Is there general advice on how to deal with questions that deal with topics already covered in wikipedia or standard textbooks?
Somehow rehashing information found in those does not seem attractive and does not add original value to the site. It may still be useful for people who looking for pointers or references.
Of course the potential for new great answers and formulations always exists, but many things like "lift" seem pretty well covered - so how best to deal with these situations?
It broadly depends on the resource. We want to avoid 'seeding' the site with general questions that are more than sufficiently answered elsewhere. We definitely want to avoid answers that mostly cite an external resource with a link to learn more.
Wikipedia articles can be very difficult to read for a lay person, especially for more advanced topics. Try to teach when answering these types of questions, bring something more to your answer than what exists out in the wild. Also, make sure the majority of your post is written by you; it's fine to include some references but your answer should be your own creation.
In short, avoid asking questions that are easily found and answered elsewhere just for the sake of getting content into the site. If a new person arrives and asks one of these, nail that question with fantastic answers that show the depth and craft of this community.
I'd try that for a while, and see how it goes. If extremely basic questions that don't really need yet another iteration of answering become a problem, we can address it then.
For expert level questions, I think it's worth the effort to see if you can produce something much better than the typical references that folks would find. That might not always be possible, but it's definitely a good goal to keep in mind.
I basically agree with everything Tim said. More broadly, I think we should allow this kind of question (basically asking for bits and pieces of a ground school course on a Q&A site), and we should probably do it as early in our Beta phases as we can, pouncing on those questions with really good comprehensive answers that we can point everybody who ever asks that question again at.
Good answers to common questions are an awesome way to drive traffic to the site, and the aviation community is small enough (and most students I've met motivated enough) that I don't think it's going to be a problem for us having people use us as a substitute for Wikipedia or their ground school textbook.
If you exclude from this site everything in Wikipedia, this won't be a very comprehensive site. The question of having information on a stackexchange site that is readily available on Google or Wikipedia has been asked on other sites. The general consensus is that you don't want to force users to leave this site and go to Wikipedia or elsewhere to get that information.
