Judging by the look of anticipation on Flandre's face I believe that is an A-10 thunderbolt II she's in and she just discovered the GAU-8 Avenger cannon.
Looking at the text next to Flandre's arm, maybe the plane's actually an F-15? (Although not that interesting as plane looks go...How about a P-38 or a JAS-39?)
In order to see fighter planes at the closest range possible, the artist is currently studying hard to join the Japan Air Self-Defense Force. When he participated in a boot camp for new recruits called "a defense course," he was allowed to sit in the cockpit of an F-15J. He was so excited at the time that his mind went blank and all he could say was, "...!! Wow...great... This is amazing!!"