I have used appx 1/32 dia stranded cable inside sheath by Sullivan for tight bend pushrod for flying stabs. I'm not sure it would make a 1/2 inch radius and be easy to move even this thin cable... The tightest I tried has been a 2 inch radius. (that works fine)

You may need to go to a pull-pull on pulleys... You can run Spider Wire fishing line using brass eyelets as pulleys on 2-56 screws for the axles. That's how I'm setting up the scale control system in a 8 ft span glow power model... Steel wire kinks with the scale size pulleys.