Simviation Forum - hmmm, where'd my contrails go?

Jun 11^th, 2009 at 8:19pm

Allen_Z Ex Member

They ought to be there @ 32,000 feet, yes? Grin

This install is about 3 years old, perhaps it's time to do the NASTY, YUK!!! Tongue

I'll use "Uninstalling and Reinstalling FS2004 - Some Tips and Tricks" by David "Opa" Marshall.

That might ease the 'pAiN' Shocked

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Reply #1 - Jun 11^th, 2009 at 8:32pm

Groundbound1 Offline
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Don't do that just yet....

What is the temperature? Set it to 10 degrees F or so, and see if they return.

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Reply #2 - Jun 11^th, 2009 at 9:13pm

Allen_Z Ex Member

Hey groundbound, thanks Cheesy

Same flight, switched to the 727, and you can see the temp on the FE report.

Contrails should be there

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Reply #3 - Jun 11^th, 2009 at 9:31pm

Groundbound1 Offline
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You'd think so. What I meant though, is try setting the temperature to 10 F or less at ground level in the weather control panel. The sim will reduce the temp proportionately the higher you are. If you don't see them after that, we'll need to look for other possibilities.

Process of elimination. Wink

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Reply #4 - Jun 11^th, 2009 at 9:37pm

Allen_Z Ex Member

There is a standard at that altitude, it's always that cold, that's why contrails usually start at around 20-25 thousand feet.

I've never seen the temp vary at alt, regardless of ground temp. But, I guess there's always a first time Grin

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Reply #5 - Jun 11^th, 2009 at 10:49pm

MiltonShupe Offline
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Contrails are controlled by air temperature.

This may vary with your aircraft as it is controlled by this statement in the aircraft.cfg.

max_contrail_temperature = -39.0 //(Stated in Celsius)

Here is what the SDK says about it:

max_contrail_temperature max_contrail_temperature=-39.0 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.

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Reply #6 - Jun 12^th, 2009 at 4:04am

microlight Offline
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Hi Allen,

My advice would always be to use an uninstall/re-install only as an absolute last resort when all else has failed; I'm not a fan of the 'routine' uninstall and reinstall; my two installs on desktop and laptop are the original ones I put on some years back, even with all the mountains of add-ons I've put in since. (But then I'm pretty AR about how I upgrade my sim!)

Appearance/disappearance of FS effects is usually cause-and-effect (if you'll pardon the pun). If contrails have disappeared where they were there previously, and you haven't substantially changed your flying environmental conditions, then it's likely you may have done something that's affected the way they display. First thing to check is that the contrail effects files are still where they should be, in the 'effects' folder. Look for the files fx_contrail_l.fx and fx_contrail_s.fx. These effects are always on by default (governed by altitude and the 'activation' temperature that Milton stated above) so if these files are still there, then the effects should show. This is different to water, wake, touchdown etc. effects that are on/off switched from the aircraft.cfg.

Let us know if the contrail effects files are still there.

Wink

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Reply #7 - Jun 12^th, 2009 at 8:36am

Groundbound1 Offline
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Quote:

There is a standard at that altitude, it's always that cold, that's why contrails usually start at around 20-25 thousand feet.

I've never seen the temp vary at alt, regardless of ground temp. But, I guess there's always a first time Grin

Trust me. I learned it the hard way. Cheesy

I couldn't figure out why I was getting contrails below 25K untill I saw that I had the weather set to winter conditions with sub-zero temps at sea level.

Mr. Shupe is also right. You can add the line (most A/C don't have it be default) he spoke of to the [GeneralEngineData] heading of the aircraft.cfg file. By manipulating that number, you could basically have contrails at any altitude you like.

microlight wrote on Jun 12^th, 2009 at 4:04am:

Hi Allen,

My advice would always be to use an uninstall/re-install only as an absolute last resort when all else has failed; I'm not a fan of the 'routine' uninstall and reinstall; my two installs on desktop and laptop are the original ones I put on some years back, even with all the mountains of add-ons I've put in since. (But then I'm pretty AR about how I upgrade my sim!)

Appearance/disappearance of FS effects is usually cause-and-effect (if you'll pardon the pun). If contrails have disappeared where they were there previously, and you haven't substantially changed your flying environmental conditions, then it's likely you may have done something that's affected the way they display. First thing to check is that the contrail effects files are still where they should be, in the 'effects' folder. Look for the files fx_contrail_l.fx and fx_contrail_s.fx. These effects are always on by default (governed by altitude and the 'activation' temperature that Milton stated above) so if these files are still there, then the effects should show. This is different to water, wake, touchdown etc. effects that are on/off switched from the aircraft.cfg.

Let us know if the contrail effects files are still there.

Wink

Another good point. That was going to be the next thing on my list. Wink

Hope this helps.

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Reply #8 - Jun 12^th, 2009 at 1:19pm

Allen_Z Ex Member

Awrighty then...

Went and checked the two planes that didn't have contrails, and they didn't have that line Mr Shupe gave us.

So I added it, you can see where the trail starts Grin

Thanks for all the help. Guess I'll have to check aircraft.cfg files as I go, but that is easier than a re-install

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Reply #9 - Jun 12^th, 2009 at 1:50pm

Groundbound1 Offline
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Remember, -39C is the default temp at which you should see contrails, so you don't HAVE to add that line to all your A/C. (In other words, if the temp is -39C, you should see a contrail behind your jets even if that line isn't there.)

Well, so long as you got'em back, then all is well again! Wink

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Reply #10 - Jun 13^th, 2009 at 12:02am

MiltonShupe Offline
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That is true Groundbound.

The only reasons you need the statement is if you wish to change the temperature that contrails will become visible, OR if it is a high altitude prop aircraft (turned off by default).

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