Like an F-15, 767, C-130, or the like?
Or will these just evolve as people ask questions related to them?
Just my opinion but ... while I wouldn't explicitly prohibit them and such fine granularity might be sometimes useful, I think it would create too many tags that would be a nightmare to control and edit in all their tag wikis. So perhaps we should go with the next superclass and use tags by their manufacturer, aircraft class, and so on, like e.g. mcdonnell-douglas, boeing, lockheed, turboprop, transport, fighter,... to add an additional way of classification on top of being able to search by text?
I'm not sure how I feel about manufacturer tags, but broad categories like turboprops like TidalWave suggests also seem logical, and complimentary with model-specific tags (e.g. a question about engine behavior in a Cessna Caravan could be tagged cessna-208 and turboprop, because it fits in both tags and might be of interest to any turboprop pilot).