Enter a keyword, eg comet and the default search will return every instance of comet that occurs in any/all of the 4 fields.
Simple search is not ideal if, say, you are looking for the 'comet' aircraft but not interested in plans from the 'comet' company. The good news is you can add a modifier by using [name, by, from, credit] along with a colon character. Try using these examples as search input:
fokker dv by:musc
fokker d from:ster
fokker e from:ster
The following are tags, here at Outerzone:
IC, Rubber, CO2, Glider, Jetex, Electric, FF, CL, RTP, RC, Trainer, Cabin, Biplane, Triplane, Parasol, Pylon, FloatPlane, Racer, Multi, Scale, Military, Fighter, Bomber, Bomber, Transport.
If you are typing any of these into this search form, then I have failed to explain how this works. You are by all means welcome to try searching like that. But a smarter way, with much better results, would be to click on the above tag links and view the results on the search/by_tag page.