn't raining and the temperature is above freezing, then you are good to go.I guess it would be possible to program something in there which reduced the lift if you'd landed with full tanks and the weather was within certain parameters as far as moisture content was concerned, since that would just be a case of the program ticking a few boxes if those criteria were met, but at best it would be an approximation. More of a problem however, is that since there is no real way for you to perform a walk around inspection in FS unless you have EZDOK or some such (and even then you'd need a set of icing textures or polygons to simulate icing on the wings), there's no way to simulate detecting the problem as pilots would do on the real thing. More to the point, even if you could, there's no way in FS to de-ice the wings either unless that too was subject to some custom creativity and animated de-icing trucks.So these issues would also have to be tackled, and you can see where that's going, in that you'd be opening a can of worms with regard to having to develop a means to have it affect the flight model, based on the weather from a previous flight and the weather and humidity on the ground, plus develop a means to test for it visually, then have it either dissipate naturally based on the sunlight, or create some sort of realistic de-icing truck simulation. And all this for an issue which really isn't that common a problem, for if it was a common problem, then you could be damn sure that budget airlines such as Ryannair, who turn aircraft around in about 25 minutes tops, would have bought the A320 instead, because they wouldn't want an airliner that had to be deiced every time it landed while there were A320 pilots taxying past it laughing their asses off.Al

I doubt it makes sense to go after such things within confines of FSX. We don't even have reliable winds, temperatures or visibility so talking about icing is like asking to have expensive artwork in a subsidized housing unit. :( Not to mention that your "cold soaking" includes element of time - who wants to sit "in FSX" for hours and wonder about ice accumulation. Any such thing is doomed to have more in common with a cheap game than with a serious flight simulation. Folks tend to have very simplistic understanding of aircraft ice which in real life is actually quite a complicated phenomena - just right temperatures and visible moisture are not enough to cause icing - we are dealing with complicated thermodynamics here, way, way beyond what a programmer can do in FSX. I personally am against any serious simulation company to waste effort on such stuff - at least until we first make some quantum leaps in basic weather modeling.

Michal,With respect, it's not "my cold soaking".It's as simple as: land a jet to a warm greek island with very cold fuel in the tanks and you'll get ice on the wing during a 1h turnaround, if conditions are suitable.These kinds of things make the difference between the real and simulated world. I am a little taken aback by the kind of idea that this is somehow "not relevant in the NGX realistic operations". Actually quite far from it. And shows how very little some of the sim pilots seem to understand about real world ops.And I do understand the problematics of creating something like this in FS too. Just an idea that popped into my mind after reading the elaborate mechanisms involved in the Brakes. Wouldn't you agree that if I had asked for the possibility of such depth of modelling for the brakes that you could have replied similarly? Read Rob's description of the Braking System again, and then think about how "out of FS" it seems to be. Tero

Wouldn't you agree that if I had asked for the possibility of such depth of modeling for the brakes that you could have replied similarly?

No, I would not agree because I would not have replied similarly. The reason is very subtle but profound - brake behavior is very well understood and can be described in a few well defined equations in Physics. Also brakes is something that pilots must be operationally aware of all the time - even taxing heavy aircraft at busy airports can overheat them. Your "cold soaking" on the other hand is as elusive as Dust Devil - it may happen or may not. You can do 10000 landings on your greek islands and never have it happen. A mathematician or physicist would say that brakes can be perfectly well simulated to 1-degree approximation but your cold soaking can not and this is a huge difference.

No, I would not agree because I would not have replied similarly. The reason is very subtle but profound - brake behavior is very well understood and can be described in a few well defined equations in Physics. Also brakes is something that pilots must be operationally aware of all the time - even taxing heavy aircraft at busy airports can overheat them. Your "cold soaking" on the other hand is as elusive as Dust Devil - it may happen or may not. You can do 10000 landings on your greek islands and never have it happen. A mathematician or physicist would say that brakes can be perfectly well simulated to 1-degree approximation but your cold soaking can not and this is a huge difference.

Ok :)Tero

Cold-soaking is just the physics of thermodynamics exactly as the brake system is. If the thermal energy of the airframe is sufficiently below the dew temperature of the air, then condensation will form. If the thermal energy is low enough, and other conditions are right, that condensation will form ice. Whether FSX has enough parameters available to model all of this is a separate question, to which I suspect the answer is no.A more basic question this throws up is whether the NGX will support turn-around flights? Can I take-off, land, refuel and take-off again? Most complex models do not handle this well.