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PMDG-Armen avatar image
PMDG-Armen suggested IcemanFBW commented

Engine Simvar N1 Shutdown Performance - Allow the ability to control Simvar N1 from Idle to Off during Shutdown

Following discussions on Discord, as recommended, I am creating a post here for the record.

Currently, when the engine is at Idle N1 and you request the engine shutdown, the Simvar N1 behaviour from Idle to Off is hard coded and far too fast. There is no way we can manipulate this behaviour.

Since our aircraft (PMDG 737) engine sounds are linked to Simvar N1, during shutdown, all the engine sounds fade away far too quickly. This is particularly noticeable in the outside views.

In SU9 you fixed this same issue for the Off > Idle startup sequence, and we successfully fixed the startup N1 performance for our aircraft. It works great.

Please can you make the same type of fix to the shutdown sequence, so we can manipulate the time it takes for Simvar N1 to be much longer in duration from Idle to Off.

Thank you,


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IcemanFBW commented

The approach our engine model developer took to dealing with incorrect primary engine parameter values during startup/shutdown was to create a set of LVars (for each engine’s N1, N2, etc) which are used by indicating systems, sounds, animations, etc. During engine running they simply mirror the sim’s N1/N2 simvars, but during startup and shutdown (which is determined using a state machine) these LVars are programmed to replicate accurate behavior and ignore incorrect simulator logic. Hope this helps.

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Thank you Iceman for the information. However, how does this work practically? So we trigger an engine state of "Shutdown" - then what configuration file will control the alternate N1 shutdown behaviour during the shutdown phase?

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IcemanFBW avatar image IcemanFBW PMDG-Armen ·
Our function engineShutdownProcedure (triggered when an engine master switch is set to off) will set our alternate n1/n2/egt variables to the right values based on a polynomial regression function here that works as a function of time and value during previous timestep. This could also be done with a lookup table as well. Although it would be nice to have a native solution in engines.cfg for all this
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