What happened
The pilot was taxiing on a north-south taxiway in preparation for departure from runway 18R. According to the ATIS, all traffic had been advised to follow instructions provided by flagmen in lieu of direct ATC communications. The pilot reported that he was actively watching the flagman as instructed.
As the aircraft approached an intersection, the flagman signaled the pilot to stop. Following this, the flagman changed the signal to indicate a right turn. The pilot began executing the right turn, noting that the flagman provided no indication of any other aircraft in the path or any instruction to do anything other than complete the turn. While approximately halfway through the maneuver, the aircraft's propeller struck the right wingtip of an RV-6.