sentences:  By September, after the RAF had lost eight B-17Cs in combat or to accidents, RAF Bomber Command had abandoned daylight bombing, due to their poor performance.The RAF transferred its remaining Fortress I aircraft to RAF Coastal Command for use as very long range patrol aircraft.These were later augmented in August 1942 by 19 Fortress Mk II and 45 Fortress Mk IIA (B-17F and B-17E, respectively).