On a whim, I decided to sketch something like "tag group: airplane types". This is how it came out.
I had hoped to do at least the basics in a more comprehensive way, but realized there was no point. For example, we have a bomber tag but nothing like fighter_plane, as far as I know. The tagging of various aircraft seems to aim at brevity rather than consistency or accuracy: for instance, the Mitsubishi A6M Zero is tagged as a6m_zero, while the Mitsubishi J2M Raiden is tagged as mitsubishi_j2m. And although I happen to know that he_111 probably refers to a Heinkel, I think tags that short are not informative enough.
This is an interesting task, but way too big for myself to handle. I might go on adding a few tags to the list every now and then, but wanted to share my observations just in case somebody else was motivated to take a look at the big picture.
Updated by ghostrigger