I am working with ardupilot for a while, but here I can not find any answer for my question:
Is Arduplane a real time program?
I mean that for airplanes, hard real time is needed, so that instructions are executed in their deadlines, and that usually needs a real time operating system "OS"
So what about Arduplane?
I can be coded and run a mission; or you can control in real time.
That means that it doesn't need any operating system?
No, there is no operating system in APM, nor is there much use of having one.