overlapping tags (e.g. ballooning, lighter-than-air)

Question

There seem to be several sets of overlapping tags - are these useful?

For example

• lighter-than-air

  • ballooning
  • but no airship or zepppelin tags

• unpowered

  • glider
    • hang-glider

so we get questions tagged

unpowered ballooning lighter-than-air.

is this desirable?

Answer 1

are these useful?

Could be, depending on the context. You can always propose a Tag synonym.

so we get questions tagged unpoweredballooninglighter-than-air

is this desirable?

Again, depends on the question, but I would say that having only the most appropriate tag for each question would be ideal.

Answer 2

In your example, the tags have different purposes.

lighter-than-air is a general tag that could be used for questions that would apply to all lighter than air aircraft and not specific to one of the aircraft categories.

The FAA categories would be balloon and airship. It would be appropriate for both balloon and airship to be created, on an as-needed basis. We don't create tags preemptively just because they "might" be used down the road, so the fact that airship doesn't exist simply means that no questions have been asked that are specific to airships yet.

For a question that is about a specific aircraft, both tags could be included in order to help find the question. For instance, if I am searching for all questions about lighter than air aircraft, I would want to see airships too. This is part of the reason that we can provide up to five tags on the same question.

In short, I would say that yes, what you are seeing is desirable.