This research paper will explore the best aircraft design features for close air support (CAS) for counterinsurgencies (COIN), particularly with respect to the current COIN efforts in Iraq and Afghanistan. There is nostalgia for simple, small, low, slow aircraft for COIN operations. Books and movies such as "Flight of the Intruder"1 and "Saving Private Ryan"2 have popularized the notion of A-1 Skyraiders or P-51 Mustangs swooping in at the last moment, guns blazing and dropping bombs or napalm to save American soldiers just in the nick of time. The A-10 Thunderbolt II is a favorite among ground troops for its tank-killing 30mm Gatling gun and the ability to turn tightly directly above troops. Recent papers have proposed basing a future USAF COIN aircraft on a crop duster3 and the T-6A Texan II.