What are some of the largest propellers post-WWII?
From Google, here are some of the largest post WWII propeller diameters:


Antonov AN-22: 20'4" (6.2 m)
Convair B-36: 19' (5.8 m)
Douglas C-133: 18' (5.5 m)
Hughes H-4 "Spruce Goose": 17'2" (5.2 m)
Boeing B-29 and B-50: 16'7" (5.1 m)
Martin Mars: 15'2" (4.6 m)
Vought Corsair: 13'4" (4.1 m)