I think unpunk hit it right here. I just found this little bit about the QB-17L target drone:
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.