This question arises in part from my first question (since deleted). I realized while asking this that perhaps it had already been asked at Aviation Stack Exchange. While they do indeed have an "aircraft design" tag, I thought that this site is a better home for my question, as it is less about "why does this aircraft have two propellers" and more about the fundamentals of aircraft design and what aerospace engineers actually do. (As it turns out, the community agreed that it was better suited for Aviation Stack Exchange, and so I removed the post.)
This led me to wonder about our scope, and, as suggested here, we need to definitively determine this. However, I think another pertinent question that goes with this (and is illustrated by my example above). What is on-topic for this site and what should belong on other Stack Exchange sites?
There are two big examples of "grey areas" I can think of.
One example is with regards to Stack Overflow. Software Engineering is certainly something we should consider catering to, but where should we draw the line between what we will answer and what should instead go on Stack Overflow?
The other is with regards to Electrical Engineering Stack Exchange. I don't think the users of that site would be happy if we tried to absorb them. But then should we rout all Electrical Engineering questions to them? Should we define the scope of our site as "including every aspect of engineering except Electrical Engineering?
In short, what is the scope of this site, especially in regards to areas where we might overlap with other Stack Exchange sites?