The B-17F, distinguished by its molded plexiglass nose assembly and wide paddle-blade propellers, could fly farther than earlier versions of the B-17 because of 1,000 gallons of additional fuel stored in self-healing tanks. Under the Boeing-Douglas-Vega nationwide, collaborative production effort, Boeing built 2,300 B-17Fs; Douglas, 600; and Lockheed (Vega), 500.