For every episode he was on, Radar was a Corporal. The one exception to this was the episode "Welcome to Korea" where Radar was given THIS EXPERIMENTAL RANK in order to get into the Officers' Bar at Kimpo. (edited at 8:11 pm, November 29, 2015 (EST))
Original question: For every episode he was on, Radar was a Corporal. The one except to this was the episode "Welcome to Korea" where Radar was given THIS EXPERIMENTAL RANK in order to get into the Officers' Bar at Kimpo.
Corporal-Captain