How force "legacy" mode for FSX imports/conversions

The moderator closed this thread without a solution being provided. Also the thread was moved from “wishlist” to “bug”.

I am converting an FSX model to MSFS20. Apparently I need to force the converted model to run in “legacy” mode. How is this done? Is a parameter added to an existing .cfg file? Is a new .cfg file created? Is this done after legacy importer is run? Can someone provide instructions for how forcing legacy mode is accomplished?


Try the sdk area.

I can not find how it is implemented. I have studied the SDK documentation and don’t find a parameter in a .cfg file to programmatically say this model is to be run “legacy” mode. Google searching turns up nothing. I will create a post on

I haven’t seen ported aircraft that still use Legacy mode come out for years.
Wouldn’t it perhaps be easier to perhaps take a similar aircraft’s flightmodel.cfg and engine.cfg and start from there? Ported flight models were usually not very good and they force the players to switch the settings from Legacy to Modern and back every time they use that plane.

My need to convert an FSX model to an MSFS model no longer exists. A person will be creating a real MSFS version of the plane I am after. So the “legacy” issue is now dead.