PMDG 747 engine start smoke non aligned

[Guest Andrea]

In addition to engine contrails issue, also the smoke emitted during engines start seems to be not in the correct place.Andrea

[opherben 0]

This happens during non-headwind start. >In addition to engine contrails issue, also the smoke emitted>during engines start seems to be not in the correct place.>>Andrea

[Guest Andrea]

Mmmm... looking at the engines in spot view and without wind I think that the position of the engine start smoke is quite abnormal.Andrea

[opherben 0]

I'm not intimately familiar with these specific engines, but am with aviation turbine powerplants. A feature many powerplants include is a pressure valve, resembling a leaf held by a spring, at the bottom inside of the combustion chamber. It is designed to flush out residual fuel during shut down. This valve closes during engine start after lightoff. If fuel accumulates prior to lightoff/ failed starts, that fuel-air mixture would come in the forms of liquid and smoke out of an engine bottom drain tube. That could contribute to smoke coming out of other than the exhaust. Additionally, engine airflow induces when stationary secondary flow patterns and vortices around it.>Mmmm... looking at the engines in spot view and without wind>I think that the position of the engine start smoke is quite>abnormal.>>Andrea

[Guest Andrea]

Better if we let PMDG beta testers to judge this minor issue.Andrea