made to test the feasibility of converting obsolete bombers to cargo aircraft. B-17E 41-2595 was chosen for the conversion. Based in India, it ferried supplies over the Himalaya to the base for the B-29 Superfortress in Chengdu, China. It proved a difficult plane to maintain, due to lack of spare parts for the Cyclone engines, and was sent back to the United States, where it was based in Bangor, Maine, and flew a cargo route to Scotland until the end of the war. It was sold to a local dealer for scrap, but the airframe survived, and is currently being restored in Illinois. The final one was built under the designation XC-108B, and was used as a tanker to transport fuel from India to Chengdu. F-9 Flying Fortress Several B-17s were converted to long-range photographic reconnaissance aircraft, designated F-9 Flying Fortress. (The F- is for 'foto' and is not be confused with the post-1948 use of F- for 'fighter'.) 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 aircraft. Those surviving in 1948 were initially redesignated RB-17G (R indicating 'reconnaissance'). FB-17: Post-war redesignation of all F-9 photo-reconnaissance aircraft. BQ-7 Aphrodite Late in World War II, at least 25 B-17s were fitted with radio controls as BQ-7 drones for Operation Aphrodite. Loaded with of Torpex high explosive and enough fuel for , they were to be used to attack Nazi U-boat pens, V-1 flying bomb sites, and bomb-resistant fortifications. The BQ-7s would be taken up to by two volunteers before transferring control to another B-17 and bailing out while still over England. The controlling B-17 would follow the BQ-7, aim to at the target and set its controls for a collision course, before itself returning. The normal cockpit lost its roof and the fairing behind it was removed. Because the remote-control hardware was inadequate, Operation Aphrodite was riddled with problems. Between August 1944 and January 1945, 15 BQ-7s were launched against Germany, but none hit their targets,