The irony is that I'm telling about open-source software flight simulators[0] and comparing them to YSFlight (which is partially open-source) from point of software.
Where 'meheleventyone' droped IL2:Sturmovik in actual thread just as "alternative game to play" — there is nothing about its software development described here and IL2:Sturmovik is not in whole or even in part open-source app.[1]