Hey gaRCfield...glad to see your interest in IMAC and improving your flying skills which flying IMAC will do for you! Smarks is basically right in that you can start with just about any entry in the basic or beginners rank BUT...as he also said the larger the aircraft the easier they are to fly.

I have several friends including myself involved in the IMAC fun and our basic entry plane when starting was a 25% or 1/4 scale Extra 260 running an OS 160 or the Aeroworks Yak 54 120 QB running an OS 160. These worked great and are an affordable plane to get you use to the eventual move you'll make into the "Gassers" of the 50cc class or larger if you stick to the IMAC blast.

What ever you choose or do, good luck, ask lots of questions, give yourself to the IMAC meets as a "scribe" so you can learn, and above all have lots of fun!