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Best AI Contrail Temperature?

L

leegra

Guest
I am using Markus Brunner's AI Contrails program, and I want to see more contrails occur in FS9. The program asks for the "Maximum contrail temperature," and I wonder if anyone can tell me which "Maximum temperature" produces the most contrails. The range is from -1 through -30, and more. I'm not clear, if I should I use a lower or a higher temperature to get the maximum contrails. Thanks in advance for any suggestions...

lee
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In real life contrails depend on variables like temperature and moisture content of the air.

That said I manually set my contrails in the aircraft.cfg at about -22.
 
Thanks Willy, for answering. The default temp is -27, but if you wanted to produce the maximum contrails, what temp would you suggest using? I tried -2 and -30, flew in the fall and winter at high altitudes, and didn't seem to get a greater number with either temp. Would welcome your suggestion...

lee
 
The lower the number the more likely you are to see them. The thing is that I'm not too sure how they work on AI aircraft. I know I set up some AI aircraft for them like I would a user flyable aircraft, but don't remember ever seeing contrails for them.

I used -22 as it just seemed like a good semi realistic number to use.
 
"The lower the number the more likely you are to see them."

That's the info I was looking for! So, I'm hoping that choosing -2 as the Maximum Contrail Temperature will produce the most contrails...You might be interested in checking-out Markus Brunner's AI Contrails program (in both AVSIM and Flight Sim libraries), because it adds contrails to all or some aircraft, and sets the maximum contrail temperature (and places all this in each airplane's .cfg file) quickly and easily...Thanks again for you help, Willy...

lee
 
And just big as life, here I was in the Beech 18 flying from Juneau to Yakakut and here comes this Alaska Airlines Convair 440 twin propliner flying by at 15,000 leaving a contrail.........
 
Actually doing a little research into the subject suggests that my setting at -22C is most likely too warm for contrails to form in real life.
 
Willy--Please let know what conditions (max contrail temp, etc.) produce the best trails. Am I correct that you are using Markus Brunner's AI Contrails program? Thanks for your input here...
lee
 
From my reading on it, to get them more realistic, we're probably looking at -25 to -30 with -25 being a tad warm.

I do mine manually in notepad.

If you're wanting more of them, go with a higher temp (-2), if you're wanting more realistic go with a lower temp (-25)

To add them manually with notepad, open your aircraft.cfg file in the aircraft that you're modifying's folder. Look for the [GeneralEngineData] section.

Then add this line:

max_contrail_temperature = -22 //Temperature (deg C) below which contrails may appear

If you want contrails to show more easier go with a higher temp. If you want them more realistic go with a colder temp. Keep in mind that this is mainly for piston engine aircraft, although I believe it will work with jet engines too.
 
Thanks for those details--very helpful...Not to belabor the point, but I think Markus Brunner's AI Contrail program will save you time, since it adds the "Maximum contrail temperature=" line and temp that you tell it to, and does it for some, or all, including AI, aircraft in FS9. He presents you with a small table and you enter the numbers, hit the start button, and the program modifies the planes you select in their .cfg file..

By the way, what OAT are you showing? Thanks, Willy...

lee
 
In that screenshot I think I was around -10 or so. I was a lot lower than the Convair as the Beech isn't pressurized. I've got it set up for contrails, but rarely fly it in cold enough air to create them.
 
From the SDK concerning contrails:
Ambient temperature, in Celsius, in which engine vapor contrails will turn on. The default value is about -39 degrees Celsius for turbine engines. For piston engines, the contrail effect is turned off unless a temperature value is set here.
Click to expand...

And when they say "turbine," that includes t-props too. I just ran a test with the default King Air by setting the temp on the ground to -50°F (~-46°C) and the contrails showed up.
 
I've seen a few propliners with the trails turned on at only -20° in the cfg. I don't know how accurate that is though - maybe the blown pistons produce more water so the trails form easier.
 
You see those old WWII pics of the B-17s leaving contrails, but they were flying a lot higher than most propliner flights. It was more economical fly the old propliners at a lower altitude so it was probably rare for them to leave a contrail.
 
Willy said:
You see those old WWII pics of the B-17s leaving contrails, but they were flying a lot higher than most propliner flights. It was more economical fly the old propliners at a lower altitude so it was probably rare for them to leave a contrail.
Click to expand...

"Rare" is probably the operative word here. Contrails can also be formed in very warm and moist air due to the disturbed air over the engines and wings (a negative pressure behind the wings, I think), the contrails are then formed or are really coming off of the wings and engines themselves instead of the exhausted water vapor from the engines. This type of contrail can even be seen at takeoff and landing which has been mistaken many times as inadvertent chemical spraying.
 
I've been testing various combinations of Max Contrail Temps, OATs, locations, altitudes, seasons, and local conditions, all in the interest of getting a range of contrail results. I've generally been flying from west of KDEN into runway 16, concentrating on fall and winter seasons. To get a high degree of trails, I set the Maximum Contrail Temp on all aircraft at -2C. This included all Ultimate Traffic AI planes, as well as the F100, A330, and B767 craft I was using...


Going into FS9 WX and setting various 0 ft altitude OATs, it was possible to get a wide range of trails around and into KDEN, including some right down to touchdown. Like, creating your own IFR conditions!...Anyway, with the Max Con. Temp at -2C, I got a lot of trails around KDEN with a 0 ft altitude OAT of 50F, which created a 7000 ft. ILS approach altitude OAT of 42F. The Tools\Traffic\Explorer table showed some 100+ planes in the area. Contrails cris-crossed the skies, some over-flying the area and others descending and turning to line up on final. A great sight!...


Thanks Willy and Tom, for your help...


lee
 
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