Puzzles/quizzes/contests sort of things seem to work in this medium, I have found.

Could be nearly anything. Maybe a close up photo of one small part of a plane, with the caption 'What kind of plane is this?'. Or perhaps some sort of aerodynamics quiz. Whatever.

Point being, take all the answers that get submitted via e-mail or whatever, draw a winner from the correct ones (if there's more than one) and give away some small 'prize' that the club could easily afford to fund...like, maybe a gallon of glow fuel or a couple of glow plugs or whatever.

HTH