Page "Boeing B-17 Flying Fortress variants" Paragraph 63

The first F-9 aircraft were sixteen B-17Fs, with bombing equipment replaced by photographic equipment.

Some of the defensive armament was kept.

An uncertain number more were converted to a similar configuration to the F-9, but differed in minor details of their cameras, and received the designation F-9A.

Some of these, along with more B-17Fs, received further camera alterations and became the F-9B.

The last variant designation was the F-9C, which was given to ten B-17G, converted in a similar fashion to the previous planes.

Those surviving in 1948 were at first redesignated RB-17G ( R indicating ' reconnaissance ').