[Oilburner]

B17 & B24 top and bottom turrets used sperry K4/K5 computing gun sight (ball turret in B17 & B24 identical - both made by sperry - except B24 could be raised/lowered). I know the K4/K5 were computing sights but I'm not sure of the difference between them and the "ace maker" as found in late spits and P51's.