Although the prototype was company-owned and never received a military serial (the B-17 designation itself did not appear officially until January 1936, nearly three months after the prototype crashed), the term "XB-17" was retroactively applied to the airframe and has entered the lexicon to describe the first Flying Fortress.
Selv om prototypen var ejet af firmaet og aldrig fik et militært serienummer (selv B-17 designationen blev først officiel i Januar 1936, næsten tre måneder efter prototypens havari), så fik flyet tildelt navnet "XB-17" retroaktivt.