Many surplus B-17s ended their lives as remotely-controlled drones. During the war, a few war-weary B-17s (mainly Fs) were used as remotely-controlled bombs for attacks against heavily-defended German targets. The designation BQ-7 was applied to these conversions.
The first peacetime use of drone Fortresses was as unmanned aircraft that would fly near or even through mushroom clouds during atomic tests. In May of 1946, sixteen B-17s were withdrawn from stores for conversion into drones with the addition of radio, radar, television, and other equipment. Six other Fortresses were converted as drone controllers. Most of the work was performed by the San Antonio Air Depot at Kelly Field in Texas. The first of these nuclear tests took place in the South Pacific under the code name *Operation Crossroads*. When the USAF was established in 1947, the director aircraft became DB-17Gs, while the drones became QB-17Gs. Further nuclear tests occurred through 1952. The drones were operated primarily by the 3205th Drone Group out of Eglin AFB, Florida.
The designation QB-17L was assigned to surplus B-17Gs that were modified during the postwar years for use as radio-controlled drones for various tests, usually as targets for missiles. They were sometimes equipped with television cameras to provide a target's view of the approaching missile. They were usually painted in red-orange Day-Glo paint with black diagonal stripes for increased visibility. Their serial numbers were prefixed by an O, indicative of their obsolete status. Sources for QB-17 conversions were new B-17s that had went directly to storage upon delivery from the factory, B-17s that had been retired from other duties, and DB-17 drone directors that were now surplus to requirements.
Most of the QB-17Ls met their end as flying targets for the early Nike Ajax surface-to-air missile or for the Hughes Falcon air-to-air missile. Often, the QB-17L would be the subject of intentional near misses to preserve the drone for as many missions as possible. Other QB-17Ls were used for various unmanned but destructive tests such as the ditching tests carried out by NACA in San Francisco Bay. The last DB-17/QB-17 mission was flown on August 6, 1959, with 44-83727 being blown out of the sky by a Falcon missile fired by a F-101 Voodoo. The last QB-17L was destroyed by an IM-99 Bomarc missile in 1960.
The QB-17N was a drone conversion similar to the QB-17L but with a different guidance system and not fitted with television cameras. The optical tracking equipment was installed in detachable wingtip pods equipped with explosive bolts and parachutes for recovery of test data in the event of the loss of the drone.
The designation DB-17P was given to obsolete B-17Gs converted as drone director aircraft. They would often be used to guide the QB-17L and N target drones during the missile tests. When they were worn out or the need was diminished, the DB-17Ps would more often than not be converted to QB drone configuration and would then be expended themselves.
The last active USAF Fortress, a drone director with the serial of 44-83684, arrived at Davis-Monthan AFB for storage in August of 1959. The few DB-17P drone controllers remaining on Air Force rolls in 1960 were transferred to various museums such as the Air Force Museum in Dayton, Ohio and the Planes of Fame Museum in Chino, California.