What's the best strategy to get users to move from an online forum to a Stack Exchange site? I'm asking this because there's a huge forum about RC model helicopters (www.helifreak.com has 155k members) and the Stack Exchange proposal Radio Controlled (RC) Modeling only has 33 followers.
I don't want to replace the whole forum, I just want a better place for Q&A. The forum is great for endless discussions, posting pictures and videos, etc.
Update: after reading some answers, I think I should rephrase the question to: "How can I get more users to commit a StackExchange beta site?"