Well, a two week trial may not be enough to get a casual new player relatively proficient and hooked on the game.
Use an already existing, little used resource so that they can spend more time learning how to fly, basic maneuvers, gunnery.
Gets them on the log in page frequently, where they can see and get curious about all the other action, throw in some advertising in the arena, and once they have had some fun with the basic biplanes, they may decide to step it up and subscribe for some WW2 action.
Sounds like it could be relatively cheap and cost effective.