The projected performance of the new twin-engined Douglas and Fokker observation aircraft was much greater than the Keystone biplanes (the Keystone B-3, B-4, B-5 and B-6) that equipped the Air Corps light bomber squadrons, and both Fokker and Douglas were instructed to complete one of their prototypes as a bomber, with the XO-36 being redesignated the XB-7, with provision to carry up to 1200 pounds of bombs on racks under the fuselage added.