Hi, is it possible to have a longer and more persistent contrail with the 747 in P3D v4? When I look at the AI traffic, they all have a very long contrail, while the 747 has a short one that quickly disappears. Are there any parameters that can be modified in the aircraft.cfg file? Thanks.

It looks like it's under effects in the aircraft.cfg, so it's based on whatever effect was selected for that action. That's about all I can really tell you since they definitely won't support any changes of this sort.

2 hours ago, jgoggi said:

Hi, is it possible to have a longer and more persistent contrail with the 747 in P3D v4? When I look at the AI traffic, they all have a very long contrail, while the 747 has a short one that quickly disappears. Are there any parameters that can be modified in the aircraft.cfg file? Thanks.

It might be the actual effect file itself that controls this so may not be editable.

1 hour ago, PMDG777 said:

It might be the actual effect file itself that controls this so may not be editable.

You can't change the effect itself, that is correct. You can, however, select a different contrail effect if you have one.

The appearance and persistence of a contrail is mostly dependent on atmospheric conditions including SAT and dewpoint or relative humidity and air movement, and none of that is modeled in our simulator platforms.  So now you are getting down to personal preference for which version of unrealisticness that you prefer (spell check didn't like that one).